title: Thermodynamic considerations for solubility and conformational transitions of poly-N-isopropyl-acrylamide.
abstract: Thermodynamic considerations based on the free energy of hydration, free energy of solvation and partition coefficient predictions of the monomer N-isopropyl-acrylamide (NIPAM) determined using various intermolecular potentials are used to elucidate the origin of hydrophobicity/hydrophilicity across the lower critical solution temperature (LCST). Thermodynamic properties are predicted for NIPAM using adaptive bias force-molecular dynamics and various popular force-fields (AMBER, OPLS-AA, CHARMM and GROMOS) at four different temperatures: below the LCST (275 K and 300 K) and above the LCST (310 K and 330 K). The effect of changes in the thermodynamic properties of the monomer NIPAM at various temperatures below and above LCST on the kinetics of conformational transition of thermo-sensitive polymers is discussed. Our findings provide encouraging prospects for understanding the LCST transition in the hydrogel poly-N-isopropylacrylamide which shows temperature-dependent conformational changes in part due to the complex interplay of hydrophilic/hydrophobic interactions.
authors.affiliation: Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Kamath
authors.forename: Sanket A
authors.initials: SA
authors.lastname: Deshmukh
authors.forename: Gary A
authors.initials: GA
authors.lastname: Baker
authors.forename: Derrick C
authors.initials: DC
authors.lastname: Mancini
authors.forename: Subramanian K R S
authors.initials: SK
authors.lastname: Sankaranarayanan