Semi-interpenetrating polymer network hydrogels between polydimethylsiloxane/polyethylene glycol and chitosan

Synthesis and properties of semi-interpenetrating polymer networks (semi-IPNs) based on polydimethylsiloxane (PDMS)/poly(ethylene glycol) (PEG)-modified chitosan were studied. 1–20 wt% of PDMS or PEG was interpenetrated into chitosan hydrogels having 10 wt% of hexamethylene-1,6-di-(aminocarboxysulfonate) (HDA) as a water-soluble crosslinker. PDMS prepolymer was synthesized via acid-catalyzed ring-opening polymerization of octamethylcyclotetrasiloxane (D4), followed by hydrosilylation reaction with allyl alcohol to obtain hydroxyl-terminated PDMS. Effect of PDMS/PEG contents (1–20 wt%) and their molecular weights (2000 and 8000 g/mol) in chitosan semi-IPNs on percent crosslinking, water swelling properties, thermal stability, surface properties, water vapor permeability and tensile properties were investigated. Percent crosslinking of the PDMS/PEG-chitosan semi-IPNs ranged between 42% and 74% depending on molecular weight and percent of PDMS/PEG added. PDMS and PEG in the semi-IPNs enhanced water swellability and water vapor permeability of the films. Also, PDMS/PEG in chitosan semi-IPNs enhanced their thermal stability and surface hydrophobicity, while their tensile properties were sacrificed.