Radical polymerization is the most versatile synthetic method of polymers due to the high reactivity and high functional group compatibility of radical species. While control of macromolecular structure was difficult by this method, recent development in reversible deactivation radical polymerization (RDRP), which is also called as living radical polymerization, has been significantly improve the control of polymer structure over molecular weight and dispersity. Despite its development, however, the polymer structure synthesized under the control has been limited to linear polymers. Here we report the synthesis of highly branched dendritic polymers by RDRP, in particular organotellurium-mediated radical polymerization.  Lu, Y.; Nemoto, T.; Tosaka, M.; Yamago, S. Nat. Commun. 2017, 8, 1836. Lu, Y.; Yamago, S. Angew. Chem. Int. Ed. 2019, 58, 3952.

Reversible deactivation radical polymerization (RDRP) is a useful method to obtain well-defined complex polymeric architectures with a narrow molecular weight distribution (MWD) and chain end functionalities. Through the reversible generation of radicals, RDRP exhibits characteristics of living polymerization. However, due to the unavoidable radical termination reactions, the mixture of living and dead chains is produced during the RDRP process. I will discuss separation and analysis of living chains of polystyrenes synthesized by atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT) polymerization.  Living chains of both polystyrenes prepared by ATRP and RAFT were separated by high performance liquid chromatography (HPLC).  Separated living polystyrene chains were characterized using size exclusion chromatography, nuclear magnetic resonance (NMR), and matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS).  

The alternating copolymer of a conjugated diene and oxygen, polyperoxide, is a main-chain degradable polymer and undergoes radical chain decomposition by mild heating such as 100 °C.  During thermal decomposition, oxygen-centered radicals are formed and thus side reactions such as hydrogen abstraction from the polymer by the oxygen-centered radicals and subsequent coupling, which prevent the decomposition, often take place especially for cross-linked polyperoxides.  Sorbic ester-based polyperoxides are suitable for introduction of various functional groups including cross-linkable groups as an ester group, and they have been applied to various degradable functional materials such as dismantlable (debondable) adhesives.  However, the aforementioned side reactions deteriorate the performance of polyperoxide-based degradable functional materials.  In this study, considering that the fact that polyperoxides undergo reductive decomposition beside thermal decomposition, addition of organic reductants to accelerate the decomposition of polyperoxides were investigated in detail.  The reactivity of polyperoxides to the reductants strongly depended on the regiostructure of polyperoxides regarding to diene monomers.  Sorbic ester-based polyperoxides, which exclusively have a 5,4-structure, were susceptible to reductive decomposition than conjugated hydrocarbon diene-based polyperoxides, which consist of 2,3- and 2,5-structures.  To control the reductive decomposition of sorbic ester based-polyperoxides, thermal latency was provided to the reductant by protection using isocyanates.  In the presence of the thermal latent reductant, the reductive decomposition of sorbic ester-based polyperoxides was well controlled, that is the decomposition was accelerated only at elevated temperatures while maintaining their stability at ambient temperature.  The performance of dismantlable adhesives using sorbic ester-based cross-linked polyperoxides was improved by the addition of the thermal latent reductant.  In addition to a faster decrease in the lap-shear adhesion strength by heating, similar dismantlability was achieved in the wade range of heating temperatures and time.  This is an important requirement for polyperoxides undergoing significant exothermic decomposition bringing about undesired temperature rise.

Reversible addition-fragmentation chain-transfer (RAFT) polymerization is a valuable tool for synthesizing macromolecules with controlled topologies and diverse chemical functionalities. However, the application of RAFT polymerization to additive-manufacturing processes has been prevented due to the slow polymerization rates of typical systems. In this work, we developed a rapid visible light mediated RAFT polymerization process and applied it to a 3D printing system. The photosensitive resins contained a metal-free dye (erythrosin B) in conjunction with a tertiary amine co-catalyst (triethanolamine) and a trithiocarbonate RAFT agent (2-(butylthiocarbonothioylthio) propanoic acid) to afford polymerization without prior deoxygenation. The reaction components are non-toxic, metal free and environmentally friendly (water based photosensitive resin), which tailors these systems toward the fabrication of biomaterials. Following optimization of the resin formulation by varying the ratio of photocatalyst and tertiary amine, a variety of 3D printing conditions were investigated to prepare functional materials using green light (λ_max = 525 nm, I₀ = 0.32 mW/cm²). Furthermore, the mechanical properties of these 3D printed materials were tested under different conditions. Interestingly, the concentration of trithiocarbonate impacted the mechanical properties and the performance of these materials. Remarkably, the use of a photoinduced polymerization process provided facile spatial control over the network structure by varying the light dose to each layer of the 3D printed material; using this strategy, a 4D printing process was demonstrated via 3D printing and subsequent swelling and dehydration induced actuation. Furthermore, the trithiocarbonate species incorporated in the polymer networks were able to be reactivated after the initial 3D printing process, which enabled post functionalization of the printed materials via secondary photopolymerization processes. This RAFT-mediated 3D and 4D printing process should provide access to a range of new functional and stimuli-responsive materials.

A rapid and efficient method to remove thiocarbonylthio end groups from polymers prepared by reversible addition− fragmentation chain transfer (RAFT) is described. The elimination process is obtained in less than 1 min by treating the solution of RAFT-synthesized polymers with 5 equiv of trialkylborane (TAB) in the presence of oxygen under ambient temperature. The versatility of this method was checked on the most relevant families of thiocarbonylthio chain transfer agents (CTA), including dithioesters, trithiocarbonates, dithiocarbamates, and xanthates, carried by the corresponding RAFT-synthesized polymers. UV, NMR, and MALDITOF characterization results all confirm the complete removal of their terminal CTA groups. 

