Precision AABB-type cyclocopolymers via alternating cyclocopolymerization of disiloxane-tethered divinyl monomers

• Published in: Polymer chemistry Vol. 11; no. 6; pp. 1171 - 1176
• Main Authors: Lu, Jun, Li, Junjiang, Wang, Jinghang, Du, Min, Liu, Hewen
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.02.2020
• Subjects: Addition polymerization; Copolymerization; Free radicals; Ions; Monomers; NMR; Nuclear magnetic resonance; Polydispersity; Polymer chemistry; Polymerization; Zinc chloride
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/C9PY01748H

Attempts to synthesize copolymers with structural sophistication and precision still remain elusive. Here, we report a facile synthesis of a new type of precision cyclocopolymer containing an AABB-type repeating chain sequence via the free radical cyclopolymerization of divinyl monomers bMA and bSt in the presence of ZnCl 2 . RAFT polymerization conditions can afford the AABB-type alternating cyclocopolymers with controlled molecular weight and narrow polydispersity. Kinetic research on the cyclocopolymerization shows that bMA and bSt polymerize in an equimolar ratio during the ZnCl 2 -modulated RAFT copolymerization process. The AABB-type alternating structures are verified by 2D 1 H– 13 C COSY techniques and MALDI-TOF MS. The main-chain CH or CH 2 NMR signals (both 1 H and 13 C NMR) in the cyclocopolymers suggest a chain sequence of a high order, and prove the absence of either the homopolymer structures or the intersecting ABAB-type structure. MALDI-TOF MS shows that the cyclocopolymer has a regularly repeating structure and a uniform repeating unit. In the absence of ZnCl 2 , bMA prefers to homopolymerize. Our work shows that the alternating cyclocopolymerization is a facile route to afford cyclocopolymers with a precision chain sequence and group spacing.