Template free preparation of nanoporous organically modified silica thin films on flexible substrates

Abstract

We report the preparation and characterization of nanoporous organically modified silica (ormosil) thin films at room temperature and neutral pH conditions from homogeneous methyl silsesquioxane (MSQ) gels. Universally applicable and stable colloidal ormosil suspensions are prepared from the gels by sonication and coated to the substrates including glass, paper and plastics. The nanoporosity and thickness of the films can be tuned, which makes them suitable for certain applications including sensing, functional coatings, and low-dielectric materials. We demonstrate the antireflection property of the films on glass, cellulose acetate (CA) and polyetherimide (PEI) substrates. The films on CA and PEI retain their antireflection property after multiple bending cycles. Furthermore, films are intrinsically hydrophobic, over a wide pH range, with static contact angles up to 143 on paper and 123 on glass and CA. Producing nanoporous ormosil thin films on flexible substrates may expand their use in low cost electronic, optical devices and sensors, and lab-on-paper applications.

Superhydrophobic and Omnidirectional Antireflective Surfaces from Nanostructured Ormosil Colloids

“…The transmission maxima of the coatings can be tuned to visible wavelengths by decreasing the thickness of the coatings simply using more dilute ormosil colloids. 27 Multifunctional Ormosil Coating. On the basis of above the results and keeping in mind that the gradually increasing refractive index through coating is crucial to achieve broad band antireflection in normal and oblique incidence angles, 34 we designed a three layer coating through the finite difference time domain (FDTD) simulations.…”

Fabrication of hydrophobic silica–cellulose aerogels by using dimethyl sulfoxide (DMSO) as solvent

“…The appropriate gelation time is propitious to restrict silica sols and dispersed MFCs in solid gels before phase separation happens. The functions of DMSO as solvent are probably these two: (1) DMSO promotes homogeneous methyl silsesquioxane (MSQ) gels probably by dissolving the cyclic and cage like structures and shortens the gelation time due to high polarity [16] and (2) DMSO decreases solvent viscosity and varies surface tension to enhance the dissolution of cellulose [17]. As for the latter, in fact, DMSO is a frequently used component mixed with ILs to increase the solubility of cellulose by positioning itself in favored order geometries in the dissolution process [18].…”

Sol–gel preparation of moisture-resistant antireflective coatings from novel hollow silica nanoparticles

“…That is why HSNs tend to aggregate with each other when the MTES/TEOS increased (Scheme 2). However, there would be many precipitates due to low solubility of cyclic and cage-like structures formed during polymerization of MTES monomer [17], which stopped us from preparing sols using higher MTES/TEOS or only MTMS monomers. …”

“…One is to improve the hydrophobic nature of silica thin films because it is closely linked to the durability of the AR coating [13]. There have been many attempts to prepare silica AR coatings with improved hydrophobicity by the introduction of organic molecules or polymers bearing hydrophobic groups into the coatings [14][15][16][17][18][19][20]. However, in order to achieve satisfiable environmental resistance, these methods need to add large amounts of polymer or hydrophobic silane precursors to give the AR coatings enough hydrophobic groups.…”