Crystalline Structures and Structural Transitions of Copolyamides Derived from 1,4-Diaminobutane and Different Ratios of Glutaric and Azelaic Acids

Abstract

Copolyamides derived from even 1,4-butanediamine and different mixtures of odd dicarboxylic acids with a great difference in the number of methylene groups (i.e., glutaric and azelaic acids with 3 and 7 groups, respectively) have been synthesized, characterized and structurally studied. Calorimetric analyses revealed a complex behavior with multiple melting peaks associated to lamellar reordering and the presence of defective crystals. Equilibrium melting temperatures were evaluated and showed a eutectic behavior with composition. Copolymers were able to crystallize even for samples with comonomer percentages close to 50%. Negative and ringed spherulites from the melt state and small lath-like lamellar crystals from dilute solution crystallizations were attained. Furthermore, calorimetric data pointed out the exclusion of the less abundant monomer from the lattice of the predominant structure. All samples at room temperature showed a similar crystalline structure (form I) defined by two predominant reflections at spacings close to 0.430 and 0.380 nm, which has been related for even-odd nylons with a two-hydrogen bonded structure. Real time synchrotron experiments showed that melt crystallized samples have two polymorphic transitions on heating, which were practically reversible and consequently were also detected during cooling from the melt state. Interestingly, a different behavior was detected among solution crystallized samples and specifically the transition to the intermediate structure (form II) was not detected during heating for samples enriched on the azelate component or more precisely when they were exclusively crystallized in the form I.

Monomers and Macromolecular Materials from Renewable Resources: State of the Art and Perspectives

“…The biological production of diamines, such as 1,3-diaminopropane, 1,4-butanediamine, 1,5-pentanediamine, 1,6-diaminohexane, 1,8-diaminooctane, 1,10-diaminodecane, and 1,12-diaminododecane, as well as other aromatic diamines, was recently reviewed [ 163 ], paving the way for a wide family of sustainable polyurethanes and polyamides. This was the case, for instance, of the polymerization of 1,4-butanediamine with different mixtures of glutaric and azelaic acids [ 164 ].…”

Azelaic Acid: A Bio-Based Building Block for Biodegradable Polymers

“…These polyamides presented a M w in the range 40,000-51,000 g/mol, a predominant melting peak in the range 220-244 • C, T d (thermal decomposition temperature) in the range 422-455 • C and a T g in the range 50-71 • C. The higher M w was achieved when AzA was 50% molar percentage in the acid mixture, while the lower T g was obtained for the homopolymer with 100% AzA. Results suggested that a similar predominant hydrogen bonding structure was present in all the analyzed polyamides [73].…”

“…Aromatic polyamides are classified as highperformance polymers for their high Tg, good resistance to chemicals, temperature, and Aliphatic polyamides, or nylons, are semicrystalline polymers with properties that change according to the ratio between amides and methylene groups. These materials are not biodegradable and possess great mechanical properties given by strong intermolecular hydrogen binding interactions [73]. Long-chain nylons, where the polar groups are separated by more than six carbon atoms, have both polyethylene properties and polyamide properties.…”

“…The higher M w was achieved when AzA was 50% molar percentage in the acid mixture, while the lower T g was obtained for the homopolymer with 100% AzA. Results suggested that a similar predominant hydrogen bonding structure was present in all the analyzed polyamides [ 73 ].…”