Poly(N-isopropylacrylamide) (PNIPAM) has a lower critical solution temperature (LCST)of ~32�C. PNIPAM chains are soluble below the LCST and insoluble above the LCST. If the concentration of PNIPAM is >1 ppm, then polymer chains after undergoing coil-to-globule transition above the LCST, aggregates to yield a stable colloidal dispersion. However, to-date the atomic scale mechanism and structure of these aggregates is not clear. Additionally, effect of salt ions such as Na+Cl-on the agglomeration mechanism of these polymers is not yet understood. Dynamical properties of these polymer agglomerates, water, and salt ions below and above the LCST of PNIPAM can be studied using molecular dynamics (MD) simulations. Two PNIPAM chains with 30 monomer units solvated in salt solution with different concentrations were simulated in the temperature range of 278 to 315 K. Simulation trajectories were analyzed to explore the agglomeration dynamics of short chain polymers.

Molecular dynamics simulation study on the effect of salt ions on the agglomeration dynamics in thermo-sensitive polymers

243rd National Meeting (2012)

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