Role of physicochemical characteristics of poly(N,N-diethylacrylamide) on the polymer thermal responsivity and interfacial properties in aqueous solution: All-atom simulation study.

Molecular dynamic behaviors of poly(N,N-diethylacrylamide) (PDEA) as well as its interfacial properties in water were studied measuring the polymer single chain in a dilute concentration regime via molecular dynamics simulation. The investigation of chain length and temperature impacts on the rate of affinity variation of PDEA to water through calculating non-bonded interactions between them showed that the increment of two mentioned items reduced the polymer hydrophilicity in water. The interactional variation altered the PDEA diffusivity in the solution so that the decrement of PDEA tendency to water enhanced the chain movements because of reducing the interfacial friction between the chain and media, particularly at the transition zone. The chains spatial dimensions, conformation and shape were determined as a function of temperature to evaluate the chain hydrodynamic features. A particular order parameter for the PDEA backbone bonds and distribution of their dihedral angles were calculated to consider entropy of the chains with temperatures. The results indicated that PDEA tended to have a rod conformation with less entropy at lower temperatures and chain lengths. Finally, a novel parameter, < P(T) >, based on the interfacial structure of water was presented to quantitate the relationship between the thermodynamics of PDEA and its structure and hydrophilicity variation with temperature.