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Lignin has gained interest in academia as a raw material for advanced materials such as thermosets. Attractive features include its natural and technical abundances, its structural compositions, distribution of functionalities and most importantly its origin from renewable sources, i.e. lignocellulosic biomass. In this chapter, we will focus on lignin-based thermosets, specifically reviewing the recent strategies for such applications in polyurethanes, phenol-formaldehyde resins and epoxy thermosets. In these contexts, the advantages and competitiveness of lignin over conventional petrol-based will be discussed based on comparisons with benchmark properties. The chapter emphasizes the unique polymer chemistries adopted by different researchers, the effects of the chemical and physical properties of lignin on both reactivities during synthesis and thermomechanical properties of materials. Furthermore, the direct use of lignin in the unmodified state is contrasted with the use of selectively modified lignins in these polymer systems. The use of multifunctional lignin oligomers as raw material is also contrasted with the use of lignin platform monomers obtained through de-polymerization approaches. Finally, the challenges of lignin or monomers thereof, as a raw material in these applications are discussed to direct the future outlook of this research area.

This work summarizes the impact of solvent fractionation on the chemical structure, antioxidant activity, heating values, and thermal and adsorption properties of industrial hardwood and softwood kraft lignins. The aim of the research was to develop a simple approach for obtaining lignin fractions with tailored properties for applications in certain materials. Four common industrial solvents, namely, ethyl acetate, ethanol, methanol and acetone, in various combinations, were found to be efficient for separating spruce and eucalyptus kraft lignins into fractions with low polydispersities. The ethanol fraction of spruce and the ethyl acetate fraction of eucalyptus afforded the highest yields. Gel-permeation chromatography analysis was used to evaluate the efficiency of the chosen solvent combination for lignin fractionation. The composition and structure of the lignin material was characterized by elemental analysis, analytical pyrolysis (Py-GC/MS/FID) and 31P NMR spectroscopy. The thermal properties of the lignin samples were studied using thermogravimetric analysis. Proximate analysis data (ash, volatile components, organic matter and fixed carbon) was obtained through the direct measurement of weight changes in each experimental curve, and the high heating values (in MJ/kg) were calculated according to equations suggested in the literature. The adsorption properties of fractionated kraft lignins were studied using methylene blue dye. The correlations observed between molecular weight, composition and functionality and the thermal, radical scavenging and adsorption properties of the lignin fractions provides useful information for selecting the appropriate solvent combinations for specific applications of lignin raw materials (including their use as antioxidants, biofuels or sorbents in water treatment processes).

A new building block, derived from dimethyl itaconate, has been synthesized through thia-Michael addition reaction and then exploited for the synthesis of a series of novel aliphatic polyesters. The new monomer, the dimethyl 2-((octylthio)methyl)succinate, demonstrated a remarkable stability toward common conditions of polycondensation (high temperatures and metal-based catalysts) and was suitable for polycondensation reactions with different diols. The resulting polyesters are characterized by high molecular weights and good stability; they are amorphous polymers with a tunable glass transition temperature depending on the rigidity of the diol. The synthetic approach presented here allows, for the first time, remarkably stable polymeric structures based on itaconic acid, circumventing its inherent thermal lability, to be achieved. Furthermore, by demonstration of the successful exploitation of thia-Michael adducts in polymer science, the bases have been set for the creation of a novel renewable platform based on dimethyl itaconate.

Poly(cyclohexane-1,4-dimethylene cyclohexane-1,4-dicarboxylate) has been prepared by solid-state polymerization using 1,4-cyclohexanedicarboxylic acid or its di-methylester and 1,4-cyclohexanedimethanol as monomers. The process consists in a first step in which a prepolymer with high crystallinity is prepared by melt polycondensation and then submitted to solid-state polymerization (SSP) at a temperature below the melting temperature of the polymer. The use of the solid state process permits to minimize the isomerization from the trans to the cis form in the polymer chain and therefore a polyester with higher crystallinity and melting temperature, compared to those synthesized by the traditional polycondensation routes, can be obtained. For this reason, the SSP process allows to obtain materials with thermo-mechanical properties that cannot be achieved using the standard polycondensation method. Moreover, the process does not involve a complex multi-step temperature ramp as in the case of the polycondensation process.

A new synthetic pathway for the production of p-toluic acid has been developed starting from reagents derived from renewable resources. A Diels-Alder reaction between sorbic and acrylic acids is followed by a combined dehydrogenation/ decarboxylation process, providing p-toluic acid in high yields. This route permits to use milder conditions compared to other Diels-Alder approaches reported in the literature, and therefore can contribute to a more sustainable terephthalic acid production.

