Polycinnamates and Block Co-polymers Prepared by Atom Transfer Radical Polymerization and Microwave Irradiation

Abstract

Homo-polymers of 2-cinnamoyloxyethyl methacrylate (PCEMA) and block co-polymers with methyl-methacrylate (MMA) synthesized via copper(I)bromide/pentamethyldiethylentriamine-mediated atom transfer polymerization (ATRP) and microwave irradiation, under homo(co)polymerization conditions, are reported. Method 1 led to homo-polymers with relatively low molecular weight (PCEMA-1: 5100; PCEMA-2: 25 000), while the second method offered polymer of 100 000 average molecular weight (PCEMA-3), the polymerization being completed within 60 min. Two di-block co-polymers, poly(2-cinnamoyloxyethyl methacrylate-block-poly(methyl methacrylate)) ((PCEMA-b-PMMA)-1, (PCEMA-b-PMMA)-2) with 0.33 and, respectively, 0.5 molar fraction of photo-cross-linkable PCEMA were also prepared and utilized for this study. Subsequent gel-permeation chromatography (GPC) measurements on block co-polymers have indicated molecular weights of 24 000 and 45 700, respectively. In addition, structural characteristics for all photo-polymers were determined by FT-IR, 1H-NMR, UV-Vis spectroscopy, AFM and SEM/ESEM measurements. Photochemistry in thin polymeric films suggested that UV irradiation is accompanied by an insolubilization of the film caused by the transformation of cinnamate moieties and the formation of intermolecular cross-links, with important effects on the morphology. As expected, it was found that by electrospinning the above photo-polymers produced electrospun fibers of small diameter.