Synthesis And Properties Of Biodegradable PH/Temperature-Sensitive Polymers

Intelligent polymer, also called stimuli-responsive polymer or environmentally-sensitive polymer, which can detect the microstimulus of environment, such as tempreture, pH, light, electrity and life matter, causing its the structure of physical and chemical change of own conformation, polarity, phase structure, composition, showing the characteristics of "intelligence", which has been widely applied in drug controlled release carrier, tissue engineering, and biomedical aspects of biomimetic materials. And now most intelligent polymer are not degradable, limiting the range of application, therefore, the design and synthesis of new biocompatible and biodegradable intelligent polymer is imminent. This paper will explore the research synthesis of novel biodegradable intelligent polymer from the modified natural polymer and synthetic polymer two aspects.In this paper, we used H2O2-Ac system to oxidize degradation of chitosan, and got a series of low molecule weight chitosan, then did a N-methyl modification. We detected the degraded chitosan molecular weight with viscosmetry, compared with FT-IR beford and after the degradation, and characteristed the N-methly chitosan by infrared spectroscopy (FT-IR), we measured the transmittance of chitosan and N-methyl chitosan at different pH values by Ultraviolet visible spectrophotometer, obtained that N-methyl chitosan was more pH sensitivity.N-methly chitosan was etherified with propylene oxide or epoxy chloropropane, and was esterified with actic anhydride, propionic anhydride, benzoyl chloride and so on.the products of etherified N-methyl chitosan and esterified N-methyl chitosan were characterized by infrared spectroscopy; we measured the transmittance of etherified N-methyl chitosan and esterified N-methyl chitosan in aqueous solution at different pH values and different temperature by Ultraviolet visible spectrophotometer. The results showed that:O-hydroxypropyl N, N-dimethyl chitosan, O-hydroxy chloride propyl N, N-dimethyl chitosan, O-benzoyl N, N-dimethyl chitosan and O-acetylglcincamy N, N-dimethyl chitosan has a dual pH and temperature sensitivity. In this paper, N, N-dimethyl threonine and N, N-dimethyl threonine lactone were synthesized by threonine, N, N-dimethyl homoserine was synthesized by methionine and we try to to synthesize N, N-dimethyl homoserine lactone; functional threonine ring monomer was synthesized by threonine; aspartic acid benzyl ester glutamic acid benzyl ester, aspartate propylamine and aspartic acid benzyl ester NCA, glutamic acid benzyl ester NCA, aspartate propylamine NCA were synthesized by aspartic acid, glutamic acid, tyrosine NCA and cystine NCA were synthesized by tyrosine and cystine. N, N-dimethyl threonine, N, N-dimethyl threonine lactone, N, N-dimethyl homoserine, aspartic acid benzyl ester NCA, glutamic acid benzyl ester NCA, aspartate propylamine NCA were determined by1H-NMR,13C-NMR and FT-IR.