Applying the Principles of Green Chemistry to Polymer Production Technology

Bulk Free Radical Terpolymerization of Butyl Acrylate, 2-Methylene-1,3-Dioxepane and Vinyl Acetate: Terpolymer Reactivity Ratio Estimation

This investigation introduces the first estimation of ternary reactivity ratios for a butyl acrylate (BA), 2-methylene-1,3-dioxepane (MDO), and vinyl acetate (VAc) system at 50 °C, with an aim to develop biodegradable pressure-sensitive adhesives (PSAs). In this study, we applied the error-in-variables model (EVM) to estimate reactivity ratios. The ternary reactivity ratios were found to be r12 = 0.417, r21 = 0.071, r13 = 4.459, r31 = 0.198, r23 = 0.260, and r32 = 55.339 (BA/MDO/VAc 1/2/3), contrasting with their binary counterparts, which are significantly different, indicating the critical need for ternary system analysis to accurately model multicomponent polymerization systems. Through the application of a recast Alfrey-Goldfinger model, this investigation predicts the terpolymer's instantaneous and cumulative compositions at various conversion levels, based on the ternary reactivity ratios. These predictions not only provide crucial insights into the incorporation of MDO across different initial feed compositions but also offer estimates of the final terpolymer compositions and distributions, underscoring their potential in designing compostable or degradable polymers.

Immunotoxic, genotoxic, and endocrine disrupting impacts of polyamide microplastic particles and chemicals

Due to their exceptional properties and cost effectiveness, polyamides or nylons have emerged as widely used materials, revolutionizing diverse industries, including industrial 3D printing or additive manufacturing (AM). Powder-based AM technologies employ tonnes of polyamide microplastics to produce complex components every year. However, the lack of comprehensive toxicity assessment of particulate polyamides and polyamide-associated chemicals, especially in the light of the global microplastics crisis, calls for urgent action. This study investigated the physicochemical properties of polyamide-12 microplastics used in AM, and assessed a number of toxicity endpoints focusing on inflammation, immunometabolism, genotoxicity, aryl hydrocarbon receptor (AhR) activation, endocrine disruption, and cell morphology. Specifically, microplastics examination by means of field emission scanning electron microscopy revealed that work flow reuse of material created a fraction of smaller particles with an average size of 1-5 µm, a size range readily available for uptake by human cells. Moreover, chemical analysis by means of gas chromatography high-resolution mass spectrometry detected several polyamide-associated chemicals including starting material, plasticizer, thermal stabilizer/antioxidant, and migrating slip additive. Even if polyamide particles and chemicals did not induce an acute inflammatory response, repeated and prolonged exposure of human primary macrophages disclosed a steady increase in the levels of proinflammatory chemokine Interleukin-8 (IL-8/CXCL-8). Moreover, targeted metabolomics disclosed that polyamide particles modulated the kynurenine pathway and some of its key metabolites. The p53-responsive luciferase reporter gene assay showed that particles per se were able to activate p53, being indicative of a genotoxic stress. Polyamide-associated chemicals triggered moderate activation of AhR and elicited anti-androgenic activity. Finally, a high-throughput and non-targeted morphological profiling by Cell Painting assay outlined major sites of bioactivity of polyamide-associated chemicals and indicated putative mechanisms of toxicity in the cells. These findings reveal that the increasing use of polyamide microplastics may pose a potential health risk for the exposed individuals, and it merits more attention.

