การเตรียมและวิเคราะห์พอลิยูรีเทนจากยางธรรมชาติที่มีหมู่ปลายเป็นไฮดรอกซิลสำหรับประยุกต์ใช้ทางชีวการแพทย์

Abstract

This research focused on preparation and characterization of the renewable and ecofriendly hydroxyl terminated natural rubber (HTNR). The appropriate molecular weight of HTNR for synthesis of HTNR based polyurethane (PU-HTNR) was preliminarily studied by testing different molecular weight polyethylene glycols (PEG) as models of diol molecules. The effect of the PEG molecular weight (about 200, 600, or 2000 g/mol) on the properties of PEG based polyurethane (PU-PEG) was studied. The results show that, among the cases tested, the PU-PEG film synthesized from PEG600 (about 14 repeating units) provided films with good tensile strength and elongation at break. Therefore, HTNR was synthesized with about 14 repeating units (600 g/mol) and aliphatic diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate, H12MDI) were used as the monomers in the synthesis of HTNR based polyurethane (PU-HTNR). Also, 1,4-butanediol (BDO) was used as the chain extender to improve the mechanical properties of the PU-HTNR. The molar proportions (H12MDI : HTNR: BDO) were controlled at (1.05: 0.50 0.50). The synthesized PU-HTNR films were intended for biomedical applications, therefore the antimicrobial activity of the PU-HTNR films had to be improved by adding 0.5 wt% of three alternative antimicrobial substances: silver nanoparticles (AgNPs), titanium nanoparticles (TiO2), and benzoic acid (BA). The effects of the antimicrobial substances on the mechanical, morphological, and thermal properties as well as on the antimicrobial activity against both gram-positive and gram-negative bacteria of the PU-HTNR composite films were studied and are reported. The results show that the PU-HTNR-BA composite film provides good transparency and good tensile strength properties (12 MPa and 278%) as well as good antimicrobial activity, and appears to be the most suitable among the choices tested for biomedical applications.