Cubic silsesquioxanes as tunable high‐performance coating materials

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100292/1/aoc3032.pd

Preface for Hybrid Materials

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100303/1/aoc3082.pd

Synthesis of acetoxyphenyl‐ and hydroxyphenyl‐terminated polyfunctional T 8 , T 10 , T 12 silsesquioxanes and initial studies on their use in the formation of highly crosslinked polyesters

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100306/1/aoc3054.pd

Pentacoordinate Silicon Complexes as Precursors to Silicate Glasses and Ceramics

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65650/1/j.1151-2916.1994.tb07242.x.pd

Photocatalytic plate‐like La2Ti2O7 nanoparticles synthesized via liquid‐feed flame spray pyrolysis (LF‐FSP) of metallo‐organic precursors

Nanoparticles (NPs) of a perovskite‐slab‐type oxide, La2Ti2O7, were synthesized using LF‐FSP coupled with subsequent heat treatments, and their photocatalytic activity was evaluated using decolorization of methyl orange solution under Uv irradiation. The LF‐FSP process used metallo‐organic precursors to produce NPs with very low agglomeration with average particle sizes (APSs) of 26 nm (LF‐FSP NP). Optimized heat treatment of these NPs at 1000°C/3 h/air gave small, plate‐like NPs with high crystallinity, and BET specific surface areas (SSAs) of 14 m2/g, that exhibited the best observed photocatalytic activity. High‐angle annular dark‐field scanning TEM showed that heat‐treating eliminates microstructural defects in these NPs, improving photocatalytic activity by ≈30%. The current approach to perovskite‐slab‐type NPs using LF‐FSP provides a simple route to materials with superior photocatalytic activity and offers the advantage of good productivity, 30 g/h.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156137/2/jace17196_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156137/1/jace17196.pd

Pressureless Sintering t -zirconia@δ-Al 2 O 3 (54 mol%) Core–Shell Nanopowders at 1120°C Provides Dense t -Zirconia-Toughened α-Al 2 O 3 Nanocomposites

Zirconia-toughened alumina (ZTA) is of growing importance in a wide variety of fields exemplified by ZTA prosthetic implants. Unfortunately, ZTA composites are generally difficult to process because of the need to preserve the tetragonal zirconia phase in the final dense ceramic, coincident with the need to fully densify the α-Al 2 O 3 component. We report here that liquid-feed flame spray pyrolysis of mixtures of metalloorganic precursors of alumina and zirconia at varying compositional ratios provide access in one step to core–shell nanoparticles, wherein the shell is δ-Al 2 O 3 and the core is a perfect single crystal of tetragonal ( t -) zirconia. Pressureless sintering studies provided parameters whereby these nanopowder compacts could be sintered to full density (>99%) at temperatures just above 1100°C converting the shell component to α-Al 2 O 3 but preserving the t -ZrO 2 without the need for any dopants. The final average grain sizes of these sintered compacts are ≤200 nm. The resulting materials exhibit the expected response to mechanical deformation with the subsequent production of monoclinic ZrO 2 . These materials appear to offer a low-temperature, low-cost route to fine-grained ZTA with varied Al 2 O 3 : t -ZrO 2 compositions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79122/1/j.1551-2916.2009.03498.x.pd

Synthesis and characterization of organic/inorganic epoxy nanocomposites from poly(aminopropyl/phenyl)silsesquioxanes

Organic/inorganic epoxy nanocomposites containing diglycidyl ether of bisphenol A (DGEBA), 4‐methylhexahydrophthalic anhydride (MHHPA) and poly(aminopropyl/phenyl) silsesquioxanes (PAPPS) were prepared and characterized. PAPPS were synthesized via fluoride‐catalyzed cage formation from random‐structured poly(phenyl)silsesquioxane (PPS) and 3‐aminopropyltriethoxysilane (APTES) in tetrahydrofuran (THF) using tetrabutylammonium fluoride (TBAF) catalyst containing substantial water. The PPS/APTES stoichiometric ratios were varied. The FTIR, 1 H, solid‐state 29 Si‐NMR studies show that PAPPS probably consists of cages, partial cages, and some linear structures containing phenyl and aminopropyl functional groups. The amine content was determined by back titration and elemental analysis. In comparison with neat epoxy, incorporation of these materials can improve the resultant thermal stabilities, raise glass transition temperatures ( T g s), and reduce coefficients of thermal expansion (CTEs) of epoxy nanocomposites as confirmed by TG/DTA, DMA and TMA tests, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97280/1/38575_ftp.pd