What Are "Bioplastics"? Defining Renewability, Biosynthesis, Biodegradability, and Biocompatibility

Today, plastic materials are mostly made from fossil resources, and they are characterized by their long lifetime and pronounced persistence in the open environment. These attributes of plastics are one cause of the ubiquitous pollution we see in our environment. When plastics end up in the environment, most of this pollution can be attributed to a lack of infrastructure for appropriately collecting and recycling plastic waste, mainly due to mismanagement. Because of the huge production volumes of plastics, their merits of being cheap to produce and process and their recalcitrance have turned into a huge disadvantage, since plastic waste has become the end point of our linear economic usage model, and massive amounts have started to accumulate in the environment, leading to microplastics pollution and other detrimental effects. A possible solution to this is offered by "bioplastics", which are materials that are either (partly) biobased and/or degradable under defined conditions. With the rise of bioplastics in the marketplace, several standards and test protocols have been developed to assess, certify, and advertise their properties in this respect. This article summarizes and critically discusses different views on bioplastics, mainly related to the properties of biodegradability and biobased carbon content; this shall allow us to find a common ground for clearly addressing and categorizing bioplastic materials, which could become an essential building block in a circular economy. Today, bioplastics account for only 1-2% of all plastics, while technically, they could replace up to 90% of all fossil-based plastics, particularly in short-lived goods and packaging, the single most important area of use for conventional plastics. Their replacement potential not only applies to thermoplastics but also to thermosets and elastomers. Bioplastics can be recycled through different means, and they can be made from renewable sources, with (bio)degradability being an option for the mismanaged fraction and special applications with an intended end of life in nature (such as in seed coatings and bite protection for trees). Bioplastics can be used in composites and differ in their properties, similarly to conventional plastics. Clear definitions for "biobased" and "biodegradable" are needed to allow stakeholders of (bio)plastics to make fact-based decisions regarding material selection, application, and end-of-life options; the same level of clarity is needed for terms like "renewable carbon" and "bio-attributed" carbon, definitions of which are summarized and discussed in this paper.

Harnessing the power of polyol-based polyesters for biomedical innovations: synthesis, properties, and biodegradation

Polyesters based on polyols have emerged as promising biomaterials for various biomedical applications, such as tissue engineering, drug delivery systems, and regenerative medicine, due to their biocompatibility, biodegradability, and versatile physicochemical properties. This review article provides an overview of the synthesis methods, performance, and biodegradation mechanisms of polyol-based polyesters, highlighting their potential for use in a wide range of biomedical applications. The synthesis techniques, such as simple polycondensation and enzymatic polymerization, allow for the fine-tuning of polyester structure and molecular weight, thereby enabling the tailoring of material properties to specific application requirements. The physicochemical properties of polyol-based polyesters, such as hydrophilicity, crystallinity, and mechanical properties, can be altered by incorporating different polyols. The article highlights the influence of various factors, such as molecular weight, crosslinking density, and degradation medium, on the biodegradation behavior of these materials, and the importance of understanding these factors for controlling degradation rates. Future research directions include the development of novel polyesters with improved properties, optimization of degradation rates, and exploration of advanced processing techniques for fabricating scaffolds and drug delivery systems. Overall, polyol-based polyesters hold significant potential in the field of biomedical applications, paving the way for groundbreaking advancements and innovative solutions that could revolutionize patient care and treatment outcomes.

Synthesis of Polymers with Narrow Molecular Mass Distribution through Interface-Initiated Room-Temperature Polymerization in Emulsion Gels

Homopolymers of n-butyl acrylate, methyl methacrylate, styrene, and their random copolymers were prepared via interface-initiated polymerization of emulsion gels at 20 °C. The polymerization was conducted in a free radical polymerization manner without inert gas protection. Compared with the polymers synthesized at 60 °C, the polymerization of emulsion gels at 20 °C produced homo- and copolymers with a higher molecular mass and a narrower molecular mass distribution. The polydispersity indices for the polymers synthesized at 20 °C were found to be between 1.12 and 1.37. The glass transition temperatures for the as-synthesized butyl acrylate copolymers agree well with the prediction from the Gordon-Taylor equation. Interface-initiated room-temperature polymerization is a robust, energy-saving polymerization technique for synthesizing polymers with a narrow molecular mass distribution.

