Effect of polymer architecture and hard/soft segment ratio on the surface morphology and mechanical properties of polyurethane films for potential orthodontic treatment

In this study, polyurethane (PU) films are prepared by using 1,4-butanediol and trimethylolpropane as chain extender and crosslinking agent, respectively. A series of prepolymers are synthesized by varying the feeding molar ratios of methylene diisocyanate to polytetramethylene ether glycol, which are hard and soft segments, respectively. The influence of polymer architecture, chemical composition, and artificial saliva treatment on the surface morphology and mechanical strength of PU films are studied. The crosslinking polymer architecture and higher content of hard segment correlates with enhanced tensile strength and less decrease of tensile strength in the condition of artificial saliva, but reduced elongation at break. The in vitro cytotoxicity study demonstrates that PU films have excellent cytocompatibility.