Polyethylene (PE) is and will continue to be the most widely used industrial polymer, benefiting from its product versatility, hydrophobicity, mechanical strength, flexibility, resistance to the harsh environment, easy processability, recyclability, along with the low cost. Covalently linked to PE polar blocks, such as polystyrene, poly(methyl methacrylate), polycaprolactone, polyethylene oxide, and polypeptides offers significant improvements in adhesion and compatibility of PE with other polar polymers and thus broadens its applications. Consequently, the design/synthesis of block copolymers of PE with polar chains is essential to both academia and industry.  In 1997, Shea and co-workers (J. Am. Chem. Soc.1997, 119, 9049-9050), inspired by the well-known in organic chemistry homologation reaction, reported a borane initiated/mediated C1 living polymerization of dimethylsulfoxonium. This C1 polymerization, coined by Shea polyhomologation, has been proven as an efficient tool to synthesize well-defined and perfectly linear hydroxyl-terminated polymethylene, equivalent to polyethylene. The OH-terminated PE can be used either as macroinitiator for ROP of cyclic ethers/esters or living/radical after transformation, to afford well defined PE/polar block copolymers with perfectly linear PE and high molecular weight homogeneity.   Along these lines, the synthesis of PE-based materials (homo/block copolymers, hybrids with silica), as well as their potential applications (e. g. PE reinforcing agents and Aggregation-Induced Emission) will be discussed. A few representative publications from our Group are given below:  ACS Macro Letters 2016, 5, 387-390; Macromolecules 2016, 49, 1590-1596; Chem. Comm. 2017, 53, 1196-1199; Polym. Chem., 2017, 8, 4062-4073; Macromolecules 2018, 51, 3193-3202; Macromolecules 2019, 52, 1955−1964; Angew. Chem. 2019, 58, 6295-6299.

Olefin metathesis has been used for synthesis of advanced polymeric materials, and (Grubbs type) ruthenium-carbene and (Schrock type) molybdenum-, tungsten-alkylidene complexes have been well known as the efficient molecular catalysts. We demonstrated (arylimido)vanadium-alkylidene catalysts containing halogenated phenoxide ligands, V(CHSiMe₃)(NAr)(OC₆X₅)(PMe₃)₂ [Ar = 2,6-Cl₂C₆H₃, X = F, Cl], which showed high catalytic activities for ring-opening metathesis polymerisation (ROMP) of cyclic olefins.  The activity increased at high temperature upon addition of PMe₃, and some polymerisations proceeded in a living manner even at 80 ºC.  The high temperature cis-specific ROMP of NBE could be demonstrated by the fluorinated alkoxide analogue, V(CHSiMe₃)(NAr)[OC(CF₃)₃](PMe₃)₂, and the cis-specific ROMP with chain transfer [synthesis ring-opened poly(NBE)s with defined chain ends] could also be demonstrated in the presence of terminal olefins.  (Arylimido)niobium(V)-alkylidene complex catalysts polymerised disubstituted acetylene as well as NBE, and recent results revealed that the activity in the 2-hexyne (and the other disubstituted acetylenes) was highly affected by the arylimido ligand employed.

Polyolefin is the largest class of thermoplastic polymers, with wide applications and huge annual production (close to 150 million tons in 2015). The introduction of even a small amount of polar functional groups into the polyolefins could excise great control over important material properties. As the most direct and economic strategy, the efficient copolymerization of olefin with polar functionalized monomers represents one of the biggest challenges in this field. This was also recognized as one of the last “holy grails” in this field. In this presentation, I want to discuss that some novel palladium catalysts that could copolymerize ethylene with a variety of polar monomers because of their slow chain walking feature, which have never been realized previously by Brookhart type α-diimine palladium catalysts. The concept of direct synthesis of polar functionalized ultra-high-molecular-weight polyethylene was introduced, which has not been deemed possible previously. These polar functionalized copolymer materials (even at low polar monomer incorporation ratio) showed greatly improved surface properties comparing with the pure polyethylene. I will also present some new strategies to modulate the olefin polymerization and copolymerization processes. Finally, some new catalysts have been designed and studied in copolymerizations of ethylene with a variety of polar comonomers.

Ring-opening metathesis polymerization (ROMP) of thioether-derived oxanorbornene imide (M1) and its copolymerization with various cycloolefin comonomers such as cyclopentene (M2), cyclopent-3-en-1-ol (M3), cycloheptene (M4) and cyclooctene (M5) using Hoveyda-Grubbs 2^nd generation catalyst (RuHG2) has been investigated. Polymerizations were performed at two different temperatures (0 and 25 ᴼC) and the obtained functional poly(olefin)s were characterized by ¹H, ¹³C NMR and IR spectroscopy as well as SEC, DSC and TGA analyses. Additionally, dependence of the polymer composition on the reaction temperature and monomer feed was studied with time-depended ¹H NMR experiments. Copolymerization of M1 with a five-membered cycloolefin monomer M2 showed relatively low ROMP reactivity irrespective of the reaction conditions in comparison to M3, M4 and M5 monomers. In general, the degree of monomer incorporation into poly(olefin)s were determined in the order of M5>M3>M4>M2, and that sheds light on the effect of cycloolefin ring strain energies in the ruthenium-alkylidene initiated ring-opening metathesis polymerization.

Reversible deactivation radical polymerization (RDRP) has undergone impressive developments over the last decades and offers today a high level of control of polymer structures. Transition metals have deeply marked the field of RDRP leading to plethora of macromolecules with predictable molar mass, precise topology, specific composition and functionalities. In particular, the organometallic-mediated radical polymerization (OMRP),^[1,2]  which relies on the temporary deactivation of the growing radical chains by a transition metal complex, notably stands out for its ability to control the polymerization of challenging ‘Less Activated Monomers’ (LAMs) deprived of radical stabilizing group on their double bond. This presentation aims at describing recent advances in the precision design of polymers by OMRP based on cobalt complexes. Special emphasis will be laid on ethylene-based polymers. The organometallic-mediated radical homopolymerization of ethylene and the ethylene/vinyl acetate copolymerization will be discussed. Unique linear and macrocyclic ethylene-containing architectures will be described. ^[3,4]   Finally, we will present the controlled radical (co)polymerization of methylene heterocycles, like vinyl carbonates produced by carboxylative cyclization of propargyl alcohol with carbon dioxide, as well as the thermal and the solution properties of the copolymers resulting therefrom. ^{[5]     [1]} Debuigne, A.; Jerome, C.; Detrembleur, C. Polymer 2017, 115, 285–307. ^[2] Demarteau, J.; Debuigne, A.; Detrembleur, C. Chem. Rev. 2019, 119 (12), 6906-6955. ^[3] Demarteau, J., De Winter, J., Detrembleur, C.,  Debuigne, A. Polym. Chem., 2018,  9(3), 273-278. ^[4] Detrembleur, C. ; Demarteau, J.; Debuigne, A.; Kermagoret, A. Patent WO2019/12409 A1. ^[5] Scholten, P., Demarteau, J., Gennen, S., De Winter, J., Grignard, B., Debuigne, A., Meier, M. A. R., Detrembleur, C. Macromolecules 2018, 51(9), 3379-3393.

