Branched methacrylate copolymers from multifunctional comonomers: the effect of multifunctional monomer functionality on polymer architecture and properties

Abstract

Soluble. branched (meth)acrylic copolymers have been synthesised via facile, one-step, batch solution polymerisations taken to high conversion. Methyl methacrylate has been copolymerised with a number of multifunctional comonomers using a chain transfer agent to prevent gelation. A variety of soluble, branched copolymer architectures have been synthesised using multifunctional monomers containing between two and six acrylate functional groups. Independent of polymer composition, all copolymers were proven to be branched with broader molecular weight distributions compared to linear analogues. The molecular weights, Mark-Houwink constants and T-g's all varied systematically depending on the functionality and concentration of the multifunctional monomer copolymerised. Although the polymer architectures are complex, this methodology is pragmatic, highly practical and very convenient. The need for high control of polymer architecture via controlled radical polymerisation for satisfying applications is questioned. It is proposed that precise control may not be necessary for many applications, whereas new, heterogeneous structures via pragmatic routes may be sufficient and more easily exploited

Influence of reaction parameters on the synthesis of hyperbranched polymers via reversible addition fragmentation chain transfer (RAFT) polymerization

“…In the latter case, as expected, all reactions showed evidence of early crosslinking, leading to insoluble material. This provides supplementary experimental evidence that the synthesis of soluble branched polymers by free-radical copolymerisation seems impossible when the reaction is taken to high conversion [1]. Fig.…”

“…Their strategy involves the conventional free radical polymerization of a vinyl monomer, in the presence of a multifunctional vinyl comonomer and a chain transfer agent to prevent crosslinking [1][2][3][4][5][6]. Besides using conventional chain transfer agents in the synthesis of branched polymers, Sherrington's group, in collaboration with Armes' group, also applied copper mediated living radical polymerization (LRP) and group transfer polymerization (GTP) to the synthesis of soluble branched polymers in facile one-pot reactions, and obtained well-controlled hyperbranched architectures [4].…”

Poly(neopentylene carbonate) Hyperstars

“…[29][30][31] A trend of decreased values of a with increased branching is seen when comparing the linear polymers to the branched four-arm stars and hyperstars (Table 1). This effect is the result of the polymers becoming denser when the branching increases.…”

Facile synthesis of branched water-soluble poly(dimethylacrylamide)s in conventional and parallel reactors using free radical polymerisation

“…Since then we and our industrial collaborators [6][7][8] have developed the methodology extensively in the case of branched poly(methyl methacrylate)s and have established some key principles in formulating polymerisations to optimise branching versus cross-linking [9]. Perhaps most importantly we have demonstrated that the number of primary linear polymer chains is essentially controlled by the number of moles of transfer agent used in excess relative to the initiator, and that providing the mole ratio of branching difunctional comonomer/transfer agent is kept 61 cross-linking can be avoided.…”