Novel Fluoroalkyl End-Capped Amphiphilic Diblock Copolymers with pH/Temperature Response and Self-Assembly Behavior

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• 作者：Hu Zhang ; Peihong Ni ; Jinlin He ; Cuicui Liu
• 刊名：Langmuir
• 出版年：2008
• 出版时间：May 6, 2008
• 年：2008
• 卷：24
• 期：9
• 页码：4647 - 4654
• 全文大小：530K
• 年卷期：v.24,no.9(May 6, 2008)
• ISSN：1520-5827

文摘

A series of fluoroalkyl end-capped diblock copolymers of poly[2-(N,N-dimethylamino)ethyl methacrylate](PDMAEMA or PDMA) and poly[2-(N,N-diethylamino)ethyl methacrylate] (PDEAEMA or PDEA) have beensynthesized via oxyanion-initiated polymerization, in which a potassium alcoholate of 4,4,5,5,6,6,7,7,7-nonafluoro-1-heptanol (NFHOK) was used as an initiator. The chemical structures of the NFHO-PDMA-b-PDEA and NFHO-PDEA-b-PDMA depended on the addition sequence of the two monomers and the feeding molar ratios of [DMA]to [DEA] during the polymerization process. These copolymers have been characterized by ¹H NMR and ¹⁹F NMRspectroscopy and gel permeation chromatography (GPC). The aggregation behavior of these copolymers in aqueoussolutions at different pH media was studied using a combination of surface tension, fluorescence probe, and transmissionelectron microscopy (TEM). Both diblock copolymers exhibited distinct pH/temperature-responsive properties. Thecritical aggregation concentrations (cacs) of these copolymers have been investigated, and the results showed that thesecopolymers possess excellent surface activity. Besides, these fluoroalkyl end-capped diblock copolymers showedpH-induced lower critical solution temperatures (LCSTs) in water. TEM analysis indicated that the NFHO-PDMA₃₀-b-PDEA₁₀ diblock copolymers can self-assemble into the multicompartment micelles in aqueous solutions under basicconditions, in which the pH value is higher than the pK_a values of both PDMA and PDEA homopolymers, while theNFHO-PDEA₁₀-b-PDMA₃₀ diblock copolymers can form flowerlike micelles in basic aqueous solution.