Acrylic ABA triblock copolymer bearing pendant reactive bicycloalkenyl functionality via ATRP and tuning its properties using thiol-ene chemistry

“One-pot” aminolysis/thia-Michael addition preparation of well-defined amphiphilic PVDF-b-PEG-b-PVDF triblock copolymers: self-assembly behaviour in mixed solvents

Novel amphiphilic PVDF-based triblock copolymer (PVDF₅₀-b-PEG₁₃₆-b-PVDF₅₀) is synthesized using RAFT polymerization and a one-pot thia-Michael addition. Self-assembly of this ABA copolymer resulted in formation of original crystalline structures.

Ethylene Glycol Dicyclopentenyl (Meth)Acrylate Homo and Block Copolymers via Nitroxide Mediated Polymerization

Nitroxide-mediated polymerization (NMP), (homo and block copolymerization with styrene (S) and butyl methacrylate/S) of ethylene glycol dicyclopentenyl ether (meth)acrylates (EGDEA and EGDEMA) was studied using BlocBuilder alkoxyamines. EGDEA homopolymerization was not well-controlled, independent of temperature (90-120 °C), or additional free nitroxide (0-10 mol%) used. Number average molecular weights (Mn) achieved for poly(EGDEA) were 4.0-9.5 kg mol-1 and were accompanied by high dispersity (Ð = Mw/Mn = 1.62-2.09). Re-initiation and chain extension of the poly(EGDEA) chains with styrene (S) indicated some block copolymer formation, but a high fraction of chains were terminated irreversibly. EGDEA-stat-S statistical copolymerizations with a low mol fraction S in initial feed, fS,0 = 0.05, were slightly better controlled compared to poly(EGDEA) homopolymerizations (Ð was reduced to 1.44 compared to 1.62 at similar conditions). EGDEMA, in contrast, was successfully polymerized using a small fraction of S (fS,0 ~ 10 mol%) to high conversion (72%) to form well-defined EGDEMA-rich random copolymer (molar composition = FEGDEMA = 0.87) of Mn = 14.3 kg mol-1 and Ð = 1.38. EGDEMA-rich compositions were also polymerized with the unimolecular succinimidyl ester form of BlocBuilder initiator, NHS-BlocBuilder with similar results, although Ðs were higher ~1.6. Chain extensions resulted in monomodal shifts to higher molecular weights, indicating good chain end fidelity.

TUNING PROPERTIES AND MORPHOLOGY IN HIGH VINYL CONTENT SBS BLOCK COPOLYMER, A THERMOPLASTIC ELASTOMER VIA THIOL-ENE MODIFICATION

Thiol-ene modification of high vinyl content thermoplastic elastomeric styrene butadiene styrene (SBS) block copolymer (BCP) was carried out using different thiolating agents in toluene at 70 °C. 1H NMR analysis confirmed the participation of vinyl double bond in the thiol-ene modification reaction of SBS. Surface morphology of the block copolymers evaluated by atomic force microscopy analysis showed higher roughness after the thiol-ene reaction. The thiol-modified SBS block copolymer showed better adhesion strength and oil resistance properties than the pristine SBS.

INSIGHTS INTO THE PREPARATION OF VINYL POLYBUTADIENE VIA COBALT-BASED CATALYST: TUNING ITS PROPERTIES BY THIOL-ENE MODIFICATION OF VINYL GROUP

Elastomers with pendant alkenyl functionality can be easily modified using different types of postpolymerization reactions that lead to improved properties. This investigation reports the preparation of polybutadiene (PB) with control vinyl content by Co-based catalyst followed by modification of vinyl functionality via thiol-ene reaction. In this case, the polymerization of butadiene was carried out in cyclohexane using cobalt octanoate (Co[oct]2) in combination with diethylaluminium chloride (DEAC) and triethylaluminium (TEAL) as cocatalysts. The effects of different parameters, such as the concentration of catalyst and cocatalyst, monomer concentration, and reaction temperature on polymerization of butadiene (BD), were evaluated and optimized to obtain the desired vinyl content in the polymer. The microstructures in PB were investigated by 1H nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy analyses. Molecular weights and dispersity (Ð) of the polymers were determined by gel permeation chromatography analysis. The viscosity average molecular weight was calculated from the intrinsic viscosity [η] using the Mark-Houwink equation. Synthesized vinyl-PB was modified by the thiol-ene reaction using benzyl mercaptan as thiolating agent and 2,2′-azobis(isobutyronitrile) as an initiator. Thiol-ene modification was confirmed by 1H NMR analysis. Surface characteristics of thiol-modified PB were characterized by goniometer. Thiol-ene–modified PB showed greatly improved adhesive strength in metal–rubber bonding, as determined by lap shear test.