Interaction of Sodium Dodecyl Sulfate with Polyelectrolyte Complexes Derived from Diazoresin and Sulfonate-Containing Polymers WEIXIAO CAO, ZHIYONG MENG, TAO YIE, DONGHUI ZHANG, BOXUAN YANG College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China Received 27 October 1998; accepted 18 January 1999 ABSTRACT: The sulfonate-containing polyelectrolytes (SPE) from sulfonation of poly- styrene (PS) and copolymerization of 3-sulfo-propyl methacrylate, potassium salt (SPMS) with styrene (S) were prepared. Photosensitive polyelectrolyte complexes (PEC DR ) derived from SPE and diazoresin (DR), which does not dissolve in water or organic solvent due to its ionic crosslinking structure, dissolves in aqueous solution of sodium dodecyl sulfate (SDS) due to the dissociation of PEC DR and the hydrophobic interaction between SDS and the polymer chain. The photosensitive behavior and thermostability of the PEC DR were investigated, and it was found that the thermosta- bility of PEC DR increases dramatically in SDS aqueous solution. It was proposed that the higher thermostability of PEC DR in SDS aqueous solution is due to an aggregation of SDS molecules around the diazonium group of the PEC DR , which protects the ON 2 + group of the DR from attack by the nucleophiles. The image-forming behavior of PEC DR by ultraviolet (UV) light was examined and considered to be different from other PECs. It was concluded that the photoimaging behavior of PEC DR is based on a reaction in which an ionic bond converts to a covalent bond. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2601–2606, 1999 Keywords: sodium dodecyl sulfate; polyelectrolyte complexes; diazoresin INTRODUCTION The self-aggregation behavior of the amphiphilic molecules has attracted much attention because of its interest in biological and high scientific technology areas. 1–5 It is well known that the natural amphiphilic molecules such as lipids form liposome, a key constituent of biological mem- branes, and the synthetic amphiphilic small mol- ecules such as surfactants form micelles or vesi- cles as they disperse in water. The complexations of surfactants (SF) with oppositely charged poly- electrolytes (PE) have been extensively studied, and it was shown that strong electrostatic and hydrophobic interactions cause the aggregation of surfactants on polymer chains. 6 –10 Compared with the studies of PE–SF systems, the investiga- tions of polyelectrolyte complex-surfactant (PEC– SF) system are very limited. We have reported the interaction of the PEC derived from poly(so- dium styrene sulfonate) (PSSS) and diazoresin (DR) with sodium dodecyl sulfate (SDS). 11 In this article, the interaction of SDS with a new kind of PEC formed from DR and sulfonate-containing polyelectrolytes is reported. EXPERIMENTAL Styrene (S) was distilled under reduced pressure before use. SDS and benzoyl peroxide (BPO) were recrystallized in ethanol. 3-Sulfopropyl methacry- Correspondence to: W. Cao Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 37, 2601–2606 (1999) © 1999 John Wiley & Sons, Inc. CCC 0887-624X/99/142601-06 2601