Amphiphilic linear PEO-dendritic carbosilane block copolymers
Amphiphilic linear PEO-dendritic carbosilane block copolymers
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DOI：
10.1021/ma9908853
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发表时间：
2000-06-13
期刊：
影响因子：
5.5
通讯作者：
Kim, C
中科院分区：
文献类型：
--
作者：
Chang, Y;Kwon, YC;Kim, C
以亲水性线性PEO和疏水性树突状碳硅烷为基础，在烯丙基端聚乙二醇的烯丙基上采用发散法合成了一类新的两亲性线性-树突状二嵌段共聚物。这些嵌段共聚物的两亲性高度依赖于疏水枝晶嵌段的大小。具有第三代枝晶部分的嵌段共聚物不能在水中分散。嵌段共聚物与第一代（PEO-Si-1G）和第二代（PEO-Si-2G）枝晶碳硅烷嵌段在水相中形成胶束。荧光法测定PEO-Si-1G和PEO-Si-2G的临界胶束浓度分别为82.6和2.3 mg/L。动态光散射法测得PEO-Si-1G和PEO-Si-2G的胶束平均直径分别为120 nm和170 nm。随着枝晶块尺寸的增大，胶束溶液中芘的分配平衡常数K-v增加，PEO-Si-1G为9.13 × 10(3)， PEO-Si-2G为1.75 × 10(5)。PEO-Si-1G的1,6-二苯基-1,3,5-六三烯（DPH）稳态荧光各向异性值(r)为0.08，PEO-Si-2G为0.10。r值低于线性聚合物两亲体，表明树突状胶束核的微粘度低于其他聚合物胶束核。
A new class of amphiphilic linear-dendritic diblock copolymers based on hydrophilic linear PEO and hydrophobic dendritic carbosilane were synthesized using a divergent approach at the allyl end group of the allyl-terminated PEG. The amphiphilic nature of these block copolymers was highly dependent on the size of the hydrophobic dendritic block. The block copolymer with the dendritic moiety of a third generation could not be dispersed in water. The block copolymers with the first (PEO-Si-1G) and, the second (PEO-Si-2G) generation of dendritic carbosilane blocks form micelles in an aqueous phase. The critical micelle concentrations of PEO-Si-1G and PEO-Si-2G, determined by a fluorescence technique, were 82.6 and 2.3 mg/L, respectively. The mean diameters of the micelles of PEO-Si-1G and PEO-Si-2G, measured by dynamic light scattering, were 120 and 170 nm. The partition equilibrium constants, K-v, of pyrene in the micellar solution increased by increasing the size of the dendritic block, e.g., 9.13 x 10(3) for PEO-Si-1G and 1.75 x 10(5) for PEO-Si-2G. The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene (DPH) were 0.08 for PEO-Si-1G and 0.10 for PEO-Si-2G. The r values were lower than the linear polymeric amphiphiles, suggesting that the microviscosity of the dendritic micellar core is lower than those of other polymeric micelles.