Bioderived Thiol-Ene Emulsion Polymerization for Hybrid Latex Particles

The thiol-ene emulsion polymerization of three dienes synthesized from bioderived compounds, and subsequent preparation of core-shell polymer latexes, is reported. Levoglucosan (LGA), levogucosenone (LGO) and isosorbide were first modified with 4-pentenoic acid to install polymerizable groups. These monomers were used along with a dithiol to prepare poly(thioether) particles via ab initio emulsion polymerization using potassium persulfate as initiator and sodium dodecyl sulfate as surfactant. The structure of the diene significantly influenced the size of the resulting polymer latex particles. Given their low glass transition temperature, the LGA-derived poly(thioether) particles were used as a seed for the seeded emulsion polymerization of either styrene or methyl methacrylate. Core-shell latex particles with a high Tg core and a low Tg bioderived shell were formed, as verified by electron microscopy and in agreement with theoretical predictions of the equilibrium particle morphology based on the interfacial tensions of each particle phase.

Valorization of Lactate Esters and Amides into Value-Added Biobased (Meth)acrylic Polymers

(Meth)acrylic polymers are massively produced due to their inherently attractive properties. However, the vast majority of these polymers are derived from fossil resources, which is not aligned with the tendency to reduce gas emissions. In this context, (meth)acrylic polymers derived from biomass (biobased polymers) are gaining momentum, as their application in different areas can not only stand the comparison but even surpass, in some cases, the performance of petroleum-derived ones. In this review, we highlight the design and synthesis of (meth)acrylic polymers derived from lactate esters (LEs) and lactate amides (LAs), both derived from lactic acid. While biobased polymers have been widely studied and reviewed, the poly(meth)acrylates with pendant LE and LA moieties evolved slowly until recently when significant achievements have been made. Hence, constraints and opportunities arising from previous research in this area are presented, focusing on the synthesis of well-defined polymers for the preparation of advanced materials.

Hydrophobic Aerogels from Vinyl Polymers Derived from Radical Polymerization: Proof-of-Concept

Hydrophilicity is one important drawback of bio-based aerogels. To overcome this issue, a novel approach for the preparation of mesoporous, water repellent aerogels is introduced, which combines synthesis of cross-linked bio-based copolymers from methacrylate copolymerizations, followed by solvent exchange and supercritical drying steps. The influence of monomers with different nonpolar ester groups (methyl, vanillin, tetrahydrofurfuryl) on textural properties and water contact angles of the dry products is assessed. Final aerogels show generally high overall porosities (≈96%), low densities (0.07-0.11 g cm-3) as well as fine, mainly mesoporous networks, and specific surface areas in the range of 120-240 m2 g-1. Hereby, choice of the methacrylate ester groups results in differences of the resulting pore-size distributions. Water repellency tests show stable static water contact angles in the hydrophobic range (≈100°) achieved for the substrate containing the vanillin ester group. On the contrary the other substrates absorb water quickly, which indicates a decisive role of the ester group. The presented approach opens up a new pathway to bio-based aerogels with intrinsic hydrophobicity. It is suggested that the properties are tailored by the choice of the monomer structure, hence enabling further adaption and optimization of the products.

Epoxy (Meth)acrylate-Based Thermally and UV Initiated Curable Coating Systems

Recently, photocurable coatings are being used frequently. However, it is worth mentioning that the use of photopolymerization has its drawbacks, especially in the case of curing coatings on three-dimensional surfaces and in places that are difficult to access for UV radiation. However, it is possible to develop a system in which UV technology and thermal methods for curing coatings can be combined. Moreover, the obtained resins are derived from low-viscosity epoxy resins or diglycidyl ethers, making them an ideal building material for photopolymerization-based three-dimensional printing techniques. Due to the need to improve this method, a series of epoxy (meth)acrylates containing both epoxy and (meth)acrylate groups were obtained via the addition of acrylic or methacrylic acid to epoxy resin, diglycydylether of bisphenol A epoxy resin (DGEBA), cyclohexane dimethanol diglycidyl ether (CHDMDE) and neopentyl glycol diglycidyl ether (NPDE). The structures of the synthesized copolymers were confirmed through spectroscopic analysis (FTIR) and studied regarding their nonvolatile matter content (NV) and acid values (PAVs), as well as their epoxy equivalent values (EEs). Due to the presence of both epoxy and double carbon-carbon pendant groups, two distinct mechanisms can be applied: cationic and radical. Hence, the obtained resins can be cured using UV radiation with thermally appropriate conditions and initiators. This type of method can be used as a solution to many problems currently encountered in using UV technology, such as failure to cure coatings in underexposed areas as well as deformation of coatings. Synthesized epoxy (meth)acrylate prepolymers were employed to formulate photocurable coating compositions. Furthermore, the curing process and properties of cured coatings were investigated regarding some structural factors and parameters. Among the synthesized materials, the most promising are those based on epoxy resin, characterized by their high glass transition temperature values and satisfactory functional properties.

