Potentiometric and Conductometric Study of Aqueous Solutions of Lithium and Sodium Salts of Poly(thiophen-3-ylacetic acid)
Abstract
The tit le poly mer, PTAA, prac ti cally free of es ter groups was ob tai ned by oxi da ti ve poly me ri za tion of methyl thiop hen- 3-yla ce ta te and sub se quent ba sic hydroly sis of pri mary poly mer. Poly(thiop hen-3-yla ce tic acid) has been tho roughly cha rac te ri zed by NMR, IR, Ra man, and UV/Vis spec tros copy.
The pol ya cid be ha vior du ring neu tra li za tion ti tra tions with lit hium and so dium hydro xi des, car ried out un der ni tro gen at mosp he re, has been stu died by con duc to me try and po - ten tio me try. Hen der son-Has sel bach plots of po ten tio me tric ti tra tion cur ves show a break point at p H around 6, whe re the cur ve slo pe drops from 1.8 (at lo wer p H) to a va lue from 1.05 to 1.3 (at hig her p H va lues).
The UV/Vis spec tra mo - ni to red du ring back ti tra tion show: (i) mo no to nous de crea se of both λmax and εmax as p H de crea ses, (ii) the pre sen ce of the isos be stic point at 401 nm that can be as cri bed to con for ma tio nal tran si tion of PTAA chains, and (iii) absen ce of the isos be stic point at 392 nm re por ted pre vi ously by ot her aut hors.