Combinatorial Nanopowder Synthesis Along the ZnO–Al 2 O 3 Tie Line Using Liquid‐Feed Flame Spray Pyrolysis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86932/1/jace4585.pd

In Situ Methylation Transforms Aggregation‐Caused Quenching into Aggregation‐Induced Emission: Functional Porous Silsesquioxane‐Based Composites with Enhanced Near‐Infrared Emission

Methylation of TPA‐DCM (2‐(2,6‐bis‐4‐(diphenylamino)stryryl‐4H‐pyranylidene)malononitrile) that exhibits aggregation‐caused quenching (ACQ) results in the fluorophore M‐TPA‐DCM (2‐(2,6‐bis((E)‐4‐(di‐p‐tolylamino)‐styryl)‐4H‐pyran‐4‐ylidene]malononitrile) that shows aggregation‐induced emission (AIE) and NIR fluorescence and has a conjugated “D‐π‐A‐π‐D” electronic configuration. Friedel‐Crafts reaction of TPA‐DCM and octavinylsilsesquioxane (OVS) resulted in a family of porous materials (TPAIEs) that contain the M‐TPA‐DCM motif and show large Stokes shifts (180 nm), NIR emission (670 nm), tunable porosity (SBET from 160 to 720 m2 g−1, pore volumes of 0.13–0.55 cm3 g−1), as well as high thermal stability (400 °C, 5 % mass loss, N2). As a simple test case, one of TPAIE materials was used to sense Ru3+ ions with high selectivity and sensitivity.Small changes with big effect: Methylation of TPA‐DCM (2‐(2,6‐bis‐4‐(diphenylamino)stryryl‐4H‐pyranylidene)malononitrile), which exhibits aggregation‐caused quenching (ACQ), gives the fluorophore M‐TPA‐DCM (2‐(2,6‐bis((E)‐4‐(di‐p‐tolylamino)‐styryl)‐4H‐pyran‐4‐ylidene)malononitrile) that shows aggregation‐induced emission (AIE) and NIR fluorescence. Friedel‐Crafts reaction of TPA‐DCM with octavinylsilsesquioxane produces a family of porous composites (TPAIEs) with the M‐TPA‐DCM motif. TPAIEs show large Stokes shifts, NIR emission, tunable porosity as well as high thermal stability.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151996/1/cplu201900568_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151996/2/cplu201900568.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151996/3/cplu201900568-sup-0001-misc_information.pd

Bottomâ up vs reactive sintering of Al2O3â YAGâ YSZ composites via one or threeâ phase nanoparticles (NPs). Bottomâ up processing wins this time

The bottomâ up approach describes the synthesis of bulk materials from the finest possible length scales to obtain the best global properties. This approach was adapted to the synthesis of multiâ phase ceramic composites produced from metal oxides produced by liquidâ feed flame spray pyrolysis (LFâ FSP). The effect of length scale of mixing was tested through two processing schemes, mixed single metalâ oxide nanopowders (NPs) and nanocomposite NPs having the desired composition within single particles. For the Al2O3â Y2O3â ZrO2 ternary system, composites prepared from nanostructured nanoparticles sinter to finer grain sizes (<410 nm) at equivalent densities of 95%TD than those prepared from mixed nanoparticle processing. These contrast with our previous studies in this area where mixed NP processing gave the best or equivalent results. The nanocomposite NPs produced in this study exhibit novel nanostructures with three phases contained within single particles <26 nm average particle size (APS). This nanostructure may directly explain the enhanced sintering of the nanocomposite NPs and may provide an impetus for future synthesis of similarly structured NPs.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137592/1/jace14761.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137592/2/jace14761_am.pd