Renewable and Functional Latexes Synthesized by Polymerization-Induced Self-Assembly for UV-Curable Films

After the development of polymer coatings and films based on renewable resources, there remains a challenge of combining the advantages of water-borne acrylic latexes with the excellent physical properties of cross-linked solvent-borne coatings. After polymerization, the renewable 4-oxocyclopentenyl acrylate (4CPA) is capable of undergoing photocyclodimerization under UV light, yielding a cross-linked polyacrylate. In this work, we investigate the polymerization-induced self-assembly (PISA) of 4CPA with several renewable acrylic monomers in the presence of a macro-RAFT agent. The produced latexes have a small particle size, good colloidal stability, and are free of volatile organic compounds. After film formation and UV curing, flexible to rigid films can be obtained depending on the monomer composition and UV irradiation time. The cross-linked films show promise as oil and water barriers in paper coating applications. This work outlines the development and application of renewable and functional cross-linkable latexes synthesized by PISA.

Polymer Colloids: Current Challenges, Emerging Applications, and New Developments

Polymer colloids are complex materials that have the potential to be used in a vast array of applications. One of the main reasons for their continued growth in commercial use is the water-based emulsion polymerization process through which they are generally synthesized. This technique is not only highly efficient from an industrial point of view but also extremely versatile and permits the large-scale production of colloidal particles with controllable properties. In this perspective, we seek to highlight the central challenges in the synthesis and use of polymer colloids, with respect to both existing and emerging applications. We first address the challenges in the current production and application of polymer colloids, with a particular focus on the transition toward sustainable feedstocks and reduced environmental impact in their primary commercial applications. Later, we highlight the features that allow novel polymer colloids to be designed and applied in emerging application areas. Finally, we present recent approaches that have used the unique colloidal nature in unconventional processing techniques.

One-Pot Catalysis: A Privileged Approach for Sustainable Polymers?

Almost all aspects of daily life involve polymers in some form or the other. However, polymer production is largely based on finite feedstocks. These limitations combined with environmental concerns force us to rethink the strategies for the synthesis of these materials. As an abundant and renewable resource, biomass is composed of a very diverse range of molecules that deserve to be valorized. The development of new methods for transforming biomass into resources suitable for polymer production remains a crucial hurdle on the road to a more sustainable chemical economy. The main challenge is to design efficient and selective transformations of abundant and inexpensive raw materials into innovative polymers. For the chemical industry to meet these challenges, process intensification must play an important role in developing cleaner and more energy-efficient technologies while aiming for safer and more sustainable processes. Catalysis is an important tool to support more sustainable plastics production by being ideally efficient, practical, and versatile. In this regard, the creation of sustainable polymers through one-pot catalysis represents an exciting frontier in materials science.In this Account, we describe some of the published advances for achieving one-pot synthesis of biobased monomers and the resulting (co)polymers. These studies demonstrate that one-pot reactions can produce sustainable materials for a wide range of applications. We show that these new multistep "one-pot" approaches are very promising from an academic and industrial point of view. These synthetic schemes have indeed allowed us to investigate the formation of new polyesters, polypeptides, and poly(meth)acrylates by different polymerization mechanisms. We discuss their efficiency by highlighting their ability to perform multiple (quantitative) synthetic transformations and bond formation steps while bypassing multiple purification procedures at the same time. While enabling the development of novel polymeric structures, we demonstrate that these one-pot procedures can also contribute to reducing the environmental footprint.In light of the growing concerns for sustainable development, these procedures may therefore allow, in the near future, one to prepare sustainable polymeric materials with advanced properties through extremely simplified routes from renewable feedstocks. Among these materials, block and alternating copolymers are unique structures that can exhibit a wide range of properties. While their multistep synthesis remains a demanding process, the one-pot synthesis of these polymers is much more scalable and can create multiblock or alternating copolymers with a wide range of potential sequences. These approaches then give access to materials whose structure and functionality can be designed to suit the need.

