Microcanonical analysis of adsorption of homopolymer chain on a surface.

The adsorption process of a homopolymer chain nongrafted on an attractive surface is numerically investigated using replica-exchange multicanonical Monte Carlo simulation. Based on the microcanonical analysis, the microcanonical entropy in the adsorption transition shows convex features. Correspondingly, with the coexistence of two phases, negative specific heat is also observed in the region, implying first-orderlike transition. The origin of the negative specific heat is due to the nonextensitivity of the energy in the system. This adsorption process has some similarities to the nucleation and growth mechanism in the crystalline process. Further study reveals that the transition type, either first- or second-orderlike, during chain adsorption is strongly dependent on the chain length, interactions among segments, whether chain grafted on the surface, and force upon segments imposed by surface. [ABSTRACT FROM AUTHOR]