Synthesis and properties of a new class of sugar-carrying amphiphilic block copolymers

在本研究项目中，我们成功地通过活性阳离子聚合合成了一类新的载糖两亲性嵌段共聚物- [CH_2CH (OCH_2CH_2OR)] _m- [CH_2CH (OiBu)] _n，其中R为d -葡萄糖或d -氨基葡萄糖残基。采用HI/Znl_2或TFA/EtAlCl_2引发体系，将异丁基乙烯基醚与带有保护羟基和/或氨基的单糖的乙烯基醚序列进行了活嵌段共聚。所得嵌段共聚物分子量分布窄（M_w/M_n-1.1），组成可控。成功地实现了前驱体聚合物的定量脱保护，以提供目标两亲体。两亲性嵌段共聚物在各种溶剂中的溶解度与嵌段组成（m/n）密切相关。在透射电子显微镜下观察到载糖嵌段共聚物的溶剂铸造薄膜，根据成分的不同，表现出不同的微相分离表面形态，如球体、圆柱体和片层。接触角测量表明，嵌段共聚物薄膜的表面性能随环境条件的变化而变化，表面的疏水异丁基段可以被水浸泡后的亲水段所取代。为了更精确地控制其精细结构，我们将Langmuir-Blodgett （LB）技术应用于该嵌段共聚物。从氯仿和甲醇的混合溶液中扩散到水面上的嵌段共聚物被发现形成稳定的单层，通过LB技术成功地将其转移到衬底上。通过共混均聚物，可以控制LB膜的层状结构。

In this research project, we have succeeded in synthesizing a new class of sugar-carrying amphiphilic block copolymers- [CH_2CH (OCH_2CH_2OR)] _m- [CH_2CH (OiBu)] _n-by living cationic polymerization, where R is a D-glucose or D-glucosamine residue. To obtain them, sequential living block copolymerization of isobutyl vinyl ether and the vinyl ether carrying a monosaccharide whose hydroxyl and/or amino groups are protected was conducted using a HI/Znl_2 or TFA/EtAlCl_2 initiating system. The obtained block copolymers had a narrow molecular weight distribution (M_w/M_n-1.1) and a controlled composition. Quantitative deprotection of the resulting precursor polymers was successfully achieved to afford the target amphiphiles. The solubility of the amphiphilic block copolymers in various solvents depended strongly on the block composition (m/n).The solvent-cast thin films of the glucose-carrying block copolymer were observed, under a transmission electron microscope, to exhibit various microphase-separated surface morphologies such as spheres, cylinders, and lamellae, depending on composition. The contact angle measurement revealed that the block copolymer film changes its surface properties depending on the environmental condition, the hydrophobic isobutyl segment on the surface can be replaced with hydrophilic segment by soaking it in water. To more precisely control its fine structure, we applied the Langmuir-Blodgett (LB) technique to this block copolymer. The block copolymer, spread from a mixture solution of chloroform and methanol onto the water surface, was found to form a stable monolayr, which is successfully transferred onto a substrate by the LB technique. The layred structure of the LB film was demonstrated to be controlled by blending the homopolymer.