화학공학소재연구정보센터
Journal of Colloid and Interface Science, Vol.553, 655-665, 2019
Scrutinizing the effect of various nitrogen containing additives on the micellization behavior of a triblock copolymer
Hypothesis: PEG-PPG-PEG contains hydrophobic (PPG) as well as hydrophilic (PEG) blocks have gained popularity due to their different physiochemical properties that make them useful in several scientific areas and industrial applications such as detergency, stabilizers for dispersion, foaming and many more. Scientific communities reported that additives have ability to tune the micellization/demicellization tendency of PEG-PPG-PEG which we further extended by the use of several N-containing additives. Especially, chemists and biochemists are interested to extend the potential role of PEG-PPG-PEG copolymer in biomedical sensing applications, that is why triblock copolymer is chosen with various additives in the present study. Experiments: The work reports the results obtained through different kinds of interactions induced among the poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG) and additives containing different structural moieties. In order to tune micellization tendency of PEG-PPG-PEG, several additives such as trimethylamine-N-oxide (TMAO), betaine, sarcosine, guanidinium hydrochloride (GdnHCl) and urea are introduced in the current part of work and studied using UV-visible and fluorescence spectroscopy, dynamic light scattering (DLS), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. Findings: The methylamines facilitate the micellization to higher extent in comparison to that in aqueous PEG-PPG-PEG system, thereby decreasing the critical micellization temperature (CMT) values of PEG-PPG-PEG. Among studied methylamines, sarcosine has the highest efficacy in inducing the micellization followed by TMAO and betaine to the least extent. Direct interactions among polymeric segments and sarcosine is thought to be the main driving force for micellization of PEG-PPG-PEG. This is not possible for the case of betaine and TMAO due to the presence of the sterically hindered N atom. In contrast to these methylamines, GdnHCl and urea provided favorable binding sites for bridging interactions among polymer segments and thus lead to higher temperature values for CMT of PEG-PPG-PEG. (C) 2019 Elsevier Inc. All rights reserved.