Expanding the monomer scope of linear and branched vinyl polymerisations via copper-catalysed reversible-deactivation radical polymerisation of hydrophobic methacrylates using anhydrous alcohol solvents

Abstract

Cu-Catalysed reversible-deactivation radical polymerisation of hydrophobic methacrylate monomers in anhydrous alcohols has been expanded to explore the scope of this unusual choice of solvent. A range of linear methacrylic homopolymers with well-targeted molecular weight and low dispersity (Đ = 1.12-1.53) have been generated in anhydrous methanol and isopropanol with relative ease. These solvents are normally considered antisolvents and employed to precipitate such polymers; therefore, our studies have assessed the polymerisation reaction mixture homogeneity and extent of reaction control. Statistical copolymerisations with the bi-functional monomer, ethylene glycol di-methacrlylate (EGDMA), has led to branched statistical copolymers with weight average molecular weights up to M w = 1.76 × 10 6 g mol −1 ; subsequent triple-detection size exclusion chromatography studies have provided insight into the impact of monomer structure on the extent of branching within the final isolated polymers. The ability to control branched copolymer molecular weights under these conditions through variation of EGDMA concentrations was seen to be highly dependent on methacrylate monomer chemistry. A number of factors which are likely to effect branching reactions during the polymerisation of hydrophobic methacrylates in anhydrous alcohols are discussed. † Electronic supplementary information (ESI) available: Experimental details, NMR spectra, TD-SEC analyses, additional figures and calculations. See

Polymerizable Gd(iii) building blocks for the synthesis of high relaxivity macromolecular MRI contrast agents

“…Having demonstrated that linear copolymers can be prepared in a controlled manner using the monomers Gd$L 1 and NAM, we turned our attention to the crosslinker complexes Gd$L 2-4 . In order to prevent gelation from occurring and based on some of our previous work and that of Flynn et al, 50,53 the crosslinked polymers were obtained by xing the concentration ratio of the crosslinker (Gd$L 2-4 ) relative to the chain transfer agent (CTA), such that [Gd$L 2-4 ]/[CTA] ¼ 0.9. Initially, a range of water soluble hyperbranched polymers were synthesized by RAFT polymerization of NAM and the crosslinker Gd$L 2 at different initial concentrations (1-2 M) in DMSO, using poly(ethylene glycol) methyl ether 2-(dodecylthiocarbono-thioylthio)-2-methyl-propionate as the CTA (Table 2, entries 1-4).…”

Mucus-responsive functionalized emulsions: design, synthesis and study of novel branched polymers as functional emulsifiers

“…The synthesis of branched vinyl copolymers using the incorporation of low concentrations of divinyl monomers (less than 1 per propagating primary chain) has been the subject of several research reports. 26 The mixing of differing monovinyl monomer chemistries within the primary chains of the complex polymer architectures 27,28 has also been used to introduce main-chain functionality; 22,23 however, the joining together of polymer chains via this approach opens a unique opportunity to also control chain-end functionality, as demonstrated by our group in the formation of hyperbranched-polydendrons with varying combinations of dendritic and polyethylene glycol (PEG) chains. [29][30][31] As mentioned above, we have recently reported the formation and application of branched copolymers consisting of OEGMA (M n ¼ 300 g mol À1 ) and EGDMA, initiated by dodecyl a-bromoisobutyrate, 1 (Dod-Br, Scheme 1), under atom transfer radical polymerisation (ATRP) conditions, as highly efficient polymeric surfactants; the copolymers contain a hydrophobic dodecyl group at every chain-end.…”

Complex polymer architectures through free-radical polymerization of multivinyl monomers

“…50 Soluble branched polymers were obtained at near complete monomer conversion, provided that the feed ratio of DVM:initiator was kept around or less than 1. [51][52][53][54] In some cases, higher (up to 5) DVMs per primary chain can be tolerated without causing the macroscopic gelation at near full vinyl conversion, an observation which can be easily attributed to increasing the intramolecular cyclization. 51,55 Nevertheless, these approaches represent the design of a RDRP of monvinyl monomers/DVMs system with a gel point at or beyond the point of complete monomer conversion (Figure 2b), such that less than one divinyl branching monomer is incorporated into each primary chain at the end of the reaction, and thus leading to the formation of branched polymers in facile one-pot reactions.…”