Synthesis and preliminary characterisation of charged derivatives and hydrogels from scleroglucan

The synthesis of negatively and positively charged polyelectrolytes from sc leroglucan is described. Polycarboxylates were synthesised through nucleoph ilic substitution with chloroacetic acid or through a selective 2,2,6,6-tet ramethyl-1-peridinyloxy (TEMPO)-mediated oxidation of the primary alcohol g roups. Amine groups were introduced through nucleophilic substitution with 2-chloroethylamine or 3-chloropropylamine. Reaction conditions were varied to obtain insight into the influence of variables on the degree of substitu tion. The conformational behaviour of the obtained polyelectrolytes was stu died as a function of pH, temperature and solvent. For the products with a low degree of modification, evidence of an ordered conformation was found, whereas the polymers with a higher degree of modification behaved as random coils ill solution. The negatively charged polymers were reticulated using the Ugi four-component condensation, obtaining negatively charged hydrogel s. The positively charged polymers were reticulated using diethyl squarate (3,4-diethoxy-3-cyclobutene-1,2-dion, DES) to obtain positively charged hyd rogels. (C) 2000 Elsevier Science Ltd. All rights reserved.