Semi-Crystalline Hydrophobic Polyamidoamines: A New Family of Technological Materials?

The hitherto known polyamidoamines (PAAs) are not suitable as structural materialsbecause they are usually water-soluble or swellable in water. This paper deals with the synthesisand characterization of semi-crystalline hydrophobic PAAs (H-PAAs) by combining different bis-secamineswith bis-acrylamides obtained from C6-C12 bis-prim-amines. H-PAAs were initially obtainedin a solution of benzyl alcohol, a solvent suitable for both monomers and polymers. Their numberaverage molecular weights, Mn, which were determined with 1H-NMR by evaluating the percentageof their terminal units, varied from 6000 to >10,000. The solubility, thermal properties, ignitability andwater resistance of H-PAAs were determined. They were soluble in organic solvents, semi-crystallineand thermally stable. The most promising ones were also prepared using a bulk process, whichhas never been previously reported for PAA synthesis. In the form of films, these H-PAAs wereapparently unaffected by water. The films underwent tensile and wettability tests. They showedsimilar Young moduli (260-263 MPa), whereas the maximum stress and the stress at break dependedon the number of methylene groups of the starting bis-acrylamides. Their wettability was somewhathigher than that of common Nylons. Interestingly, none of the H-PAAs considered, either as films orpowders, ignited after prolonged exposure to a methane flame.