Isoprenecarboxylic acid (ICA-H), available from glucose via one of its major metabolites mevalonate, has been converted to cross-linked networks by radical polymerization. Monomer feeds comprising various ratios of ICA-H and its sodium salt (ICA-Na) were used to give hydrogels that show attractive performance in comparison with (nonbioderived) poly(acrylate) hydrogels. In particular, these new materials show increasing levels of water uptake (i.e., swelling ratio) across the entire range of ionization (10-90 %Na). This behavior is attributed to the larger distance between carboxylate moieties in the hydrogels, a feature that reduces the average amount of charge repulsion between proximal sodium carboxylate ion pairs (counterion condensation).
Bibliographical noteFunding Information:
The authors appreciate guidance provided by Professor Ronald A. Siegel, University of Minnesota. Financial support for this research was provided by (i) the Center for Sustainable Polymers at the University of Minnesota, an NSF-supported Center for Chemical Innovation (CHE-1413862), and (ii) University of Minnesota Doctoral Dissertation Fellowship. Some of the NMR data were recorded on an instrument purchased with support of the NIH Shared Instrumentation Grant program (S10OD011952). SEM imaging was performed in the Characterization Facility at the University of Minnesota, which receives partial support from the NSF through the MRSEC program.