C5 and C6 Polymerizations by Anion Migrated Ring-Opening of 1-Cyclopropylvinylbenzene and 1-Cyclobutylvinylbenzene

Abstract

As an emerging method, anion migrated ringopening polymerization (AMROP) can effectively regulate the carbon skeletons of polymer backbones with specific vinyl monomers. As reported here, polymers with C5 and C6 skeletons were synthesized by AMROP of 1-cyclopropylvinylbenzene (CPVB) and 1-cyclobutylvinylbenzene (CBVB). Moreover, C4 polymerization of 1-phenyl-1,3-butadiene (1-PB) was also conducted (in a general anionic polymerization process) for comparison with C5 and C6 polymerizations. Among the three base polymers prepared with the C4, C5, and C6 polymerizations, PCBVB exhibited the most flexible carbon skeleton structure and the lowest glass transition temperature (T g = −18.8 °C). Then, the resultant base polymers with different carbon skeletons were hydrogenated and cyclized. The hydrogenation of P(1-PB), PCPVB, and PCBVB resulted in the formation of products with unique alternating styrene/ethylene (alt-SE), periodic styrene/ethylene/methylene (pd-SEM), and periodic styrene/ethylene/ethylene (pd-SEE) structures. Moreover, pd-SEM and pd-SEE can be considered as sequence-defined template polymers, and these structures cannot be synthesized through general copolymerization of styrene and ethylene. Owing to the specific carbon skeletons exhibited in alt-SE, pd-SEM, and pd-SEE, their T g values showed significant differences (24.6, 10.9, and −6.0 °C, respectively). Additionally, the specific carbon skeletons of the base polymers resulted in the formation of cyclized polymers with different annular substituents. Moreover, diverse annular substitutes endowed the cyclized polymers with prominent thermal resistance and luminescence properties. Through the above investigations, it is clearly demonstrated that small changes in carbon skeleton structure can remarkably affect the polymer properties. Moreover, AMROP provides a new strategy to design novel polymers with C5 and C6 skeleton structures.

Anion Migrated Ring Opening and Rearrangement in Anionic Polymerization Induced C7 and C8 Polymerizations

“…Moreover, the polymers CPBB (PCPBB, Run 13-1, T g = 78.2 °C) and CBBB (PCBBB, Run 14-1, T g = 84.8 °C) with a C4 skeleton structure contain an isolated double bond and substituents with steric hindrance in the chain; thus, the T g values were much higher than those of poly(1-phenyl-1,3-butadiene) (P(1-PB), T g = 30.5 °C). 50 Moreover, because the steric hindrance of the cyclobutyl group is larger than that of the cyclopropyl group, the T g value of PCBBB generated in Run 14-1 was higher than that of PCPBB produced in Run 13-1. In terms of the C7 polymer obtained from Run 5, although the polymer has a long carbon skeleton structure, its T g value (T g = 72.3 °C) is analogous to PCPBB with a C4 skeleton structure.…”

“…However, the movement of the polymer chain may be limited when one of the hydrogen atoms in the isolated double bond is replaced by a phenyl ring (poly­(2-phenyl-1,3-butadiene), P­(2-PB)), and the T g value ( T g = 31.0 °C) increases substantially . With the extension of the carbon skeleton structure, the chain flexibility of the CPVB polymer (C5 skeleton structure, T g = −4.5 °C) and CBVB polymer (C6 skeleton structure, T g = −18.8 °C) improved compared with that of P­(2-PB). Moreover, the polymers CPBB (PCPBB, Run 13-1, T g = 78.2 °C) and CBBB (PCBBB, Run 14-1, T g = 84.8 °C) with a C4 skeleton structure contain an isolated double bond and substituents with steric hindrance in the chain; thus, the T g values were much higher than those of poly­(1-phenyl-1,3-butadiene) (P­(1-PB), T g = 30.5 °C) .…”

“…46,48 Additionally, based on our previous work, 1cyclopropylvinylbenzene (CPVB) and 1-cyclobutylvinylben-zene (CBVB), bearing cyclopropyl and cyclobutyl groups, respectively, undergo combination nucleophilic addition and ring-opening reactions. 49,50 During each propagation step, the carbanion is generated during the nucleophilic addition between living species and the double bond. Then, the carbanion migrates to the opened cyclopropyl or cyclobutyl group, and the generated polymers exhibit unique C5 and C6 skeleton structures.…”

“…The high ring strain of cyclopropyl and cyclobutyl groups is the key factor in the versatility of the structure of molecules. − Further investigations of whether the available olefin monomers with cyclopropyl or cyclobutyl groups are useful to prepare unprecedented polymer structures through a new polymerization mechanism are worthwhile. To date, cyclopropenes and their derivatives have been well-employed not only in ROMP (C3 polymerization) − but also in living/controlled vinyl addition polymerization (C2 polymerization). , Additionally, based on our previous work, 1-cyclopropylvinylbenzene (CPVB) and 1-cyclobutylvinylbenzene (CBVB), bearing cyclopropyl and cyclobutyl groups, respectively, undergo combination nucleophilic addition and ring-opening reactions. , During each propagation step, the carbanion is generated during the nucleophilic addition between living species and the double bond. Then, the carbanion migrates to the opened cyclopropyl or cyclobutyl group, and the generated polymers exhibit unique C5 and C6 skeleton structures.…”

Alternating Copolymerization Realized with Alternating Transformation of Anion-Migrated Ring-Opening Polymerization and Anionic Polymerization Mechanisms

“…Thus, exploring novel monomer pairs that can undergo nonhomopolymerization is a pioneering and innovative focus in the development of strictly alternating copolymerization in polymer chemistry. More recently, specific features in the anionic polymerization (AP) of 1-cyclopropylvinylbenzene (CPVB) and 1-cyclobutylvinylbenzene (CBVB) have been deeply investigated by our group. , The novel mechanism of this reaction has been confirmed as anion-migrated ring-opening polymerization (AMROP), which is also an emerging and original method of regulating the chain structures of olefin polymers. In particular, CPVB/CBVB cannot homopolymerize at ordinary temperatures ( k CC = 0 at 20 °C) but can homopolymerize at high temperatures ( k CC = 0.016 (L/mol) 1/2 ·min –1 at 60 °C).…”