Novel hydrogels based on a high-molar-mass water-soluble dimethacrylate monomer

S. V. ASMUSSE; M. L. GOMEZ; C. I. VALLO

POLYMER INTERNATIONAL

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2018 vol. 67 p. 606 - 614

0959-8103

This report describes the preparation and swelling behaviour of novel hydrogels based on a water soluble dimethacrylate monomer (EBisEMA); which is characterized by a relatively high molar mass (Mn ~1700 g mol-1) and contains a high proportion of aliphatic ether bonds in its structure. This feature results in moderately crosslinked and flexible polymer networks. EBisEMA photopolymerized in bulk absorbs 68 wt. % water after 24 h immersion while the water uptake of EBisEMA photopolymerized in aqueous solution (0.5 g EBisEMA/ml) is 104 wt. % after 48 h immersion. Thiol-methacrylate hydrogels were prepared by visible light photopolymerization of EBisEMA with a tetrafunctional thiol (PETMP) at different EBisEMA: PETMP molar ratios. These hydrogels contained unreacted thiol groups because of a faster homopolymerization reaction of EBisEMA. Hydrogels were also prepared in bulk by propylamine catalysed Michael addition reaction. No significant differences in swelling were observed between specimens prepared from pure EBisEMA and photocured EBisEMA/PETMP specimens. Conversely, a marked increase in water uptake (110 wt. %) was seen in the EBisEMA-PETMP hydrogels prepared by the Michael addition reaction catalysed by propylamine. These trends are explained in terms of a balance between the mass fraction of hydrophilic groups and the crosslinking density of the network. EBisEMA/PETMP hydrogels formulated with thiol in excess showed a marked tendency to adhere to a variety of substrates, including metals, glass, paper and skin. This feature makes them especially attractive in applications for which adhesion is particularly critical. pH sensitive hydrogels were prepared by copolymerization of EBisEMA with dimethylaminoethylmethacrylate (DMAEMA). Swelling studies showed that, as a result of the high molar mass of EBisEMA, the pH sensitivity was evident at EBisEMA:DMAEMA molar ratios lower than 0.2:0.8.