Hypervalent iodine(III) compounds with the structure ArIL₂ (Ar = aryl, L = ligand such as (pseudo)halide or carboxylate) can participate in both radical and ionic reactions, which makes them very attractive reagents for the synthesis of functional, responsive, and/or dynamic polymers. Applications of ArIL₂ in polymer science and technology include: i) polymerization initiators, ii) reagents for post-polymerization functionalizations, and iii) structural elements of complex macromolecules. The homolysis of the bonds I-L in ArIL₂ or I-Nu in ArINu₂ (usually formed in situ by ligand exchange with the nucleophilic anions Nu^-) in the presence of vinyl monomers yields linear polymers with L (or Nu) groups at the chain ends. When crosslinkers are added, branched polymers with multiple “peripheral” L (or Nu) functionalities are formed prior to gelation. Branched polymers are also conveniently synthesized by (co)polymerization of carboxylic acid-containing monomers (e.g., (meth)acrylic or vinylbenzoic acid) initiated by (diacetoxyiodo)benzene C₆H₅I(O₂CCH₃)₂ or similar compounds. In this case, the exchange of acetoxy ligands with carboxylate ligands derived from the polymerizable acid leads to the formation of inimer, the polymerization of which affords highly branched macromolecules. Further, the radicals L^· (or Nu^·) produced by homolytic decomposition of ArIL₂ (or ArINu₂) can be employed to functionalize pre-made synthetic or natural polymers, such. The reaction of ArIL₂ with compounds containing multiple carboxylic acid or tetrazole groups is a useful route to dynamic and in some cases – self-healing – network polymers containing the –I(Ar)– structural motif. All mentioned reactions and their utility will be described.

Structural and kinetic investigations of radicals formed in the early stage of polymerizations have been conducted by the ESR technique with various time resolutions. Time-resolved ESR observations of water-soluble (meth)acrylate radicals formed in aqueous phase free-radical polymerization and controlled radical polymerization systems were conducted. These measurements had not been examined previously in spite of their fundamental importance in understanding the initiation procedures in radical polymerizations. Clear and well-resolved TR ESR spectra of sodium (meth)acrylates in water were observed and the structures and molecular dynamics of the radicals formation and reactions were discussed. Acrylic acid (AA) and methacrylic acid (MA) were used as water soluble monomers for TR ESR measurements in the aqueous phase. In the case of MA, a well-resolved spectrum with very good S/N ratio was also observed in the flow system. The TR ESR spectrum of NaMA initiated by LiTMPO in water at 25°C and 90°C are shown in Figure 1 along with schematic diagram of radical polymerization of MA and 3D image of the TR ESR spectrum at 25°C. Temperature dependent change in the line widths were observed. Radical polymerizations of (meth)acrylamides in aqueous phase were also investigated.

A poly(methyl methacrylate) (PMMA) with an unsaturated chain end (PMMA–Y) was transformed to PMMA-iodide (PMMA-I) in situ in the organocatalyzed living radical polymerization of butyl acrylate; the generated PMMA-I worked as a macroinitiator to successfully generate a PMMA-PBA-I block copolymer, where PBA is poly(butyl acrylate). The use of PMMA–Y overcomes the drawback of the direct use of the isolated PMMA–I, i.e., its general lack of long-term stability upon storage, and thus significantly improves the ease of operation, This method is highly suitable to practical use. A quantitative mechanistic study on the transformation of PMMA–Y to PMMA–I was also conducted, which indicated that the unsaturated chain end of PMMA-Y transfers to the chain end of PBA to generate PBA-Y during the course of polymerization. Structural analyses revealed that the PMMA-PBA-I block copolymer synthesized by this method possesses branching points in the PBA domain, possibly due to copolymerization of PBA-Y with the propagating chain end.

Diimine Pd catalysts promote polymerization of ethylene and a-olefins to give the corresponding polymers with unique branched structure, owing to the frequent isomerization during the chain growth. We recently found that the Pd catalysts are effective for controlled isomerization polymerization of alkylcyclopentenes and alkenylcyclohexanes. The produced polymers have 1,3-cyclopentylene and 1,4-cyclohexylene groups, respectively, with regulated stereochemistry. The Pd catalysts are also effective for bulky monomers, such as methylenecyclohexanes, which are hardly utilized as monomer in the polymerization catalyzed by conventional catalysts. Herein, I will report on Pd-catalyzed polymerization and copolymerization of new olefin monomers and thermal properties the produced polymers.

Development of Sustainable Solid Polymer Electrolytes from Biomass Satyannarayana PANCHIREDDY, Christophe DETREMBLEUR, Jean Francois GOHY Bio and soft mater, IMCN, UCLouvain, Belgium Email: satyannarayana.panchireddy@uclouvain.be Abstract:Over the decades, liquid electrolytes have been utilized as key materials to sustain the high demand of energy storage devices for portable electronics and electric vehicles, but they suffer from inadequate electrochemical and thermal stabilities and poor safety.¹To date, solid polymer electrolytes (SPEs) are promising alternatives to replace liquid electrolytes for energy applications because of their inherent safety, affordable cost, excellent electrochemical stability, compatibility, long cycle lives and potential to prevent dendrite growth. Owing to these benefits, based on current trends and challenges face in the forthcoming years, more efforts are needed to develop innovative bio-polymers as viable energy storage systems. Despite fast growing interest in polymer electrolytes (PEs), many challenges remain in both limited fossil fuels and ever-increasing demand for sustainable PEs from biomass.
Herein, we aim to develop a novel bio and CO₂-sourced functionalized thermosetting polymer electrolytes with specific interactions to conduct lithium salts and upgrade their features by reinforced functionalities and plasticizers.^2,3The benefit of our approach in structurally designed multifunctional biopolymer electrolytes is displayed by unique properties over conventional polyurethane-SPE and can be exploited as next generation of energy materials.⁴ References:1         M. R. Busche, T. Drossel, T. Leichtweiss, D. A. Weber, M. Falk, M. Schneider, M.-L. Reich, H. Sommer, P. Adelhelm, J. Janek, Nat. Chem., 2016, 8, 426–434.2         S. Panchireddy, B. Grignard, Thomassin, C. Jerome, C. Detrembleur, Polym. Chem., 2018, 9, 2650–2659.3         S. Panchireddy, B. Grignard, Thomassin, C. Jerome, C. Detrembleur, ACS Sustain. Chem. Eng., 2018, 6, 14936–14944.4         F. Boujioui, F. Zhuge, H. Damerow, M. Wehbi, B. Améduri, J.-F. Gohy, J. Mater. Chem. A, 2018, 6, 8514–8522.

