● Introduction 时态根据具体内容而定 ntroduction通常由以下几方面组成: 介绍研究背景、研究意义 Spiro orthocarbonates(SOCs) undergo double ring-opening polymerization with an expansion in volume[1-4. This unique property attracted the interest of polymer chemists [5, 6 Since the early 1960s, several synthetic, degradable polymer systems have been used as medical implant materials. Some widely investigated examples include poly (lactic acid)[1, 21, and polyorthoesters[6,71 Wichterle <*t>and Lim developed the first synthetic polymeric hydrogels based on hydroxyethyl methacrylate, for use as biomaterials [2]. Since then, there has been continuing interest in the development of novel types of hydrogel materials for biomedical application elopment of biodegra ing extensively promoted as one of the solutions to plastic waste disposal. Aliphatic polyesters are currently considered the most promising materials for the production of biodegradable plastics In recent years more and more technical fields have begun to use low-temperature plasm Important new applications have been found in biomedical techniques.. Good examples for novel techniques very near application and already applied are plasmas sterilization..This is important not only for polymeric biomaterials, but also for other materials. A lot of publications already exist in this field. It is well known that poly(N-isopropylacrylamide)(PNIPA) gel is thermally sensitive in its response to external temperature changes... PNIPA gel has attracted great interest and been extensively studied in the recent 20 years due to its applications in many fields, such as artificial muscle [2], on-off switches [3], and immobilization of enzymes[4], etc Very recently, Kricheldorf et al. have reported the synthesis of high molecular weight polycarbonate., although the detailed mechanism is not clear The anionic living polymerization technique yielding polymers with narrow molecular weight distributions has been widely adopted as a method to prepare homo and especially block copolymers Gene therapy is a relatively new technic the field of biotechnology and medicine that is attracting a lot of attention4 z Introduction 时态根据具体内容而定 Introduction 通常由以下几方面组成 一 介绍研究背景﹑ 研究意义 Spiro orthocarbonates (SOCs) undergo double ring-opening polymerization with an expansion in volume [1-4]. This unique property attracted the interest of polymer chemists [5,6]. Since the early 1960s, several synthetic, degradable polymer systems have been used as medical implant materials. Some widely investigated examples include poly(lactic acid) [1,2], …, …, and polyorthoesters [6,7]. Wichterle < 姓 > and Lim developed the first synthetic polymeric hydrogels based on hydroxyethyl methacrylate, for use as biomaterials [2]. Since then, there has been continuing interest in the development of novel types of hydrogel materials for biomedical application. Development of biodegradable plastics is being extensively promoted as one of the solutions to plastic waste disposal. Aliphatic polyesters are currently considered the most promising materials for the production of biodegradable plastics. In recent years more and more technical fields have begun to use low-temperature plasmas. Important new applications have been found in biomedical techniques….Good examples for novel techniques very near application and already applied are plasmas sterilization….This is important not only for polymeric biomaterials, but also for other materials. A lot of publications already exist in this field. It is well known that poly(N-isopropylacrylamide) (PNIPA) gel is thermally sensitive in its response to external temperature changes. … PNIPA gel has attracted great interest and been extensively studied in the recent 20 years due to its applications in many fields, such as artificial muscle [2], on-off switches [3], and immobilization of enzymes [4], etc. Very recently, Kricheldorf et al. have reported the synthesis of high molecular weight polycarbonate…, although the detailed mechanism is not clear. 5 The anionic living polymerization technique yielding polymers with narrow molecular weight distributions has been widely adopted as a method to prepare homo- and especially block copolymers1). Gene therapy is a relatively new technique in the field of biotechnology and medicine that is attracting a lot of attention