Copolymers of xylan-derived furfuryl alcohol and natural oligomeric tung oil derivatives

Recent advances in the development of green furan ring-containing polymeric materials based on renewable plant biomass

Fossil resources are rapidly depleting, forcing researchers in various fields of chemistry and materials science to switch to the use of renewable sources and the development of corresponding technologies. In this regard, the field of sustainable materials science is experiencing an extraordinary surge of interest in recent times due to the significant advances made in the development of new polymers with desired and controllable properties. This review summarizes important scientific reports in recent times dedicated to the synthesis, construction and computational studies of novel sustainable polymeric materials containing unchanged (pseudo)aromatic furan cores in their structure. Linear polymers for thermoplastics, branched polymers for thermosets and other crosslinked materials are emerging materials to highlight. Various polymer blends and composites based on sustainable polyfurans are also considered as pathways to achieve high-value-added products.

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

A progressively increasing concern about the environmental impacts of the whole polymer industry has boosted the design of less aggressive technologies that allow for the maximum use of carbon atoms, and reduced dependence on the fossil platform. Progresses related to the former approach are mostly based on the concept of the circular economy, which aims at a thorough use of raw materials, from production to disposal. The latter, however, has been considered a priority nowadays, as short-term biological processes can efficiently provide a myriad of chemicals for the polymer industry. Polymers from renewable resources are widely established in research and technology facilities from all over the world, and a broader consolidation of such materials is expected in a near future. Herein, an up-to-date overview of the most recent and relevant contributions dedicated to the production of monomers and polymers from biomass is presented. We provide some basic issues related to the preparation of polymers from renewable resources to discuss ongoing strategies that can be used to achieve original polymers and systems thereof.

Chemical constitution of polyfurfuryl alcohol investigated by FTIR and Resonant Raman spectroscopy

The actual chemical structure of polyfurfuryl alcohol (PFA) is still uncertain in spite of several studies on the topic, variations during the polymerization processes being one reason that must be addressed. The use of a limited set of analytical techniques is often insufficient to provide an exhaustive chemical characterization. Moreover, it is still not possible to exactly determine presence and amount of each specific functional group in the polymeric structure. We employed both Fourier Transform Infrared Spectroscopy (FTIR) and Resonant Raman spectroscopy (RR), corroborated by quantum mechanically aided analysis of the experimental spectra, to infer about the chemical structure of two samples of PFAs, synthetized in different ways and appearing macroscopically different, the first one being a liquid and viscous commercial sample, the second one being a self-prepared solid and rigid sample produced following a thermosetting procedure. The vibrational spectroscopic analysis confirms the presence of differences in their chemical structures. The viscous form of PFA is mainly composed by short polymeric chains, and is characterized by the presence of isolated furfuryl alcohol and furfural residues similar to 5-hydroxymethylfurfural; the thermosetted PFA is formed by more cross-linked structures, characterized by several ketones and alkene double bonds, as well as a significant presence of Diels-Alder structures. In summary, the present study evidences how the use of both FTIR and RR spectroscopy, the latter carried out at several laser excitation wavelengths, indicates an accurate way to spectroscopically investigate complex polymers enabling to satisfactorily infer about their peculiar chemical structure.

Efficient identification of raw and ripe tung oil using headspace GC-MS

To differentiate between the raw type and ripe type of tung oil, it is important to distinguish between the types of tung oil before its application. In the present work, an efficient headspace gas chromatography-mass spectrometry (HS-GC-MS) method was developed for identifying eight samples T1-T8, including the raw tung oil and ripe tung oil. The HS-GC-MS experiments results showed that octanoic acid existed only in ripe tung oil of T2, T4, T6, T8, not in raw tung oil of T1, T3, T5, T7. Combined with structural characterization by tandem mass spectrometry, octanoic acid was screened as an effective marker for distinguishing between raw tung oil and ripe tung oil. Then, the HS-GC-MS method was applied into the putty samples of X1 (raw tung oil with lime) and X2 (ripe tung oil with lime) and successfully identified the samples X1 mixed with raw tung oil and X2 mixed with ripe tung oil. The further validations results suggested that the detection limit of our HS-GC-MS method could reach 1.05 mg/L for octanoic acid, whereas the detection limit of derivative gas chromatography-mass spectrometry (DR-GC-MS) method was 2.74 mg/L for methyl octanoate. The investigation results can also provide the useful information and technical support for the selection of restoration materials and technology in ancient buildings.

Furfuryl alcohol/tung oil matrix-based composites reinforced with bacterial cellulose fibres

Polymeric materials have drastically changed the society in the last century. However, their non-renewable origin, together with their indiscriminate use and disposal, resulted in a huge accumulation of waste in the environment and raised a wide discussion about the emission of greenhouse gases, which must be considerably reduced to minimize global warming. Thus, the establishment of a consolidated production of polymers prioritizing the use of renewable sources of raw materials became a hot research topic. Vegetable oils are protagonists of this initiative, and their carbon-carbon double bonds are convenient reactive sites for chain growth polymerization reactions. However, typical vegetable oil-based homopolymers often do not display competitive thermo-mechanical properties, and the preparation of the corresponding copolymers and composites is therefore an interesting alternative strategy. Herein, the preparation of composites based on a tung oil/furfuryl alcohol co-continuous network reinforced with bacterial cellulose fibers is described. For this purpose, the cellulose nanofibers were suspended in furfuryl alcohol, and different amounts of the ensuing suspension were mixed with tung oil in the presence of trifluoroacetic acid as cationic initiator. Fourier-transform infrared spectroscopy analysis of all samples indicated the association of both tung oil and furfuryl alcohol in the final materials, with peaks belonging to cellulose superposed at the fingerprint regions of composites. Differential scanning calorimetry and thermogravimetry demonstrated an interesting relationship between the composition and the corresponding thermal properties, and the morphology of the materials was assessed by scanning electron microscopy (SEM), which revealed a homogeneous distribution of cellulosic fibers at lower concentrations. The results gathered here contribute to the development of original macromolecular materials exclusively based on the renewable platform.

The Prospering of Macromolecular Materials Based on Plant Oils within the Blooming Field of Polymers from Renewable Resources

This paper provides an overview of the recent progress in research and development dealing with polymers derived from plant oils. It highlights the widening interest in novel approaches to the synthesis, characterization, and properties of these materials from renewable resources and emphasizes their growing impact on sustainable macromolecular science and technology. The monomers used include unmodified triglycerides, their fatty acids or the corresponding esters, and chemically modified triglycerides and fatty acid esters. Comonomers include styrene, divinylbenzene, acrylics, furan derivatives, epoxides, etc. The synthetic pathways adopted for the preparation of these materials are very varied, going from traditional free radical and cationic polymerizations to polycondensation reactions, as well as metatheses and Diels-Alder syntheses. In addition to this general appraisal, the specific topic of the use of tung oil as a source of original polymers, copolymers, and (nano)composites is discussed in greater detail in terms of mechanisms, structures, properties, and possible applications.