Halogenated monomers and transition metal catalysts have generally been necessary for the controlled synthesis of p-conjugated polymers. The contamination of transition-metal-based and halogen-based byproducts sometimes leads to low performance of organic optoelectronic devices. In this study, we demonstrate a green synthesis of poly(3-alkylthienylene vinylene) (P3ATV) and poly(N-alkyl-2-oxyindolin-3-ylidene thienylene vinylene) (POITV) based on an Horner-Wadsworth-Emmons^[1] and an aldol condensation reactions, respectively. The proposed polymerization method requires neither transition metals nor halogenated compounds. The electrophilicity of the formyl group in the AB-type monomer (1) could be deactivated probably by a resonance effect after the proton abstraction with a proper base, suppressing the self polymerization of the monomer in a step-growth manner. The initiator (2) which contains an active formyl group readily initiated the polymerization to afford P3ATV and POITV, as expected. The number-average molecular weights (M_n = 1,800-10,200) of the polymers could be controlled by the feeding ratio of [1]₀/[2]₀, while maintaining relatively narrow molecular weight distributions (M_w/M_n = 1.20-1.28) in the case of P3ATV. All the results suggested the chain-growth manner of the proposed polymerization method. The characteristics of the organic thin-film transistor (OTFT) device based on P3ATV with a shearing treatment showed a moderate hole mobility (µ_h) of 1.22 x 10^-2 (cm²V^-1s^-1) with a high on/off ratio of 2.0 x 10⁶.

Reconstituted networks of natural extracellular matrices (ECMs), such as collagen or fibrin show a large increase in stiffness upon externally applied stress or deformation. Recently, a new biomimetic hydrogel, based on oligo(ethylene glycol)-grafted polyisocyanopeptide (PIC), was developed in our group. These extremely stiff helical polymers form gels upon warming at concentrations as low as 0.005 %-wt polymer, with materials properties almost identical to those of intermediate filaments and natural ECMs. The application of these materials in cell growth and drug therapeutics revealed the importance of polymer non-linear mechanics.Here we present the synthesis and optomechanical studies of novel PIC- and biopolymer-based hybrid networks. By implementing confocal–rheology (a combination of a customised rheometer and a confocal microscope) as the main tool for the characterization of the network structure and topology, we gain insights on how the 3D architecture and mechanics relate to one another. We elaborate on the confocal-rheometer's fine measurement capabilities and applications, where the influence of mechanical force applied on the material by the rheometer component can be concurrently visualized by the confocal microscope. We believe that this setup provides us with new means of studying natural and synthetic ECM materials, understanding the processes associated with mechanotransduction in biological model systems and as an end goal to understand in more detail the interface of ECM and cells.Approaches on how to control the hybrid hydrogel properties, their detailed micro-rheological studies, and demonstration of the power confocal–rheology in studies of both synthetic and biological systems will be presented.

Emulsion polymerizations, used to produce many commodity materials, require stabilizing agents to prevent phase separation. Incorporation of these stabilizers in the final polymer may have negative effects on product properties, so the design of new stabilizers is being actively pursued. Amphiphilic diblock copolymers are a promising type of emulsion polymerization stabilizerand are the focus of this work (Fig. 1). First, the tolerance of an amphiphilic diblock copolymer stabilizer’s performance to high molecular weight dispersity and homopolymer impurity has been investigated. Polystyrene-b-poly(acrylic acid) block copolymers were studied due to their previously demonstrated efficacy as stabilizers in emulsion polymerization, and their similarity to commercially important polystyrene-r-poly(acrylic acid) stabilizers. Neither greater molecular weight dispersity nor homopolymer impurity wasfound to negatively impact the stabilization performance of these block copolymers, suggesting that the economically unfavorable conditions required to achieve low molecular weight dispersity and homopolymer impurity may be avoided. We then examined novel polystyrene-b-[polystyrene-r-poly(acrylic acid)] block-random copolymers which were shown to stabilize emulsion polymerizations with up to 50 weight percent solids content, exceeding what was possible using the polystyrene-b-poly(acrylic acid) block copolymers. Of even greater significance and scientific value is that the block-random copolymers were also observed to have unusual solution behavior, self-folding rather than self-assembling, to give single chain nanoparticles. Emulsion polymerizations stabilized by these block-random copolymers had a total particle surface area which was directly proportional to the stabilizer concentration and wasunaffected by polymerization kinetics. A novel“seeded-coagulative” emulsion polymerization mechanism has been proposed to explain these results, which were unexplainable by any known emulsion polymerization mechanism.

Generally, polymeric particles prepared in a heterogeneous polymerization system tend to become spherical in shape as the interfacial free energy between particles and medium is minimized. Unlike spherical particles, non-spherical particles usually have some additional properties including rheological, optical, and mechanical properties. Rod-like particles, in particular,arethe most typical non-spherical particles reported in literature: rod-like particles have been applied in drug delivery systems, morphological simulations and other such applications. Such rod-like particles can generally be prepared by mechanically stretching spherical particles embedded in a proper polymeric matrix.In this study, we demonstrate a facile and novel approach to prepare monodisperse polystyrene (PS) particles having a “cylindrical” shape. The proposed synthetic method involved dispersion polymerization of the spherical PS particles stirred in a polyvinylpyrrolidone (PVP) aqueous solution for several hours using a magnetic stirrer at room temperature. In the presence of PVP, the spherical PS particles deformed into cylindrical shapes following stirring; however, the particles did not deform in the absence of PVP. The deformation rate of the particles was affected by the molecular weight of the dissolved PVP. This stirring method is not only highly efficient and provides high yield, but is also applicable to other materials such as polymethyl methacrylate. Moreover, cylindrical polystyrene particles were applied as a particulate stabilizer to prepare a Pickering emulsion of decane (oil)/water. Unlike the spherical particles that are typically used in Pickering emulsions, the cylindrical particles enhanced the emulsion’s stability (up to 1 year). Furthermore, the cylindrical particulate stabilizer enabled a stable emulsion across a wide range of pH. Notably, unique adsorption behavior of the cylindrical particles on an oil droplet was observed, in which the cylindrical particles connected head to head to form a network that acted as a cage around the oil droplet.

