title: Properties of shape memory polyurethane used as a low-temperature thermoplastic biomedical orthotic material: influence of hard segment content.
abstract: A series of PCL-based shape memory polyurethanes was synthesized via bulk pre-polymerization. Their thermal, mechanical properties, shape memory properties, softening and hardening processes were investigated by the experimental approach and made comparison with a commercially available orthotic material. The cytotoxicity of the low-temperature thermoplastic polyurethane was tested. The results suggest that the soft segment phase of the shape memory polyurethanes has a melting transition at about 36-46 degrees C, which makes them possible low-temperature thermoplastic materials. The hard segment phase has a two-fold effect on the shape memory polyurethane as a low-temperature thermoplastic orthotic material: increasing tensile mechanical strength at room temperature, which enables it to be used in circumstances where high tensile strength is required; and reducing low-temperature malleability and fixity ratio, which make it difficult to fabricate orthotic devices. To obtain a shape memory polyurethane with excellent low-temperature thermoplastic properties for orthopaedical surgical use, the hard segment content should not be above 22 wt%. At last, a prototype wrist orthosis was easily fabricated at 60 degrees C with hand using a shape memory polyurethane with 16 wt% hard segment content. Cytotoxicity tests indicate that the wrist orthotic material is not cytotoxic.
authors.affiliation: Institute of Textiles and Clothing, Hong Kong Polytechnic University, Kowloon, Hong Kong, P. R. China.
authors.forename: Qinghao
authors.initials: Q
authors.lastname: Meng
authors.forename: Jinlian
authors.initials: J
authors.lastname: Hu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001697:Biomedical and Dental Materials / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D002072:Butylene Glycols / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002460:Cell Line; D006244:Hardness; D017953:Isocyanates / Q000737:chemistry; D008422:Materials Testing / Q000379:methods*; D051379:Mice; D009989:Orthotic Devices; D011091:Polyesters / Q000737:chemistry; D011140:Polyurethanes / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D001559:Benzhydryl Compounds
chemical_list: D001672:Biocompatible Materials; D001697:Biomedical and Dental Materials; D002072:Butylene Glycols; D017953:Isocyanates; D011091:Polyesters; D011140:Polyurethanes; C016240:polycaprolactone; C039681:1,4-butanediol; C005969:4,4'-diphenylmethane diisocyanate; D001559:Benzhydryl Compounds