<b>Synthesis of carboxylate complexes and evaluation of their catalytic activities for polyesterification of castor oil (<i>Ricinum communis</i>) with terephthalic acid

Abstract

 

The use of castor oil (Ricinus communis) has been pointed out as an interesting alternative to produce several polymers obtained from step-growth polymerization and are suitable to be used as resins and coatings. The ricinoleate metal complexes Ni[C₁₇H₃₄(OH)COO]₂, Sn[C₁₇H₃₄(OH)COO]₂, Co[C₁₇H₃₄(OH)COO]₂ and Fe[C₁₇H₃₄(OH)COO]₂ have been prepared and used as catalyst precursors for polyesterification of castor oil and terephthalic acid (TFA). The observed catalytic activity decreased in the order: Fe[C₁₇H₃₄(OH)COO]₂ > Co[C₁₇H₃₄(OH)COO]₂ > Sn[C₁₇H₃₄(OH)COO]₂ > Ni[C₁₇H₃₄(OH)COO]₂. The new polymeric materials did not show homogeneity in their chains, as indicated by their high polydispersity. Indeed, the polydispersity index value varied from 5.49 for the polymer produced in the presence of the nickel complex to 12.42 for these prepared with the cobalt compound. On the other hand, the final material presented high molecular weight, being the lower value (M_w = 13400 Da) observed for the polymer prepared with the nickel complex and the highest (M_w = 36400 Da) verified for the one obtained with the cobalt compound. It was observed only a glass transition temperature for all the materials, suggesting an amorphous structure of polymeric chains.