Grafting on polysilanes using atom transfer radical polymerisation

Abstract

Atom transfer radical polymerisation (ATRP) was used in an attempt to prepare a graft polymer based on poly(methylphenylsilane) (PMPS). A partially bromomethylated PMPS was subjected to ATRP conditions in order to grow poly(methyl methacrylate) (PMMA) grafts onto that backbone. Following the grafting reaction, a substantial increase in molecular weight was observed by size exclusion chromatography, analysis using refractive index detection. However, a bimodal product molecular weight distribution was observed using a UV detector set at wavelengths at which only the PMPS backbone can be detected. The lower molecular weight fraction was identified as homopolymeric PMPS although it appears to include some material with short grafts, while the higher molecular weight fraction corresponds to PMPS with long grafts. These observations are interpreted as the formation of a substantial amount of PMMA that is not grafted onto PMPS through a radical process initiated independently of the ATRP. However, since MMA is barely susceptible to thermal polymerisation, this is not easily rationalised. © 2002 Society of Chemical Industry

ARGET ATRP of methyl methacrylate in the presence of nitrogen‐based ligands as reducing agents

“…ATRP7–13, 20 is one of the most efficient CRP techniques allowing the synthesis of well‐defined block copolymers with predictable molecular weight, narrow molecular weight distribution, wide range of functionalities, high degree of chain end‐functionality and controllable macromolecular architecture 21–36. Especially interesting are block copolymers prepared by transformation of one to another mechanism, as demonstrated by Jones and others 37–57…”

Synthesis of well‐defined polystyrene‐graft‐poly(methyl methacrylate)

“…In the ‘grafting‐through’ technique via ATRP, a macromonomer is copolymerized with a low‐molecular‐weight comonomer, producing graft copolymers with good control of (1) the length of the side‐chain made by living polymerization, (2) the chain length of the backbone controlled by the living ATRP process and (3) the average side‐chain density and the spacing distribution of the side‐chains determined by the apparent reactivity ratio of the macromonomer in the copolymerization and the ratio of the macromonomer in the feed. In the ‘grafting‐from’ technique via ATRP,18–53 a polymer having ATRP‐active halide atoms as side‐groups is used as a macroinitiator for the ATRP of a second monomer. Generally, the macroinitiators can be obtained directly by copolymerizing a monomer containing an ATRP‐initiating group by using a polymerization mechanism different from ATRP20–30, 36, 37 or by copolymerization of a monomer carrying a precursor group that can be transformed to an ATRP‐initiating group 31–34, 38–53.…”

“…The macroinitiators with benzyl chloride or bromide initiating groups are the most widely used for the synthesis of graft copolymers in the ‘grafting‐from’ technique via ATRP 20–23, 36–46, 52, 53. However, benzyl halide is a poor initiator for methacrylate monomers, with slow initiation when compared with propagation, and then low initiation efficiency 54.…”