Dynamic covalent polymer networks are a class of materials which form a "bridge" between classical thermosets and thermoplastics.¹ These materials are covalently crosslinked, but rather than being permanent, the crosslinks are dynamic and may rearrange upon heating above the so-called vitrimer transition temperature. This leads to greater dimensional stability and creep resistance at lower temperatures and (re)processability of the materials at higher temperatures.  Here, our recent results^2-4 on the development of a new type of semi-crystalline vitrimer based on poly(butylene terephthalate) (PBT) will be presented. Glycerol and other crosslinkers were incorporated into the amorphous phase of PBT via solid-state polymerization using Zn²⁺ as a transesterification catalyst (see Fig. 1). It was found that the crystallization characteristics of PBT were not significantly affected by the incorporation of the crosslinker, leading to similar thermo-mechanical properties below the melting point. Above the melting point, a rubbery plateau was observed (consistent with a crosslinked material). The modulus of this rubbery plateau is almost exclusively governed by the cross-linker (glycerol) content, whereas the ratio of the glycerol to the Zn(II) catalyst content strongly influences both the elastic and stress relaxation properties.^2,4 Recently, we also extended our studies to amorphous polyesters and in the current presentation our work on PBT and other polyester vitrimers will be discussed. Acknowledgement: The work presented here was carried out by the graduate students Yanwu Zhou, Eveline Maassen, Huiyi Zhang and Soumabrata Majumdar in collaboration with Han Goossens (SABIC), Rolf van Benthem and Rint Sijbesma (TU/e). Funding from SABIC, the TU/e Impuls 2 scheme and NWO is gratefully acknowledged. References:¹Denissen, W. et al. Chem. Sci. 2016, 7, 30.²Zhou, Y. et al. Macromolecules 2017, 50, 6742.³Zhou, Y. et al. Macromol. Rapid Commun. 2018, 39, 1800356.⁴Zhou, Y. et al. Polymer Chemistry 2019, 10, 136.

Polymer colloids are used in a large range of industries: paints, industrial coatings, tire manufacturing, pressure sensitive adhesives. Application fields such as medical diagnostics, catalyst support and storage device application are growing research areas. The synthesis route will affect the particle size and/or shape, the molecular weight, the rheological properties and the system stability. Controlling the morphology and understanding the properties necessitate characterization requirements over broad length scales and experimental conditions. Small Angle X-ray Scattering (SAXS) is a powerful characterization method for investigating polymer colloids. SAXS not only provides size information in the range from 1 nm to beyond 250 nm but also provides deeper knowledge such as particle-particle interactions (repulsion, attraction), formation of dimers, trimers… Furthermore, mesoscale phase identification, internal structures of more complex colloidal objects as such as micelles, cuboids or vesicles can be revealed and characterized. The method requires little sample preparation, is non-destructive and, in contrast to microscopy, probes a large volume of the sample enabling a statistically meaningful result. Moreover, the same technique can be applied to surface only in the so-called “grazing incidence geometry”. When combined with Wide Angle X-ray Scattering (WAXS) one can also get information on crystalline structure. Major developments in components and subassemblies achieved the past years, offer capabilities for fast routine measurements, screening process parameters or samples. Most of the time such experiment can be conducted with sample maintained in normal atmospheric conditions, without further preparation, enabling a simplified access to the nanostructure information. Hence, in contrast to microscopy techniques, wet or solvent containing samples can then be easily studied. This presentation will show some illustrations of results obtained with Xenocs instruments. We will address nanoparticle sizing, complex fluid investigation such as shampoo and study of a temperature phase transition on a gel based on DODMAC, among others.

The visible-light induced living/controlled radical copolymerization of acrylates or acrylamides and 1-octene (1-Oct) was mediated by organocobalt complexes at ambient temperature. In the presence of an external photoinitiator such as TPO, the copolymerization of various acrylic monomers and 1-Oct was highly controlled giving copolymers with predetermined molecular weights, narrow polydispersities, and moderate end group fidelities. However, in the absence of TPO, copolymers with hydrogen atom at α end and C=C double bond at ω end could be observed by ¹H NMR and MALDI-TOF-MS spectra, indicating the main side reaction was chain transfer reaction catalyzed by organocobalt complex. Given by the kinetic model of copolymerization, the method to determine the reactivity ratio of acrylic monomer r_M from conversion and molar fraction of 1-Oct (MF(1-Oct)) of corresponding copolymer has been developed with no requirement of complicated fitting methods. The electronic effect of functional group of acrylic monomers was found to influence r_M, as well as MF(1-Oct), dramatically. The r_M was calculated as 13 and MF(1-Oct) was measured as 9% for methyl acrylate. Electron-donating group resulted in increased r_M as 43 along with declined MF(1-Oct) as 3%, while electron-withdrawing group had the opposite effect, leading to lower r_M as 1.1 with higher MF(1-Oct) as 34%. Inspired by the Hammett equation, a linear relationship between the logarithm of reactivity ratio and charge density on propagating radical q was described by the formula of ln(r_M^-1)=(8.5±0.7)+(121±8)q. This study not only explored the methodology to synthesize copolymers of functional monomer and α-olefin, but also found the correlation between charge density on propagating radical and reactivity ratio, which is applicable to all types of functional groups, and could be extended to evaluate other chain copolymerization systems.

The concept of green chemistry has revolutionized the way we think of chemistry. However, there has been little impact on the preparation of functional polymers and high performance polymers. Most of the synthetic routes, developed several decades ago, employ polluting and non renewables chemicals and generate significant wastes.  In this presentation, we will present our efforts to prepare high Tg polymeric materials using environmentally acceptable methods.  We will first present a novel series of ultra-high Tg thermosets that have properties that rival those of polyimides, yet which have been developed using green chemistry concepts in mind. We will also present our attempts to prepare similar materials using only biosourced raw materials.  Finally, we will look at the preparation of novel epoxy resins using biosourced terpenes as starting materials. 

