Anionic Copolymerization of 4-Trimethylsilylstyrene: From Kinetics to Gradient and Block Copolymers

Synthesis and real-time 1H NMR kinetic studies on the living anionic copolymerization of 4-trimethylsilylstyrene (4TMSS), an electronically intricate monomer, are reported. Statistical copolymers of 4TMSS with styrene (S) and isoprene (I) with Mn up to 50 kg mol-1 were synthesized and analyzed with respect to dispersity, comonomer composition, and glass-transition temperatures, Tg. Access to well-defined di- and triblock copolymers ensured comprehensive synthetic control. Real-time 1H NMR kinetic measurements unraveled an enthralling gradient microstructure (r4TMSS = 2.76; rS = 0.087 and rI = 3.28; r4TMSS = 0.15) in the copolymers. The sequence distribution provided by a tandem MALDI-MS2 study validated an enhanced reactivity of 4TMSS in comparison to styrene in cyclohexane at room temperature. Furthermore, the kinetics of 4TMSS homopolymerization revealed detailed mechanistic insights. The possibility to tailor Tg and hydrophobicity of the copolymers by varying the 4TMSS content provides a promising approach to design copolymer-based materials for high-end applications, for example, in gas separation membranes.

Automated summary

This study reports the synthesis and real-time 1H NMR kinetic studies on the living anionic copolymerization of 4-trimethylsilylstyrene (4TMSS). The results reveal an intriguing gradient microstructure in the synthesized copolymers, with 4TMSS exhibiting higher reactivity compared to styrene. Furthermore, the properties of the copolymers can be tailored by varying the content of 4TMSS.