We comprehensively study nonequilibrium relaxation and aging processes in the two-dimensional randomsite Ising model through numerical simulations. We discuss the dynamical correlation length as well as scaling functions of various two-time quantities as a function of temperature and of the degree of dilution. For already modest values of the dynamical correlation length L deviations from a simple algebraic growth, L͑t͒ϳt 1/z , are observed. When taking this nonalgebraic growth properly into account, a simple aging behavior of the autocorrelation function is found. This is in stark contrast to earlier studies where, based on the assumption of algebraic growth, a superaging scenario was postulated for the autocorrelation function in disordered ferromagnets. We also study the scaling behavior of the space-time correlation as well as of the time integrated linear response and find again agreement with simple aging. Finally, we briefly discuss the possibility of superuniversality in the scaling properties of space-and time-dependent quantities.

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Using numerical simulations we investigate the properties of the dynamic phase transition that is encountered in the three-dimensional Ising model subjected to a periodically oscillating magnetic field. The values of the critical exponents are determined through finite-size scaling. Our results show that the studied non-equilibrium phase transition belongs to the universality class of the equilibrium three-dimensional Ising model.

Understanding the interaction between polyimide and inorganic surfaces is vital in controlling interfacial adhesion behavior. Here, molecular dynamics simulations are employed to study the adhesion of polyimide on both crystalline and glassy silica surfaces, and the effects of hydroxylation, silica structure, and polyimide chemistry on adhesion are investigated. The results reveal that polyimide monomers have stronger adhesion on hydroxylated surfaces compared to nonhydroxylated surfaces. Also, adhesion of polyimide onto silica glass is stronger compared to the corresponding crystalline surfaces. Finally, we explore the molecular origins of adhesion to understand why some polyimide monomers like Kapton have a stronger adhesion per unit area (adhesion density) than others like BPDA-APB. We find this occurs due to a higher density of oxygen’s in the Kapton monomer, which we found to have the highest contribution to adhesion density.