A Nonconventional Approach toward Multihydroxy Functional Polystyrenes Relying on a Simple Grignard Reagent

Abstract

Capitalizing on the inertness of styrene toward Grignard reagents, 4-vinylphenyl­magnesium bromide was utilized for the rapid and convenient preparation of the protected monomer 2,2-dimethyl-4-(4-vinylbenzyl)-1,3-dioxolane (DMVBDO), avoiding the use of catalysts and painstaking purification protocols. Well-defined homopolymers, statistical copolymers, and block copolymers with styrene (S) as a comonomer were prepared in THF at −78 °C via carbanionic living polymerization. The overall molecular weights ranged from 4.5 to 68.9 kg mol–1 with low dispersities (Đ 1.04–1.15). Copolymers were synthesized with styrene feed ratios (X feed) from 15 to 95 mol % with glass transition temperatures (T g) between 46 and 91 °C. Whereas polystyryllithium served as an excellent macroinitiator for the preparation of the block copolymer PS0.5-b-P­(DMVBDO)0.5, the inverse block order, i.e., synthesis of P­(DMVBDO)0.5-b-PS0.5, yielded a bimodal molecular weight distribution (MWD) with increased dispersity, which is ascribed to slow crossover. Rapid deprotection of both homo- and copolymers to release two hydroxyl groups per DMVBDO unit was achieved via acidic hydrolysis. The deprotected block copolymer PS0.5-b-P­(VPPDO)0.5 showed phase separation, indicated by two T g values (68 and 86 °C). Homogeneous brush copolymers of the type P­(S85-co-VPPDO5)-g-PLLA and P­(S85-co-VPPDO6)-g-PEO were demonstrated by using quantitative “grafting from” with l-lactide and ethylene oxide, respectively. The brush-like copolymers were obtained in quantitative yields while maintaining monodisperse MWD.

MyrDOL, a Protected Dihydroxyfunctional Diene Monomer Derived from β-Myrcene: Functional Polydienes from Renewable Resources via Anionic Polymerization

“…The corresponding acetonide represents a suitable protective group for 1,2-diols. It was demonstrated in the literature that this protective group is stable under carbanionic conditions in combination with styrene monomers . Details and NMR spectra are given in the Supporting Information (Figures S1–S6).…”

“…Catechol-based monomers were investigated for different applications based on surface binding . The catechol group shows outstanding adhesion and complexation properties due to the chelate effect of catechol. − 2,2-Dimethyl-1,3-dioxolanes represent a base-stable protecting group for diol moieties, and deprotection can readily be achieved by acidic hydrolysis under mild conditions after polymer formation. − In pronounced contrast to the labile catechol moiety, aliphatic diols are stable and resistant to oxidation, which provides long-time storage stability . Such aliphatic diols present a promising class of polymer materials, as they can be used as macroinitiators for the synthesis of graft copolymers …”

Anionic Polymerization of 4-Allyldimethylsilylstyrene: Versatile Polymer Scaffolds for Post-Polymerization Modification

“…For substituted styrene monomers with reactive functional groups, optimum reaction conditions have to be determined by variation of initiators, solvent, and temperature. 14,18,27 However, substituted styrene monomers containing active hydrogen(s) and/or functional groups such as OH, SH, SiOR, NH 2 , CHO, COOH, and so forth are not compatible with living anionic polymerization conditions and require protective group strategies for successful polymerization. 1,14,19,28,29 An alternative strategy to circumvent this limitation is employing post-polymerization strategies to functionalize the polymers for specific requirements.…”

“…14,18,27 However, substituted styrene monomers containing active hydrogen(s) and/or functional groups such as OH, SH, SiOR, NH 2 , CHO, COOH, and so forth are not compatible with living anionic polymerization conditions and require protective group strategies for successful polymerization. 1,14,19,28,29 An alternative strategy to circumvent this limitation is employing post-polymerization strategies to functionalize the polymers for specific requirements. 30,31 The success of this method depends on its efficiency and orthogonality, which are key requirements to achieve well-defined functional materials.…”

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

“…Since the development of living anionic polymerization, the method has occupied an eminent status for the synthesis of well-defined polymers with controlled molecular weights and dispersity. , Despite significant advances in the field of reversible deactivation radical polymerization techniques in the recent past, − living anionic polymerization is still the preferred technique for the commercial synthesis of a variety of high-value functional polymers and thermoplastic elastomers (TPEs). ,, Styrene and its derivatives − are amenable to living anionic polymerization leading to a wide range of macromolecular architectures such as star, graft, hyperbranched, multiblock, and so forth . Functionalized styrene monomers are of particular interest as polymers therefrom can be further employed for post-polymerization modification or serve as precursors for the synthesis of graft copolymers. − Notably, the nature and position of the substituent at the styrene monomer can drastically modify the reactivity of the substituted styrene monomer in anionic polymerization. − …”