Polymer compounds, imaging mass

Process Analysis - Diffusion. - Water diffusion in methacrylate based copolymer hydrogels and incorporaion of vitamin B12, aspirin or chlorhexidine Diacetate into such copolymer hydrogels were investigated." The diffusion of water into cylinders of poly-2-hydroxyethyl methacrylate (PHEMA) and copolymers of (HEMA) with tetrahydrofurfuryl methacrylate (THFMA), butyl- methacrylate (BMA), and cyclohexyl methacrylate (CHMA) were studied over a range of copolymer compounds." The diffusion of water into the polymers was found to follow a Fickian, or case 1 mechanism. The diffusion coefficients of water were determined from mass measurements and NMR imaging studies. They were found to vary from 1.7 0.2 x 10 " m s for polyHEMA at 37°C to lower values for the copolymers. The mass of water absorbed at equilibrium relative to the mass of dry polymer varied from 52-58 wt% for polyHEMA to lower values for the copolymers. 

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