2,5-Furandicarboxylic Acid: An Intriguing Precursor for Monomer and Polymer Synthesis

The most versatile furanic building block for chemical and polymer applications is 2,5-furandicarboxylic acid. However, the classical 2,5-furandicarboxylic acid production methodology has been found to have significant drawbacks that hinder industrial-scale production. This review highlights new alternative methods to synthesize 2,5-furandicarboxylic acid that are both more advantageous and attractive than conventional oxidation of 5-hydroxymethylfurfural. This review also focuses on the use of 2,5-furandicarboxylic acid as a polymer precursor and the various potential applications that arise from these furan-based materials.

RAFT Polymerization of a Biorenewable/Sustainable Monomer Via a Green Process

A biorenewable polymer was synthesized via a green process using the RAFT principle for the first time in supercritical CO2 at 300 bar and 80°C. α-Methylene-γ-butyrolactone polymers of various chain lengths and molecular weights were obtained. The molecular weights varied from 10000 up to 20000 with low polydispersity indexes (PDI <1.5). Furthermore, the monomer conversion in supercritical CO2 was substantially higher, respectively 85⁺ % for ScCO2 compared to around 65% for polymerizations conducted in dimethyl formamide (DMF) solvent. Chain extensions were carried out to confirm the livingness of the formed polymers in ScCO2. This opens up future possibilities of the formation of different polymer architectures in ScCO2. The polymers synthesized in ScCO2 have glass transition temperature (Tg) values ranging from 155°C up to 190°C. However, the presence of residual monomer encapsulated inside the formed polymer matrix affected the glass transition of the polymer which was lowered by increasing monomer concentrations. Hence, additional research is required to eliminate the remaining monomer concentration in the polymer matrix in order to arrive at the optimal Tg. This article is protected by copyright. All rights reserved.

The Correlation for Effective Distribution Coefficient with Initial Impurity Concentration and Growth Rate for Acrylic Acid in Melt Crystallization

The layer growth rates and resulting crystal purity during solid-layer melt crystallization were experimentally measured for acrylic acid (AA) with impurity propionic acid (PA) operated at various cooling temperatures. A power law was adopted to correlate the growth rate with the temperature difference between melt and coolant. The effective distribution coefficient was determined from the resulting crystal purity for each condition. An empirical equation modified from the analytical solution for the mass transfer boundary layer was proposed in this work to relate the effective distribution coefficient to the initial impurity concentration and growth rate.

Reverse atom transfer radical polymerization of dimethyl itaconate initiated by a new azo initiator: AIBME

Reverse atom transfer radical polymerization (RATRP) was used to synthesize poly(dimethyl itaconate) (PDMI) using an AIBME/CuBr₂/dNbpy system. The number average molecular weight (M _n) of PDMI was as high as M _n = 15 000 g mol^-1, the monomer conversion rate reached up to 70%, and the dispersity remained low (Đ = 1.06-1.38). The first-order kinetics of PDMI are discussed in detail. The AIBME initiator had a higher initiation efficiency than the AIBN initiator. As the ratio of initiator (AIBME) to catalyst (CuBr₂) decreased, the M _n and Đ of PDMI decreased. At 60 °C and 80 °C, the M _n of PDMI was much higher than the theoretical number average (M _n,th), and the Đ of PDMI broadened with the conversion rate. At 100 °C, the Đ of PDMI remained low, and the M _n of PDMI was closer to the M _n,th. As the ratio of monomer (DMI) to initiator (AIBME) increased, the M _n of PDMI changed little over time. These phenomena could be explained by the influence of the initiator and catalyst on polymerization kinetics.

Highly Efficient Biobased Synthesis of Acrylic Acid

Petrochemical based polymers, paints and coatings are cornerstones of modern industry but our future sustainable society demands greener processes and renewable feedstock materials. A challenge is to access platform monomers from biomass resources while integrating the principles of green chemistry in their chemical synthesis. We present a synthesis route starting from biomass-derived furfural towards the commonly used monomers maleic anhydride and acrylic acid, implementing environmentally benign photooxygenation, aerobic oxidation and ethenolysis reactions. Maleic anhydride and acrylic acid, transformed into sodium acrylate, were isolated in yields of 85 % (2 steps) and 81 % (4 steps), respectively. With minimal waste and high atom efficiency, this biobased route provides a viable alternative to access key monomers.

Diverse chemically recyclable polymers obtained by cationic vinyl and ring-opening polymerizations of the cyclic ketene acetal ester “dehydroaspirin”

Chemically recyclable polymers composed of carbon and/or ester backbones were prepared by vinyl and ring-opening polymerizations of a cyclic ketene acetal ester.

