Comment on "Relating side chain organization of PNIPAm with its conformation in aqueous methanol" by D. Mukherji, M. Wagner, M. D. Watson, S. Winzen, T. E. de Oliveira, C. M. Marques and K. Kremer, Soft Matter, 2016, 12, 7995. Issue 42 (20th October 2017)

• Record Type: Journal Article
• Authors: Pica, Andrea; Graziano, Giuseppe
• Is Part Of: Soft matter. Volume 13:Issue 42(2017)
• Page Start: 7698
• Page End: 7700
• Publication Date: 2017-10-20
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c7sm01065f
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : We try to clarify some issues that were raised by an article that appeared in Soft Matter, 2016, 12, 7995. PNIPAM cononsolvency is not due to the bridging mechanism of MeOH molecules; it is caused by geometric-energetic frustration. Abstract : In a recent article, Kremer and co-workers have combined NMR measurements and very long, all-atom MD simulations to strengthen their original claim that PNIPAM cononsolvency in water–methanol solutions is driven by the ability of MeOH molecules to bridge different monomers far away along the polymeric chain. In this comment, the results presented by Kremer and co-workers are reviewed, analyzed, and questioned regarding their ability to provide support to the bridging mechanism. Here, some pieces of evidence are provided to show that: (1) the solvent-excluded volume effect plays always a fundamental role in polymer collapse; (2) PNIPAM cononsolvency is caused by the geometric-energetic frustration experienced by the polymer when it can interact with both water and methanol molecules at the same time.