Thermodynamically controlled surface modifications

The clean, precise, and reversible modification of surfaces represents an important opportunity to expand the application range of self-assembly. In particular, the thermodynamic control and reversibility of CSA can be exploited for the error-free generation of three-dimensional architectures directly on surfaces. 

ABSTRACT. The paper examines the influence of interactions at polymer surfaces and interfaces on the properties of polymer systems, with emphasis on acid/base interactions. The method of inverse gas chromatography is used to evaluate the donor-acceptor interaction potential of components in polymer systems. The usefulness of the interaction parameters is established by their ability to rationalize diverse properties of polymer systems, including the adsorption of polymers on pigments, and the effectiveness of thermal stabilizers in pigmented polymers. Various strategies for controlling surface and interfacial interactions in polymer systems are reviewed, with emphasis placed on the ability of polymers to adopt various surface orientations and compositions. TTiese inherent surface modification effects are attributed to thermodynamic driving forces, and are shown to influence polymer adhesion, barrier and other properties dependent on surface and interfacial forces. 

The final category of surface modifications to be considered has its origins in the thermodynamics of interfaces and interphases within multi>component polymers and is therefore an inherent feature of such systems. It is, in a sense, beyond the control of the scientist or engineer involved. Inherent modifications are noted here in some detail because they are apt to be neglected in practise, and yet represent an important built-in source of variations in the performance of bonds, barrier and mechanical properties of polymer systems. 

The modification of polymer end-group chemistry has been utilized as a method of controlling the surface activity of polymeric materials. The synthesis of polymers with low surface energy end-groups can generate sufficient thermodynamic driving forces to dictate that polymer surface chemistry is dominated by end-groups. 

Cyclic voltammetric studies of these metallodendrimers showed one reversible oxidation wave, characteristic of independent, non-interacting redox centers. Also, the use of these materials for the modification of electrode surfaces was explored [37-39]. The researchers found that platinum, glass, and carbon-disk electrodes modified by electrodeposited films of these dendrimers are extremely durable and reproducible, with no detected loss of electroactivity even after their use in different electrolyte solutions or after standing for long periods in air. Studies on the thermodynamics and kinetics of adsorption of these redox-active dendrimers onto Pt electrodes by means of electrochemical and electrochemical quartz crystal microbalance techniques were conducted. These showed the adsorption processes to be activation-controlled rather than diffusion-controDed, and to be dependent on... 

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