摘要
近期研究发现两亲性嵌段共聚物刷能引发“有序自发乳化”,一步法制备有序多孔光晶微球.上述研究主要基于侧链为线形聚合物的嵌段共聚物刷,而侧链拓扑结构变化对乳液受限自组装的影响尚不明确.本工作中设计合成了亲水和疏水的降冰片烯基楔形单体,并通过顺序开环易位聚合(ROMP)成功合成了一类两亲性树枝状嵌段共聚物刷.通过核磁氢谱(1H-NMR)清晰表征了产物的化学结构,凝胶渗透色谱(GPC)表明共聚物的分子量呈较窄的单峰分布,聚合反应过程具有较好的可控性.通过改变单体和催化剂的比例获得不同分子量的共聚物刷,利用凝胶渗透色谱联用光散射(GPC-MALS)研究了侧链结构对聚合物溶液构象的影响,结果显示一代树枝状共聚物刷表现为无规线团构象,而二代产物则呈现棒状构象,单个聚合物链的原子力(AFM)表征证实了上述结果.
Amphiphilic brush block copolymers(BBCPs)have demonstrated interesting self-assembly behaviors different from their coil-like linear analogues,and their rigid molecular conformation make it straightforward to fabricate ordered nanostructured materials useful in many important applications such as photonics,therapeutics,etc.However,influence of side chain topology on self-assembled nanostructures as well as physical properties remained unclear due to the lack of amphiphilic BBCPs bearing different topological side chains.Herein,we successfully synthesize a group of novel amphiphilic BBCPs with wedge-like dendritic side chains,i.e.,lipophilic benzyl ether(Bn)and hydrophilic triethylene glycol(TEG).Firstly,two generations of norbornene-terminated macromonomers are obtained by esterification,nucleophilic substitution,imidization reactions,etc.Secondly,dendronized BBCPs bearing two generations of side chains are prepared through sequential ring-opening metathesis polymerization(ROMP).Chemical structures of the obtained BBCPs are clearly characterized using proton nuclear magnetic resonance spectroscopy(1H-NMR).Absolute molecular weights are determined using gel permeation chromatography(GPC)equipped with a multi-angle laser scattering detector(MALS),and single GPC peaks as well as small polydispersity indices(PDI<1.20)indicate a constant number of catalytic centers during the polymerization process.Weight average molecular weight are tunable from 164 kDa to 431 kDa by varying the feed ratio of monomer to catalyst.Moreover,side chain effect on molecular conformation in solution is investigated using GPC-MALS.Random coil conformation is observed for the first-generation polymers as indicated by the small slope values of linearly fitted lines in double-logarithmic plots of radii of gyration versus molecular weight,while the second-generation polymers with larger side chains exhibit a rod-like molecular conformation,which are further confirmed using atom force microscopy(AFM).This work provides a highly efficient syntheti
作者
郑默涵
王棒棒
宋东坡
李悦生
Mo-han Zheng;Bang-bang Wang;Dong-po Song;Yue-sheng Li(School of Materials Science and Engineering,Tianjin University,Tianjin 300350)
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2023年第5期584-592,共9页
Acta Polymerica Sinica
基金
国家自然科学基金(基金号22071176)资助项目.
关键词
嵌段共聚物
开环易位聚合
分子构象
Block copolymer
Ring-opening metathesis polymerization
Molecular conformation