A Global Challenge: Sustainability of Submicrometer PEO and PVP Fiber Production

The field of submicrometer polymeric production currently has a predominant research focus on morphology and application. In comparison, the sustainability of the manufacture of submicrometer polymeric fibers, specifically the energy efficiency, is less explored. The principles of Green Chemistry and Green Engineering outline frameworks for the manufacture of "greener" products, where the most significant principles in the two frameworks are shown to be centered on energy efficiency, material wastage, and the use of non-hazardous materials. This study examines the power consumption during the production of Polyethylene oxide (PEO) and Polyvinylpyrrolidone (PVP) submicrometer fibers under magnitudes of the key forming parameters to generate fibers via pressure spinning. The energy consumption, along with the fiber diameter, and production rate during the manufacture of fibers is predominantly attributed to the characteristics of polymeric solutions utilized.

Synthesis of Polymer Nanoweb via a Lipid Template

We report a generalized platform for synthesizing a polymer nanoweb with a high specific surface area via a bicellar template, composed of 1,2-dipalmitoyl phosphocholine (DPPC), 1,2-dihexanoyl phosphocholine (DHPC), and 1,2-dipalmitoyl phosphoglycerol (DPPG). The pristine bicelle (in the absence of monomer or polymer) yields a variety of well-defined structures, including disc, vesicle, and perforated lamella. The addition of styrene monomers in the mixture causes bicelles to transform into lamellae. Monomers are miscible with DPPC and DPPG initially, while polymerization drives polymers to the DHPC-rich domain, resulting in a polymer nanoweb supported by the outcomes of small angle neutron scattering, differential scanning calorimetry, and transmission electron microscopy.

Sustainable Elastomers for Actuators: "Green" Synthetic Approaches and Material Properties

Elastomeric materials have great application potential in actuator design and soft robot development. The most common elastomers used for these purposes are polyurethanes, silicones, and acrylic elastomers due to their outstanding physical, mechanical, and electrical properties. Currently, these types of polymers are produced by traditional synthetic methods, which may be harmful to the environment and hazardous to human health. The development of new synthetic routes using green chemistry principles is an important step to reduce the ecological footprint and create more sustainable biocompatible materials. Another promising trend is the synthesis of other types of elastomers from renewable bioresources, such as terpenes, lignin, chitin, various bio-oils, etc. The aim of this review is to address existing approaches to the synthesis of elastomers using "green" chemistry methods, compare the properties of sustainable elastomers with the properties of materials produced by traditional methods, and analyze the feasibility of said sustainable elastomers for the development of actuators. Finally, the advantages and challenges of existing "green" methods of elastomer synthesis will be summarized, along with an estimation of future development prospects.

The curious case of polyphenols as green corrosion inhibitors: a review on their extraction, design, and applications

Over the past century, a substantial amount of research focused on developing corrosion inhibitors, with a special focus on green "plant-based" corrosion inhibitors. Among the various types of inhibitors, polyphenols emerged as a promising candidate due to their advantageous characteristics, which include being inexpensive, biodegradable, renewable, and, most importantly, safe for both the environment and humans. Their performance as sustainable corrosion inhibitors have encouraged many electrochemical experiments as well as theoretical, mechanistic, and computational studies, with many papers reporting inhibition efficiencies of over 85%. In this review, the majority of literature contributions on the inhibition of various types of polyphenols, their natural extraction techniques, and their applications as "greener" corrosion inhibitors for metals are thoroughly described and discussed with a focus on their preparation, inhibition mechanism, and performance. Based on the reviewed literature, it can be concluded that polyphenols have a very promising potential to be used as both green and powerful corrosion inhibitors; therefore, further investigations, experimental or computational, are still required to realize higher inhibition efficiencies reaching up to ≈ 100%.

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.

Review of quantitative and qualitative methods for monitoring photopolymerization reactions

Authomatic in-situ monitoring and characterization of photopolymerization.

