Chitosan-based hydrogels: A new polymer-based system with excellent laser-damage threshold properties

Two types of chitosan hydrogel systems have been prepared that have a laser damage threshold (LDT) up to 35 times higher than commercial PMMA bulk mat erials. For these samples, the LDT increases with increasing water content. The mechanism of laser damage and the contribution of water to their high laser damage resistance have been examined. DSC measurements indicate water within the hydrogels exist in various states, each with different laser da mage resistance properties. These various states play a key role in determi ning the LDT by controlling the dissipation of laser energy and providing a mechanism for self-healing. This preliminary research shows that polymer h ydrogels have potential for high power laser applications because they comb ine good mechanical integrity due to the polymer frame and good energy diss ipation and healing characteristics due to the molecular mobility of water. These two traits allow for bulk shape-retaining films with high laser dama ge thresholds and potential reversibility in damage processes. (C) 1999 Joh n Wiley & Sons, Inc.