Thermodynamic analysis of the conformational transition in aqueous solutions of isotactic and atactic poly(methacrylic acid) and the hydrophobic effect
ID Kogej, Ksenija (Author)

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The affinity of amphiphilic compounds for water is important in various processes, e.g., in conformational transitions of biopolymers, protein folding/unfolding, partitioning of drugs in the living systems, and many others. Herein, we study the conformational transition of two isomer forms of poly(methacrylic acid) (PMA), isotactic (iPMA) and atactic (aPMA), in water. These isomers are chemically equivalent and differ only in the arrangement of functional groups along the chain. A complete thermodynamic analysis of the transition of the PMA chains from the compact to the extended form (comprising the conformational transition) in water in the presence of three alkali chlorides is conducted by determining the free energy, enthalpy, and entropy changes of the process as a function of temperature, and therefrom also the heat capacity change. The heat capacity change of the transition is positive (+20 J/K mol) for aPMA and negative (–50 J/K mol) for iPMA. This result suggests a different affinity of PMA isomers for water. The conformational transition of iPMA is parallel to the transfer of polar solutes into water, whereas that of aPMA agrees with the transfer of nonpolar solutes into water.

Keywords:polymethacrylic acid, isotactic, conformational transition, thermodynamics, temperature dependence, hydrophobic effect, hydrophobic hydration
Work type:Article
Typology:1.01 - Original Scientific Article
Organization:FKKT - Faculty of Chemistry and Chemical Technology
Publication status:Published
Publication version:Version of Record
Number of pages:19 str.
Numbering:Vol. 8, iss. 5, art. 168
PID:20.500.12556/RUL-130304 This link opens in a new window
ISSN on article:2073-4360
DOI:10.3390/polym8050168 This link opens in a new window
COBISS.SI-ID:1536889283 This link opens in a new window
Publication date in RUL:13.09.2021
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Shortened title:Polymers
Publisher:Molecular Diversity Preservation International
COBISS.SI-ID:517951257 This link opens in a new window


License:CC BY 4.0, Creative Commons Attribution 4.0 International
Description:This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
Licensing start date:01.05.2016

Secondary language

Keywords:fizikalna kemija, vodne raztopine, polielektrolitske raztopine, polielektroliti, termodinamika, konformacijski prehodi, temperaturna odvisnost, hidrofobni efekt, hidrofobnost, polimetakrilna kislina, izotaktična polimetakrilska kislina, PMA


Funder:ARRS - Slovenian Research Agency
Project number:P1-0201
Name:Fizikalna kemija

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