Enviromentally Benign polymers: Characterization and Modeling

D. REYNA; J. VICH BERLANGA; D. M. MARTINO; D. A. ESTENOZ; G. MEIRA

Porto Galinhas

Congreso; CBECIMAT, 18° Congresso Brasileiro de Engenharia e Ciência dos Materiais; 2008

Bioinspired polymers similar to polystyrene (PS), except that thymine and charged functional groups are chemically bonded to the structure of the PS, were investigated. These environmentally benign, water-soluble and non-toxic polymers undergo a photodimerization reaction of thymine units when exposed to UV radiation (~254nm), creating crosslinked networks in regions of UV exposure and rendering the polymer insoluble in those areas. These materials have numerous applications from microelectronic, to antibacterial coatings and hair styling. We investigated the synthesis and curing conditions, which determine the molecular structure (MWD, chemical composition) and the physical properties (solubility, photoreactivity) of the polymers. Vinylbenzylthymine (VBT) was copolymerized with vinylbenzyltriethylammonium chloride (VBA) in a free radical polymerization (2,2’-azobisisobutyronitrile-AIBN). Aqueous solutions of copolymers were distributed homogeneously on different substrates and irradiated with 254nm or with 520nm using a sensitizer (Eosin Y, lmax=520nm). The crosslink was monitored in function of irradiation time and comonomer ratio, using IR and AFM. The curing process was modeled and validated with experimental data.