Post-synthesis modification of hydrogels. Total and partial rupture of crosslinks: Formation of aldehyde groups and re-crosslinking of cleaved hydrogels

Abstract

Post-synthesis modification of hydrogels is frequently used for chemical functionalization, immobilization of molecules or optimization of mechanical properties. In this work, novel gels were developed using a divinyl compound (+) N, N′-diallyltartramide (DAT) as a crosslinking agent. DAT possesses a vicinal diol and it was found that can be selectively cleaved by reaction with periodate, obtaining aldehydes as products. The treatment of the gels crosslinked only with DAT leads to complete digestion of the material, obtaining a liquid as a product. The cleavage reaction in gels crosslinked with two agents, one reactive with periodate and another inert, allows modification of the crosslinking degree, maintaining the state of the gel. The change in the mechanical properties of the gels due to periodate reaction was followed by rheological studies. Furthermore, the reaction of periodate with DAT, the aldehyde obtained as a product and its reactivity with adipic acid dihydrazide (ADH) was studied by nuclear magnetic resonance (NMR) spectroscopy.