We investigate a minimal equilibrium polymerization model of the general competition between self-assembly on a boundary and in solution that arises when an assembling system is near a boundary. Adsorption generally occurs upon cooling, but assembly (equilibrium polymerization) may arise either upon cooling or heating. Both cases are shown to exhibit di erent manifestations of the coupling between adsorption and self-assembly. When both assembly and adsorption proceed upon cooling, a simply change in the ratio of the enthalpy of adsorption to the enthalpy of assembly in solution can switch the system between a predominance of of self-assembly in solution and a dominance of assembly on the substrate. If assembly occurs upon heating and adsorption upon cooling, as in many self-assembling proteins in aqueous solution, then a self-assembly analog of a closed loop phase boundary is found. In particular, the order parameter for assembly on the surface exhibits a peak as a function of temperature. As demonstrated by examples, the coupling between surface adsorption and self-assembly provides a powerful means of switching self-assembly processes on and off. Understanding and controlling this phenomenon will be useful in designing and directing self-assembly processes on surfaces for nanomanufacturing applications and in developing treatments for diseases arising from pathological adsorption-induced assembly.
Citation: Journal of Chemical Physics
Pub Type: Journals
adsorption, self-assembly, adsortion-induced assembly, equilibrium polymerization, amyloid fiber formation