A molecular interplay for osmolytes-induced phase behaviour of poly (vinyl methyl ether)

Naturally occurring osmolytes are small organic compounds that affect the functioning of the macro-molecule and ever-present in the living systems. Trimethylamine N-oxide (TMAO), betaine and sarcosine are among the family of methylamines which are a class of osmolytes that may lead to the alteration in the transition behaviour of thermo-responsive polymers (TRPs). In this context, we have extended our work in the direction of exploring influence of various methylamines on the lower critical solution temperature (LCST) of poly (vinyl methyl ether) (PVME). Herein this study, we used various biophysical techniques to explore the impactful aspect of methylamines on the PVME polymer. The structural integrity of the additive is found to play a major role in altering the phase transition temperature of PVME. These additives are observed to have high binding affinity for water as compared to the polymer which result in the swollen to collapsed transition of PVME at the lower temperatures than the typical LCST of the polymer. One of the common aspects in all the three additives is their positive and negative charges separation that allows their effective binding with the water molecules. Although, each osmolytes decreases the LCST of the PVME, however, highest decrease is observed with sarcosine and lowest for TMAO. In case of sarcosine, less sterically hindered N atom may directs the possibility of its H-bonding ability towards water as compared to that for TMAO and betaine containing sterically hindered N atom. (C) 2017 Elsevier Ltd. All rights reserved.