Evaluation of Marker Materials and Spectroscopic Methods for Tracer-Based Sorting of Plastic Wastes

Plastics are a ubiquitous material with good mechanical, chemical and thermal properties, and are used in all industrial sectors. Large quantities, widespread use, and insufficient management of plastic wastes lead to low recycling rates. The key challenge in recycling plastic waste is achieving a higher degree of homogeneity between the different polymer material streams. Modern waste sorting plants use automated sensor-based sorting systems capable to sort out commodity plastics, while many engineering plastics, such as polyoxymethylene (POM), will end up in mixed waste streams and are therefore not recycled. A novel approach to increasing recycling rates is tracer-based sorting (TBS), which uses a traceable plastic additive or marker that enables or enhances polymer type identification based on the tracer’s unique fingerprint (e.g., fluorescence). With future TBS applications in mind, we have summarized the literature and assessed TBS techniques and spectroscopic detection methods. Furthermore, a comprehensive list of potential tracer substances suitable for thermoplastics was derived from the literature. We also derived a set of criteria to select the most promising tracer candidates (3 out of 80) based on their material properties, toxicity profiles, and detectability that could be applied to enable the circularity of, for example, POM or other thermoplastics.

Toward Green Atom Transfer Radical Polymerization: Current Status and Future Challenges

Reversible-deactivation radical polymerizations (RDRPs) have revolutionized synthetic polymer chemistry. Nowadays, RDRPs facilitate design and preparation of materials with controlled architecture, composition, and functionality. Atom transfer radical polymerization (ATRP) has evolved beyond traditional polymer field, enabling synthesis of organic-inorganic hybrids, bioconjugates, advanced polymers for electronics, energy, and environmentally relevant polymeric materials for broad applications in various fields. This review focuses on the relation between ATRP technology and the 12 principles of green chemistry, which are paramount guidelines in sustainable research and implementation. The green features of ATRP are presented, discussing the environmental and/or health issues and the challenges that remain to be overcome. Key discoveries and recent developments in green ATRP are highlighted, while providing a perspective for future opportunities in this area.

Natural Polymer in Soft Electronics: Opportunities, Challenges, and Future Prospects

Pollution caused by nondegradable plastics has been a serious threat to environmental sustainability. Natural polymers, which can degrade in nature, provide opportunities to replace petroleum-based polymers, meanwhile driving technological advances and sustainable practices. In the research field of soft electronics, regenerated natural polymers are promising building blocks for passive dielectric substrates, active dielectric layers, and matrices in soft conductors. Here, the natural-polymer polymorphs and their compatibilization with a variety of inorganic/organic conductors through interfacial bonding/intermixing and surface functionalization for applications in various device modalities are delineated. Challenges that impede the broad utilization of natural polymers in soft electronics, including limited durability, compromises between conductivity and deformability, and limited exploration in controllable degradation, etc. are explicitly inspected, while the potential solutions along with future prospects are also proposed. Finally, integrative considerations on material properties, device functionalities, and environmental impact are addressed to warrant natural polymers as credible alternatives to synthetic ones, and provide viable options for sustainable soft electronics.

Copolymers of starch, a sustainable template for biomedical applications: A review

The outstanding versatility of starch offers a source of inspiration for the development of high-performance-value-added biomaterials for the biomedical field, including drug delivery, tissue engineering and diagnostic imaging. This is because starch-based materials can be tailored to specific applications via facile grafting or other chemistries, introducing specific substituents, with starch being effectively the "template" used in all the chemical transformations discussed in this review. A considerable effort has been carried out to obtain specific tailored starch-based grafted polymers, taking advantage of its biocompatibility and biodegradability with appealing sustainability considerations. The aim of this review is to critically explore the latest research that use grafting chemistries on starch for the synthesis of products for biomedical applications. An effort is made in reviewing the literature that proposes synthetic "greener" approaches, the use of enzymes and their immobilized analogues and alternative solvent systems, including water emulsions, ionic liquids and supercritical CO₂.

