Synthesis of Flexible Polyamide Aerogels Cross-Linked with a Tri-Isocyanate.

A new series of flexible polyamide (PA) aerogels was synthesized using terephthaloyl chloride (TPC), 2,2'-dimethylbenzidine (DMBZ) and cross-linked with an inexpensive, commercially available tri-isocyanate (Desmodur N3300A) at polymer concentrations of 6-8 wt.% total solids and repeating units, , from 30 to 60. The cross-linked DMBZ-based polyamide aerogels obtained, after supercritically drying using liquid CO, had shrinkages of 19-27% with densities ranging from 0.

Polyimide aerogels for ballistic impact protection.

The ballistic performance of edge-clamped monolithic polyimide aerogel blocks (12 mm thickness) has been studied through a series of impact tests using a helium-filled gas gun connected to a vacuum chamber and a spherical steel projectile (approximately 3 mm diameter) with an impact velocity range of 150-1300 m s. The aerogels had an average bulk density of 0.17 g cm with high porosity of approximately 88%.

Flexible Polyimide Aerogels with Dodecane Links in the Backbone Structure.

Polyimide aerogels using 1,12-dodecyldiamine (DADD), 3,3'-dimethylbenzidine (DMBZ), and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and cross linked using 1,3,5-triaminophenoxybenzene (TAB) were synthesized. Substitution of the aromatic diamine, DMBZ, with varying amounts of the aliphatic diamine, DADD, increases the flexibility in the backbone structure of the prepared aerogel. These aerogels are also lightweight, low density, have a low dielectric constant, and high modulus.

Polyimide Aerogels Using Triisocyanate as Cross-linker.

A family of polyimide (PI)-based aerogels is produced using Desmodur N3300A, an inexpensive triisocyanate, as the cross-linker. The aerogels are prepared by cross-linking amine end-capped polyimide oligomers with the triisocyanate. The polyimide oligomers are formulated using 2,2'-dimethylbenzidine, 4,4'-oxydianiline, or mixtures of both diamines, combined with 3,3',4,4'-biphenyltetracarboxylic dianhydride, and are chemically imidized at room temperature.

Highly Porous, Rigid-Rod Polyamide Aerogels with Superior Mechanical Properties and Unusually High Thermal Conductivity.

We report here the fabrication of polyamide aerogels composed of poly-p-phenylene-terephthalamide, the same backbone chemistry as DuPont's Kevlar. The all-para-substituted polymers gel without the use of cross-linker and maintain their shape during processing-an improvement over the meta-substituted cross-linked polyamide aerogels reported previously. Solutions containing calcium chloride (CaCl) and para-phenylenediamine (pPDA) in N-methylpyrrolidinone (NMP) at low temperature are reacted with terephthaloyl chloride (TPC).

Carbon nanotube epoxy nanocomposites: the effects of interfacial modifications on the dynamic mechanical properties of the nanocomposites.

Surface functionalization of pretreated carbon nanotubes (CNT) using aromatic, aliphatic, and aliphatic ether diamines was performed. The pretreatment of the CNT consisted of either acid- or photo-oxidation. The acid treated CNT had a higher initial oxygen content compared to the photo-oxidized CNT and this resulted in a higher density of functionalization.

Graphene polyimide nanocomposites; thermal, mechanical, and high-temperature shape memory effects.

Flexible graphene polyimide nanocomposites (0.1-4 wt %) with superior mechanical properties over those of neat polyimide resin have been prepared by solution blending. Imide moieties were grafted to amine-functionalized graphene using a step-by-step condensation and thermal imidization method.

Reinforced thermoplastic polyimide with dispersed functionalized single wall carbon nanotubes.

Molecular pi-complexes were formed from pristine HiPCO single- wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4-N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used.

Tailoring elastic properties of silica aerogels cross-linked with polystyrene.

The effect of incorporating an organic linking group, 1,6-bis(trimethoxysilyl)hexane (BTMSH), into the underlying silica structure of a styrene cross-linked silica aerogel is examined. Vinyltrimethoxysilane (VTMS) is used to provide a reactive site on the silica backbone for styrene polymerization. Replacement of up to 88 mol % of the silicon from tetramethoxyorthosilicate with silicon derived from BTMSH and VTMS during the making of silica gels improves the elastic behavior in some formulations of the cross-linked aerogels, as evidenced by measurement of the recovered length after compression of samples to 25% strain.