Studies On The Polycondensation And Copolymeirzation Of Glycolic Acid And The Application Of The Products

Polyglycolic acid and its copolymers are important biodegradable materials, and theyhave broad and important applications in many biomedical fields as well as in daily life.Currently an intermediate product-lactide is often required in synthesis of polyglycolic acidand its copolymers. Due to the harsh synthetic conditions, low yield and high cost, alarge-scale application of polyglycolic acid and copolymers is limited. This study aims tosolve this problem and reduce the cost of polyglycolic acid and copolymers in two aspects.The one is looking for a new synthetic process for preparing lactide with high yields, andanother is to synthesis copolymer containing polyglycolic acid by direct condensation.Firstly, synthetic process was investigated by using a new self-designed reactor. Theprocess contained four steps: polycondensation, dehydration, pyrolysis and purification. Thedifferent factors were studied. At last, the best optimized conditions were obtained. Themass ratio of0.75%was added antimony trioxide catalyst azeotropic solvent triethyleneglycol, molten prepolymer under210℃for2h, the cracking chamber is introduced into5.Then, to20℃/min Heating rate was raised to280℃cleavage reaction. The collectedglycolide under the same quality as the steam dissolved in ethyl acetate in65℃and wascooled to0℃. Separated by filtration and dried, was repeated three times, the final product isobtained. In this process, the final product of glycolide ratio up50%.In the second part and third part of this study1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide group for the condensingagent, in the water environment, glycolic acid, D, L-lactic acid and GA/LA components arecombined with sodium alginate. Analyzed by infrared spectra,1H-NMR analysis, and Tg,DSC structure and thermal properties of the product. The results confirmed the feasibility ofthe reaction. Figure micelles obtained by scanning electron microscopy found the size of theparticles at the nanoscale. PLA samples which reached a minimum level of80-100nm, PLGAsamples were left in the PGA150and250nm. Modified hydrogel microspheres of calciumcrosslinking obtained by ibuprofen drug research drug load its performance. The results showthe success obtained with the hydrophobic modification nanoscale micelles, hydrophobicdrugs ibuprofen and drug encapsulation efficiency ratios improved. Three different drugsample rate reached50.4%, respectively,51.5%and55.0%. The experimental results showedthat the sample by adjusting the ratio of the hydrophobic segment can be effectively improvedrelease properties, and have a pH-sensitive.