Molecular dynamics study of wetting behavior of grafted thermo-responsive PNIPAAm brushes

• Type: Article in International Scientific Journal
• Date: 2016

Authors

Bhandary, D (Author) Other; Benkova, Z (Author) Other; Natalia N D S Cordeiro (Author) FCUP; Singh, JK (Author) Other

Journal

Title: Soft Matter

Vol. 12

Pages: 3093-3102

ISSN: 1744-683X

Publisher: Royal Society of Chemistry

Indexing

ISI Web of Knowledge - 18 Citations

Scopus - 18 Citations

Other information

Authenticus ID: P-00K-AFW

DOI: 10.1039/c5sm02684a

Abstract (EN): In this work, the effect of temperature on the contact angle of a water droplet on grafted thermoresponsive poly-(N-isopropylacrylamide) (PNIPAAm) polymer brushes is studied using all-atom molecular dynamics simulations in the temperature range of 270-330 K. A shift from 551 to 65 degrees in contact angle values is observed as the temperature increases from 300 K to 310 K, which is in line with the experimental reports. The behavior of a water droplet on PNIPAAm brushes is analyzed using hydrogen bond analysis, water diffusion, radial distribution functions, the potential of mean force, excess entropy and the second virial coefficient (B-2). The thermo-responsive behavior of PNIPAAm brushes, quantified using the excess entropy and B-2 of PNIPAAm-water and water-water interactions, is mainly governed by polymer-water interactions. In particular, the excess entropy and B-2 of PNIPAAm resulting from the PNIPAAm-water interactions are found to increase with increasing temperature. The dehydration of PNIPAAm brushes and the increase in the contact angle of water were confirmed to be entropy driven processes.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10