| 摘要: | 聚羥基烷酯（Polyhydroxyalkanote，PHA）是由微生物發酵生產出來的塑膠，有別於現在的石化合成塑膠。PHA具有許多之優點，同時符合「清潔生產」與「環保材料」的要求，因此在國內外引起學術界與工業界廣泛研究。至今，有將近三百種細菌被發現可製造出90種不同單元結構之PHA，其中最具代表性的是聚羥基丁酯(Polyhydroxybutyrate，PHB)，為大多數細菌所生產的PHA種類，不過PHB在生產及應用上碰到一些問題，包括了加工窗口窄、韌性偏低和價格昂貴。解決問題的方法有生產共聚合體以及摻合其他高分子，本計畫同時利用這兩個技術，將共聚合體聚(羥基丁酯-羥基己酯)(PHBHHx)摻合一柔軟性的聚醋酸乙烯酯(PVAc)高分子以增加材料的韌性和成膜性，同時能降低成本。將PHBHHx直接和PVAc以不同比例進行摻混，結果發現成膜性佳，所有不同組成的摻合體都呈現單一玻璃轉移溫度(Tg)，同時Tg隨著PVAc比例的增加而增加，證實PHBHHx和PVAc能夠相容，而且此摻合系統的Tg和組成之關係可以利用Gordon-Taylor方程式來描述。而在熱穩定性上，TGA測試結果顯示隨著PVAc組成的增加，PHBHHx的熱裂解溫度隨之提高，意即加工窗口溫度隨之增寬，有利加工。另外隨著PVAc組成的增加，摻合體的損耗正切峰面積亦隨之增加，顯示材料的韌性因為添加了PVAc而增加。另外在評估作為組織工程材料上，為了可以製作出孔徑小於100um的人工支架，又不破壞材料本身，我們選擇以準分子雷射加工製作，利用合適的參數即可製作孔徑為50與20um的2D 人工支架。
Polyhydroxyalkanoate (PHA), produced from the fermentation of microbial organisms, has many advantages and meets all the requirements of the "environmentally friendly materials" and "green process". Therefore, it has drawn great interest and studies from the academics and industries. Nowadays, three hundred kinds of bacterial have been found that can product PHA and 90 different compositions are identified in the structure unit of PHA. Among them, polyhydroxybutyrate (PHB) is most widely known and can be produced by most bacterial. However, the cost of PHB is relatively high compared with most synthetic polymers, and PHB is intrinsically a brittle material with a low elongation at break. Two methods can be used to solve these problems, namely, copolymerization and blending. In this study, these two methods were adopted together, i.e., a copolymer PHBHHx was blended with a flexible poly(vinyl acetate) (PVAc). In this way, hopefully, the toughness and film formability would be increased. In addition, the cost can be lower due to the addition of cheaper PVAc. It was found that the produced blends had good film formability and all the blends exhibited a single glass transition temperature (Tg), proving they were miscible. Another advantage was found that the thermal stability of PHBHHx component was increased with an increase in the composition of PVAc. This is beneficial to the processing of PHBHHx blends. In addition, the toughness and the elongation at break were also found to be increased with increasing the composition of PVAc. For the applications in biomedical engineering, we chose excimer laser to produce scaffold having diameters smaller than 100um. With suitable parameters, we could produce scaffold with diameter exactly at 50um and 20um. |
