Talita M. Lacerda

Progress of Polymers from Renewable Resources: Furans, Vegetable Oils, and Polysaccharides

Oils, and Polysaccharides Alessandro Gandini,*,†,‡ Talita M. Lacerda,†,‡ Antonio J. F. Carvalho,‡ and Eliane Trovatti†,‡ †Saõ Carlos Institute of Chemistry, University of Saõ Paulo, Avenida Trabalhador Saõ-carlense 400, CEP 13566-590, Saõ Carlos, Saõ Paulo, Brazil ‡Department of Materials Engineering, Saõ Carlos School of Engineering, University of Saõ Paulo, Avenida Joaõ Dagnone 1100, CEP 13563-120, Saõ Carlos, Saõ Paulo, Brazil

Recycling Tires? Reversible Crosslinking of Poly(butadiene)

Furan-modified poly(butadiene) prepared by the thiol-ene click reaction is crosslinked with bismaleimides through the Diels-Alder reaction, giving rise to a novel recyclable elastomer. This is possible because of the thermal reversibility of the adducts responsible for the formation of the network. The use of this strategy provides the possibility to produce recyclable tires.

A straightforward double coupling of furan moieties onto epoxidized triglycerides: synthesis of monomers based on two renewable resources

The bulk reaction of 2-furfuryl amine with epoxidized linseed oil took place at both its ester moieties (aminolysis) and oxirane groups (ring opening) producing three fatty acid furan amides incorporating further furan heterocycles along their chains. These reactions were followed spectroscopically and the ensuing monomers used in Diels–Alder reversible polycondensations.

Effect of acid concentration and pulp properties on hydrolysis reactions of mercerized sisal.

The influence of sulfuric acid concentration (H2SO4 5-25%, 100°C), crystallinity and fibers size on the hydrolysis reaction of sisal pulps were investigated, with the goal of evaluating both the liquor composition, as an important step in the production of bioethanol, and the residual non-hydrolyzed pulp, to determine its potential application as materials. Aliquots were withdrawn from the reaction media, and the liquor composition was analyzed by HPLC. The residual non-hydrolyzed pulps were characterized by SEM, their average molar mass and crystallinity index, and their size distribution was determined using a fiber analyzer. Sulfuric acid 25% led to the highest glucose content (approximately 10gL(-1)), and this acid concentration was chosen to evaluate the influence of both the fiber size and crystallinity of the starting pulp on hydrolysis. The results showed that fibers with higher length and lower crystallinity favored glucose production in approximately 12%, with respect to the highly crystalline shorter fibers.

Polymers From Renewable Resources

This article provides an up-to-date overview of the vigorously growing field of polymers from renewable resources, that is, macromolecular materials derived from the biomass. Three distinct approaches are discussed: (i) the synthesis of polymers already available from fossil resources, but using renewable counterparts, (ii) the exploitation of natural polymers as such, or after specific chemical modifications, and (iii) the use of monomers and polymers from renewable resources for the synthesis of novel macromolecular materials. The first topic deals mostly with polyolefins and polyesters; the second discusses polysaccharides, lignin, and natural rubber; the third covers sugars, furans, terpenes and rosin, diols and diacids, glycerol, plant oils, and poly(lactic acid) and poly(hydroxyalkanoate)s. Keywords: lignin; natural rubber; polymers from renewable resources; polysaccharides; renewable resources

Two alternative approaches to the Diels–Alder polymerization of tung oil

Novel linear and crosslinked polymers from non-modified and modified tung oil are reported. These materials are based on the exploitation of the Diels–Alder reaction using, on the one hand, the dienic character of the three conjugated double bonds of tung oil and their susceptibility to react with a dienophile, and, on the other hand, the bulk reaction of furfuryl amine at the ester moieties of tung oil to produce three fatty acid furan amides, still bearing the three conjugated double bonds, and their linear polymerization with bismaleimides.

A minimalist furan–maleimide AB-type monomer and its thermally reversible Diels–Alder polymerization

The present study reports an easy and direct route for the synthesis of highly pure 2-furfurylmaleimide, a minimalist furan–maleimide AB-type monomer, which was used for the preparation of a rigid thermally reversible polymer based on the Diels–Alder reaction. This strategy has high potential for the development of novel polymers and copolymers mainly derived from renewable resources.

Metal-Based Drugs for Treatment of Malaria

Despite the incessant efforts to decrease exorbitant number of daily deaths, malaria remains a major threat to the public health in many countries. Transmitted by Anopheles mosquitoes, it is caused by infection with Plasmodium parasites that have become resistant to many antimalarial drugs. In this context, series of metal-based compounds have been screened for optimal activity against different Plasmodium species and strains. This chapter briefly reviews current and potential uses of metal complexes (such as iron, cobalt, nickel, gallium, copper, gold, and silver), metal chelators, and organometallic compounds, as interesting medicinal agents that greatly benefits the fight against malaria.