Sustainability in Heritage Wood Conservation: Challenges and Directions for Future Research

Conserving the world’s cultural and natural heritage is considered a key contributor to achieving the targets set out in the United Nation’s Sustainable Development Goals, yet how much attention do we pay to the methods we use to conserve and protect this heritage? With a specific focus on wooden objects of cultural heritage, this review discusses the current state-of-the-art in heritage conservation in terms of sustainability, sustainable alternatives to currently used consolidants, and new research directions that could lead to more sustainable consolidants in the future. Within each stage a thorough discussion of the synthesis mechanisms and/or extraction protocols, particularly for bio-based resources is provided, evaluating resource usage and environmental impact. This is intended to give the reader a better understanding of the overall sustainability of each different approach and better evaluate consolidant choices for a more sustainable approach. The challenges facing the development of sustainable consolidants and recent research that is likely to lead to highly sustainable new consolidant strategies in the future are also discussed. This review aims to contribute to the ongoing discussion of sustainable conservation and highlight the role that consolidants play in truly sustainable heritage conservation.

Controlling polymer stereochemistry in ring-opening polymerization: a decade of advances shaping the future of biodegradable polyesters

This review highlights recent developments in the field of biodegradable polymeric materials intended to replace non-degradable conventional plastics, focusing on studies from the last ten years involving the stereoselective ring-opening polymerization of cyclic esters. This encompasses exciting advances in both catalyst design and monomer scope. Notably, the last decade has seen the emergence of metal-free stereocontrolled ROP for instance, as well as the synthesis and stereocontrolled polymerization of new types of chiral monomers. This study will emphasize recent stereoselective polymerization catalysts and chiral monomers and will focus on stereocontrol quantification, the mechanisms of stereocontrol and their differentiation if reported and studied for a specific catalyst system.

Highly Efficient Synthesis of Poly(silylether)s: Access to Degradable Polymers from Renewable Resources

The design of new materials with tunable properties and intrinsic recyclability, derived from biomass under mild conditions, stands as a gold standard in polymer chemistry. Reported herein are platinum complexes which catalyze the formation of poly(silylether)s (PSEs) at low catalyst loadings. These polymers are directly obtained from dual-functional biobased building blocks such as 5-hydroxymethylfurfural (HMF) or vanillin, coupled with various dihydrosilanes. Access to different types of copolymer architectures (statistical or alternating) is highlighted by several synthetic strategies. The materials obtained were then characterized as low T_g materials (ranging from -60 to 29 °C), stable upon heating (T_-5% up to 301 °C) and resistant towards uncatalyzed methanolysis. Additionally, quantitative chemical recycling of several PSEs could be triggered by acid-catalyzed hydrolysis or methanolysis. These results emphasize the interest of biobased poly(silylether)s as sustainable materials with high recycling potential.

Multicatalytic Transformation of (Meth)acrylic Acids: a One-Pot Approach to Biobased Poly(meth)acrylates

Shifting from petrochemical feedstocks to renewable resources can address some of the environmental issues associated with petrochemical extraction and make plastics production sustainable. Therefore, there is a growing interest in selective methods for transforming abundant renewable feedstocks into monomers suitable for polymer production. Reported herein are one-pot catalytic systems, that are active, productive, and selective under mild conditions for the synthesis of copolymers from renewable materials. Each system allows for anhydride formation, alcohol acylation and/or acid esterification, as well as polymerization of the formed (meth)acrylates, providing direct access to a new library of unique poly(meth)acrylates.

Glycerol waste to value added products and its potential applications

The rapid industrial and economic development runs on fossil fuel and other energy sources. Limited oil reserves, environmental issues, and high transportation costs lead towards carbon unbiased renewable and sustainable fuel. Compared to other carbon-based fuels, biodiesel is attracted worldwide as a biofuel for the reduction of global dependence on fossil fuels and the greenhouse effect. During biodiesel production, approximately 10% of glycerol is formed in the transesterification process in a biodiesel plant. The ditching of crude glycerol is important as it contains salt, free fatty acids, and methanol that cause contamination of soil and creates environmental challenges for researchers. However, the excessive cost of crude glycerol refining and market capacity encourage the biodiesel industries for developing a new idea for utilising and produced extra sources of income and treat biodiesel waste. This review focuses on the significance of crude glycerol in the value-added utilisation and conversion to bioethanol by a fermentation process and describes the opportunities of glycerol in various applications.

Graphic abstract

Matsuda-Heck arylation of itaconates: a versatile approach to heterocycles from a renewable resource

Itaconic acid esters and hemiesters undergo Pd-catalyzed coupling reactions with arene diazonium salts in high to excellent yields. The coupling products of ortho-nitro arene diazonium salts can be converted in one or two steps to benzazepine-2-ones.