不同构型乳酸对乳酸-羟基乙酸直接熔融共聚产物的影响  

Influences of Different Lactic Acid Conformation on Copolymer of Lactic Acid and Glycolic Acid Synthesized via Direct Melt Copolymerization

作　　者：汪朝阳[1] 赵耀明[1] 王方[1] 

机构地区：[1]华南理工大学材料学院

出　　处：《材料科学与工程学报》2005年第2期172-176,225,共6页Journal of Materials Science and Engineering

基　　金：高等学校博士学科点专项科研基金资助项目 (980 561 1 0 );广东省自然科学基金资助项目 (980 50 4;0 2 0 885)

摘　　要：分别以外消旋乳酸 (D ,L LA)和左旋乳酸 (L LA)为原料 ,与乙醇酸 (GA)直接熔融共聚 ,以 0 .5 %氯化亚锡为催化剂 ,在 16 5℃、70Pa下反应 10h ,合成了不同配比的系列生物降解高分子乳酸 乙醇酸共聚物 (PLGA)。用GPC、FTIR、1 HNMR、DSC、X 射线衍射等进行表征 ,发现原料乳酸 (LA)的构型对聚合物的Mw、Tg、结晶性、组成等产生影响。单体投料摩尔比LA GA =5 0 5 0时 ,D ,L PLGA的 [η]和Mw比L 型大。以D ,L LA为原料时 ,共聚物结构相对简单 ,共聚物性质易受GA链段控制。投料摩尔百分比LA(或GA)≥ 90 %时 ,共聚物易于结晶 ,以L LA为原料时更为明显。利用1 HNMR数据计算共聚物组成 ,发现GA组分含量高于其投料值 ,且D ,L PLGA中GA的组成高于L 型产物。根据上述实验事实 ,提出D ,L LA、L LA分别与GA共聚时 ,由于GA在共聚中反应速率比LA高 ,并且D ,L LA与L LA存在反应速率差异 ,故有不同反应机理。Respectively using L-lactic acid (L-LA) and D,L-lactic acid (D,L-LA) as starting material, and via direct melt copolycondensation with glycolic acid (GA), serial poly(lactic acid-glycolic acid) (PLGA) with different mol feed were synthesized after 10h's polymerization under 165℃ and 70Pa, and 0.5 wt% SnCl 2 as catalyst. These biodegradable polymers were characterized with GPC, FTIR, 1H NMR, DSC and X-ray diffraction. It was found that PLGA synthesized from L-LA and D,L-LA have many differences in Mw, Tg, crystallity and composition. When the mol feed ratio of LA to GA was 50/50, both the intrinsic viscosity ( [η] ) and weight-average molecular weight (Mw) of D,L-PLGA were higher than that of L-PLGA. Using D,L-LA as starting material, the structure of copolymer PLGA was relatively simple, and its properties were apt to be controlled by GA chain segment in copolymer. When the feed mol percentage of monomer (LA or GA) was more than or equal to 90%, the copolymer was apt to be crystalline, and the aptness was more obvious for L-LA monomer. The composition percentage of GA in PLGA was not only higher than the feed mol percentage of GA, but also the GA percentage in D,L-PLGA was higher than in L-PLGA. Based on the above, the copolymerization mechanism was proposed. The different monomers may have different reaction velocities, the reaction velocity of GA was quicker than that of L-LA, and that of D,L-LA was the slowest of three. Thus, when monomer GA respectively reacting with D,L-LA and L-LA, the reaction mechanism of direct melt copolycondensation was different..

关 键 词：外消旋乳酸(D L-LA) 左旋乳酸(L-LA) 直接熔融共聚 生物降解高分子 乳酸-乙醇酸共聚物(PL-GA) 反应机理 

分 类 号：TB39[一般工业技术—材料科学与工程] TQ316[化学工程—高聚物工业]