Hydrogels have three-dimensional network structures, high water content, good flexibility, biocompatibility, and stimulation response, which have provided a unique role in many fields such as industry, agriculture, and medical treatment. Poly(vinyl alcohol) PVA hydrogel is one of the oldest composite hydrogels. It has been extensively explored due to its chemical stability, nontoxic, good biocompatibility, biological aging resistance, high water-absorbing capacity, and easy processing. PVA-based hydrogels have been widely investigated in drug carriers, articular cartilage, wound dressings, tissue engineering, and other intelligent materials, such as self-healing and shape-memory materials, supercapacitors, sensors, and other fields. In this paper, the discovery, development, preparation, modification methods, and applications of PVA functionalized hydrogels are reviewed, and their potential applications and future research trends are also prospected.

A facile spray coating preparation of ultraviolet (UV) shielding Poly(methyl methacrylate) (PMMA) based colloidal photonic crystal (PC) films was presented, where the UV radiation was physically resisted by the periodic structure. The specific wavelength within the UV regime could be tuned as required by varying the size of the monodispersed PMMA colloids. Such crystal coatings could be rapidly prepared in optical glasses with controllable thickness of ~5 μm, which could simultaneously resist UV-254 with the efficiency of 77.43%. The monochromaticity of the crystal coatings ensures their potential in UV shielding materials of direct physical skin contact type.

A functional lens coating, based on the structure of inversed colloidal photonic crystals, is proposed. The color-reflecting colloidal crystal was first prepared by self-assembly of nano-colloids and was infiltrated by adhesive polymer solution. As the polymer was crosslinked and the crystal array was removed, a robust mesh-like coating was achieved. Such a functional coating has good transmittance and has a shielding efficiency of ~9% for UV–blue light according to different particle sizes of the nano-colloids, making it an ideal functional material.

Ophthalmic resin lenses are widely used to correct myopia and defend harmful light waves. Ophthalmic lens with anti-reflective (AR) coating has become the mainstream product in the lens market. The AR coating is composed by inorganic metal oxides, which is very different to the organic lens substrate in thermal expansion coefficients. In a normal wearing environment, coating delaminating often occurs resulting that AR function is disabled. How to evaluate adhesion of the AR coating is important. In this paper, a specially designed cutting tool was used to scratch two grids on each surface of the lens. The peel off operation was carried out with the tape within specified adhesion range. The coating detachment was evaluated by visual inspection and microscopy based on the methods defined in ISO 2409 and GB 10810.4, the applicability was compared and discussed.