Trimethylene Carbonate and ϵ-Caprolactone Based (co)Polymer Networks: Mechanical Properties and Enzymatic Degradation

Abstract

High molecular weight trimethylene carbonate (TMC) and epsilon-caprolactone (CL) (co)polymers were synthesized. Melt pressed (co)polymer films were cross-linked by gamma irradiation (25 kGy or 50 kGy) in vacuum, yielding gel fractions of up to 70%. The effects of copolymer composition and irradiation dose on the cytotoxicity, surface properties, degradation behavior, and mechanical and thermal properties of these (co)polymers and networks were investigated. Upon incubation with cell culture medium containing extracts of (co)polymers and networks, human foreskin fibroblasts remained viable. For all (co)polymers and networks, cell viabilities were determined to be higher than 94%. The formed networks were flexible, with elastic moduli ranging from 2.7 to 5.8 MPa. Moreover, these form-stable networks were creep resistant under dynamic conditions. The permanent deformation after 2 h relaxation was as low as 1% after elongating to 50% strain for 20 times. The in vitro enzymatic erosion behavior of these hydrophobic (co)polymers and networks was investigated using aqueous lipase solutions. The erosion rates in lipase solution could be tuned linearly from 0.8 to 45 mg/(cm (2) x day) by varying the TMC to CL ratio and the irradiation dose. The copolymers and networks degraded essentially by a surface erosion mechanism.

Hydrolytic and enzymatic degradation of a poly(ε-caprolactone) network

“…Thermal, mechanical, and morphological characteristics as well as the degradability of the PCL networks were studied. Bat et al [15] developed a method to obtain formstable and elastic networks upon gamma irradiation based on high molecular weight (co)polymers of trimethylene carbonate and (ε-caprolactone). The in vitro enzymatic erosion behavior of these hydrophobic networks was studied using aqueous lipase solutions.…”

Resorbable elastomeric networks prepared by photocrosslinking of high-molecular-weight poly(trimethylene carbonate) with photoinitiators and poly(trimethylene carbonate) macromers as crosslinking aids

“…Chemically crosslinked networks have been obtained by ring-opening polymerization [10][11][12][13], polycondensation [14,15], or heat-induced [16,17] or light-induced (photocrosslinking) [18][19][20][21][22][23][24] free radical polymerization reactions. High energy irradiation of linear polymers can also lead to crosslinking [25,26]. To meet the specific requirements of different tissue engineering or controlled release applications, the development of resorbable elastomers with tunable properties is essential.…”

Advanced microstructures based on poly(trimethylene carbonate) : microfabrication and stereolithography

“…[65,[98][99][100] In vivo, linear high molecular weight PTMC films were found to degrade in 3 weeks. [99] Upon crosslinking by gamma irradiation doses of 25 to 100 kGy, PTMC network films eroded upon subcutaneous implantation in rats within 4 weeks.…”

“…The degradation rates of linear polytrimethylene carbonate polymers and networks can be further tuned by copolymerization of trimethylene carbonate with -caprolactone or D,L-lactide. [93,[98][99] With regard to applications in tissue engineering, porous structures have been prepared from high molecular weight PTMC. [102][103][104] By phase separation micromolding, microstructured porous PTMC films with pore sizes between 2-20 m and porosities of up to 31 % were obtained.…”