Synthesis of CO₂-responsive gradient copolymers by switchable RAFT polymerization and their controlled self-assembly

Abstract

Switchable reversible addition-fragmentation chain-transfer (RAFT) agents, so-called because they can be reversibly switched by the acid/ base stimulus to offer very good control over polymerization of both “more-activated” monomers (MAMs)...

Fine-Tuning Gradient Copolymers with Diverse and Controlled Microstructure and Mechanical Properties via Monomer Sequence Distribution: An In Silico Study

“…There are several techniques for synthesizing gradient copolymers, including anionic , and cationic , polymerization, ring-opening polymerization, ,− and controlled radical polymerization (CRP). ,,− The advantage of the CRP method is that the chain structure can be precisely controlled by the simultaneous or sequential reaction of different monomers, resulting in the synthesis of various types of copolymers. There are two primary strategies for achieving compositional gradient changes in copolymers.…”

Facile Synthesis of CO2‐Responsive Nano‐Objects: Batch versus Semi‐Batch RAFT Copolymerization

“…Carbon dioxide (CO 2 ), which is a benign, green, cost‐effective, abundant, biocompatible, and non‐toxic trigger for stimuli‐responsive polymers, has received much attention over the last decade. [ 1–4 ] Due to the very interesting properties of CO 2 as a trigger, CO 2 ‐responsive polymers have found great potential applications in different areas including latexes, [ 5 ] fibers, [ 6 ] gels, [ 7 ] surfactants, [ 8 ] self‐assemblies, [ 1 ] drug carriers, [ 9 ] and so on. [ 10–12 ] As we all know, statistical and block copolymers are widely used for CO 2 ‐responsive polymers since the monomer composition profiles can be easily regulated through batch or stepwise monomer feeding method.…”

“…[ 2–4 ] Unlike block copolymers with a sharp change in monomer composition, gradient copolymers vary their monomers composition and properties gradually along polymer chains, which have received increasing interest recently. [ 1 ] Gradient copolymers have been formed along with the development of reversible deactivation radical polymerization (RDRP) techniques. [ 13 ] Depending on the different reactivity ratios of the monomer pairs, two kinds of gradient copolymers could be prepared: a) spontaneous gradient copolymers formed in batch process, using the large differences in reactivity ratios between two monomeric species to induce spontaneously change in monomer composition along polymer chains.…”

“…[ 17–19 ] For example, Thang and co‐workers reported a one‐pot batch polymerization of more‐activated monomer N, N ‐diethylaminoethyl methacrylate (DEAEMA) and less‐activated monomer N ‐vinylpyrrolidone by using switchable macroRAFT agent to obtain well‐defined spontaneous gradient structures. [ 1 ] The advantages of batch process are good repeatability and easy to execute, since the spontaneous copolymer composition gradient depends on the monomer reactivity ratios and initial feed concentration. However, its main disadvantage is that under the given composition of given monomer pairs, only one spontaneous polymer composition gradient can be obtained.…”

“…[ 25 ] Recently, we have focused our activities on the CO 2 ‐responsive gradient copolymers and try to understand the effect of monomer distribution and polymer architecture on the stimuli‐responsive properties of these nano‐objects. [ 1 ] In this paper, we prepared a series of CO 2 ‐responsive nano‐objects of gradient, statistical and block copolymers by reversible addition–fragmentation chain‐transfer (RAFT) polymerization using PEG macro‐RAFT agents to regulate the copolymerization of hydrophobic monomer benzyl methacrylate (BzMA) and CO 2 ‐responsive monomer DEAEMA ( Scheme ) and systematically studied their CO 2 ‐responsive behaviors. And the gradient copolymers were generated by using semi‐batch methods with programmed monomer feeding rate controlled by syringe pumps, achieving precise control over the desired composition distribution of the gradient segment.…”