Selective Frustrated/Nonfrustrated Anion-Migrated Ring-Opening Polymerization of 1-Cyclopropylvinylbenzene

Abstract

Exploring novel polymerization mechanisms for the preparation of switchable isomers in chains from homopolymerization with only monomers is undoubtedly an exhilarating and challenging pursuit in polymer chemistry. Therefore, this work presents a novel strategy for realizing reversible cycle anion migrated ring-opening polymerization (AMROP) and general anionic polymerization (thermodynamics limits the further ring-opening reaction of the 1-cyclopropylvinylbenzene (CPVB) unit, and this process is defined as frustrated AMROP). By employing alkali metal alkoxides (potassium tert-butoxide (t-BuOK) and sodium 2,3-dimethylpentan-3-olate (NaODP)) as additives, the opening of the cyclopropyl group in CPVB can be controlled during homopolymerization. Additionally, the structure and sequence distribution of inserted CPVB units are determined by distinct selective polymerization mechanisms. Thus, the synthetic polymer includes two structural units, i.e., ring-opened CPVB (ro), which is generated from AMROP, and nonopened CPVB (ga), which results from frustrated AMROP (F-AMROP). Furthermore, in view of steric hindrance from the penultimate-unit effect during chain growth of CPVB, the process of F-AMROP cannot continuously occur and requires the AMRO process of CPVB to decrease the steric hindrance around active centers. Therefore, under the influence of steric hindrance from the penultimate unit, AMRO, and thermodynamics, a reversible cycle of frustrated and nonfrustrated AMROP can be activated during the polymerization process, which further realizes a single monomer to prepare an alternating polymer with different isomers. Ultimately, the mechanisms for AMROP and F-AMROP are explored deeply with density functional theory calculations. This intriguing mechanistic finding will become a pioneering and innovative strategy for development of polymerization mechanisms and unprecedented polymer structures in polymer synthesis.

Synthesis of Sequence-Controlled Homopolymer via Anionic Self-Alternating and Chemoselective Polymerization of 4-Vinyl-1,1-diphenylethylene Derivatives

“…This type of substituent effect has been well established experimentally by investigating the anionic polymerization of styrene and DPE derivatives. − ,− Herein, we focus on the substituent effect in the self-alternating polymerization of VD derivatives to synthesize a sequence-controlled polymer. In fact, the introduced substituents strongly affect several polymerization behaviors, including the polymerization rate, mechanism, and mode, as shown in Scheme . , …”

“…In fact, the introduced substituents strongly affect several polymerization behaviors, including the polymerization rate, mechanism, and mode, as shown in Scheme 2. 41,42 ■ RESULTS AND DISCUSSION Anionic Polymerization of VD Derivatives. The anionic polymerizability of VD derivatives ClVD, MeVD, MeOVD, and Me2NVD was investigated at −78 °C for 72 h using diphenylmethylpotassium (Ph 2 CHK), a bulky and π-conjugated initiator, in THF (ClVD-1, MeVD-1, and MeOVD-1; Table 1).…”

Anionic Self-alternating Polymerization of 1-(4-Vinylphenyl)-1-phenylethylene

“…In addition, very recently, when 1-cyclopropylvinylbenzene is anionically polymerized in an apolar solvent in the presence of potassium tert-butoxide (tBuOK), it is demonstrated that the polymer containing the alternating sequence of opened/nonopened-cyclopropane structures can be synthesized from a single monomer. 36 In this study, we propose a novel perspective for synthesizing an "alternating homopolymer" from a single monomer. If monomers comprise the comonomer pair A and B that exhibits alternating copolymerization behavior, it is anticipated that the monomers should undergo intermolecular "alternating homopolymerization".…”

“…Utilizing this unique reactivity, the anionic copolymerization of DPE derivatives with styrenes − or 1,3-dienes − afforded the corresponding alternating copolymers via cross-propagation. In addition, very recently, when 1-cyclopropylvinylbenzene is anionically polymerized in an apolar solvent in the presence of potassium tert -butoxide ( t BuOK), it is demonstrated that the polymer containing the alternating sequence of opened/nonopened- cyclopropane structures can be synthesized from a single monomer …”

Investigation of eight-arm tapered star copolymers prepared by anionic copolymerization and coupling reaction

“…Compared with the "core-first" method depending on a multifunctional initiator, the "arm-first" route first synthesizes a linear polymer chain, which then reacts with coupling agents, leading to a high level of control over the structure of arm chains. As for the living anionic polymerization system, [38][39][40][41] the established strategies usually involve coupling reactions between living carbanionic polymer chains and electrophilic linking agents containing multifunctional chlorosilane or benzyl bromide moieties. 42,43 However, the coupling step is often time-consuming (up to several weeks) and prone to impurities.…”