Starch Phosphate Hydrogels. Part I: Synthesis by Mono‐phosphorylation and Cross‐linking of Starch

Starch‐based hydrogels were synthesized by cross‐linking monostarch monophosphates (MSMP) with different di‐ and tricarboxylic acids such as succinic, adipic or citric acid. Phosphorylation of starch was performed in a semi‐dry process using a mixture of primary and secondary sodium phosphates. The phosphorus content and degree of substitution of phosphate groups (DS P ) of the resulting MSMP were determined using a photometric method. For structural characterization of starch phosphates 31 P NMR was used. Investigations showed that MSMP hydrogels were strong water absorbing polymer networks with a free swelling capacity (FSC) of up to 185 g water / g dry hydrogel.