Green synthesis of various saturated S-heterocyclic scaffolds: an update

Development of reliable and eco-friendly novel schemes for the synthesis of organic compounds is an important step in the field of organic and medicinal chemistry. Green chemistry-based strategies involving use of catalysts, green solvents, atom economic reactions etc. play a key role because of their exceptional ability to minimize the toxicity or hazards of the side products and processes. With the use of these green techniques, a number of researchers were able to synthesis a wide range of heterocyclic compounds. This chapter highlights the potential and diverse biological activities of saturated sulphur containing heterocyclic compounds including thiirane, thiane, thiolane and many more. The aim of this chapter is to provide fresh perspective on the various techniques employed for the formation of C–S bond by summarizing all green synthesis from 2016 to 2021.

Surface Design of Liquid Separation Membrane through Graft Polymerization: A State of the Art Review

Surface modification of membranes is an effective approach for imparting unique characteristics and additional functionalities to the membranes. Chemical grafting is a commonly used membrane modification technique due to its versatility in tailoring and optimizing the membrane surface with desired functionalities. Various types of polymers can be precisely grafted onto the membrane surface and the operating conditions of grafting can be tailored to further fine-tune the membrane surface properties. This review focuses on the recent strategies in improving the surface design of liquid separation membranes through grafting-from technique, also known as graft polymerization, to improve membrane performance in wastewater treatment and desalination applications. An overview on membrane technology processes such as pressure-driven and osmotically driven membrane processes are first briefly presented. Grafting-from surface chemical modification approaches including chemical initiated, plasma initiated and UV initiated approaches are discussed in terms of their features, advantages and limitations. The innovations in membrane surface modification techniques based on grafting-from techniques are comprehensively reviewed followed by some highlights on the current challenges in this field. It is concluded that grafting-from is a versatile and effective technique to introduce various functional groups to enhance the surface properties and separation performances of liquid separation membranes.

Tuning the Properties of PNIPAm-Based Hydrogel Scaffolds for Cartilage Tissue Engineering

Poly(N-isopropylacrylamide) (PNIPAm) is a three-dimensional (3D) crosslinked polymer that can interact with human cells and play an important role in the development of tissue morphogenesis in both in vitro and in vivo conditions. PNIPAm-based scaffolds possess many desirable structural and physical properties required for tissue regeneration, but insufficient mechanical strength, biocompatibility, and biomimicry for tissue development remain obstacles for their application in tissue engineering. The structural integrity and physical properties of the hydrogels depend on the crosslinks formed between polymer chains during synthesis. A variety of design variables including crosslinker content, the combination of natural and synthetic polymers, and solvent type have been explored over the past decade to develop PNIPAm-based scaffolds with optimized properties suitable for tissue engineering applications. These design parameters have been implemented to provide hydrogel scaffolds with dynamic and spatially patterned cues that mimic the biological environment and guide the required cellular functions for cartilage tissue regeneration. The current advances on tuning the properties of PNIPAm-based scaffolds were searched for on Google Scholar, PubMed, and Web of Science. This review provides a comprehensive overview of the scaffolding properties of PNIPAm-based hydrogels and the effects of synthesis-solvent and crosslinking density on tuning these properties. Finally, the challenges and perspectives of considering these two design variables for developing PNIPAm-based scaffolds are outlined.

