Progress Toward Sustainable Reversible Deactivation Radical Polymerization

Green Copolymers and Nanocomposites from Myrcene and Limonene Using Algerian Nano-Clay as Nano-Reinforcing Filler

In this work, we report a new facile method for the preparation of myrcene-limonene copolymers and nanocomposites using a Lewis acid as a catalyst (AlCl₃) and organo-modified clay as a nano-reinforcing filler. The copolymer (myr-co-lim) was prepared by cationic copolymerization using AlCl₃ as a catalyst. The structure of the obtained copolymer is studied and confirmed by Fourier Transform Infrared spectroscopy, Nuclear Magnetic Resonance spectroscopy, and Differential Scanning Calorimetry. By improving the dispersion of the matrix polymer in sheets of the organoclay, Maghnite-CTA⁺ (Mag-CTA⁺), an Algerian natural organophilic clay, was used to preparenanocomposites of linear copolymer (myr-co-lim). In order to identify and assess their structural, morphological, and thermal properties, the effect of the organoclay, used in varyingamounts (1, 4, 7, and 10% by weight), and the preparation process were investigated. The Mag-CTA⁺ is an organophylic montmorillonite silicate clay prepared through a direct exchange process in which they were used as green nano-reinforcing filler. The X-ray diffraction of the resulting nanocomposites revealed a considerable alteration in the interlayer spacing of Mag-CTA⁺. As a result, interlayer expansion and myr-co-lim exfoliation between layers of Mag-CTA⁺ were observed. Thermogravimetric analysis provided information on the synthesized nanocomposites' thermal properties. Fourier transform infrared spectroscopy and scanning electronic microscopy, respectively, were used to determine the structure and morphology of the produced nanocomposites (myr-co-lim/Mag). The intercalation of myr-co-lim in the Mag-CTA⁺ sheets has been supported by the results, and the optimum amount of organoclay needed to create a nanocomposite with high thermal stability is 10% by weight. Finally, a new method for the preparation of copolymer and nanocomposites from myrcene and limonene in a short reaction time was developed.

Molecular polymer bottlebrushes in nanomedicine: therapeutic and diagnostic applications

Molecular polymer bottlebrushes are densely grafted, individual macromolecules with nanoscale proportions. The last decade has seen an increased focus on this material class, especially in nanomedicine and for biomedical applications. This Feature Article provides an overview of major developments in this area to highlight the many opportunities that these polymer architectures bring to nano-bio research. The article covers aspects of bottlebrush synthesis and summarises their use in drug and gene delivery, imaging, as theranostics and as prototype materials to correlate nanoparticle structure and composition to biological function and behaviour. Areas for future research in this area are discussed.

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.

Fatty Acids and their Derivatives as Renewable Platform Molecules for the Chemical Industry

Oils and fats of vegetable and animal origin remain an important renewable feedstock for the chemical industry. Their industrial use has increased during the last 10 years from 31 to 51 million tonnes annually. Remarkable achievements made in the field of oleochemistry in this timeframe are summarized herein, including the reduction of fatty esters to ethers, the selective oxidation and oxidative cleavage of C-C double bonds, the synthesis of alkyl-branched fatty compounds, the isomerizing hydroformylation and alkoxycarbonylation, and olefin metathesis. The use of oleochemicals for the synthesis of a great variety of polymeric materials has increased tremendously, too. In addition to lipases and phospholipases, other enzymes have found their way into biocatalytic oleochemistry. Important achievements have also generated new oil qualities in existing crop plants or by using microorganisms optimized by metabolic engineering.

Green Nanofabrication Opportunities in the Semiconductor Industry: A Life Cycle Perspective

The turn of the 21st century heralded in the semiconductor age alongside the Anthropocene epoch, characterised by the ever-increasing human impact on the environment. The ecological consequences of semiconductor chip manufacturing are the most predominant within the electronics industry. This is due to current reliance upon large amounts of solvents, acids and gases that have numerous toxicological impacts. Management and assessment of hazardous chemicals is complicated by trade secrets and continual rapid change in the electronic manufacturing process. Of the many subprocesses involved in chip manufacturing, lithographic processes are of particular concern. Current developments in bottom-up lithography, such as directed self-assembly (DSA) of block copolymers (BCPs), are being considered as a next-generation technology for semiconductor chip production. These nanofabrication techniques present a novel opportunity for improving the sustainability of lithography by reducing the number of processing steps, energy and chemical waste products involved. At present, to the extent of our knowledge, there is no published life cycle assessment (LCA) evaluating the environmental impact of new bottom-up lithography versus conventional lithographic techniques. Quantification of this impact is central to verifying whether these new nanofabrication routes can replace conventional deposition techniques in industry as a more environmentally friendly option.

Progress in the Free and Controlled Radical Homo- and Co-Polymerization of Itaconic Acid Derivatives: Toward Functional Polymers with Controlled Molar Mass Distribution and Architecture

Polymeric derivatives of itaconic acid are becoming increasingly more interesting for research and industry because itaconic acid is accessible from renewable resources. In spite of the structural similarity of poly(itaconic acid derivatives) to poly(methacrylates), they are much less reactive, homopolymerize only sluggishly by free radical polymerization (FRP), and are often obtained with low molar masses and conversions. This has so far limited their use. The reasons for the low reactivity of itaconic acid derivatives (including itaconimides, diitaconates, and diitaconamides) are combined steric and electronic effects, as demonstrated by the body of literature on the FRP homopolymerization kinetics of these monomers which is summarized herein. These problems can be solved to a large extent by using controlled radical polymerization (CRP) techniques, notably atom transfer radical polymerization (ATRP) and reversible addition and fragmentation chain transfer radical polymerization (RAFT). By optimizing the reaction conditions for the ATRP and RAFT of itaconic acid derivatives, in particular the reaction temperature, linear relations between molar mass and conversion are obtained in many cases, and homopolymers with high molar masses and reasonably narrow polydispersity indices become accessible. This review presents the state-of-the-art FRP and CRP of itaconic acid derivatives, and highlights functional polymers obtained by these methods.