Hyperbranched aramids

When monomers of the AB2 types are used, hyperbranched polymers will be formed on polymerization. The polymers can be employed to initiate bismaleimide polymerization. Another application of these polymers is to increase the toughness for thermosets such as bismaleimide polymers and epoxies. 

Sulfiron Teijin Chemicals Sulfur modified aramid 

Thermatex Difco Performance Aramid and aramid blend 

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Monticelli O, Russo S, Campagna R, Voit B (2005) Preparation and characterisation of blends based on polyamide 6 and hyperbranched aramids as palladium nanoparticle supports. 

Tabuani D, Monticelli O, Chincarini A, Bianchini C, Vizza F, Moneti S, Russo S (2003) Palladium nanoparticles supported on hyperbranched aramids synthesis, chaiacterizatimi, and some applications in the hydrogenation of unsaturated substrates. Macnnnolecules 36 4294 301... 

Tabuani D, Monticelli O, Komber H, Russo S (2003) Preparation and characterisation of Pd nanoclusters in hyperbranched aramid templates to be used in homogeneous catalysis. Macromol Chem Phys 204 1576-1583... 

Monticelli O, Oliva D, Russo S, Clausnitzer C, Potschke P, Voit B (2003) On blends of polyamide 6 and a hyperbranched aramid. Macromol Mater Eng 288 318-325... 

Figure 5. Hyperbranched aramid with random branching.

Reichert and Mathias prepared related branched aramids, to those of Kim,t5-34] from 3,5-dibromoaniline (23) under Pd-catalyzed carbonylation conditions (Scheme 6.7). These brominated hyperbranched materials (24) were insoluble in solvents such as DMF, DMAc, and NMP, in contrast to the polyamine and polycarboxylic acid terminated polymers that Kim synthesized, which were soluble. This supports the observation that surface functionality plays a major role in determining the physical properties of hyperbranched and dendritic macromolecules J4,36 A high degree of cross-linking could also significantly effect solubility. When a four-directional core was incorporated into the polymerization via tetrakis(4-iodophenyl)adamantanc,1371 the resultant hyperbranched polybromide (e.g., 25) possessed enhanced solubility in the above solvents, possibly as a result of the disruption of crystallinity and increased porosity. 

Work reported recently by Rasmussen et al. [115] suggests that dihalodicyanoimid-azoles undergo thermal self condensation to the hyperbranched heterocycle illustrated in Scheme 10. These cyanoazacarbons with empirical formula (C5N4)n contain no hydrogen and are viewed as heterocyclic analogs of aramides. 

Polymer-stabilized palladium nanoparticles (or nanoclusters) [125-127] have recently received increasing attention in the field of synthetic organic chemistry [128, 129]. Thus, for example, the poly(iV-vinyl-2-pyrrolidone) (PVP)-supported Pd particle catalyzed the Suzuki-Miyaura coupling in water [130]. Poly(amidoamine) (PAMAM) dendrimer-encapsulated palladium nanoparticles were designed and prepared to provide highly selective catalysts for hydrogenation of olefins [131-133]. Hyperbranched aromatic amides (aramids) and PS-DVB-methacryloylethylenesulfonic acid resin have also been... 

Poly(amidoamine) (PAMAM) dendrimer-encapsulated palladium nanoparticles were designed and prepared to provide highly selective catalysts for hydrogenation of olefins [131-133]. Hyperbranched aromatic amides (aramids) and PS-DVB-methacryloylethylenesulfonic acid resin have also been... 

Polymer 4 was partially soluble in DMSO and amide solvents such as DMF and DMAc. Solution and solid-state NMR were used to confirm the product structure. Peaks due to the adamantane moiety and aramid carbonyls were present indicating reaction. Again, residual solvent peaks were observed in the solid-state NMR spectra, even after extensive extraction and vacuum drying. It appears that hyperbranched structures and adamantane incorporation disrupts crystalline packing and leads to a more open and molecularly-porous branched structure that is capable of taking up and holding solvent. 

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