Synthesis and property of polyurethane elastomer for biomedical applications based on nonaromatic isocyanates, polyesters, and ethylene glycol

Piotr Król,Bożena Król,Łukasz Uram,Kinga Pielichowska,Małgorzata Walczak,Marta Sochacka-Piętal

doi:10.1007/s00396-020-04667-8

Piotr Król, Bożena Król + Show 4 more

Open Access

https://doi.org/10.1007/s00396-020-04667-8

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Abstract

Polyurethane (PU) elastomers were synthesized by the reaction of HDI or IPDI diisocyanates and poly(ε-caprolactone) (PCL or poly(ethylene adipate) (PA) diols and ethylene glycol as a polymer chain extender. IR, 1H, and 13C NMR spectroscopy and X-ray analysis were used for the structural analysis of the formed films. The molecular weight distribution was examined by GPC chromatography. Based on the measured contact angles, free surface energy parameters were calculated. The obtained results were analyzed for the possible use of these polyurethanes as biomaterials. The most promising in this respect was PU-3, which was synthesized from IPDI and PCL. This was due to its high molecular weight of approximately 90,000, the presence of a crystalline phase, and the relatively high hydrophobicity, with a SEP value below 25 mJ/m2. These films showed a good resistance to hydrolysis during incubation in Baxter physiological saline during 6 weeks. Both Gram-positive (Bacillus sp.) and Gram-negative (Pseudomonas sp.) types of bacterial strains were used to test the biodegradation property. Synthesized PUs are biodegradable and showed moderate or even mild cytotoxicity against human normal fibroblasts (BJ) and immortalized keratinocytes (HaCaT), estimated with direct contact assay. The most biocompatible was PU-3 film, which revealed rather mild reactivity against both cell lines, and the least was PU-2 film, synthesized from HDI and PA (severe toxicity for HaCaTs).

Highlights

Polyurethanes (PU) are traditionally used as foams, elastomers, coatings, adhesives, and varnishes in some technical applications, but in recent years, they have been usedPreliminary results were presented during the 7th International Seminar on Modern Polymeric Materials for Environmental Applications, May 15–17, 2019, in Krakow, MPM 2019 conference proceedings: P
The BD chain extender, used in a previous work [14], has been replaced by ethylene glycol (EG), which should increase the film’s hydrophilicity, and it is favorably beneficial for improving the mechanical properties of the obtained films and at the same time maintaining their good hydrolytic resistance
Dehydrated PCL or PA polyester heated to liquid form was dosed at 80 °C during 1 h to the appropriate amount of HDI or IPDI diisocyanate; 0.01 wt% DBTL catalyst was added to the polyester immediately before synthesis

Summary

Introduction

Polyurethanes (PU) are traditionally used as foams, elastomers, coatings, adhesives, and varnishes in some technical applications, but in recent years, they have been used. Modified PUs can be valuable and used as prospective materials in the biomedical field, e.g., as thin protective layers [11,12,13] They need to fulfill additional requirements concerning hydrolytic resistance, antibacterial properties, and above all, no cytotoxicity. Polyurethanes were obtained using two nonaromatic diisocyanates (HDI and IPDI) and two kinds polyester polyols (PCL and PA) In these syntheses, the BD chain extender, used in a previous work [14], has been replaced by ethylene glycol (EG), which should increase the film’s hydrophilicity, and it is favorably beneficial for improving the mechanical properties of the obtained films and at the same time maintaining their good hydrolytic resistance. The obtained results are the step toward developing new polyurethane materials for medical applications

Reagents and methods

Results and discussion

Compliance with ethical standards

Conclusion