Structures and thermodynamics of nondilute polymer solutions confined between parallel plates


Lattice Monte Carlo simulations were conducted to study the thermodynamics and structures of linear chain molecules in solutions confined between two parallel plates of various widths over a wide range of concentrations. The results for the chemical potentials, anisotropic chain dimensions, and scattering structure factors are shown and compared with the scaling-law predictions by Daoud and de Gennes. The transition from a 3D-like solution to a 2D-like solution is observed in both dilute and semidilute regions when the confinement strength increases. In the dilute solution limit, the transition is characterized by an expansion in the chain dimension along the slit walls. In the semidilute region, the transition from 2D dilute pancakes to 2D semidilute pancakes and finally to 3D semidilute spheres with increasing concentration is observed in the dependence of the chain dimension on the concentration. This transition, however, is not clearly seen in the chemical potentials. The single chain structure factors of the confined chains exhibit 2D characteristics in the dilute solution with strong confinement but approach the Debye function in the 2D semidilute and 3D semidilute solutions.

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