The authors describe a process that may eventually reduce the risk of scar formation after glaucoma surgery. For this, a thin hydrogel coating is photochemically generated and linked to the sclera surface at the surgical site. This coating is generated from a photoreactive prepolymer containing anthraquinone groups, which is administered as a thin pad to the sclera surface. Short UV irradiation leads to a reaction of the photogroups with neighboring chains via C–H insertion crosslinking, thus transforming the precursor polymer into a hydrogel. Simultaneously, a reaction between the photogroups and the underlying sclera tissue occurs, so that the hydrogel patch becomes covalently linked to the tissue. The authors show that the resulting thin coating is strongly cell repellent and hinders tenon fibroblasts to form tenon tissue at the site of the coating and is suitable for inclusion into a surgical procedure.

We describe the formation process of surface-attached polymer networks generated through photochemically induced C,H insertion crosslinking (CHic). To achieve surface attachment, light must be able to penetrate all the way to the interface between the film and the substrate to trigger the necessary reactions. Although light penetration is typically a nonissue for thin films below 1 μm, it may become difficult for thicker layers. In this contribution, we show that a critical light dose is needed to ensure full percolation. This critical dose can be derived from Lambert–Beer's law and percolation theory. Both experiments and calculations lead to a model, which is able to predict the percolation points of films as a function of light intensity and film thickness, even for very thick films. The only parameters that need to be determined for this model are the linear absorption coefficient of the polymer, its change with increasing irradiation time due to photobleaching, and the percolation point of a thin film.

No abstract

Teak wood is widely used for the housing interior and decoration because of its beautiful grains appearance; however, it often suffers from surface damage especially in the tiling application. The remedy is to apply a protective layer such as polyurethane (PU). In this work, the sol-gel inorganic reinforced hard coating formulation based on silicon dioxide (SiO 2 ) nanoparticles (SNPs) and methyltrimethoxysilane (MTMS) was investigated as a protective layer for teak wood. The coating formulation was applied by brushing, followed by pre-cured at 65 °C for 1 hr and cured at 95 °C for 3 hrs, yielding a transparent nanocomposite film.The SiO 2 nanocomposite coating showed an improvement in abrasion resistance property, tested with Taber abrasion at 5 N for 1000 cycles, as evidenced by a lower weight loss than an uncoated counterpart. The nanocomposite film also showed a higher wear through resistance than the commercial PU coating. Water can be easily absorbed by uncoated wood while the nanocomposite coated wood showed an improvement in water resistance as evidence by water contact angle. The crosssectional image showed that the nanocomposite film and the wood surface were forming a physical interlocking.