Lignin is the most abundant renewable source of phenolic compounds with great application potential in renewable materials, biofuels and platform chemicals. The current technology for producing cellulose-rich fibers co-produces heterogeneous lignin, which includes an untapped source of monomeric phenolics. One such monomer also happens to be the main monomer in soft wood lignin biosynthesis, namely coniferyl alcohol. Herein, we investigate the potential of coniferyl alcohol as a platform monomer for the biomimetic production of tailored functionalized oligolignols with desirable properties for material synthesis. Accordingly, a bifunctional molecule with at least one carboxyl-ended functionality is included with coniferyl alcohol in biomimetic lignin synthesis to, in one pot, produce a functionalized lignin. The functionalization mechanism is a nucleophilic addition reaction to the quinone methide intermediate of lignin polymerization. The solvent system applied was pure water or 50% aqueous acetone. Several bi-functional molecules differing in the second functionality were successfully inserted in the lignin demonstrating the platform component of this work. Detailed characterization was performed by a combination of NMR techniques which include 1H NMR, COSY-90, 31P NMR, 13C NMR, 13C APT, HSQC, HMBC and HSQC TOCSY. Excellent selectivity towards benzylic carbon and a high functionalization degree were noted. The structure of lignin was tailored through the solvent system choice, with 50% aqueous acetone producing a skeletal structure favorable for a high degree of functionalization. Finally, material concepts are demonstrated using classical thiol–ene- and Diels–Alder-chemistries to show the potential for the thermoset and thermoplastic concepts, respectively. The functionalization concept presents unprecedented opportunities for the green production of lignin-based recyclable biomaterials.

Aromatic material constituents derived from renewable resources are attractive for new biobased polymer systems. Lignin, derived from lignocellulosic biomass, is the most abundant natural source of such structures. Technical lignins are, however, heterogeneous in both structure and polydispersity and require a refining to obtain a more reproducible material. In this paper the ethanol-soluble fraction of Lignoboost Kraft lignin is selectively allylated using allyl chloride by means of a mild and industrially scalable procedure. Analysis using1H-,31P-, and 2D HSQC NMR give a detailed structural description of lignin, providing evidence of its functionalization and that the suggested procedure is selective toward phenols with a conversion of at least 95%. The selectively modified lignin is subsequently cross-linked using thermally induced thiol-ene chemistry. FT-IR is utilized to confirm the cross-linking reaction, and DSC measurements determined the Tgof the thermosets to be 45-65 °C depending on reactive group stoichiometry. The potential of lignin as a constituent in a thermoset application is demonstrated and discussed.

Interest in polymers from renewable resources has been witnessing an incessant growth in both academia and industry with these blooming activities covering a progressively wider domain of sources and approaches worldwide. The association of these innovative scientific and technological investigations with the need of introducing a growing dose of green chemistry connotations in their conception is opening the way to an all-inclusive sustainability for this new generation of polymers, which justifies their vision as macromolecular materials for the XXI century. After the first comprehensive monograph dealing with these materials, published in 2008, [1] numerous reviews and books have appeared, mostly dealing with specific topics or brief analyses of the overall state of the art, [2,3] with a very recent update, [4] which was however aimed at highlighting trends, rather than at detailing the numerous papers covering different aspects of the vast field. Given the structure of this book, the present chapter concentrates exclusively on the use of biobased building blocks as potential monomers and on the recent studies dealing with their polymerizations and copolymerizations, as well as on the properties of the ensuing materials. Interestingly, moreover, the rate at which new interesting results are being published, amply justifies the coverage given here, since it also provides a “further update” of the mentioned “recent update”, [4] at least within its specific scope. Natural polymers (polysaccharides, lignin, suberin, proteins, natural rubber, etc.) and their modifications fall outside that scope and the reader will find information about the multitude of equally exciting and equally incessant studies and applications of these renewable resources in such materials as thermoplastics, thermosets, blends and composites, in other publications. [1-4] The topics discussed here are divided into two major sections, one dealing with polymers from pristine and chemically modified natural monomers, notably terpenes, rosin, sugars and vegetable oils, and the other dealing with polymers from monomers obtained from various vegetable biomass components, notably furans, diacids, diols, hydroxyacids and glycerol. The polymerizations involving classical fossil-derived monomers, such as ethylene and terephthalic acid, now also prepared from renewable resources, are obviously not discussed here, since the novelty of these systems only resides in the alternative mode of monomer synthesis. No attempt was made to cover each family of monomers exhaustively, but rather to concentrate on contributions that appeared to provide originality and hence potential follow-ups. This personal choice did not hinder a critical approach whenever it was deemed constructively appropriate. Given the modest amount of space allotted to this chapter, even some of the numerous interesting studies had to be sacrificed to avoid a list of cursory mentions and privilege instead a reasoned treatment of carefully selected examples.