Towards Advances in Molecular Understanding of Boric Acid Biocatalyzed Ring-Opening (Co)Polymerization of δ-Valerolactone in the Presence of Ethylene Glycol as an Initiator

Following our previous studies on the molecular level structure of (co)oligoesters obtained via anionic homo- and co-polymerization of novel β-substituted β-lactones, prepared by the atmospheric pressure carbonylation reaction of respective epoxides, the boric acid biocatalyzed ring-opening (co)polymerization of δ-valerolactone has been studied. As a co-monomer the 6-methy-ε-caprolactone, prepared by the one-pot oxidation of respective alcohol, and ethylene glycol as polymerization initiator were used. The obtained copolymers were characterized by 1H-NMR, GPC and ESI-MS, respectively in order to confirm their chemical structures and identity. Subsequently, tandem mass spectrometry (MS-MS studies) via collision-induced dissociation were utilized to characterize the fragmentation pattern. ESI-MS and NMR analyses confirmed the formation of random linear copolymer chains composed of different polyester repeat units. MS-MS experiments showed that fragmentation proceeds via ester bound cleavage along the (co)polyester chains. The innovative aspect of this contribution is related to the elaboration of the telechelic (co)polymers end-capped with hydroxyl end groups and well-defined molecular architectures, which could facilitate the development of new flexible macromolecular systems for potential biomedical applications.

Sodium Butylated Hydroxytoluene: A Functional Group Tolerant, Eco-Friendly Base for Solvent-Free, Pd-Catalysed Amination

NaBHT (sodium 2,6-di-tert-butyl-4-methylphenolate), a strong, but hindered and lipophilic base, has been effectively paired with similarly lipophilic, high-reactivity Pd-NHC (N-heterocyclic carbene) catalysts to produce an ideal combination for performing solvent-free (melt) cross-coupling amination. The mild nucleophilicity of NaBHT, coupled with the anti-oxidant properties of its conjugate acid byproduct, BHT means the process seems to have no functional group incompatibilities. Highly effective coupling of base-sensitive and redox-active functional groups was observed in all cases with only 0.1-0.2 mol percent catalyst. Comparisons using the standard base for this reaction, KOtBu, led to poor couplings or complete degradation in most applications - only NaBHT works.

Recent Advances on Properties and Utility of Nanomaterials Generated from Industrial and Biological Activities

Today is the era of nanoscience and nanotechnology, which find applications in the field of medicine, electronics, and environmental remediation. Even though nanotechnology is in its emerging phase, it continues to provide solutions to numerous challenges. Nanotechnology and nanoparticles are found to be very effective because of their unique chemical and physical properties and high surface area, but their high cost is one of the major hurdles to its wider application. So, the synthesis of nanomaterials, especially 2D nanomaterials from industrial, agricultural, and other biological activities, could provide a cost-effective technique. The nanomaterials synthesized from such waste not only minimize pollution, but also provide an eco-friendly approach towards the utilization of the waste. In the present review work, emphasis has been given to the types of nanomaterials, different methods for the synthesis of 2D nanomaterials from the waste generated from industries, agriculture, and their application in electronics, medicine, and catalysis.

Elemental sulphur in the synthesis of sulphur-containing polymers: reaction mechanisms and green prospects

The synthesis of polymers using elemental sulphur as a chemical agent has been studied in relation to the worldwide overproduction of cyclo-octasulphur. Herein, the mechanisms of the processes leading to the inclusion of elemental sulphur into macromolecules have been reviewed and the main methods for reduction of the reaction temperature required for the S8 ring opening have been shown. Approaches to the activation of cyclo-octasulphur in the synthesis and macromolecule cross-linking reactions were discussed in the context of finding the chemical agents and conditions that satisfy the principles of green chemistry.

Greener, Faster, Stronger: The Benefits of Deep Eutectic Solvents in Polymer and Materials Science

Deep eutectic solvents (DESs) represent an emergent class of green designer solvents that find numerous applications in different aspects of chemical synthesis. A particularly appealing aspect of DES systems is their simplicity of preparation, combined with inexpensive, readily available starting materials to yield solvents with appealing properties (negligible volatility, non-flammability and high solvation capacity). In the context of polymer science, DES systems not only offer an appealing route towards replacing hazardous volatile organic solvents (VOCs), but can serve multiple roles including those of solvent, monomer and templating agent-so called "polymerizable eutectics." In this review, we look at DES systems and polymerizable eutectics and their application in polymer materials synthesis, including various mechanisms of polymer formation, hydrogel design, porous monoliths, and molecularly imprinted polymers. We provide a comparative study of these systems alongside traditional synthetic approaches, highlighting not only the benefit of replacing VOCs from the perspective of environmental sustainability, but also the materials advantage with respect to mechanical and thermal properties of the polymers formed.

