Playing construction with the monomer toy box for the synthesis of multi‐stimuli responsive copolymers by reversible deactivation radical polymerization protocols

Abstract

In this review article, we survey the 2016–June 2021 scientific literature on the synthesis of multi‐stimuli responsive (MSR) polymers, the main focus being on reversible deactivation radical polymerization techniques (RDRPs, also known as controlled radical polymerizations). In fact, along more than 40 years of extensive research, RDRPs have boosted the synthesis of stimuli‐responsive polymers. RDRPs are now robust, versatile, relatively user‐friendly and even interconvertible, thus allowing control over composition, sequence, and topology of polymers. Such control can afford materials with well‐defined responses to physical, chemical, and biological external stimuli. Furthermore, “click” reactions are used to combine macromolecular precursors or to introduce specific functional groups in the target structure. As a result, MSR polymers are obtained from diverse combinations of commercial or specially synthesized building blocks arranged at will into desired sequences and architectures. Thanks to this versatility, self‐assembling polymeric structures are designed either to respond to triggers and perform specific applicative tasks, or to investigate the influence of structural variables on the responsivity of polymers. The “green” trend emerging in the field of responsive polymers and RDRPs is also briefly discussed.

RAFT-Based Polymers for Click Reactions

“…Azide functionality can also be introduced through the modification of a perfluorobenzene substituent in the R group of the commercially available RAFT agent by treatment of the polymer with sodium azide, similar to the procedure described in [ 35 ] for perfluorobenzyl methacrylate ( Scheme 19 ).…”

“…Therefore, the design of a synthetic route is crucial to produce macromolecules with the desired architecture and functionalities. Since the 2000s, the numerous publications and reviews summarized the application of click reactions in the synthesis of macromolecules with complex architecture [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. Nowadays, click reactions are used to assemble macromolecules, the parts of which are pre-prepared by living anionic polymerization, pseudo-living cationic polymerization, and reversible deactivation radical polymerization (RDRP) [ 39 ].…”

Influence of Nanoaggregation Routes on the Structure and Thermal Behavior of Multiple-Stimuli-Responsive Micelles from Block Copolymers of Oligo(ethylene glycol) Methacrylate and the Weak Acid [2-(Hydroxyimino)aldehyde]butyl Methacrylate

“…The products were then dried under high vacuum at room temperature for 7 days. The purified products were characterized by 1 H NMR and GPC (M n and Đ, Table 1 and Figures S1−S3).…”

“…NMR Spectroscopy. 1 H analyses were performed on a Bruker AVANCE II operating at a proton frequency of 300 MHz. All polymers were dissolved in CDCl 3 or DMSO-d 6 for NMR analysis.…”

“…We used OEGMA with different pendent chain lengths (G2, G4, and G9), and the hydrophilic blocks were obtained either as G2, G4, or G9 homopolymers or as G2G9 random copolymers with different G2/G9 ratios. Monomer conversions, as determined by 1 H NMR, exceeded 95% in all cases, so we assumed degree of polymerization, DP = 75 (based on [M] 0 /[CTA] = 75:1, with [M] 0 = initial monomer concentration and [CTA] = concentration of the chain-transfer agent in the reaction mixture) within experimental error. Therefore, we were able to extend the resulting macro-CTA (Scheme 1) by simply adding the HIABMA monomer to an aliquot of the reaction mixture and re-initiating the polymerization reaction, assuming that incorporation of the residual OEGMA in the second block would not affect our results significantly.…”