Polysaccharides and polypeptides are getting more and more attentions in recent decades due to their good biocompatibility, huge reserves and green harmlessness. Polytetrahydrofuran (PTHF), an aliphatic saturated polyether elastomer, behaves wet strength, flexibility, hydrolytic stability and biocompatibility. Polyisobutylene (PIB) is a hydrophobic linear saturated elastomer with excellent gas barrier property, biocompatibility, thermo-oxidative stability and hydrolytic stability. A series of graft copolymer based on Poly(γ-benzyl-L-glutamate) (PBLG), Chitosan (CS) and Sodium Alginate (SA) with PTHF or PIB  branches were prepared via “grafting onto” method by combination of living cationic polymerization with nucleophilic substitution of living PTHF⁺ or PIB-PTHF⁺ to amino groups or hydroxyl groups along macromolecular backbone. Well-dispersed silver nanoparticles (Ag-NPs, ~10 nm) were in-situ generated from coinitiator (AgClO₄). The length of branches (M_{n, branches}) could be controlled by setting the molar ratio of monomer (THF, IB) to initiator and monomer conversion. The grafting numbers (G_N) could be mediated by changing the molar ratio of living chains to amino or hydroxyl groups along macromolecular backbone. The graft copolymers exhibited obvious microphase separation phenomenon between macromolecular backbone and side chains due to their thermodynamic incompatibility. The hydrophilicity and crystallization behaviour of graft copolymer was decreased with increasing M_{n, branches} and G_N. Thermal induction and solvent induction could influence the hydrophobicity and crystallization behaviour due to the self-assembly of soft branches onto the film surface of graft copolymer. The graft copolymers could be manufactured as drug carrier microspheres with obvious pH-dependent drug release behaviour and behave enhanced anti-protein adsorption performance against bovine serum albumin. The graft copolymers-based composites with Ag-NPs (0.3~5.7wt%) impart the materials with excellent antibacterial properties against S. aureus and E. coli. Moreover, the nanocomposites behave non-cytotoxicity against HEK 293 cell lines and HeLa cell lines.

The utilization of elemental sulfur is a global concern considering its large surplus and the safety/environmental problems caused during its storage. Sulfur is an idea source for the preparation of sulfur-containing polymers, however, it is quite challenging to transform sulfur because of its poor solubility and toxicity to metal catalysts. Our strategy is to utilize the unique chemical reactivity of elemental sulfur to develop multicomponent polymerizations (MCPs) to realize sulfur conversion. In this talk, a series of elemental sulfur-based MCPs will be introduced. For example, a catalyst-free MCP of elemental sulfur, alkynes, and aliphatic amines can proceed smoothly at 100 ^oC in a catalyst-free manner with high atom utilization to afford polythioamides with well-defined structures, high molecular weights (M_ws), and high yields. Moreover, more reactive isocyanide monomers were adopted to realize sulfur conversion at room temperature and a catalyst-free MCP of isocyanide, sulfur, and amine was developed at room temperature. The polymerization enjoys mild condition in air and general monomer applicability for primary/secondary amines and aliphatic/aromatic isocyanides, generating 16 polythioureas with well-defined structures, good solubility, high yields (up to 95%), and large M_ws (up to 242 500 g/mol). The fluorescent polythiourea products can be utilized to detect mercury pollution with high sensitivity and high selectivity, clean Hg²⁺ from aqueous solution with 99.99% removal efficiency to achieve drinking water standard with a single treatment, and monitor the real-time Hg²⁺ removal process by fluorescence. These sulfur-based MCPs are economic, efficient, and convenient tools for the direct conversion from sulfur to profitable functional polymers such as polythioamides, polythioureas, and polythiophenes, which might provide solutions to problems regarding to sulfur waste utilization, mercury pollutions, and gold enrichment.

The bio-renewable monomers to produced elastomers have been the subject of intense research during the last few years. For instance, terpenes are natural unsaturated hydrocarbons constituents of resin plants and essential. One of the main molecular features of terpenes is their carbon skeletons build for isoprene units, which contain an electronic environment similar to isoprene, and some of them for instance ocimene, myrcene and farnesene have the potential to be polymerized by the same mechanisms as the isoprene, such as coordination polymerizations. This route is the only one that allows highly stereospecific polymers with a satisfactory molecular weight control, as well as in the molecular weight distribution. In an effort to contribute in this fieldin this work, the coordination polymerization of terpenes was examined using differentZiegler-Natta catalytic systems based on neodymium, affording three different bio-based engineering elastomers (BEEs) such as polyocimene (POc), polymyrcene (PMy) and polyfarnesene (PFa). The obtained BEEs were characterized by size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) in order to determine their molecular weights, microstructures and thermal behaviors.The neodymium versatate (NdV₃) and neodymium isopropoxide Nd(Oi-Pr)₃as catalytic precursors for coordination polymerization of terpenes and activated with several halogen source and aluminum trialkyl, compounds exhibited high polymer yields,high polymer molecular weights and broad molecular weight distributions. The neodymium catalytic systems produce polyterpenes withhigh cis-1,4 content (>90%). The three kinds of polyterpenes type BEEs can be considered as amorphous and rubbery nature according to the values of Tg (POc: Tg =  -34 to -26 ºC, PMy: Tg ≈ -64 and PFa = -72 ºC).

There is an increasing need for simple synthetic procedures that allow catalyst-free polymer synthesis and modification under stoichiometric conditions at mild temperatures, without the need for tedious and costly purification steps. In this regard, Du Prez et al. have recently shed a new light on the use of γ-thiolactones in the field of polymer chemistry with the so-called amine-thiol-ene conjugation strategy. We recently reported the synthesis of a library of substituted γ-thiolactones using a versatile and robust synthetic procedure based on xanthate chemistry, that will be introduced.In order to explore the potential of thiolactone chemistry for the field of reversible-deactivation radical polymerization (RDRP), we have developed a toolbox of γ-thiolactone-based RDRP agents including xanthates, bromides, and an alkoxyamine. These RDRP agents were used for the polymerization of a broad range of monomers using appropriate RDRP techniques such as RAFT/MADIX, ATRP, and NMP. Well-defined thiolactone-terminated polymers were obtained and characterized for different degrees of polymerizations. The great reactivity of the thiolactone end-group for postpolymerization modification was proven using primary amines such as benzylamine or propargylamine, which ring-opened the thiolactone with subsequent thiol−thiolsulfonate reaction to scavenge the generated thiol. The original S-naphthalene ethanethiosulfonate was used to give fluorescence properties to the polymers.Our last generation of γ-thiolactones and their use in step-growth polymerizations will also be presented.

