Tunable Crystalline Phases in UV-Curable PEG-Grafted Ladder-Structured Silsesquioxane/Polyimide Composites.

A series of UV-curable hybrid composite blends containing a carboxylic acid functionalized polyimidewith varying amounts of high molecular weight (~1 K) PEG-grafted ladder-structured polysilsesquioxanes copolymerized with methacryl groups were fabricated and their structural, thermal, mechanical, and surface properties characterized. At a composite weight ratio of polyimide above 50 wt.%, a stark shift from amorphous to crystalline polyethylene glycol (PEG) phases were observed, accompanied by a drastic increase in both surface moduli and brittleness index. Moreover, fabricated composites were shown to have a wide range water contact angle, 9.8°-73.8°, attesting to the tunable surface properties of these amphiphilic hybrid polymer composites. The enhanced mechanical properties, combined with the utility of tunable surface hydrophilicity allows for the possible use of these hybrid polymer composites to be utilized as photosensitive polyimide negative photoresists for a myriad of semiconductor patterning processes.

Physical properties of thin PVDF/MWNT (multi-walled carbon nanotube) composite films by melt blending.

Poly(vinylidene fluoride)(PVDF)/Multi-walled carbon nanotube (MWNT) composites were melt blended using internal mixer. The relationships between structures and physical properties of thin PVDF/MWNT composite films were studied. With increasing the content of MWNT, the size of spherulites in PVDF decreased. MWNT was used as a nucleating agent. The incorporation of MWNT produced a polar beta-form crystal structure of PVDF. The permittivities of thin PVDF/MWNT composite films were increased with increasing the MWNT content. The percolation level in electrical conductivity occurred between 2 and 2.5 wt%. The critical conductivity saturation point for the electrical conductivity in PVDF was confirmed. Similar tendency was also observed in thermal conductivity.

Multifunctional Mesoporous Ionic Gels and Scaffolds Derived from Polyhedral Oligomeric Silsesquioxanes.

A new methodology for fabrication of inorganic-organic hybrid ionogels and scaffolds is developed through facile cross-linking and solution extraction of a newly developed ionic polyhedral oligomeric silsesquioxane with inorganic core. Through design of various cationic tertiary amines, as well as cross-linkable functional groups on each arm of the inorganic core, high-performance ionogels are fabricated with excellent electrochemical stability and unique ion conduction behavior, giving superior lithium ion battery performance. Moreover, through solvent extraction of the liquid components, hybrid scaffolds with well-defined, interconnected mesopores are utilized as heterogeneous catalysts for the CO2-catalyzed cycloaddition of epoxides. Excellent catalytic performance, as well as highly efficient recyclability are observed when compared to other previous literature materials.

Lithium Dendrite Suppression with UV-Curable Polysilsesquioxane Separator Binders.

For the first time, an inorganic-organic hybrid polymer binder was used for the coating of hybrid composites on separators to enhance thermal stability and to prevent formation of lithium dendrite in lithium metal batteries. The fabricated hybrid-composite-coated separators exhibited minimal thermal shrinkage compared with the previous composite separators (<5% change in dimension), maintenance of porosity (Gurley number ∼400 s/100 cm(3)), and high ionic conductivity (0.82 mS/cm). Lithium metal battery cell examinations with our hybrid-composite-coated separators revealed excellent C-rate and cyclability performance due to the prevention of lithium dendrite growth on the lithium anode even after 200 cycles under 0.2-5C (charge-discharge) conditions. The mechanism for lithium dendrite prevention was attributed to exceptional nanoscale surface mechanical properties of the hybrid composite coating layer compared with the lithium metal anode, as the elastic modulus of the hybrid-composite-coated separator far exceeded those of both the lithium metal anode and the required threshold for lithium metal dendrite prevention.

Rational molecular design of PEOlated ladder-structured polysilsesquioxane membranes for high performance CO2 removal.

Poly(methoxy(polyethyleneoxy)propyl-co-methacryloxypropyl) silsesquioxane membranes with different copolymer ratios were successfully fabricated via UV-induced crosslinking with mechanical stability. By selectively introducing polyethylene oxide (PEO) groups covalently bound to the ladder-structured polysilsesquioxane, we effectively suppressed the PEO crystallization, allowing for excellent CO2/H2 and CO2/N2 separation under single as well as mixed gas conditions.

A new, higher yielding synthetic route towards dodecaphenyl cage silsesquioxanes: synthesis and mechanistic insights.

Cage dodecaphenylsilsesquioxane (T12-Phenyl) was synthesized in a one batch, mildly basic aqueous solution under room temperature conditions using a trialkoxysilane precursor. Significant improvements in synthetic yield (>95%) were observed compared with previous reports. Kinetic studies of the hydrolysis of phenyltrimethoxysilane were conducted and the condensation was monitored by (29)Si NMR which revealed the presence of a transient, intermediary T1 species as the pathway to dodecaphenylsilsesquioxane spherulites, and the tendency for T12 structures over T8, T10, and other substructures was explained through MM2 simulations.