Disulfide-linked covalent organic polymers (COPs) were prepared through catalyst-free oxidative coupling polymerization. Owing to the excellent swelling behavior, low cost, and efficient synthesis, these materials can be promising materials for removal of organics in concentrated streams. COPs show 1,4-dioxane uptake up to 1.8 g g−1.

Aromatic polyamide/organoclay nanocomposites were synthesized using the solution blending technique. Treatment of montmorillonite clay with p-phenylenediamine produced reactive organophilic clay for good compatibility with the matrix. Polyamide chains were prepared by condensing a mixture of 1,4-phenylenediamine and 4-4′-oxydianiline with isophthaloyl chloride under anhydrous conditions. These chains were end capped with carbonyl chloride using 1% extra acid chloride near the end of reaction to develop the interactions with organoclay. The dispersion and structure–property relationship were monitored using FTIR, XRD, FE-SEM, TEM, DSC and tensile testing of the thin films. The structural investigations confirmed the formation of delaminated and disordered intercalated morphology with nanoclay loadings. This morphology of the nanocomposites resulted in their enhanced mechanical properties. The tensile behavior and glass transition temperature significantly augmented with increasing organoclay content showing a greater interaction between the two disparate phases.

Conductive nanocomposites were synthesized from surface modified clay and polypyrrole grafted triblock copolymer, polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS-g-PPy). The grafting of PPy was carried out on SEBS using FeCl3 as an oxidant and the formation of subsequent materials was monitored by IR, 1H NMR spectroscopy and Gel permeation chromatography (GPC). Surface treatment of the clay was carried out by ion exchange method using the cationic salt of 2,2-bis[4-(4-aminophenoxy)phenyl]propane for better adhesion with the polymer matrix. Thin composite films containing 1–8-wt.% organoclay were investigated by FTIR, XRD, TEM, tensile testing, TGA, DSC and electrical conductivity measurements. The molar mass as determined by GPC was around 37,000. XRD pattern and TEM images described good dispersion of clay platelets in the nanocomposites. Tensile testing revealed improvement in mechanical properties up to 3-wt.% of organoclay. The bulk electrical conductivity was increased up to 7-wt.% with increase in resonance of delocalized electrons of stretched PPy chains due to hydrogen bonding with organoclay in the nanocomposites. Thermal decomposition temperatures of the nanocomposites were in the range 435–448 °C. The decomposition of the nanocomposites was observed at higher temperatures relative to the pure polymer matrix with increasing clay loading. The weight retained after 900 °C was approximately equal to the amount of organoclay added in the composites. These composite materials exhibited improvement in glass transition temperature as compared to SEBS-g-PPy.

The CO2 uptake capacity and CO2/N2 selectivity of Tröger's base-bridged nanoporous covalent organic polymers (TB-COPs) were investigated. The TB-COPs were synthesized by reacting the terminal amines of tetrahedral monomers – namely, tetraanilyladamantane and tetraanilylmethane – with dimethoxymethane in a one-pot reaction under relatively mild conditions. Interestingly, these two tetrahedral monomers formed nanoporous polymers with substantially different surface areas. While the polymer resulting from the Trögerization of the tetraanilyladamantane monomer (TB-COP-1) exhibited a high surface area of 1340 m2 g−1, that from the tetraanilylmethane monomer (TB-COP-2) was found to be only 0.094 m2 g−1. This unusual phenomenon can be explained by the proximity of the amino moieties to each other within the monomeric unit. A shorter distance between the amino groups enables intramolecular as well as intermolecular cyclization, thus resulting in a much lower porosity. TB-COP-1 exhibited significant CO2 uptake capacities of up to 5.19 and 3.16 mmol g−1 at 273 and 298 K under ambient pressure, and CO2/N2 selectivities of 79.2 and 68.9 at 273 and 298 K at 1 bar for a gas mixture of CO2[thin space (1/6-em)]:[thin space (1/6-em)]N2 at a ratio of 0.15[thin space (1/6-em)]:[thin space (1/6-em)]0.85. It is noteworthy that TB-COP-1 showed remarkable selectivity retention when increasing the temperature from 273 to 298 K.

A family of azo-bridged covalent organic polymers(azo-COPs) was synthesized through a catalyst-free directcoupling of aromatic nitro and amine compounds underbasic conditions. The azo-COPs formed 3D nanoporous net-works and exhibited surface areas up to 729.6 m2g1, withaCO2-uptake capacity as high as 2.55 mmolg1at 273 K and1 bar. Azo-COPs showed remarkable CO2/N2selectivities(95.6–165.2) at 298 K and 1 bar. Unlike any other porous ma-terial, CO2/N2selectivities of azo-COPs increase with risingtemperature. It was found that azo-COPs show less than ex-pected affinity towards N2gas, thus making the framework“N2-phobic”, in relative terms. Our theoretical simulations in-dicate that the origin of this unusual behavior is associatedwith the larger entropic loss of N2gas molecules upon theirinteraction with azo-groups. The effect of fused aromaticrings on the CO2/N2selectivity in azo-COPs is also demon-strated. Increasing thep-surface area resulted in an increasein the CO2-philic nature of the framework, thus allowing usto reach a CO2/N2selectivity value of 307.7 at 323 K and1 bar, which is the highest value reported to date. Hence, itis possible to combine the concepts of “CO2-philicity” and“N2-phobicity” for efficient CO2capture and separation. Iso-steric heats of CO2adsorption for azo-COPs range from24.8–32.1 kJmol1at ambient pressure. Azo-COPs are stableup to 3508C in air and boiling water for a week. A promisingcis/transisomerization of azo-COPs for switchable porosity isalso demonstrated, making way for a gated CO2uptake.