温敏性两亲嵌段共聚物的合成及其自组装性能研究

发布时间：2018-04-14 23:13

本文选题：RAFT聚合 + 嵌段共聚物　；参考：《青岛科技大学》2017年硕士论文

【摘要】：温敏性两亲嵌段共聚物在水溶液中可以自组装形成温敏性胶束,可广泛应用于药物载释、萃取分离、酶固定化、分子机器、组织工程等领域。本文以丙烯酸十八酯(ODA)为疏水单体、N-异丙基丙烯酰胺(NIPAAm)为亲水单体,三硫代碳酸酯(TTC)为链转移剂,偶氮二异丁腈(AIBN)为引发剂,通过可逆加成-断裂链转移聚合法(RAFT)分别合成了一系列温敏性嵌段共聚物PNIPAAm-b-PODA-b-PNIPAAm(ABA-型)和PODA-b-PNIPAAm-b-PODA(BAB-型)。系统研究了两种嵌段共聚物在水溶液中的温敏性和胶束化性能,并利用苏丹红为模型药物初步研究了嵌段聚合物的载药性能。1、通过IR和1H NMR对ABA-型嵌段共聚物的结构进行表征,表明成功合成了ABA-型嵌段共聚物。2、ABA-型嵌段共聚物的GPC测量结果表明,NIPAAm的含量越大,嵌段共聚物的分子量也越大。嵌段共聚物的聚合度分散指数(Mw/Mn)始终控制在1.50之内(1.3~1.49),说明由RAFT法合成的嵌段共聚物的聚合过程是可控的且分子量分布均匀。3、两种嵌段共聚物均表现出表面活性,ABA-型嵌段共聚物的CMC值均大于与其亲疏水质量比相同的BAB-型嵌段共聚物的CMC值。ABA-型嵌段共聚物的亲水链段越长,CMC值越小;BAB-型嵌段共聚物CMC值变化规律与ABA-型嵌段共聚物相反,即BAB-型嵌段共聚物的亲水链段越长,CMC值越大。4、测得不同嵌段比共聚物胶束溶液的透光率随温度的变化,结果表明两种嵌段共聚物溶液均表现出良好的双温敏性行为,且LCST值随亲水嵌段NIPAAm含量的增加而升高。BAB-型嵌段共聚物比ABA-型嵌段共聚物的第一个LCST处的透光率下降速率大,第二个LCST处的透光率下降速率小,且总透光率也比ABA-型嵌段共聚物总透光率下降的少。5、通过动态光散射法(DLS)测定不同嵌段共聚物胶束的粒径及粒径分布随温度的变化,低温下(小于LCST)ABA-型嵌段共聚物胶束粒径及粒径分布PdI为一定值,当温度大于LCST时ABA-型嵌段共聚物会发生团聚。而BAB-型嵌段共聚物在温度高于LCST时不发生团聚,且BAB-型嵌段共聚物的PdI值较小(小于0.7),粒径分布均匀。6、两亲性嵌段共聚物胶束核壳结构使得纳米粒子具有可以作为疏水性药物运载工具的潜力,负载药物(苏丹红)后的胶束尺寸明显增大,表明该药物被包封到胶束中。
[Abstract]:Temperature-sensitive amphiphilic block copolymers can self-assemble into thermosensitive micelles in aqueous solution and can be widely used in the fields of drug delivery, extraction and separation, enzyme immobilization, molecular machinery, tissue engineering and so on.In this paper, octadecyl acrylate (ODAA) as hydrophobic monomer (N-isopropylacrylamide) as hydrophilic monomer, trithiocarbonate (TTC) as chain transfer agent, azodiisobutyronitrile (AIBN) as initiator,A series of thermo-sensitive block copolymers PNIPAAm-b-PODA-b-PNIPAAmABA- type and PODA-b-PNIPAAm-b-PODA-BAB-type were synthesized by reversible addition-break chain transfer polymerization (RAFT).The thermosensitivity and micellization properties of two block copolymers in aqueous solution were systematically studied. The drug loading properties of block polymers were preliminarily studied by using Sudan as model drug. The structure of ABA- type block copolymers was characterized by IR and 1H NMR.The results of GPC measurement show that the higher the content of niPAAm, the higher the molecular weight of block copolymers.The polymerization degree dispersion index (MW / mn) of block copolymers is kept within 1.50, indicating that the polymerization process of block copolymers synthesized by RAFT method is controllable and the molecular weight distribution is uniform .3. both block copolymers exhibit surface activity.The CMC values of the block copolymers were higher than those of the block copolymers with the same hydrophilic mass ratio. The longer the block segments were, the smaller the CMC values of the block copolymers were. The CMC values of the block copolymers were opposite to those of the block copolymers.That is, the longer the hydrophilic chain segment of Bab-type copolymers is, the larger the CMC value is. 4. The light transmittance of micelle solutions with different block ratios is measured. The results show that both block copolymers exhibit good double-temperature sensitivity.The LCST value increased with the increase of hydrophilic block NIPAAm content. The decrease rate of transmittance in the first LCST of ABA- type block copolymer was higher than that in the first LCST of ABA- type block copolymer, and the decrease rate of light transmittance in the second LCST was lower than that in the first LCST of the ABA- type block copolymer.The total transmittance of the copolymers is also lower than that of ABA- type block copolymers. The particle size and particle size distribution of the micelles of different block copolymers are measured by dynamic light scattering (DLSs).At low temperature (smaller than LCST-ABA- type block copolymer micelle size and particle size distribution PdI is a certain value, ABA- block copolymer agglomerates when temperature is higher than LCST).However, when the temperature of Bab-type block copolymers is higher than LCST, no agglomeration occurs.The PdI value of Bab-type block copolymers is smaller (less than 0.7g, the particle size distribution is even .6. the micelle core-shell structure of amphiphilic block copolymers makes the nanoparticles have the potential to be used as hydrophobic drug delivery vehicles.The micelle size of the loaded drug (Sudan red) increased significantly, indicating that the drug was encapsulated into the micelle.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O631

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