Shape-Memory Bionanocomposites Based on Chitin Nanocrystals and Thermoplastic Polyurethane with a Highly Crystalline Soft Segment

• Published in: Biomacromolecules 2013-12, Vol.14 (12), p.4475-4482
• Main Authors: Saralegi, Ainara, Fernandes, Susana C. M, Alonso-Varona, Ana, Palomares, Teodoro, Foster, E. Johan, Weder, Christoph, Eceiza, Arantxa, Corcuera, Maria Angeles
• Format: Article
• Language: English
• Subjects: Animals; Applied sciences; Biocompatible Materials - chemistry; Biocompatible Materials - toxicity; Calorimetry, Differential Scanning; Cell Line; Cell Survival - drug effects; Chemical Sciences; Chitin - analogs & derivatives; Chitin - chemistry; Composites; Elastic Modulus; Exact sciences and technology; Fibroblasts - drug effects; Fibroblasts - physiology; Forms of application and semi-finished materials; Materials Testing; Mice; Microscopy, Atomic Force; Nanocomposites - chemistry; Nanocomposites - toxicity; Nanocomposites - ultrastructure; Nanoparticles - chemistry; Nanoparticles - toxicity; Nanoparticles - ultrastructure; Polymer industry, paints, wood; Polymers; Polyurethanes - chemistry; Technology of polymers; Transition Temperature
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm401385c

Shape-memory bionanocomposites based on a naturally sourced segmented thermoplastic polyurethane and chitin nanocrystals were synthesized, and their mechanical properties and thermally activated shape-memory behavior were studied. The chitin nanocrystals were incorporated during the synthesis of the prepolymer made from a castor oil-based difunctional polyol and hexamethylene diisocyanate. The polymerization was completed by addition of propanediol, as a corn-sugar based chain extender, bringing the weight content of components from renewable resources to >60%. Thermal analysis of the bionanocomposites revealed a phase-separated morphology, which is composed of soft and hard domains, which bestow the material with two melting transitions at 60 and 125 °C, that are exploitable for a shape memory effect. The soft segment is responsible for temporary shape fixing, while the hard segment crystallites are responsible for the permanent shape. The introduction of small amounts (0.25–2 wt %) of chitin nanocrystals was found to increase the crystallinity of the hard segment by way of nucleation, which in turn improves the shape recovery considerably. The thermally activated shape-memory behavior of the synthesized bionancomposites is exploitable with a programming and release temperature of 60 °C. The materials display good in vitro cell response, as shown by short-term cytotoxicity assays, and therefore, the bionanocomposites appear to be potentially useful for biomedical applications.