Cell wall polysaccharides from Mandevilla velutina (Apocynaceae) cultured cells: extraction and chemical structure

The homogeneous grafting of methyl methacrylate (MMA) onto methacrylate-modified cellulose (CEMA) was achieved by a two-step process at three different temperatures (Tp) in the range 40¯70°C. Grafting yield (GP%) and grafting efficiency (GE%) were determined and related to the conditions of synthesis. The role of various reaction parameters on GP% and GE% (namely, reaction temperature and time, cellulose degree of substitution (DS), molar ratios of MMA to methacrylate pendant groups (¯MA) and of MMA to initiator) was evaluated. Molecular weights of grafted chains and of PMMA homopolymer were determined at the chosen Tp and compared to each other. The average number of grafts per cellulose molecule (ng) was calculated and, together with the molecular weight data of the grafted chains, utilized to interpret the experimental trend of GP% vs. Tp. On the basis of the above results, interesting perspectives of the homogeneous grafting method were outlined.