Water-Soluble Conjugated Polyelectrolytes with Branched Polyionic Side Chains

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• 作者：Seoung Ho Lee ; Sevnur Ko虉mu虉rlu虉 ; Xiaoyong Zhao ; Hui Jiang ; Gustavo Moriena ; Valeria D. Kleiman ; Kirk S. Schanze
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：June 28, 2011
• 年：2011
• 卷：44
• 期：12
• 页码：4742-4751
• 全文大小：1001K
• 年卷期：v.44,no.12(June 28, 2011)
• ISSN：1520-5835

文摘

A new series of conjugated polyelectrolytes (CPE) consisting of an arylene鈥揺thynylene backbone featuring phenyl (Ph), 2,1,3-benzothiadiazole (BTD), or 4,7-bis(2鈥?thienyl)-2,1,3-benzothiadiazole (TBT) units have been synthesized and characterized. On each polymer repeat unit the CPEs contain two branched ionic side groups each featuring a 鈥渢riad鈥?of carboxylate (R-CO₂^{鈥?/sup>Na+) or ammonium (R-NH₃+Cl鈥?/sup>) units, giving the polymers six ionic charges per repeat. The photophysical properties of the series of CPEs were investigated in CH₃OH and H₂O solution by absorption, steady-state fluorescence, and fluorescence lifetime spectroscopy. The different arylene units in the backbone lead to the variation of the HOMO鈥揕UMO gap across the series. The branched, polyionic side chains suppress aggregation of the polymer chains, even in aqueous solution, leading to higher fluorescence quantum yields relative to similar CPEs with linear side chains. UV鈥搗is absorption spectra show that CPEs with anionic branched side chains (R-bCO₂鈥?/sup>Na) aggregate at low pH, while retaining the photophysical properties of their organic-soluble precursors at high pH. CPEs having branched cationic side chains (R-bNH₃+Cl鈥?/sup>) exhibit the opposite response to pH change.}