Investigation Of Multi-Functional Polyurethane And Polyester With Shape Memory Properties For Application In Biomaterials

With the development of science and technology, the application of conventional thermal-induced shape memory polymers (SMPs) is limited and in the face of the ever-increasing demands on the using of intelligent medical materials due to the fact that they can only remember one temporary shape. In recent years, the multi-stimuli sensitive and multi-functional shape memory polymers become a hot topic of intelligent materials due to they could meet the demands of intelligent for shape memory polymers.In this dissertation, polyurethane and polyester with well biocompatibility as polymeric matrix. We designed and prepared multi-stimuli sensitive SMPs, dual-and triple SMPs, temperature memory polymer and multi-functional SMPs. And we discussed all the intelligent polymers from their structure, thermodynamics, mechanism and cytotoxicity.Firstly, a system of photo-induced and thermal-induced shape memory polyurethane was prepared in chapter two. Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR) and ultraviolet-visible absorption spectrum (UV-Vis) confirmed the chemical structure of the polyurethane. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results indicated that the polyurethane possessed good shape memory effect(SME), and the transition temperature of polyurethane could be adjusted to body temperature by alter the proportion of the soft and hard segments. Lastly, the polyurethane possessed good photo-induced and thermal-induced shape fixity ratio and shape recovery ratio by the investigation of the photo-and thermal-induced shape memory process.Based on the property of cinnamon groups of photo-induced shape memory polyurethane, we investigated the shape memory effect of photo cross-linked polyurethane (TSMPU) by 365 nm ultraviolet light in chapter three. DSC and DMA results indicated that the TSMPU possessed two transition temperature regions, one is owing to the melting transition of soft segments, and the other belongs to the glass transition temperature region of crosslinked hard segments. Then, we investigated the triple shape memory effect of TSMPU by DMA, and the results of DMA indicated that the crosslinked polymer showed good triple shape memory effect, and we analysed the triple shape memory mechanism from the structure of TSMPU. Lastly, Alamar blue assay showed that the polymer has good non-cytotoxicity and can be potentially used in biomaterial devices.Then, in chapter four we investigated the water-and thermal-induced shape memory effect of poly (vinyl akohol)-graft-polyurethane (PVA-PU). DSC, DMA and swelling experiments were carried out to find that the PVA-PU possessed good water-induced SME and thermal-induced SME, moreover, we studied the mechanism of the water-induced SME: the transition temperature of polymer decreased when it swelled in water, so the water-induced SMP is a kind of indirect thermal-induced SMPs. In addition, the results of thermodynamics and structure of PVA-PU indicated the polymer possessed a good triple shape memory effect, and 35℃ and 55℃ were selected for the transition temperature in the triple shape memory process. The DMA results indicated that the polymer possessed good triple SME. Lastly, the cell experiment confirmed that the polymer has good non-cytotoxicity.In chapter five, we synthesized a kind of star poly cross-linked star poly(ε-caprolactone)-poly(ethylene glycol) (c-4sPCL-PEG) with an excellent temperature memory effect (TME) by photo-crosslinking of cinnamon group terminated four arms poly(ε-caprolactone) (4sPCL-CA) and cinnamon group terminated poly(ethylene glycol) (PEG-CA) through the irradiation of 365 nm UV light. The results of DSC, DMA and swelling experiment confirmed the molecular weight of PCL, optimal proportion of PCL and PEG, the crosslinked time. Moreover, those results indicated that the c-PCL-PEG possessed a widely transition temperature and an appropriate crystalline. All the results indicated that the crosslinked polymer possessed a good TME. And then 37℃ and 45℃ were selected for the investigation of the TME. The DMA results showed that there is a maximum instantaneous strain recovery rate when it reaches the deformed temperature during the recovery process. Lastly, the mechanism of the TME was studied by X-ray diffractometry in different temperature and two-dimensional infrared correlation spectroscopy.Finally, we designed and prepared a polyester (PIE) containing isonicotinic group in chapter six. And the SME of metal coordination polymers was investigated. Firstly, Ag coordinated PIE was prepared, the results of DMA indicated that Ag-PIE possessed a larger storage modulus than PIE, and accounted for the good shape memory property of Ag-PIE. Then, the antibacterial properties of the Ag-PIE were investigated by coating method and ELIS A testing. The results indicated that the Ag-PIE possessed good antibacterial property, and the released amount of Ag ions in 37℃ phosphate buffer solution (PBS) was studied by inductivelycoupledplasmamassspectrometry (ICP), after the release of 24 h, the released amount of Ag ions is 0.91 ppm, and far below the safe concentration 10 ppm). Lastly, the cells experiment confirmed that the material has good non-cytotoxicity.In addition, the shape memory and self-healing properties of the cupper coordinated PIE (Cu-PIE) were investigated in the last chapter. The Cu-PIE showed that the more coordinated amount and less released amount than Ag-PIE in 37℃ PBS for 24 h from the results of Atomic absorption spectroscopy(AAS) and ICP. The Thermogravimetric analysis (TG) and DMA results indicated that the Cu-PIE had better thermal stability than Ag-PIE. Lastly, the self-healing property of Cu-PIE was studied by cutting-off method. The results indicated that the Cu-PIE with 5% water content emerged a good self-healing property at 45℃, and we analyzed the mechanism of the self-healing property through the molecular structure.