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

Polyurethanes based on poly(epsilon-caprolactone) (PCL) (750-2800g/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 degreesC 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). (C) 2004 Elsevier Ltd. All rights reserved.</p

Tissue ingrowth polymers and degradation of two biodegradable porous with different porosities and pore sizes

Commonly, spontaneous repair of lesions in the avascular zone of the knee meniscus does not occur. By implanting a porous polymer scaffold in a knee meniscus defect, the lesion is connected with the abundantly vascularized knee capsule and heating can be realized. Ingrowth of fibrovascular tissue and thus healing capacity depended on porosity, pore sizes and compression modulus of the implant, To study the lesion healing potential, two series of porous polyurethanes based on 50/50 epsilon-caprolactone/L-lactide with different porosities and pore sizes were implanted subcutaneously in rats. Also, in vitro degradation of the polymer was evaluated. The porous polymers with the higher porosity, more interconnected macropores, and interconnecting micropores of at least 30 mum showed complete ingrowth of tissue before degradation had started. In implants with the lower macro-porosity and micropores of 10-15 mum degradation of the polymer occurred before ingrowth was completed. Directly after implantation and later during degradation of the polymer, PMN cells infiltrated the implant. In between these phases the foreign body reaction remained restricted to macrophages and giant cells. We can conclude that both foams seemed not suited for implantation in meniscal reconstruction while either full ingrowth of tissue was not realized before polymer degradation started or the compression modulus was too low, Therefore, foams must be developed with a higher compression modulus and more connections with sufficient diameter between the macropores. (C) 2002 Elsevier Science Ltd. All rights reserved

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

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/m2.