Ease-of-manufacture highly transparent thin polyvinyl alcohol aerogel

Abstract

Abstract The earliest silicon-based aerogels attracted attention due to their nanoscale porous structure and high transparency. Still, they need to be more balanced with the poor mechanical properties. Their brittle structure limits the development of this promising new material. Therefore, the goal of this work is to optimize the mechanical properties of aerogels while maintaining transparency. The good mechanical properties of polymers have made them the material of choice for this work. Polyvinyl alcohol (PVA), which can undergo self-crosslinking through side-chain hydroxyl groups forming hydrogen bonds, was chosen as the raw material to simplify and expedite the production process. The production process was experimented with, analyzed, and refined. Considering the time efficiency of the experimental process, a one-step gelling method was invented to facilitate the sol-gel transition. The one-step gelling method maintained the high transparency of PVA aerogels and reduced the time required for the gelation process compared to the freeze-thawing method. This work employs carbon dioxide supercritical drying to ensure minimal structural collapse and maximize the porous structure’s retention. The transmittance of PVA aerogels can reach up to 93.67% at a wavelength of 1333 nm. The internal structure of aerogels with different PVA concentrations was observed using a Scanning electron microscope. Applying Beer-Lambert’s Law eliminated the effect of sample thickness on transparency. The relationship between the transparency of PVA aerogels, their microstructure, and macroscopic concentration was studied and analyzed for the first time. While ensuring light transmittance, the modulus of the PVA aerogel reached as high as 6.18 ± 0.56 MPa at 13 wt%.