Polymer properties are determined by compositional and topological features. Ideally one needs precision design at the molecular level accounting for non-idealities due to side reactions or diffusional limitations. In this contribution it is illustrated that model-based design is a powerful tool to support the field of macromolecular engineering. Starting from a generic multi-scale modeling framework examples are included focusing on the connectivity of monomer sequences and polymer segments on the level of the individual (macro)molecule.

Chain transfer techniques are useful tools for functionalization of polymers. Thiol agents are instantly one of most popular chain transfer agents for radical polymerization and used for control of molecular weight and functionalization of alpha end group of a polymer. Catalytic chain transfer (CCT) polymerization and addition-fragmentation chain transfer (AFCT) polymerization are also useful for production of polymers functionalized by polymer architecture or an end group with functional group. CCT polymerization technique with a Co complex is a useful tool for production of methacrylic macromonomer (MM) which has a double bond at the end of polymer chain. Mitsubishi Chemical Corporation can produce methacrylic MM on an industrial scale and has researched on various copolymers derived from methacrylic MM and their applications. The copolymers can have various polymer architectures such as block copolymer or graft copolymer via AFCT. In the case of copolymerization of methacrylic MM and an acrylate, block copolymer with unsaturated end firstly generated via AFCT and copolymerized with an acrylate. As a result, a graft copolymer occurred. However the copolymerization with methacrylic MM had an issue that it was difficult to achieve both high consumption of methacrylic MM and suppression of homopolymer of an acrylate, we achieved both of them by the optimization of copolymerization condition. As a result, the obtained copolymer showed the 5% weight loss temperature of >320°C, which indicated a good thermal stability. In addition, we recently succeeded synthesis of a block copolymer by reversible complexation mediated polymerization or reversible iodine transfer polymerization of a methacrylic MM and an acrylate via AFCT. Methacrylic MM was converted to polymethacrylate radical via AFCT of PBA radical to methacrylic MM. The generated polymethacrylate radical subsequently added BA monomers to yield a PMMA–PBA block copolymer in one pot.

UV-curing process based on photo-induced radical polymerization has been widely utilized for inks, paints, adhesives, and photo-resist materials. Especially, facile tuning of UV intensity, wavelength, irradiation area etc, has enabled their industrial applications, however the precise control of photo-polymerization is not trivial due to their too rapid reaction time (within seconds). Delicate balance of reaction kinetics, deformation (shrinkage), and phase-separation associated to polymer network formation needs to be considered.Controlled (or living) radical polymerization techniques such as atom-transfer controlled radical polymerization (ATRP) have greatly impacted the advancement of polymer synthesis in the last 20 years, allowing well-defined polymers with precise molecular weight distribution and segment blocks. Recently, further temporal (on/off) control of polymerization via external stimuli such as photo-excitation has proposed and gained increased attention. Here we focus on organo-catalyzed iodine-transfer controlled radical polymerization, which allows reversible photo-activation of polymeric dormant without metal catalysts. In this study, we synthesized polymeric dormant with C-I endgroup and utilized to the UV-curing process to challenge the precise control of photo-polymerization and phase-segregation simultaneously. Telechelic polymeric dormant was also successfully prepared by single unit monomer insertion reaction. The obtained coatings were optically clear, but internal nanostructure of the coating exhibited unprecedented, bicontinuous nanodomains with gradient size distribution. The domain size was tunable with UV intensity, crosslinker content, and other processing aids. Post-functionalization of the evolved nanostructures will be also discussed. 

Quaternary ammonium iodide (R₄N⁺I^–) catalysts immobilized on silica particles, Fe₃O₄ magnetic particles, and organic resin particles were developed for organocatalyzed living radical polymerization. A random copolymer containing the catalytic R₄N⁺I^– moieties and the anchoring triethoxysilyl moieties was synthesized and immobilized onto silica and Fe₃O₄ particles to give the silica particle- and Fe₃O₄ particle-supported R₄N⁺I^– catalysts. A tertiary-amine-containing polymer resin particle was quaternized to give the resin particle-supported R₄N⁺I^–catalyst. The supported catalysts were successfully used to synthesize homopolymers and block copolymers of methyl methacrylate, functional methacrylates, styrene, and acrylonitrile with low dispersities. The supported catalysts were able to be separated (recovered) from the polymerization solutions in simple manners, i.e., with centrifugation or with a magnet. The catalysts were reused in five polymerization cycles without a noticeable decrease in the catalytic efficiency. The facile preparation of the supported catalysts, the broad monomer scope, and the feasibility of the catalyst reuse and recycle are attractive features.  

Synthetic polymers, featuring both excellent processibility and durability, are among the most important materials widely used in our modern life. However, widespread single-use of non-degradable plastics also brings great problems concerning sustainability. Currently, a major challenge in polymer science is to develop strong, processable, and recyclable polymers to replace the existing plastics. To this end, polyesters that display similar performance as existing polymers but can be thermally or chemically recycled into their building block chemicals via depolymerization have attracted increasing interests in recent years. In this work, three benzo-thia-caprolactones (BOTOs) were synthesized by a modular approach, and their polymerization and depolymerization behaviors were investigated. Ring-opening polymerization of BOTOs successfully gave corresponding P(BOTO)s with high molecular weights. These P(BOTO)s were all semi-crystalline materials while P(BOTO-I) showed the highest Tm of 146^oC and the highest T_g of 59^oC. Depolymerization of these P(BOTO)s in solution gave BOTOs and cyclic oligomers, whereas bulk thermal depolymerization of (PBOTO)s allowed for efficient recovery of pure BOTOs.

