pH响应型阴离子共轭聚电解质的聚集介导光学性质

Aggregation-mediated optical properties of pH-responsive anionic conjugated polyelectrolytes.

作者信息

Wang Fuke, Bazan Guillermo C

机构信息

Department of Materials and Chemistry & Biochemistry, Institute for Polymers and Organic Solids, University of California, Santa Barbara, California 93106, USA.

出版信息

J Am Chem Soc. 2006 Dec 13;128(49):15786-92. doi: 10.1021/ja065061x.

DOI:10.1021/ja065061x

PMID:17147388

Abstract

Conjugated polyelectrolyte copolymers containing 2,1,3-benzothiadiazole- (BT) and oligo(ethylene oxide)-substituted fluorene and phenylene units have been designed and synthesized. The phenylene pendent groups also have carboxylic acid functionalities, which allow probing the effect of pH on optical properties. The BT content in the backbone can be regulated at the synthesis stage. Dynamic light scattering studies show that polymers aggregate in water at low pH. Increased interchain contacts give rise to a lowering of the photoluminescence (PL) efficiency via self-quenching when the BT units are absent and increased levels of FRET from the phenylene-fluorene segments to BT. Furthermore, the PL efficiency of BT increases in the aggregated structures. Examination of solvent effects indicates that the increased BT efficiencies are likely due to decreased contact with water. The changes in PL efficiencies are reversible, showing that the aggregates are dynamic and not kinetically constrained.

摘要

含有2,1,3-苯并噻二唑（BT）以及寡聚（环氧乙烷）取代芴和亚苯基单元的共轭聚电解质共聚物已被设计并合成。亚苯基侧基还具有羧酸官能团，这使得能够探究pH对光学性质的影响。主链中的BT含量可在合成阶段进行调控。动态光散射研究表明，聚合物在低pH值的水中会发生聚集。当不存在BT单元时，链间接触增加会通过自猝灭导致光致发光（PL）效率降低，并且从亚苯基 - 芴链段到BT的荧光共振能量转移（FRET）水平会增加。此外，BT在聚集结构中的PL效率会提高。对溶剂效应的研究表明，BT效率的提高可能是由于与水的接触减少。PL效率的变化是可逆的，这表明聚集体是动态的，而非动力学受限的。