1Chemistry Department, Faculty of Science, University of Benghazi, Benghazi, Qar Yunis, Libya
Adv. Mater. Lett., 2019, 10 (10), pp 741-745
Publication Date (Web): May 10, 2019
Copyright © IAAM-VBRI Press
In the present work, the critical concentration for self-assembly of dansyl-polyacrylic acid (DANS-PAA) in aqueous solution has been characterized by a combination of spectrophotometric and tensiometric techniques, number average molar mass, degree of polymerization, and average number of bonds were also determined. The normalized absorbance value for DANS-PAA (10-4 wt%) as a function of PAA concentration was at maximum below a critical self-assembly concentration (CAC) of 0.0005 g·mL−1 and decreased dramatically with PAA concentration above this CAC. This supposes that upon adding more polymer, assembly occurs in a short concentration range about 0.0005 g·mL−1. Similarly, surface tension measurements for DANS-PAA decreased markedly with concentration after a threshold of around 0.0005 g·mL−1, above which it remained constant at ca. 20 dyne·cm−1. Consequently, the binary techniques produced an equivalent estimation of the CAC. Additionally, surface tension studies showed that the DANS-PAA polymer miscible with water caused surface tension to decrease by 49 % over a concentration range of 0 to 0.0014 g·mL−1, whereas marked reduction in surface tension (33 %) upon adding PAA, and slight decreasing (7%) was recorded upon adding acrylic acid monomer (AA) to water. © VBRI Press.
Polyacrylic acid, dansyl-poly (acrylic acid), redox polymerization, absorbance, surface tension