Synthesis and polymerisation of macromonomers
Three novel macromonomer systems have been synthesised, characterised and free-radically polymerised. Both copolymerisations and homopolymerisations have been studied. The macromonomers are vinylbenzyl-terminated poly(methyl methacrylate) (PMMA), vinylbenzylterminated poly(butyl methacrylate) (PBMA) and vinylbenzoyl-terminated poly(ethylene oxide) (PEO). The PMMA (number average molar mass 1.4 x l03g!mol) and PBMA (number average molar mass 1.8 x 103 g!mol) macromonomers were synthesised by the same method. This involved the solution free-radical polymerisation of MMA or BMA in the presence of matched initiator and chain transfer agent (4,4' -azobis( 4-cyanovaleric acid) (ACV A) and thiogycollic acid (TGA), respectively). This produced monofunctional carboxyl-terminated prepolymers which were subsequently converted to acyl chloride-terminated prepolymers using oxalyl chloride. This was then combined with pre-synthesised vinylbenzylamine in the presence of triethylamine, to produce vinylbenzyl~terminated macromonomer. The PEO macromonomer (number average molar mass 2.1 x 103 g!mol) was produced by combining commercially available hydroxyl-terminated PEO with pre-synthesised 4-vinylbenzoyl chloride in the presence of triethylamine. All three macromonomers were each free-radically homopolymerised using 2,2' -azobis(isobutyronitrile) (AIBN) as the initiator. The PMMA and PEO macromonomers were studied in more detail in order to establish their solution polymerisation behaviours. This was achieved by carrying out several polymerisations using different initial macromonomer and initiator concentrations. Solution copolymerisations of all three macromonomers with maleic anhydride were also attempted in order to produce altemating single graft copolymers. Maleic anhydride was chosen as the comonomer on the understanding that stYrene produces altemating copolymers with it. The vinylbenzyl-terminated PBMA and PMMA macromonomers were shown to produce graft copolymers containing approximately a 0.5 : 0.5 molar ratio of macromonomer : maleic anhydride, regardless of the initial feed concentrations of the two. All polymers were characterised by gel permeation chromatography (GPC) and IH nuclear magnetic resonance spectroscopy eH NMR). Fourier transform infra-red spectroscopy (FT-IR) was used to characterise the carboxyl-terminated and acyl chloride-tenninated PMMA and PBMA prepolymers, as well as all three macromonomers. A selection ofPMMA graft copolymers were further characterised by solution viscometry and 13CNMR.