Fabrication of superhydrophobic coatings with self-cleaning properties on cotton fabric based on Octa vinyl polyhedral oligomeric silsesquioxane/polydimethylsiloxane (OV-POSS/PDMS) nanocomposite

HYPOTHESIS

Wetting behavior of solid surfaces plays an important role in various industrials and even daily life applications. Controlling the surface wettability through fabricating strongly hydrophilic or hydrophobic properties is achieved by tailoring surface topography and chemical composition. Polyhedral oligomeric silsesquioxanes (POSSs) are a class of hybrid materials with the possibility of hydrophobicity enhancement through simultaneous increase in surface roughness and reduction of surface energy.

EXPERIMENTS

In this study, octavinyl-POSS (OV-POSS) structures were utilized in fabrication of superhydrophobic cotton fabric. Coating was successfully performed through creating a two-layer topography via spraying method. In brief, surface roughness was enhanced by spraying a base layer of TiO₂ sol over the surface followed by applying a nanocomposite layer composed of 0.02 wt% of POSS in polydimethylsiloxane (PDMS).

FINDINGS

It was observed that, water contact angle (WCA) of pristine and TiO₂ coated fabric was enhanced from 0° up to ∼168° using 0.02 wt% OV-POSS/PDMS nanocomposite with a water sliding angle (WSA) of <10°. According to the results, environmentally friendly nature of precursors, high thermal, mechanical and chemical stability, self-cleaning and anti-adhesion propertiesof the as-prepared coating and simple preparation method with no special post-treatment requirement, confirm that the as-prepared coating is perfect candidate for large-scaled applications.

Controlled click-assembly of well-defined hetero-bifunctional cubic silsesquioxanes and their application in targeted bioimaging

A general procedure for the assembly of hetero-bifunctional cubic silsesquioxanes with diverse functionality and a perfectly controlled distribution of functional groups on the inorganic framework has been developed. The method is based on a two-step sequence of mono- and hepta-functionalization through the ligand-accelerated copper(I)-catalyzed azide-alkyne cycloaddition of a readily available octaazido cubic silsesquioxane. The stoichiometry of the reactants and the law of binomial distribution essentially determine the selectivity of the key monofunctionalization reaction when a copper catalyst with strong donor ligands is used. The methodology has been applied to the preparation of a set of bifunctional nano-building-blocks with orthogonal reactivity for the controlled assembly of precisely defined hybrid nanomaterials and a fluorescent multivalent probe for application in targeted cell-imaging. The inorganic cage provides an improved photostability to the covalently attached dye as well as a convenient framework for the 3D multivalent display of the pendant epitopes. Thus, fluorescent bioprobes based on well-defined cubic silsesquioxanes offer interesting advantages over more conventional fully organic analogues and ill-defined hybrid nanoparticles and promise to become powerful tools for the study of cell biology and for biomedical applications.