Preparation of Antifog Hard Coatings Based on Carboxy-Functionalized Polyhedral Oligomeric Silsesquioxane Cross-Linked with Oligo(ethylene glycol)s

In this study, we prepared antifog hard coatings by heating a mixture of carboxy-functionalized polyhedral oligomeric silsesquioxane (POSS-C) and oligo(ethylene glycol)s (OEGs, HO(CH2CH2O) n H, n = 1-6) in N,N-dimethylformamide, applying the mixture onto a glass substrate, and subsequently removing the solvent via heating. In addition, we evaluated the water resistance, hardness, and antifogging performance of the coatings. In particular, the coating produced at a 2:1 functional group ratio of POSS-C to tetraethylene glycol (OEG, n = 4) coating exhibited high surface hardness (6H), as determined using pencil scratch testing. The coating remained clear after exposure to the vapor of warm water at 40 °C at a height of 2 cm for 10 s, demonstrating its antifogging property. Furthermore, no dissolution or cracking was observed when the POSS-C/OEG coating (n = 4, COOH/OH = 2:1) was immersed in water at room temperature for 1 h, confirming its water resistance. The Fourier transform infrared/attenuated total reflectance results showed the formation of ester bonds, indicating the construction of a network structure that enhanced the water resistance and hardness of the coating.

Ionic Liquids Containing Silsesquioxane and Cyclic Siloxane Frameworks

This paper describes the author's recent work on the preparation and properties of thermally stable ionic liquids (ILs) containing siloxane frameworks. Quaternary ammonium and imidazolium salt-type ILs containing random oligosilsesquioxane frameworks were successfully prepared via the hydrolytic condensation of the corresponding organotrialkoxysilanes by using an aqueous superacid bis(trifluoromethanesulfonyl)imide (HNTf2 ) solution as a catalyst and solvent. Imidazolium salt-type ILs containing polyhedral oligomeric silsesquioxane (POSS) frameworks were also prepared through a reaction similar to that described above by using a water/methanol mixed solution of HNTf2 . In addition, amorphous POSSs with two types of ionic groups randomly distributed in the side chain were prepared. These POSSs were ILs exhibiting fluidity at relatively low temperatures. Furthermore, imidazolium and ammonium salt-type ILs containing cyclic oligosiloxane frameworks were prepared through a reaction similar to that of the corresponding organodialkoxysilanes. The thermal decomposition temperatures of the above ILs containing siloxane frameworks were higher than those of general ILs.

Recent Progresses on Designable Hybrids with Stimuli-Responsive Optical Properties Originating from Molecular Assembly Concerning Polyhedral Oligomeric Silsesquioxane

In this review, we describe recent progresses on the stimuli-responsive hybrid materials based on polyhedral oligomeric silsesquioxane (POSS) and their applications as a chemical sensor. In particular, we explain the unique functions originating from molecular assembly concerning POSS-containing soft materials mainly from our studies. POSS has an inorganic cubic core composed of silicon-oxygen (Si-O) bonds and organic substituents at each vertex. Owing to intrinsic properties of POSS, such as high thermal stability, rigidity, and low chemical reactivity, various robust hybrid materials have been developed. From the numerous numbers of POSS hybrids, we herein focus on the environment-sensitive optical materials in which molecular assembly of POSS itself and functional units connected to POSS should be a key factor for expressing material properties. We also explain the mechanisms of chemical sensors originating from these stimuli-responsive optical properties. Stimuli-responsive excimer emission and pollutant detectors, nanoplastic sensors with the water-dispersive POSS networks, trans fatty acid sensors, turn-on luminescent sensors for aerobic condition and fluoride anion sensors are described. We also mention the mechanochromic polyurethane hybrids and the thermally-durable mechanochromic luminescent materials. The roles of the unique optical properties from soft materials composed of rigid POSS, which doesn't have significant light-absorption and emission properties in the visible region, are surveyed.

Preparation of Soluble POSS-Linking Polyamide and Its Application in Antifogging Films

In this study, we prepared a polyhedral oligomeric silsesquioxane (POSS)-linking polyamide (POSS polyamide) by a polycondensation of ammonium-functionalized POSS (POSS-A) and carboxyl-functionalized POSS (POSS-C) in dehydrated dimethyl sulfoxide (DMSO) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as condensing agents. The obtained POSS polyamide was soluble in various highly polar solvents, and it could form a self-standing film. FT-IR, ¹H NMR, and ²⁹Si NMR analyses showed that POSS polyamide is a polymer in which POSS-A and POSS-C are linked almost linearly by amide bonds. Furthermore, the cast film obtained by heat-treating the polymer at 150 °C for 30 min exhibited excellent transparency and hard-coating (pencil scratch test: 5H) and antifogging properties (evaluation by water vapor exposure).