Radiation-Grafting of Cotton-g-DMAEMA for Biomedical Applications
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Radiation-Grafting of Cotton-g-DMAEMA for Biomedical Applications Marco A. Luna-Straffon1, Gerardo Cedillo2, and Emilio Bucio1 1
Departamento de Química de Radiaciones y Radioquímica, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México DF 04510, México 2 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México DF04510, México ABSTRACT This work covers the design of stimuli-responsive membranes and their ever-expanding range of use. Stimuli-responsive membranes that change their physicochemical properties in response to changes in their environment were synthesized for biomedical application. Responsive cotton-g-[2-(dimethylamino) ethyl methacrylate] membranes were obtained using γrays by mutual irradiation (direct method). The effect of absorbed dose, dose rate, and monomer concentration on the grafting yield was determined. The grafted samples were verified by the FTIR-ATR, 1H and 13C HRMAS NMR and 13C CPMAS NMR spectroscopies; thermal properties were analyzed by TGA and DSC and the stimuli-responsive behavior was studied by DSC. INTRODUCTION Radiation grafting is a suitable technique for surface modification of polymeric materials since it allows introducing active functional groups on the polymer backbone [1-5]. This method is applicable for many substrates and monomers combinations and, unlike chemically induced grafting; it does not require initiators [6]. There are several methods of radiation grafting: i) the direct (or mutual) grafting method in which the polymeric material is irradiated in contact with a monomer; homopolymerization being a collateral effect; ii) the pre-irradiation method, which involves the irradiation of the polymer matrix in the absence of air and then the grafting is initiated by macroradicals trapped in the irradiated polymer backbone; radiation dose is usually larger than in the direct method and polymer degradation may occur; and iii) the pre-irradiation oxidative grafting method consists in the pre-irradiation of the polymer in the presence of air or oxygen, so that the macroradicals formed are converted to peroxides and/or hydroperoxides; then when the irradiated polymer is heated in the presence of monomer the peroxides decompose to give the macroradicals [6, 7]. Cotton is an abundant, natural, biodegradable and renewable biopolymer, which makes it a very promising raw material available for modification with various functional polymers. The surface properties of cotton are of crucial significance for its widespread applications [8, 9]; for example, the creation of super-hydrophobic and oleophobic cotton fabrics, which have great potentiality in industrial application [10]. Chemical modification of cotton has been extensively studied for the past years in order to improve its wrinkle resistance, shrinkage resistance and dimensional stability [11, 12].
Poly(N,N´dimethyldimethylaminoethyl methacrylate) (PDMAEMA) is a polymer that exhibi
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