Aggregation Behavior of Rodlike Ionogenic Polymers in Chloroform

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• 作者：Markus Susoff ; Dominik Winter ; Claus D. Eisenbach ; Wilhelm Oppermann
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：April 17, 2008
• 年：2008
• 卷：112
• 期：15
• 页码：4519 - 4525
• 全文大小：87K
• 年卷期：v.112,no.15(April 17, 2008)
• ISSN：1520-5207

文摘

The rodlike ionogenic polymers poly(p-pyridylene-phenylene) and poly(p-pyridylene/phenylene-ethynylene)form polyelectrolytes when protonated with toluene sulfonic acid or ethane sulfonic acid in chloroform solution.This molecular modification, clearly indicated by a marked red shift of the UV absorption band, induces theformation of prolate, bundlelike aggregates, whose size and shape are obtained from their rotational dynamicsas revealed by electric birefringence relaxation and their translational dynamics as measured by dynamiclight scattering. The aggregates have a length of 400-600 nm and a high aspect ratio >15. In general, thepolyelectrolyte molecules are arranged with their long axes parallel to the long axis of the aggregates. Theyprobably attract each other through the electrostatic interaction with counterions. The counterions are notbound to specific sites but may be shifted under the action of an external electric field to account for thehighly anisotropic electric polarizability. When inert salt or excess sulfonic acid is added, these compoundsseem to accumulate within the aggregates and influence the attractive forces. This is generally leading to anelongation of the aggregates and, in the case of added salts, even to a marked reduction of birefringence.