Hyperbranched acrylate copolymer via initiator-fragment incorporation radical copolymerization of divinylbenzene and ethyl acrylate: Synthesis, characterization, hydrolysis, dye-solubilization, ag particle-stabilization, and porous film formation

Abstract

Soluble hyperbranched acrylate copolymers were prepared by the copolymerization of divinylbenzene (0.10 mol·L-1) and ethyl acrylate (0.50 mol·L-1) using dimethyl 2.2′-azoisobutyrate of high concentrations (0.30-0.50 raol·L -1) as initiator at 70 and 80°C in benzene. The copolymer formed at 80°C for 1 h showed the weight-average molecular weight of 2.5 × 105, the small radius of gyration of 10 nm, the low second virial coefficient of 5.7 × 10-7 mL·g-2 as shown by the MALLS measurements at 25°C in tetrahydrofuran, and also the very low intrinsic viscosity of 0.10 dL·g-1 at 30°C in benzene. The hyperbranched copolymer exhibited an upper critical solution temperature (35°C on cooling) in an acetone-water (60:11 v/v). The copolymer showed an ability to encapsulate and transfer Rhodamine 6G as a dye probe and could stabilize Ag nanoparticles. The porous film was prepared by simply casting an acetone solution of the hyperbranched copolymer on a cover glass. The copolymer molecules radially arranged on the surface layer of the spherical pores as observed by the polarized optical microscope. The hyperbranched acrylate copolymer was hydrolyzed by KOH to yield poly(carboxylic acid). © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.