Schué Emmanuelle, Rickertsen Dillon R L, Korpusik Angie B, Adili Alafate, Seidel Daniel, Sumerlin Brent S
George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida Gainesville FL 32611 USA
Center for Heterocyclic Compounds, Department of Chemistry, University of Florida Gainesville FL 32611 USA.
Chem Sci. 2023 Oct 2;14(40):11228-11236. doi: 10.1039/d3sc03827k. eCollection 2023 Oct 18.
Synthesis of olefin-styrene copolymers with defined architecture is challenging due to the limitations associated with the inherent reactivity ratios for these monomers in radical or metal-catalyzed polymerizations. Herein, we developed a straightforward approach to alternating styrene-propylene and styrene-ethylene copolymers by combining radical polymerizations and powerful post-polymerization modification reactions. We employed reversible addition-fragmentation chain transfer (RAFT) copolymerization between styrene derivatives and saccharin (meth)acrylamide to generate alternating copolymers. Once polymerized, the amide bond of the saccharin monomers was highly reactive toward hydrolysis, an observation exploited to obtain alternating styrene-acrylic acid/methacrylic acid copolymers. Subsequent mild decarboxylation of the (meth)acrylic acid groups in the presence of a photocatalyst and a hydrogen source under visible light resulted in the styrene--ethylene/propylene copolymers. Alternating copolymers comprised of either propylene or ethylene units alternating with functional styrene derivatives were also prepared, illustrating the compatibility of this approach for functional polymer synthesis. Finally, the thermal properties of the alternating copolymers were compared to those from statistical copolymer analogs to elucidate the effect of microarchitecture and styrene substituents on the glass transition temperature.
由于自由基或金属催化聚合中这些单体固有的反应活性比存在局限性，合成具有特定结构的烯烃 - 苯乙烯共聚物具有挑战性。在此，我们通过结合自由基聚合和强大的后聚合改性反应，开发了一种直接合成交替苯乙烯 - 丙烯和苯乙烯 - 乙烯共聚物的方法。我们采用苯乙烯衍生物与糖精（甲基）丙烯酰胺之间的可逆加成 - 断裂链转移（RAFT）共聚反应来生成交替共聚物。一旦聚合，糖精单体的酰胺键对水解具有高反应活性，利用这一观察结果获得交替苯乙烯 - 丙烯酸/甲基丙烯酸共聚物。随后，在光催化剂和氢源存在下，在可见光下对（甲基）丙烯酸基团进行温和脱羧反应，得到苯乙烯 - 乙烯/丙烯共聚物。还制备了由丙烯或乙烯单元与功能性苯乙烯衍生物交替组成的交替共聚物，说明了这种方法在功能性聚合物合成中的适用性。最后，将交替共聚物的热性能与统计共聚物类似物的热性能进行比较，以阐明微观结构和苯乙烯取代基对玻璃化转变温度的影响。
