Preparation, Structure And Characteristics Of Novel Environment-friendly PPO-PCL Polyurethane Materials

In the past decades, biodegradable materials have been receiving increasingly more attention due to their potential applications in the fields such as biomedicalsand environmental protection. Among them, aliphatic polyesters are most attractive because of their excellent biocompatibility, processing properties and nontoxic degradation products which are finally converted to water and carbon dioxide.Poly(ε-caprolactone)(PCL) has been one of the degradable aliphatic polyesters that attract the most attention of researchers. However, PCLis brittle and of low melting point. Experiments show that the defects can be modified by copolymerizing PCL with other materials, and variable degradability and lower production costs can also be realized. In this work, random copolymers arecopolymerization ofpropylene oxide and ε-caprolactone(CL), triarm block are synthesized from domestic poly(propylene oxide) (PPO) together with PCL. Furthermore, novel environmental friendly degradable polyurethane (PU) materials were investigated. The main contents are as follows.(1) Fourier transform infrared (FTIR), gel permeation chromatography (GPC), proton nuclear magnetic resonance (]H-NMR), and 13C nuclear magnetic resonance (13C-NMR) were carried out to investigate the chemical structure and composition of the domestic novel polypropylene oxide-poly s-caprolactone(PPO-PCL) copolymer, which are synthesized by continuous process using double metal cyanide complex catalysts. The molecular structure of PPO-PCL copolymer are characterized and compared with the general PPO or PCL. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are measured to evaluate the thermal properties of the PPO-PCL copolymer, X-ray diffraction(XRD) are used to study the crystallization behavior of the PPO-PCL copolymer. Basic data are provided for further developing of new materials.(2)A series of thermoplastic polyurethane elastomer(TPU) based on PPO-PCL copolymer as soft segments,4,4’-diphenylmethane diisocyanate(MDI) as hard segments are synthesized. The microphase morphology of thermoplastic polyurethane elastomers are investigated by FTIR and DSC. The results show that both microphase mixing and microphase separation are presented in thermoplastic polyurethane elastomer between the hard segments and the soft segments. The mechanical tests show that the elongation at breakof TPU made from random copolymer is2200%, better than those of general polyurethane elastomer.(3)The alkaline hydrolytic degradation studies are performed in 10wt/vol%NaOH aqueous solution at 37℃ degree. In this case, the degradation rate of PPO-b-PCL based TPU (T-b) is faster than POCL-8 based TPU (T-8),20% and 5% respectively. The degradation process is studied by SEM and DSC. The degradationof PCLshow that small spherulititers are initially embedded inside the matrix, then reveal due to surface erosion of amorphous regions, and follow by bulk degradation of matrix and PCL crystals.