Interest in polymers from renewable resources has been witnessing an incessant growth in both academia and industry with these blooming activities covering a progressively wider domain of sources and approaches worldwide. The association of these innovative scientific and technological investigations with the need of introducing a growing dose of green chemistry connotations in their conception is opening the way to an all-inclusive sustainability for this new generation of polymers, which justifies their vision as macromolecular materials for the XXI century. After the first comprehensive monograph dealing with these materials, published in 2008, [1] numerous reviews and books have appeared, mostly dealing with specific topics or brief analyses of the overall state of the art, [2,3] with a very recent update, [4] which was however aimed at highlighting trends, rather than at detailing the numerous papers covering different aspects of the vast field. Given the structure of this book, the present chapter concentrates exclusively on the use of biobased building blocks as potential monomers and on the recent studies dealing with their polymerizations and copolymerizations, as well as on the properties of the ensuing materials. Interestingly, moreover, the rate at which new interesting results are being published, amply justifies the coverage given here, since it also provides a “further update” of the mentioned “recent update”, [4] at least within its specific scope. Natural polymers (polysaccharides, lignin, suberin, proteins, natural rubber, etc.) and their modifications fall outside that scope and the reader will find information about the multitude of equally exciting and equally incessant studies and applications of these renewable resources in such materials as thermoplastics, thermosets, blends and composites, in other publications. [1-4] The topics discussed here are divided into two major sections, one dealing with polymers from pristine and chemically modified natural monomers, notably terpenes, rosin, sugars and vegetable oils, and the other dealing with polymers from monomers obtained from various vegetable biomass components, notably furans, diacids, diols, hydroxyacids and glycerol. The polymerizations involving classical fossil-derived monomers, such as ethylene and terephthalic acid, now also prepared from renewable resources, are obviously not discussed here, since the novelty of these systems only resides in the alternative mode of monomer synthesis. No attempt was made to cover each family of monomers exhaustively, but rather to concentrate on contributions that appeared to provide originality and hence potential follow-ups. This personal choice did not hinder a critical approach whenever it was deemed constructively appropriate. Given the modest amount of space allotted to this chapter, even some of the numerous interesting studies had to be sacrificed to avoid a list of cursory mentions and privilege instead a reasoned treatment of carefully selected examples.

none 6 no Potentially bio-based aromatic polyesters with a kinked structure based on resorcinol have been successfully prepared. The process involves an optimized reaction between resorcinol and ethylene carbonate: the diol thus obtained was polymerized with several aliphatic and aromatic dicarboxylic acids. The chemical structure and the thermal properties of the new polyesters were analysed in order to find correlations between structure and properties. All the polymers present a high thermal stability and are mainly amorphous, with a wide range of glass transition temperatures, according to the diacid structures. On the basis of the results it is clear that resorcinol, which can be derived from renewable resources, is a potential bio-based aromatic monomer, suitable to prepare amorphous polyesters containing 1,3 substituted aromatic moieties, for coating and packaging applications. Gioia, Claudio; Banella, Maria Barbara; Vannini, Micaela; Celli, Annamaria; Colonna, Martino; Caretti, Daniele Gioia, Claudio; Banella, Maria Barbara; Vannini, Micaela; Celli, Annamaria; Colonna, Martino; Caretti, Daniele

Four different materials used for the production of ski boots have been analyzed in order to determine their performance in the thermo-formation process used to modify the shape of ski boots and therefore improve their comfort. As a first step, the chemical composition and the thermo-mechanical properties have been analyzed pointing out that materials based on a blend of nylon with methacrylate ionomers provide the largest decrease of the storage modulus at 80 °C. The results of the thermo-formation process indicate that the boot based on the methacrylate ionomer has the larger deformation after the thermo-formation process and the lowest memory effect. These results indicate that the decrease in modulus from 0 °C to 80 °C is the most important factor to be considered in order to obtain a more consistent and permanent modification of the boot shape.