Architecture of Prototype Copolymer Brushes by Grafting-from ATRP Approach from Functionalized Alternating Comb-Shaped Copolymers

Abstract

Atom transfer radical polymerization (ATRP) was applied to a novel synthesis of prototype copolymer brushes. The procedure included the following steps: (1) free-radical copolymerization of vinylbenzylterminated polystyrene (PS-VB) macromonomer and N-(4-hydroxyphenyl)maleimide gave well-defined alternating comb-shaped copolymers, (2) subsequent esterification reaction [N-(4-hydroxyphenyl)maleimide sites] of such comb-shaped copolymer with 2-bromoisobutyryl bromide yielded a comb-shaped polyinitiator, and (3) the graftingfrom ATRP method of methyl methacrylate (MMA) using comb-shaped polyinitiator provided PS/poly(methyl methacrylate) (PMMA) alternating copolymer brushes. Dilute solution properties and morphological results of both comb-shaped polyinitiator and prototype copolymer brushes were investigated by static and dynamic light scattering and transmission electron microscopy. As a result, prototype copolymer brush composed of short aspect ratio changed the shape from ellipsoid to starlike conformation because both polystyrene (PS) and PMMA side chains were stretched by introduction of PMMA grafted chains.

Synthesis of amphiphilic copolymer brushes possessing alternating poly(methyl methacrylate) and poly(N‐isopropylacrylamide) grafts via a combination of ATRP and click chemistry

“…In general, comb‐shaped polymer brushes can be categorized into homopolymer brushes and copolymer brushes. Since the pioneering work reported by Tsukahara et al3, 4 in 1989, extensive investigations have been devoted to the synthesis of homopolymer brushes mainly via three approaches including grafting‐through,5–20 grafting‐from,21–39 and grafting‐onto 40–46. In the past decade, the advent of controlled polymerization techniques, such as ring‐opening polymerization (ROP),5, 24, 25, 30, 37, 43 nitroxide‐mediated polymerization (NMP),47–49 atom transfer radical polymerization (ATRP),16, 31–33, 35, 39 and reversible addition‐fragmentation chain transfer (RAFT) polymerization,50, 51 have rendered the grafting‐from approach more appealing, starting with macroinitiators with the initiating sites distributed on every repeating unit.…”

“…On the other hand, copolymer brushes typically consist of more than one type of polymer side chains. When two types of polymer grafts are involved, they can be arranged in a random,43, 46, 47 alternating,5, 12–14, 18, 19, 25, 34 block,22, 26, 51, 52 or “centipede” manner 33, 37, 53. Compared to homopolymer brushes, the incorporation of another type of polymer graft endows copolymer brushes with extra structural versatility and unique aggregation properties, resulting from the intrinsic immiscibility between two types of polymer grafts.…”

Case Study to Bridge the Gap between Chemistry and Chemical Product Engineering: From Molecules to Products Based on Brush Copolymers Having Different Backbone Composition Profiles

“…30−41 Simultaneously the controlled preparation of macromolecular brushes by "grafting from" a macroinitiator via ATRP has been extensively studied. 42,43 This method can be used to prepare brushes with a high grafting density without being affected by steric hindrance. And the products can be easily purified through removing the low molecular weight monomer.…”

Novel Dual-Grafted Copolymer Bearing Glassy Polystyrene and Crystalline Poly(Ethylene Oxide) as Side Chains

“…As such grafts include two types of polymer graft chains, their possible topologies can be divided into three types, namely, dual-brush or block type (1-5), Janus-like or prototype (6)(7)(8)(9)(10)(11), and double-cylinder type (12)(13)(14)(15). Polymer brushes with two different grafts distributed along the backbone have great scientific significance.…”

“…A combination of two chemically distinct domains that do not enclose each other endows the polymer with unique physical properties and potential applications in giant surfactants (1), nanomaterials (16,17), drug encapsulation and delivery (18), and biological systems (19). Such complex copolymer grafts can be obtained through diverse polymerization processes, such as atom transfer radical polymerization (ATRP) (12,(20)(21)(22), nitroxide mediated polymerization (NMP) (1), reversible addition-fragmentation chain transfer (RAFT) (1, 2, 23), or ring opening metathesis polymerization (ROMP) (24). However, the preparation of a well-defined structure and unimodal copolymer is still the preferred strategy.…”