直接缩聚法制备可降解乳酸基共聚物-高分子化学与物理专业论文.docx

以PLA、β-CD和AGE作为原料，先合成出带有烯丙型双键官能团的可聚合PCD和PPLA大分子单体，然后以甲苯/DMSO作溶剂、AIBN作引发剂进行自由基聚合，得到了可完全生物降解的交联微凝胶。通过改变PCD的烯丙基官能度和其与PPLA的加料比例来控制微凝胶的交联度。单体的结构表征结果显示，PCD和PPLA具有预期结构。PLA-β-CD共聚物微凝胶的热分解温度均在200°C以上。微凝胶在25oC水中的溶胀率随着时间的推移逐渐趋缓，40h后则基本达到溶胀平衡，粒径不再变化。较高交联度和较低β-CD含量的微凝胶的溶胀度较小，反之则溶胀度较大。在PPLA与PCD的加料比例不变的情况下，由平均烯丙基官能度为3的PCD制得的微凝胶的溶胀度最大。微凝胶的交联度越高、β-CD的相对含量越高，其降解速率越慢。若保持PCD的烯丙基官能度不变而增加PCD的相对含量，所得的微凝胶的降解速率随之下降；同样，若保持PCD相对与PPLA的加料比不变而增加PCD的烯丙基官能度，微凝胶的降解速率也随之下降。微凝胶微粒呈球形，且表面比较光滑。当交联度增加时，微粒的粒径相对减小；当PCD相对增加时，粒径则随之增加。关键词：生物可降解高分子，乳酸共聚物，直接缩聚，聚酯酰胺ABSTRACTPolylacticacid(orPolylactide)(PLA)whichwaswidelyusedinmanyfieldbecauseofitsbiodegradableandbiocompatibleproperties,havegainedenormousattentionrecently.However,onefoldstructureandpropertieslimitstheapplicationsofPLAhomopolymer.Themostcommonstrategytoovercomethisdifficultyistopreparedthecopolymers.Awiderangeofbiodegradablecopolymersmatricesweredescribedinthisreviewwithaspecialemphasisonpolylactidebecauseofmoreeco-friendlinessfromitsoriginascontrasttothefullypetroleum-basedpolymersandcontrolofcarbondioxidebalanceaftertheircomposting.Lacticacid(orlactide)copolymerizedwithhydroxylacid,aminoacidorpolymerssuchaspoly(ethyleneglycol),starch,etc.,canobviouslyimprovethestrength,toughness,hydrophilicandcontrolled-degradablepropertiesofPLA,inthesametime,canobtainthelinear,comb-like,star-likeorcross-linkedcopolymers.Thesematerialsareattractingconsiderableinterestinmaterialsscienceresearch.Thisreviewaimsathighlightingon recent developmentsin preparation of biodegradablelinear,comb-like,star-likeorcross-linkedPLAcopolymersandthecatalysts(system)usingincopolymerization.Thethesisconsistsofmaincontentsasfollowings:Poly(lacticacid-glycolicacid)wassynthesizedfromlacticacidandglycolicacidbydirectpolycondensationusingvariouscatalystsintheabsenceoforganicsolventsat170oC.TheeffectofcatalystanditsdosageonmolecularweightandyieldofPLGAwasinvestigated.Asaresult,the sulfuric acid(98%), p-toluenesulfonic acidisbest.Atthesametime,thephthalicanhydrideisbestwhenitmixwithSnCl2·