Su Lu, Wang Chenmeng, Polzer Frank, Lu Yan, Chen Guosong, Jiang Ming
The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
TEM Group, Institute of Physics, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
ACS Macro Lett. 2014 Jun 17;3(6):534-539. doi: 10.1021/mz500211v. Epub 2014 May 23.
Protection-deprotection of carbohydrate is often required in the preparation of glycopolymers, which causes an obvious polarity change of the polymers, but it has been neglected in the studies of self-assembly. In this paper, a new strategy for self-assembly of sugar-containing block copolymers is suggested based on the protection-deprotection chemistry. We found that deacetylation of a series of block copolymers of (PS, polystyrene block; PMan, "sugar block" with acetylated α-mannopyranoside side groups) in THF resulted in structures of the deprotected copolymer , i.e., vesicles with a sugar wall and micelles with a sugar core. Besides, vesicle-to-micelle transition of the assemblies with decreasing the relative length of the sugar block was observed. These unique assemblies show interesting functions, such as generating homogeneous Au nanoparticles within the layer of the glyco-block from AuCl without any additional reducing reagents or energy input. Control experiments prove that the polar layer of glyco-polymer inside the vesicle provides an essential reduction environment.
在糖聚合物的制备过程中，碳水化合物的保护-脱保护操作常常是必要的，这会导致聚合物的极性发生明显变化，但在自组装研究中却一直被忽视。本文基于保护-脱保护化学提出了一种含糖嵌段共聚物自组装的新策略。我们发现，一系列（PS，聚苯乙烯嵌段；PMan，带有乙酰化α-甘露糖苷侧基的“糖嵌段”）嵌段共聚物在四氢呋喃中脱乙酰化后，得到了脱保护共聚物的结构，即具有糖壁的囊泡和具有糖核的胶束。此外，还观察到随着糖嵌段相对长度的减小，组装体发生了从囊泡到胶束的转变。这些独特的组装体展现出有趣的功能，比如在没有任何额外还原剂或能量输入的情况下，能从氯化金在糖嵌段层内生成均匀的金纳米颗粒。对照实验证明，囊泡内部糖聚合物的极性层提供了必要的还原环境。
