Water-soluble random and alternating copolymers of styrene monomers with adjustable lower critical solution temperature

Abstract

Random copolymers of 4-vinylbenzyl tri(oxyethylene) and tetra(oxyethylene) ethers, as well as alternating copolymers of 4-vinylbenzyl methoxytetra(oxyethylene) ether and a series of N-substituted maleimides, were synthesised by conventional free radical polymerisation, reversible addition fragmentation chain transfer (RAFT) and atom transfer radical polymerisation (ATRP). Their thermosensitive behaviour in aqueous solution was studied by turbidimetry and dynamic light scattering. Depending on the copolymer composition, a LCST type phase transition was observed in water. The transition temperature of the obtained random as well as alternating copolymers could be varied within a broad temperature window. In the case of the random copolymers, transition temperatures could be easily fine-tuned, as they showed a linear dependence on the copolymer composition, and were additionally modified by the nature of the polymer end-groups. Alternating copolymers were extremely versatile for implementing a broad range of variations of the phase transition temperatures. Further, while alternating copolymers derived from 4-vinylbenzyl methoxytetra(oxyethylene) ether and maleimides with small hydrophobic side chains underwent macroscopic phase separation when dissolved in water and heated above their cloud point, the incorporation of maleimides bearing larger hydrophobic substituents resulted in the formation of mesoglobules above the phase transition temperature, with hydrodynamic diameters of less than 100 nm

Effect of the zwitterion structure on the thermo-responsive behaviour of poly(sulfobetaine methacrylates)

“…[7][8][9] In fact, LCST behaviour is a common phenomenon of non-ionic polymers in aqueous solution. 2 Moreover, their transition temperatures can be easily fine-tuned via their molecular structure, as they can be synthesised not only by various polymerisation methods directly from the respective monomers, 1,2 but also by copolymerisation 3,[10][11][12] or by post-polymerisation modification. 4,[13][14][15] In contrast, the number of polymers showing UCST behaviour in water is quite limited.…”

Simultaneous Control over Monomer Sequence and Molecular Weight Using the RAFT Process

“…Functional groups could be introduced in the corresponding random or alternating copolymers in a post-polymerization functionalization step: the alkyne moiety present in the styrene derivatives could efficiently be functionalized with an azide containing functional group in a copper-catalyzed cycloaddition, whereas the PFS residue could be functionalized using thiols in a nucleophilic para-substitution reaction (Figure 3). (37,38).…”

“…A wide variety of maleimides can be copolymerized with styrene to yield alternating copolymers, but also many styrene derivatives have been used. RAFT copolymerizations for such systems have been described (31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43), among others for the synthesis of polyampholytes, thermo-and photoresponsive polymers and graft-copolymers. Examples of the maleimides and styrene derivatives that were used are displayed in Figure 1B and C, respectively.…”

Synthesis of block polymer miktobrushes

“…We were inspired by the work of Chen and coworkers who investigated the alternating copolymerization of two different MMs bearing N-2-hydroxylethyl maleimide (MI) and styrene (Sty) functionalities; MI-PCL and Sty-PEO to form alternating copolymer brushes. 97,98 The alternating copolymerizations of maleic anhydrides/N-substituted maleimides with styrene have been well studied, [99][100][101][102][103] and even utilized in grafting from approaches towards brush copolymers or codendrimers. 104-107 In Chen's study, the alternation of MI-PCL and Sty-PEO was inferred by determining the reactivity ratios of the MMs to be equivalent to each-other and close to the values of Sty and MI (ca.…”