Preparation of thermoresponsive hydrogels via polymerizable deep eutectic monomer solvents

We report the preparation of thermoresponsive hydrogels via free-radical polymerization and crosslinking of NIPAM based deep eutectic monomer solvents (DEMs).

Review on the Impact of Polyols on the Properties of Bio-Based Polyesters

Bio-based polyol polyesters are biodegradable elastomers having potential utility in soft tissue engineering. This class of polymers can serve a wide range of biomedical applications. Materials based on these polymers are inherently susceptible to degradation during the period of implantation. Factors that influence the physicochemical properties of polyol polyesters might be useful in achieving a balance between durability and biodegradability. The characterization of these polyol polyesters, together with recent comparative studies involving creative synthesis, mechanical testing, and degradation, have revealed many of their molecular-level differences. The impact of the polyol component on the properties of these bio-based polyesters and the optimal reaction conditions for their synthesis are only now beginning to be resolved. This review describes our current understanding of polyol polyester structural properties as well as a discussion of the more commonly used polyol monomers.

Cellulose Nanocrystal (CNC)-Latex Nanocomposites: Effect of CNC Hydrophilicity and Charge on Rheological, Mechanical, and Adhesive Properties

Cellulose nanocrystals (CNCs), a sustainable nanomaterial, are in situ incorporated into emulsion-based pressure-sensitive adhesives (PSAs). Commercially available CNCs with different surface hydrophilicity and surface charge (CNC101 and CNC103 from CelluForce) are used to explore their role in PSA property modification. Viscosity measurements and atomic force microscopy reveal differences in degree of association between the CNCs and the latex particles depending on the surface properties of the CNCs. The more hydrophilic and higher surface charge CNCs (CNC101) show less association with the latex particles. Dynamic strain sweep tests are used to analyze the strain-softening of the nanocomposites based on CNC type and loading. The CNC101 nanocomposites soften at lower strains than their CNC103 counterparts. This behavior is confirmed via dynamic frequency tests and modeling of the nanocomposites' storage moduli, which suggest the formation of CNC aggregates of, on average, 3.8 CNC101 and 1.3 CNC103 nanoparticles. Finally, PSA properties, i.e., tack, peel strength, and shear strength, simultaneously increase upon addition of both CNC types, although to different extents. The relationship between the PSA properties and CNC surface properties confirms that the less hydrophilic CNCs lead to improved CNC dispersion in the PSA films and therefore, enhance PSA properties.

Physicochemical properties of raw starches and their impact on electrochemical activity - Biomolecule-based anode material

Starch is a modern and prospective biodegradable material, which could improve lithium-ion batteries by making them safer and thus increasing the energy density and capacity of the cells. The main aim of this study was to research the influence of the physical and chemical properties of different botanical origin starches on their electrochemical properties. The investigation was carried out by examining the colloid stability of starches in water solution at room temperature, and the size of particles, which gave really good stability results. Moreover, the vibrations and the functional groups structure were described by Fourier Transform Infrared Spectroscopy (FTIR). The surface properties were characterized by determining the specific surface area, pore diameter and volume diameter. The structures of the granules were determined by scanning electron microscope (SEM) measurement. The results of the electrochemical investigations showed good cyclic reversibility and stability. The research was aimed at improving and modifying current lithium-ion cells using biodegradable material as an active anode material, which is connected with the currently well-known "Green Chemistry".

