Sol—gel derived coatings on glass

Uhlmann, D. R.; Suratwala, Tayyab; Davidson, Kevin; Boulton, J. M.; Teowee, G.

doi:10.1016/s0022-3093(97)00162-2

Cited by 152 publications

(92 citation statements)

References 55 publications

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“…For an ideal antireflective coating n f = (n 1 n 2 ) 1/2 , where n 1 and n 2 are the refractive indices of air and the substrate, respectively [39]. Consequently, assuming a glass substrate with a refractive index of ~1.5, a single antireflective coating should have the refractive index ~1.22; the lowest refractive index known for a solid nonporous dielectric material is 1.35 [40]. As seen in figure S2 and S3 in the supporting information, thin films presented in this paper have refractive indices in the ranges of 1.56-1.52 and 1.46-1.45 throughout the visible wavelengths 400-700 nm for the PVAm-NFC and the PVAm-SiO 2 -PVAm-NFC films, respectively.…”

Section: Resultsmentioning

confidence: 99%

Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films

Eita

Arwin

Granberg³

et al. 2011

Journal of Colloid and Interface Science

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Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability.In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO 2 -PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO 2 -PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer 2 for the PVAm-NFC system and the PVAm-SiO 2 -PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved.

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Section: Resultsmentioning

confidence: 99%

Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films

Eita

Arwin

Granberg³

et al. 2011

Journal of Colloid and Interface Science

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“…Many high-quality anti-reflection coatings are applied in high-temperature and high-vacuum processes when the substrate can withstand the elevated temperature. Solution and low-temperature vacuum deposition techniques can also be used for lower temperature substrates (Chen 2001;Uhlmann et al 1997). Solution techniques such as sol-gel are preferable over vacuum techniques from an economic perspective due to the capital and maintenance costs.…”

Section: Coatingsmentioning

confidence: 99%

Gradient Index Optics at DARPA

Teichman¹,

Holzer²,

Balko³

et al. 2013

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Executive SummaryThe Defense Advanced Research Projects Agency (DARPA) asked the Institute for Defense Analyses (IDA) to assemble a summary of work on gradient index optics completed under funding from the Agency. The purpose was to archive the efforts, motivation, and accomplishments that the Agency supported and to provide a reference for any future programs that explore this new area of optics.Although optical instruments, such as lenses and mirrors, dating back thousands of years ago have been unearthed, lenses were not put into practical use until the invention of eyeglasses in the thirteenth century. The microscope and the telescope were invented in the seventeenth century, but no revolutionary changes occurred in these complex lens systems for the next 200 years. Most lens systems remained homogeneous multi-element systems with spherical glass surfaces and fixed optical properties. Recently, however, new materials and lens designs have been developed, inspired by properties of biological eyes. Materials with a gradient index (GRIN) allow the development of compact systems that have high focusing power while correcting for aberration.In 2002, DARPA initiated the Bio-Optic Synthetic Systems (BOSS) program, which aimed to synthesize the components of a biologically inspired vision system and demonstrate a level of performance beyond that of standard optical imaging systems (i.e., with reduced size and complexity). Out of more than a dozen exploratory efforts, four efforts were selected for further development and demonstration: fluidic adaptive zoom lenses, foveated imaging, photon sieves, and nanolayer lenses.As an example, Case Western Reserve University (CWRU) and the Naval Research Laboratory (NRL) collaborated on the nanolayer lens effort to create a synthetic lens that would mimic the structure and capabilities of an octopus eye. The CWRU/NRL team used a forced assembly nanolayer coextrusion process to form films that had a tailored refractive index consisting of thousands of nanolayers of two different polymers that had different refractive indices. The films of various n were stacked to create a refractive index range (Δn) and formed into hemispheres, which were combined to form the synthetic bi-convex octopus lens. A zoom lens system constructed from three of these GRIN lenses was demonstrated on a small unmanned aerial vehicle (UAV).Limited manufacturing capabilities have hindered practical applications of GRIN lenses. In 2008, DARPA initiated the Manufacturable Gradient Index Optics (M-GRIN) program to address GRIN lens manufacturing issues in the development of low-cost, iii customizable GRIN-based optics for use in a variety of military systems. This effort included a significant focus on metrology, where new tools were required for monitoring the polymer nanolayer process for GRIN optics. Performers in the M-GRIN program included the following teams:

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“…Photochromic molecules, accommodated in porous silicates, have been studied with respect to the influence of host-guest interactions on the photoprocesses, giving indications for strongly increased lightfastness. [7][8][9][10] Also, enhanced stability against thermal relaxation and improved photoswitching reversibility are observed for spiropyran derivatives in porous silica and faujasite, [11,12] or for azobenzene in the zeolite ZSM-5 and in microporous aluminophosphate AlPO 4 -5. [13,14] In contrast, fast thermal relaxation was observed when embedding photochromic molecules in the hydrophobic parts of template-containing Si-MCM-41 thin films.…”

Section: Introductionmentioning

confidence: 95%

Tuning the Thermal Relaxation of a Photochromic Dye in Functionalized Mesoporous Silica

Mühlstein

Sauer²,

Bein

2009

Adv Funct Materials

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In this study, it is shown that the kinetics of the back‐switching reaction of a photochromic spirooxazine dye encapsulated in mesoporous silica materials can be significantly influenced both by the space available to the dye molecules and by the functionalization of the silica wall. Steric hindrance of the ring‐closing process due to high dye content or small pore size leads to a slow fading speed of the irradiated dye species. Further, the density of surface silanol‐groups present at the silica walls has an effect on the switching behavior of the dye because of their ability to stabilize the zwitterionic merocyanine isomers, thereby slowing the fading process from the open to the closed form. This stabilization effect is further enhanced in the presence of acidic functional groups, while, in contrast, basic functional groups reduce the stabilization of the open‐from dye isomers, and thus a faster decay of the irradiated species is observed. Control over the fading speed of photochromic dyes is interesting for applications requiring a particularly fast or slow fading speed.

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Sol—gel derived coatings on glass

Cited by 152 publications

References 55 publications

Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films

Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films

Gradient Index Optics at DARPA

Tuning the Thermal Relaxation of a Photochromic Dye in Functionalized Mesoporous Silica

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