Amide initiators were used successfully for copper-mediated living radical polymerization (often
called ATRP) of a range of methacrylates to narrow molecular weight homopoymers and block copolymers from
initiator species containing a bromo-2-methylpropionamide. The polymerization of methyl methacrylate (MMA)
occurs efficiently with a copper chloride (Cu(I)Cl)/N-n-octyl-2-pyridylmethanimine catalyst by maintaining a
relatively low temperature for initiation and slowly increasing to the reaction temperature. By keeping the reaction
at 25 °C for 30 min before heating to 90 °C, a number-average molecular weight (M
n) of 12 900 g mol-1 and a
polydispersity of (PDI) = 1.24 at 70% conversion (where [MMA]/[initiator] = 100) were obtained. The polymers
produced showed molecular weights in good agreement with the theoretical and polydispersities of 1.20. Where
the reaction was heated to 90 °C, immediately high mass was obtained (26 600 g mol-1) in low yield (33%).
When copper bromide (Cu(I)Br) was used in place of Cu(I)Cl, the obtained mass was much higher than the
theoretical values. Polymerization from an initiator based on l-alanine under these conditions gave poly(methyl
methacrylate) (PMMA) with M
n = 8100 g mol-1 (PDI = 1.23) as compared to the theoretical value of 5900 at
this conversion (58% after 7 h). Polymerization of a other methacrylates including butyl methacrylate (M
n =
8700 (PDI = 1.27), M
n,theo = 7000), benzyl methacrylate (M
n = 11 400 (PDI = 1.25), M
n,theo = 9700),
dimethylaminoethyl methacrylate (DMAEMA) (M
n = 10 900 (PDI = 1.24), M
n,theo = 8100), and also poly(ethylene glycol) methacrylate (M
n = 8100 (PDI = 1.24), M
n,theo = 6500) were also polymerized. The successful
polymerization of styrene using bromo-2-methylpropionamide initiators is also reported with optimum conditions
needing 110 °C in the presence of Cu(I)Br and N-n-octyl-2-pyridylmethanimine yield polymer with M
n = 5800
(PDI = 1.27). Poly(methyl methacrylate) was also used as macroinitiator with DMAEMA to form an AB block
copolymer, confirming the living nature of the polymers (M
n = 34 700 (PDI = 1.25)). A triblock polymer of
methyl methacrylate and poly(dimethylsiloxane) (PDMS) was also prepared from a difunctional bromo-2-methylpropionamide poly(dimethylsiloxane) initiator (M
n = 29 600 (PDI = 1.27)).
The synthesis of 3-, 5-and 8-arm dimethylaminoethyl methacrylate star polymers are reported, final M n (PDI) = 12.2 K (1.09), 18.9K (1.10) and 38.4 K (1.11), respectively. The synthesis of 3-arm methyl methacrylate and dimethylaminoethyl methacrylate block co-polymer stars is also described. Living polymerisation occurred in all cases providing well defined stars with predictable molecular weights and narrow polydispersity. A fluorescent tag, 2-(8-methacryloyloy-3,6-dioxaoctyl)thioxantheno[2,1,9-dej]isoquinoline-1,3-dione, derived from a commercially available pigment, was incorporated into the star polymers. The fluorescence spectra of the polymers prepared were recorded over a range of pH and the peak emission frequency and intensity have been reported, k ex = 462 nm. All of the multi-arm polymers exhibit fluorescence across a broad pH range with maximum emission at pH 4. A 3-arm star polymer has been demonstrated to show good bioadhesion in rat tissue. A reduced adhesion in epithelial tissues not covered by a viscoelastic mucus gel indicates an increased tendency for mucoadhesion over bioadhesion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.