Bismuth as Smart Material and Its Application in the Ninth Principle of Sustainable Chemistry

This paper reports an overview of Green Chemistry and the concept of its twelve principles. This study focusses on the ninth principle of Green Chemistry, that is, catalysis. A report on catalysis, in line with its definition, background, classification, properties, and applications, is provided. The study also entails a green element called bismuth. Bismuth’s low toxicity and low cost have made researchers focus on its wide applications in catalysis. It exhibits smartness in all the catalytic activities with the highest catalytic performance among other metals.

Surface Initiated Polymer Thin Films for the Area Selective Deposition and Etching of Metal Oxides

The area selective growth of polymers and their use as inhibiting layers for inorganic film depositions may provide a valuable self-aligned process for fabrication. Polynorbornene (PNB) thin films were grown from surface-bound initiators and show inhibitory properties against the atomic layer deposition (ALD) of ZnO and TiO₂. Area selective control of the polymerization was achieved through the synthesis of initiators that incorporate surface-binding ligands, enabling their selective attachment to metal oxide features versus silicon dielectrics, which were then used to initiate surface polymerizations. The subsequent use of these films in an ALD process enabled the area selective deposition (ASD) of up to 39 nm of ZnO. In addition, polymer thickness was found to play a key role, where films that underwent longer polymerization times were more effective at inhibiting higher numbers of ALD cycles. Finally, while the ASD of a TiO₂ film was not achieved despite blanket studies showing inhibition, the ALD deposition on polymer regions of a patterned film produced a different quality metal oxide and therefore altered its etch resistance. This property was exploited in the area selective etch of a metal feature. This demonstration of an area selective surface-grown polymer to enable ASD and selective etch has implications for the fabrication of both micro- and nanoscale features and surfaces.

Using Lignin to Modify Starch-Based Adhesive Performance

Unmodified kraft lignin was used to create a starch-based adhesive via the Stein Hall process. Lignin up to 35 wt% was used in several formulations. Lignin was incorporated in both the carrier and slurry portions of the formulations and the effect on adhesive strength and water resistance was studied. The addition of lignin resulted in a significant increase in adhesive strength when the lignin was added solely to the slurry portion. When lignin was added solely to the carrier portion, the adhesive strength decreased. Other formulations, where lignin was present in both the carrier and slurry portions, showed moderate increases in adhesive strength. Finally, the addition of lignin increased the water-resistance of the adhesive bond in the paperboard.

A tripodal heptadentate Schiff base as an active ligand for atom transfer radical polymerization

The use of a tripodal heptadentate Schiff base, tris[N-(2-pyridylmethyl)-2-iminoethyl]amine (Py₃Tren), as an active ligand for atom transfer radical polymerization (ATRP) is reported.

Greener synthesis of chemical compounds and materials

Modern trends in the greener synthesis and fabrication of inorganic, organic and coordination compounds, materials, nanomaterials, hybrids and nanocomposites are discussed. Green chemistry deals with synthesis procedures according to its classic 12 principles, contributing to the sustainability of chemical processes, energy savings, lesser toxicity of reagents and final products, lesser damage to the environment and human health, decreasing the risk of global overheating, and more rational use of natural resources and agricultural wastes. Greener techniques have been applied to synthesize both well-known chemical compounds by more sustainable routes and completely new materials. A range of nanosized materials and composites can be produced by greener routes, including nanoparticles of metals, non-metals, their oxides and salts, aerogels or quantum dots. At the same time, such classic materials as cement, ceramics, adsorbents, polymers, bioplastics and biocomposites can be improved or obtained by cleaner processes. Several non-contaminating physical methods, such as microwave heating, ultrasound-assisted and hydrothermal processes or ball milling, frequently in combination with the use of natural precursors, are of major importance in the greener synthesis, as well as solventless and biosynthesis techniques. Non-hazardous solvents including ionic liquids, use of plant extracts, fungi, yeasts, bacteria and viruses are also discussed in relation with materials fabrication. Availability, necessity and profitability of scaling up green processes are discussed.