Uncatalyzed synthesis, thermal and mechanical properties of polyurethanes based on poly( ε -caprolactone) and 1,4-butane diisocyanate with uniform hard segment

• Published in: Biomaterials 2005-07, Vol.26 (20), p.4219-4228
• Main Authors: Heijkants, Ralf G.J.C., Calck, Ralph V. van, van Tienen, Tony G., de Groot, Jacqueline H., Buma, Pieter, Pennings, Albert J., Veth, Reen P.H., Schouten, Arend Jan
• Format: Article
• Language: English
• Subjects: Absorbable Implants; Biocompatible Materials - analysis; Biocompatible Materials - chemistry; Butanes - analysis; Butanes - chemistry; Catalysis; Compressive Strength; Degradation; Elasticity; Elastomer; Hardness; Materials Testing; Molecular Weight; Nitriles - analysis; Nitriles - chemistry; Polycaprolactone; Polyesters - analysis; Polyesters - chemistry; Polyurethane; Scaffold; Stress, Mechanical; Surface Properties; Temperature; Transition Temperature
• ISSN: 0142-9612; 1878-5905
• DOI: 10.1016/j.biomaterials.2004.11.005

Polyurethanes based on poly( ε -caprolactone) (PCL) (750–2800 g/mol) and 1,4-butane diisocyanate (BDI) with different soft segment lengths and constant uniform hard segment length were synthesized in absence of catalysts for the production of a degradable meniscus scaffold. First the polyesterdiols were endcapped with BDI yielding a macrodiisocyanate with a minimal amount of side reactions and a functionality of 2.0. Subsequently, the macrodiisocyanates were extended with 1,4-butanediol in order to obtain the corresponding polyurethane. The polyurethanes had molecular weights between 78 and 160 kg/mol. Above molar masses of 1900 g/mol of the polyesterdiol crystalline PCL was found while the hard segment showed an increase in melting point from 78 to 122 °C with increasing hard segment content. It was estimated that the percentage crystallinity of the hard segment varied between 92 and 26%. The Young's modulus varied between 30 and 264 MPa, the strain at break varied between 870 and 1200% and tear strengths varied between 97 and 237 kJ/m 2.