Study On Biodegradable HO-PDLLA-OH Polyurethane And Montmorillonite Nanocomposites

A new kind of block copolymers were made from the molecular designing, using D,L-lactide, 1,6-hexamethylene diisocyanate, 1,4-butanediol and 1,4-butanediamine. These block copolymers with strong hydrophilicity, thermosensitive, controllable acidity of degradation, is a kind of biodegradable poly(D,L-lactic acid)-polyurethane. Furthermore, preparing poly(D,L-lactic acid)-polyurethane/montmorillonite nano- composites using solvent method. These products were characterized by fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance spectrometer (NMR), differential scanning calorimeter (DSC), X-ray diffractometer (XRD) and the classical chemical analysis to explore the structures and the properties. The main works and conclusions are included as follows:1. HO-PDLLA-OH was synthesized by melt ring-opening polymerization of D,L-lactide and butanediol with Sn(Oct)2 as a catalyst. The results of the reactive time and the reactive ratio of D,L-lactide and butanediol on the molecular weight, structures and properties were discussed.①FTIR, NMR, and chemical analysis showed that HO-PDLLA-OH was successfully synthesized as a copolymer from D,L-lacide and butanediol.②As the reactive ratio of D,L-lactide and butanediol is 25:1, the Mw of product is 3600; and the molecular distribution of this copolymer is narrow when the reactive time is 24h.③The glass transition temperature of HO-PDLLA-OH by DSC was 36.33℃, whose molecular weight is 3600.2. A kind of linear copolymer from HO-PDLLA-OH, HDI and BDA was made in solution with Sn(Oct)2 as a catalyst. The reactive activity of HO-PDLLA-OH and HDI from the water content of reaction system, the ratio of catalyst and the reactive temperature were discussed, and in exploring the structures and the properties of these products.①The water content of reaction system was far less than that possibly to consume HDI after the non-aqueous treatment.②FTIR, NMR, and chemical analysis claimed that the copolymer is a type of poly(D,L-lactic acid)-polyurethane.③The optimized reactive condition of preparing the product were that: the ratio of catalyst and HO-PDLLA-OH was 0.75%, the reactive temperature was 75℃.④In order to obtain the preferable thermosensitive material, the ratio of HO-PDLLA-OH, HDI and BDA was 1:1.1:0.1. The glass transition temperature of the product is 37.68℃, approached the normal temperature of human.3. The properties of HO-PDLLA-OH and poly(D,L-lactic acid)-polyurethane material based substrate films were investigated ,including surface wettability and biodegradation. The surface wettability evaluation was based on static water contact angle (sessile drop contact angle) and water adsorption ratio, while the actual degradation experimentation in vitro was used to estimate the biodegradation behavior. The results follows:①Due to the introduction of BDA, increased the content of NH, enhance the force between the surface of material and water molecular, improved the surface wettability.②Owing to the introduction of BDA, decreased obviously the acid catalyzed auto-accelerating degradation of the product.4. The poly(D,L-lactic acid)-polyurethane/montmorillonite nanocomposites was successfully prepared by HO-PDLLA-OH, MMT and HDI in solution with Sn(Oct)2 as a catalyst, and in exploring the structures and the properties of the product①A new kind of poly(D,L-lactic acid)-polyurethane/montmorillonite nano- composites was prepared.②Increased the organic compatibility of layered montmorillonite by means of nanocomposites.