Self-Assembling Structure in Solution of a Semirigid Polyelectrolyte

• Published in: Macromolecules Vol. 41; no. 5; pp. 1791 - 1799
• Main Authors: Yang, Wei, Furukawa, Hidemitsu, Shigekura, Yukari, Shikinaka, Kazuhiro, Osada, Yoshihito, Gong, Jian Ping
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 11.03.2008
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Solution and gel properties; Molecular rigidity; Self assembly; Nylon; Aromatic polymer; Experimental study; Functional polymer; Polyelectrolyte; Sulfonate polymer; Ionic strength; Liquid crystal polymers; Concentration effect; Aqueous solution; Lyotropic state; Saline solution
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma071251w

We investigated the self-assembling structure in aqueous solution of polyelectrolyte poly(2,2‘-disulfonyl-4,4‘-benzidine terephthalamide) (PBDT), which has a rigid chemical structure of polyaramide in the main chain. It is found that PBDT exhibits a stretched semirigid conformation in solution, regardless of PBDT concentration, C P, or salt addition. PBDT in water exhibits both a very low overlap concentration, C*, and a lower critical concentration of nematic liquid crystal, C LC*. In the intermediate region of C* < C P < C LC*, PBDT forms cluster-like isotropic self-assembly. Moreover, in the intermediate region of C* < C P < C LC*, the addition of NaCl induces the alternation of structure from a cluster-like isotropic self-assembly to a fiber-like anisotropic one. Further addition of NaCl induces a network-like huge self-assembling structure, as the stoichiometric molar ratio of [NaCl] to [NaSO3 -] increases beyond 1. The semirigid polyelectrolyte probably has hidden potential for structural polymorphism in aqueous solutions in the presence of salt.