Contents lists available at ScienceDirect Materials Science & Engineering C journal homepage: www.elsevier.com/locate/msec Study of chemical, physico-mechanical and biological properties of 4,4′- methylenebis(cyclohexyl isocyanate)-based polyurethane films Piotr Król a, ⁎ , Łukasz Uram a , Bożena Król a , Kinga Pielichowska b , Małgorzata Walczak a a Department of Polymer and Biopolymer, Faculty of Chemistry, Rzeszów University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland b Department of Biomaterials, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland ARTICLE INFO Keywords: Polyurethane films H 12 MDI Chemical structure Thermal properties Surface properties Cytotoxicity ABSTRACT Polyurethane films were obtained in the solvent-free cycloaliphatic polyaddition process of 4,4′-methylenebis (cyclohexyl isocyanate), poly(ε-caprolactone) diol or poly(oxytetramethylene) glycol and 1,4-butanediol. Chemical structures of the polymers were confirmed by FTIR, NMR and GPC methods. Their surface, thermal and mechanical properties have been evaluated. Results of biological studies with polyurethane films as potential biomaterials for medical applications revealed their mild cytotoxicity against normal human fibroblasts (BJ) and immortalized keratinocytes (HaCaT). Statement of significance: The research is relevant for the potential uses of polyurethane films made from com- mercial raw materials as general medical supplies. 1. Introduction Polyurethanes (PUs) are traditionally used as foams, elastomers, films, coatings, adhesives and varnishes, and in recent years they have also been used as biomaterials [1,2]. This is due to their good me- chanical and surface properties, hydrolytic resistance to bacterial en- zymes, low cytotoxicity and good hemocompatibility [3]. These fea- tures are essential for PU applications as orthopedic scaffolds, coatings used to regenerate soft tissues and vascular prosthetics, and nerve re- generation [4,5]. Nevertheless, technical application of polyurethanes, where cytotoxicity issues are not crucial is also known. Examples in- clude medical equipment requiring sterilization, protective coatings of medical devices, polyurethane coatings coming into contact with food and controlled dosing drugs [6–8]. It is already known, that the type of isocyanate raw material from which PUs are produced is crucial for tissue biocompatibility, due to toxic action of amine derivatives of isocyanates formed even in trace amounts during their spontaneous hydrolysis in the biological en- vironment. Therefore, despite the poorer mechanical properties, PUs obtained from aliphatic diisocyanates such as HDI, H12MDI or TMDI are more favorable in biomedical applications than widely used PUs synthesized from the most popular aromatic diisocyanates as MDI and TDI [9,10]. For this reason, in recent years, polyurethane biomaterials have been produced using L-lysine diisocyanate, whose amine precursor and potential product of hydrolytic degradation is also important amino acid for protein biosynthesis [11,12]. However, poly (ε-caprolactone) diols are particularly important among many polyol raw materials. The reduced hydrolytic stability typical for polyester PUs is here compen- sated by the hydrophobic properties, resulting from the presence of numerous e(CH 2 ) 5 e groups [13]. PU synthesis conditions also play an important role. In order to reduce the formation of a low molecular weight products, solution polymerization and subsequent precipitation are preferred. The most commonly used bulk polymerization can lead to the formation of PUs with wide molecular weight distributions [14]. In order to separate the high molecular weight PU, it is preferred to its dissolve and isolate the high molecular weight fraction by precipitation from the solution a suitable non-solvent and isolation by centrifugation. It is necessary to remove small molecule substances formed in this process, which may have additionally toxic effects on the human body. For this reason, it is necessary to control the distribution of molecular weight. The aim of this study was to evaluate the cytotoxicity of PUs with potential biomedical application, synthesized using diisocyanate H 12 MDI, poly(ε-caprolactone) diol and/or poly(oxytetramethylene) glycol. PUs play an important role in many medical applications and their cytotoxicity must be examined in relation to their specific che- mical composition and method of synthesis. In this work we focused on determining the degree of toxicity of PUs against two different types of human skin cells - fibroblasts and https://doi.org/10.1016/j.msec.2018.07.082 Received 20 November 2017; Received in revised form 5 July 2018; Accepted 30 July 2018 ⁎ Corresponding author at: Chemical Faculty, Rzeszow University of Technology, 6 Powstańców Warszawy Street, 35-959 Rzeszow, Poland. E-mail address: pkrol@prz.edu.pl (P. Król). Materials Science & Engineering C 93 (2018) 483–494 Available online 10 August 2018 0928-4931/ © 2018 Published by Elsevier B.V. T