Complexation behavior of α-, β-, and γ-cyclodextrin in modulating and constructing polymer networks
Complexation behavior of α-, β-, and γ-cyclodextrin in modulating and constructing polymer networks
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DOI：
10.1021/la800859w
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发表时间：
2008-08-05
期刊：
影响因子：
3.9
通讯作者：
Lincoln, Stephen F.
中科院分区：
文献类型：
--
作者：
Li, Li;Guo, Xuhong;Lincoln, Stephen F.
本文系统地研究了α-、β-和γ-环糊精（CD）在自由态和聚丙烯酸（PAA）上取代正十八烷基（HMPAA）的主客体络合作用及其对聚合物聚集和网络形成的影响。游离的α-CD、β-CD和γ-CD掩盖了水溶液中HMPAA的C18取代基之间的疏水缔合，并在0.5重量%聚合物浓度下形成具有1：1或CD：C18取代基化学计量的主客体复合物。对于α-CD，在聚合物浓度>= 1wt%时，这种主体-客体化学计量变为2：1或2 α-CD：C18，但对于β-CD和γ-CD则不然。当γ-CD络合C18 HMPAA取代基时发生剪切增稠。加入十二烷基硫酸钠SDS（SDS：CD = 1：1）后，C18之间的疏水缔合被α-CD掩蔽所减弱，完全恢复，β-CD仅部分恢复，γ-CD未恢复。当α-和β-CD取代的PAA（α-CDPAA和β-CDPAA）与HMPAA聚合物混合时，形成网络。对于游离β-CD，β-CDPAA的β-CD取代基也与HMPPA的C18取代基形成1：1或β-CD：C18化学计量的主-客体复合物。α-CDPAA的α-CD取代基还形成1：1或α-CD：C18化学计量的主体-客体复合物，在聚合物浓度>= 1重量%时，有迹象表明形成2：1或2 α-CD：C18化学计量的主体-客体复合物。由β-CDPAA与HMPAA形成的聚合物网络比由α-CDPAA形成的聚合物网络粘性小，对于α-CDPAA，在聚合物浓度>= 2wt%时发生剪切增稠。很明显，CD环尺寸的差异及其与HMPAA的C18的匹配控制了α-CD、β-CD、γ-CD、α-CDPAA和β-CDPAA与HMPAA相互作用的多样性。
A systematic study of the host-guest complexation by alpha-, beta-, and gamma-cyclodextrin (CD) in either the free state or as substituents of poly(acrylic acid) (PAA) with the hydrophobic n-octadecyl groups, C18, substituted onto PAA (HMPAA) and its effect on polymer aggregation and network formation is reported. Free alpha-CD, beta-CD, and gamma-CD mask hydrophobic associations between the C18 substituent of HMPAA in aqueous solution and form host-guest complexes with a 1: 1 or CD:C18 substituent stoichiometry at 0.5 wt % polymer concentration. For alpha-CD this host-guest stoichiometry changes to 2:1 or 2 alpha-CD:C18 at >= 1 wt % polymer concentrations but not for beta-CD and gamma-CD. Shear-thickening occurs when gamma-CD complexes C18 HMPAA substituents. Upon addition of sodium dodecyl sulfate, SDS (SDS:CD = 1:1), the hydrophobic associations between C18 diminished by alpha-CD masking were fully restored, were only partly restored in the case of beta-CD, and not restored for gamma-CD. When alpha- and beta-CD substituted PAA (alpha-CDPAA and beta-CDPAA) were mixed with HMPAA polymer, networks formed. As for free beta-CD, the beta-CD substituents of beta-CDPAA also formed 1:1 or beta-CD:C18 stoichiometry host-guest complexes with the C18 substituents of HMPAA. The alpha-CD substituents of alpha-CDPAA also formed 1:1 or alpha-CD:C18 stoichiometry host-guest complexes with some indication of the formation of 2:1 or 2 alpha-CD:C18 stoichiometry host-guest complexes at polymer concentrations >= 1 wt %. The polymer networks formed by beta-CDPAA with HMPAA are less viscous than those formed by alpha-CDPAA, for which shear-thickening occurs at polymer concentrations >= 2 wt %. It is evident that the difference in CD annular size and its match with the C18 of HMPAA control the diversity of the interactions of alpha-CD, beta-CD, gamma-CD, alpha-CDPAA, and beta-CDPAA with HMPAA.