Poly(amino acid) is an important biomimetic materials due to their unique biocompatibility, and potential application in gene transfection, drug delivery, and prevention of viral infections. For example, poly(ε-lysine) (ε-PL) is an uncommon cationic homopolymer produced by the fermentation process. Due to its significant antimicrobial activity and nontoxicity to humans, ε-PL is now industrially produced as an additive, e.g. for food and cosmetics. However, due to the lack of appropriate polymerization method, ε-PL is now produced mainly by a fermentation process. Here, we report a new chemical strategy, based on ring-opening polymerization (ROP) of lactam, to obtain ε-PL with diverse molecular weight from renewable lysine monomer. Meanwhile, typical ring-opening catalysts are subject to unavoidable racemization of most amino acid monomers, which hampers the synthesis of highly isotactic crystalline polymers. We also describe an effective bifunctional single-molecule organocatalysis for selective ring-opening polymerization of amino acid-derived monomers without epimerization.

Although polymerization of traditional vinyl monomers proceeds by chain addition with the creation of carbon-carbon bonds, some cyclic monomers bearing vinyl or exomethylene groups can be polymerized by a radical pathway through a ring-opening mechanism. Radical ring-opening polymerization (rROP) thus combines the advantages of both ring-opening polymerization and radical polymerization, that is the production of polymers having heteroatom and/or functional groups in the main chain together with the robustness, the ease of use and the mild polymerization conditions of a radical process. Cyclic ketene acetals (CKA) were reported by Bailey and coworkers in the 80s as suitable monomers for rROP. This monomer family was then extensively studied as a way to produce similar polymers to classic aliphatic polyesters, but through a radical pathway. This technique has been recently rejuvenated by the possibility to copolymerize CKA with classic vinyl monomers, leading to cleavable functions into the copolymer backbone. This led to a broad range of novel (bio)degradable materials suitable for a large scope of applications.Recently, thionolactones compounds were also proposed as a new efficient monomers for the radical ring-opening polymerization.In this presentation, I will highlight the lastest results we obtain in our group about the synthesis of (bio)degradable materials by (co)polymerization of commun vinyl monomers and cyclic monomers able to undergo a ring-opening process.

Polymer networks are essential for the production of next-generation materials. The design of such large-scale chemical entities is a demanding task with as bottleneck the limited understanding of the effect of reaction conditions on the final macroscopic properties of polymer gels and their product performance due to lack of proper characterization tools for such complex topologies. In this work, for the first time, a combined kinetic Monte Carlo and molecular dynamics tool is presented accounting for kinetics, thermodynamics and topological features of the formed polymeric networks. This in silico based characterization tool allows a complete characterization of the evolution of the structure of individual macromolecules/segments during network formation. This not only enables the fundamental construction of structure-property relationships that truly connect the molecular and material scale but also the design of synthesis protocols toward maximal material performance. Experimental validation is carried out for network polymers synthesized by both organic and inorganic chemistries. Dedicated experimental analysis has been applied to tune the model parameters and a good agreement between experimental and modeled data is obtained. Next, it is demonstrated that the model-predicted topological features of the polymeric network structures such as pore size distributions and network heterogeneity allow predicition of elementary material properties such as gelation point, swelling degree and tensile strength.

       Organic nanopolymers ingeniously combines carbon nanotube-like properties with polymer-featured solution processing and hierarchical construction, which are distinguished from covalent organic frameworks and graphene-typed derivatives. Versus nanoscale main-chains constructed by dendrimers, fullerenes, porphyrins and graphene segments, fluorene-derived polygrids represent excellent wide-bandgap semiconductors but suffer from difficult stereocontrol during the synthetic process that influences the chain configuration, aggregation behaviors, crystallinity as well as optoelectronic properties. Herein, we report a diastereoselective polygridization from the superelectrophilic A₂B₂-typed monomers DCs with double crescent shapes, generating the organic nanopolymers composed of Drawing Hands Gridarenes (DHGs) blocks. Compared with the gridization model reactions that reach 60~70% diastereomeric excess (de) of meso-selectivity, the optimized polygridization further improves to 90% de along with 80~85% yields in 30 seconds! We also find that the nitrogen atoms of the superelectrophilic species and the oxygen of the side-chains play a crucial role in the stereoselectivity. The molecular weight dependence on the reaction time and the monomeric concentration reveals that such polycondensation observe the step-growth polymerization but is not consistent with the traditional kinetics of the second-order rate. It is noted that the molecular weights (characterized by gel permeation chromatography) of these ring-chain-alternating nanopolymers have been carefully recalibrated by a series of oligomers, indicating the 8~24 nm in chain length as well as a Mark-Houwink exponent of 1.651 that suggests the high rigidity. The stereoselectivity-determining step was deduced from the centre-symmetric molecular stacking of two superelectrophilic intermediates with synergistic hydrogen bonding and coulombic repulsions.

Crystalline-state polymerizations have been attracted considerable interest, because they provide the controlled polymers with different selectivity from those in solution-state polymerizations.  Controlled monomer arrangement and restriction of movement in the crystalline state should cause unique selectivity in polymerization.  Therefore, supramolecular control of monomer arrangement is still challenging for designing polymer structure as a kind of precious polymerizations.  In this presentation, a new type of crystalline polymerization named as “crystal cross-linking” will be presented. Our new idea for crystalline-state polymerization is based on the polymerization between the host monomers immobilized in the open frameworks and the guest monomers mobile in the nanopores.  The guest monomers polymerize or crosslink the host monomers by step-wise chemical reactions to grow or crosslink the polymer chain.  Two examples by using polymerizable metal organic frameworks (MOF) as the host frameworks will be presented; azide-tagged MOF by multi-alkyne cross-linkers via click reaction and cyclodextrin MOF by diglycidyl ethers.  When multi-functional monomers are employed, the crystal cross-linking provides various polyhedral polymer gels with the controlled size and shapes by changing the monomers and metal ions for formation of MOF.  Furthermore, we demonstrate the control of degree of polymerization in the linear polymers by the crystal cross-linking between the bifunctional monomers and immobilized monomers in MOF. The polymerization behaviors differ completely from those in the solution state. The probabilistic process of the chemical reaction between the nearest monomers plays a crucial role for the termination of the polymerization and the controlled degree of polymerization, which is supported by the Monte Carlo simulation. Therefore, it should be a new method for fabrication of well-defined soft polyhedral architectures and the controlled polymerization in A-A/B-B type stepwise polymerization.