Preparation of water-soluble hyperbranched polymers with tunable thermosensitivity using chain-growth CuAAC copolymerization

Abstract

Thermoresponsive hyperbranched polymers with dangling oligo(ethylene oxide) chain on every monomer unit were constructed using the chain-growth copper-catalyzed azide–alkyne cycloaddition (CuAAC) copolymerization of two AB2-F monomers.

Click chemistry strategies for the accelerated synthesis of functional macromolecules

“…In contrast to the step growth mechanism for most CuAACPs, chain growth‐like behavior was reported for polymerization of hyperbranched derivatives by Gao 446–449 . In the initial stage, random monomer‐monomer coupling occurred to form triazole rings, which could then complex in situ with Cu(I) species resulting in minimal free Cu(I) species in the solution (Figure 10).…”

“…445 In contrast to the step growth mechanism for most CuAACPs, chain growth-like behavior was reported for polymerization of hyperbranched derivatives by Gao. [446][447][448][449] In the initial stage, random monomer-monomer coupling occurred to form triazole rings, which could then complex in situ with Cu(I) species resulting in minimal free Cu(I) species in the solution (Figure 10). Therefore, the remaining AB 2 monomers could only react with the Cu(I)-coordinated polytriazole oligomers to give high MW hyperbranched polymers with comparatively low dispersity (Đ <1.4).…”

Recent advances on synthesis and biomaterials applications of hyperbranched polymers

“…Despite this, some special monomers have been designed to deviate this equal reactivity scenario, creating an accelerating reaction of the second B group than the first B group to vary the reaction kinetics, polymer molecular weight and to achieve higher DB than 0.5 (Segawa, Higashihara, & Ueda, 2013). A diverse range of monomers based on various organic reactions has been reported to achieve hyperbranched polymers through step‐growth mechanism, including polyesterfication (Hawker, Lee, & Frechet, 1991), polyetherification (Liu et al, 2014; Uhrich, Hawker, Frechet, & Turner, 1992), polyamidation (Uhrich, Boegeman, Fréchet, & Turner, 1991; Yamakawa, Ueda, Takeuchi, & Asai, 1999; Yang, Wu, Liu, Qiu, & Liu, 2019), palladium‐catalyzed Suzuki coupling (Monomer 3, Table 1; Xue et al, 2010), and copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) reactions (Cao, Shi, Wang, Graff, & Gao, 2016; Gan, Cao, Shi, Zou, & Gao, 2018; Shi et al, 2015; Shi, Cao, Zou, et al, 2016), among many others. Recently, acid‐catalyzed Friedel‐Crafts substitution of aromatic AB 2 monomers, consisting of both an electron‐rich arene and a maleic functionality, resulted in hyperbranched polymers with DB = 100% made possible by accelerated rate of the intermediate species (Yang & Kong, 2016).…”

Synthesis and functionalization of hyperbranched polymers for targeted drug delivery

“…These units can be chosen to be responsive to one or multiple stimuli (e.g. pH, [19][20][21][22][23] temperature, [24][25][26][27] redox, [28][29][30] light, [31][32][33][34][35] enzyme [36,37]) to induce a change in conformation of the polymer chain or its degradation to trigger drug release. [38] Their globular three-dimensional structures lead to the formation of internal cavities that can be used to encapsulate small-molecule drugs (less than 900 g mol -1 ), e.g.…”