Self-Cleaning and Anti-Fog Surfaces via Stimuli-Responsive Polymer Brushes

The (3-aminopropyl)triethoxysilane (APTES) self-assembled monolayer (SAM) has been widely used in fundamental research and engineering applications; however, characterization of its surface wetting properties remains problematic. Surface wetting properties of the APTES SAM were systematically investigated using different contact angle measurement techniques. The observed unique nonideal wetting was related to the APTES SAM structure, including surface hydrogen bond formation, the surface roughness, and the effect of water penetration. The contact angle decreased dramatically with the residence time on the APTES SAM surface, and a special contact angle hysteresis phenomenon was observed. The contact angle could be distorted by the calculation method used for the nonideal APTES SAM surface. Values calculated by the tangent-leaning method were thought to be more accurate and credible. Our findings demonstrated that static advancing contact angles were the most stable and credible for characterizing the APTES SAM surface wettability.

Surface Wettability of (3-Aminopropyl)triethoxysilane Self-Assembled Monolayers

Surface functionalisation for the self-assembly of nanoparticle/polymer multilayer films

Directed square lattice models of polymers and vesicles have received considerable attention in the recent mathematical and physical sciences literature. These are idealized geometric directed lattice models introduced to study phase behaviour in polymers, and include Dyck paths, partially directed paths, directed trees and directed vesicles models. Directed models are closely related to models studied in the combinatorics literature (and are often exactly solvable). They are also simplified versions of a number of statistical mechanics models, including the self-avoiding walk, lattice animals and lattice vesicles. The exchange of approaches and ideas between statistical mechanics and combinatorics have considerably advanced the description and understanding of directed lattice models, and this will be explored in this review. The combinatorial nature of directed lattice path models makes a study using generating function approaches most natural. In contrast, the statistical mechanics approach would introduce partition functions and free energies, and then investigate these using the general framework of critical phenomena. Generating function and statistical mechanics approaches are closely related. For example, questions regarding the limiting free energy may be approached by considering the radius of convergence of a generating function, and the scaling properties of thermodynamic quantities are related to the asymptotic properties of the generating function. In this review the methods for obtaining generating functions and determining free energies in directed lattice path models of linear polymers is presented. These methods include decomposition methods leading to functional recursions, as well as the Temperley method (that is implemented by creating a combinatorial object, one slice at a time). A constant term formulation of the generating function will also be reviewed. The thermodynamic features and critical behaviour in models of directed paths may be informative about the underlying properties that determine phase diagrams for wider classes of models, including physical models of polymers. Of particular interest are adsorption and collapse transitions in models of polymers and copolymers. The properties of thermodynamic quantities in those models are described by tricritical scaling. This is reviewed for directed path models, and the generating function approaches can be used to apply tricritical scaling to models of adsorbing, inflating and collapsing directed lattice paths. Critical exponents for a variety of models can be obtained in this manner, and with it a better understanding, and a classification, of the models.

S.B. Samanta

Papers

Effect of pH on electrical and optical properties of sol–gel derived microcrystalline Ba0.5Sr0.5TiO3 thin films

Surface order and structure studies of polymer-solid interface