Secondary Polymer Research Articles

When the Host Encounters the Cell Wall and Vice Versa.

Peptidoglycan (PGN) and associated surface structures such as secondary polymers and capsules have a central role in the physiology of bacteria. The exoskeletal PGN heteropolymer is the major determinant of cell shape and allows bacteria to withstand cytoplasmic turgor pressure. Thus, its assembly, expansion, and remodeling during cell growth and division need to be highly regulated to avoid compromising cell survival. Similarly, regulation of the assembly impacts bacterial cell shape; distinct shapes enhance fitness in different ecological niches, such as the host. Because bacterial cell wall components, in particular PGN, are exposed to the environment and unique to bacteria, these have been coopted during evolution by eukaryotes to detect bacteria. Furthermore, the essential role of the cell wall in bacterial survival has made PGN an important signaling molecule in the dialog between host and microbes and a target of many host responses. Millions of years of coevolution have resulted in a pivotal role for PGN fragments in shaping host physiology and in establishing a long-lasting symbiosis between microbes and the host. Thus, perturbations of this dialog can lead to pathologies such as chronic inflammatory diseases. Similarly, pathogens have devised sophisticated strategies to manipulate the system to enhance their survival and growth.

Potassium Phthalimide Doped with Delta‐Site Structures to Construct Ultra‐Long Cycle Life Aqueous Zn‐Polymer Batteries

AbstractAqueous Zn‐polymer batteries hold great promise for environmentally friendly energy storage systems. However, the poor cycling performance caused by irreversible structural deformation and polymer chain entanglement during the embedding and de‐embedding processes of Zn2+ and H+ ions is one of the key challenges facing their development. Here a new polyaniline cathode doped is developed with potassium phthalimide using a secondary doping approach. This polymeric electrode integrates the conjugated backbone for charge transport with an anionic phthalimide dopant for constructing a triangular‐site structure, as illustrated by the density functional theory calculations. This unique molecular structure is favorable for improving conductivity and structural stability by effectively modulating the localized electron cloud density. The Zn‐polymer battery holds an outstanding capacity retention of 76.1% after 25,000 cycles at a current density of 1 A g−1 with the coulombic efficiency maintained above 99.4%. This secondary doped polymer strategy offers a new host alternative for the ultra‐long cycle life of Zn‐polymer batteries. The molecular design strategy and the insight into the relationship between the structure and performance may provide some guidelines for developing polymer cathodes with high stability.

SECONDARY POLYMERS AS A PROSPECTIVE RAW MATERIAL FOR THE PRODUCTION OF HIGH-OCTANE AUTOMOBILE GASOLINE

The article analyzes the possibility of expanding the raw material base of the production process of commercial high-octane automobile gasoline of the A-92 and A-95 brands due to the involvement of secondary polymer raw materials. The types of raw materials that will make it possible to obtain basic fractions or components of commercial gasolines that will be used in the production of commercial automobile gasolines that, according to their chemical composi- tion and properties, will meet the requirements of environmental safety standards adopted in Ukraine and the countries of the European Union have been determined. It was established that the main raw material capable of replacing oil and gas condensate is secondary polyolefin raw material, represented by polyethylene (HDPE and LDPE) and polypropylene (PP), and the main process of its processing is thermal or thermocatalytic pyrolysis. Priority is given to raw materials that are directly generated in production in the form of waste and raw materials that come from sorting points. At the same time, secondary polymer raw materials, regardless of their source of origin, must undergo a stage of preliminary preparation, which includes sorting, crushing, washing and drying of raw materials. Practical studies have shown that this process is implemented on reactor-type installations at temperatures of 320–450 °C and pressures of 0.1–3.5 MPa and allows obtaining a significant yield (35–70 %) of the liquid product of pyrolysis – a gasoline fraction with a boiling point of 30–200 °C. Along with liquid products, more than 15 % of gases (ethylene, propylene and butylene) are formed, which should be processed into polymer gasoline (base fraction) and high-octane components – alkylates. As a result of the research, a scheme for the production of commercial high-octane automobile gasoline from secondary polymer raw materials (HDPE, LDPE and PP) is proposed, which is based on the rational use of production resources and production by-products.

A Two‐Stage Polymerization Strategy for Preparing Polymer‐Network Liquid Crystals with Oxygen‐Sensing Property

Polymer‐network liquid crystal (PNLC) possesses both advantages of low‐molecular‐weight liquid crystal (LMWLC) and liquid crystal (LC) polymer. Herein, a two‐stage polymerization strategy for the formation of unique PNLC with oxygen‐sensing properties is reported. The reaction mixture consists of 6% diacrylate RM257, 93.5% LMWLC 4‐cyano‐4′‐pentylbiphenyl (5CB), and 0.5% photoinitiator dimethoxy‐2‐phenylacetophenone (DMPA). In the first stage, the mixture is exposed to UV light for 2 min to form a primary polymer network, which is highly uniform with a planar orientation. However, some free radicals are trapped inside the LC due to the short UV exposure time. Subsequently, the trapped free radicals are released by heating the PNLC sample into an isotropic state. Under this condition, the free radicals can move freely and react with surrounding monomers to form a secondary polymer network, which is highly disordered and scatters light strongly. Because oxygen can deactivate free radicals trapped inside the PNLC, the phenomenon to detect oxygen and monitor the diffusion of oxygen through the PNLC is exploited. The PNLC‐based oxygen sensor is potentially useful for the detection of oxygen and monitoring the exposure time to oxygen.

FEATURES OF RECEIVING THE GASOLINE FRACTION BY THERMAL PYROLYSIS OF POLYOLEFIN RAW MATERIALS

The article examines the peculiarities of the process of thermal pyrolysis of secondary polymer raw materials, aimed at obtaining a gasoline fraction - the basis for obtaining mixed or synthetic automobile gasoline. Based on the global experience of polymer processing, polyolefins represented by high-density polyethylene (HDLP) and polypropylene (PP) were chosen for the study. Thermal pyrolysis was carried out at atmospheric pressure (0.10-0.12 MPa) on a reactor-type laboratory installation with subsequent removal of the gasoline fraction (30-210 °C) from liquid pyrolysis products according to the ASTM D 86 method. It has been established that the temperature interval in which pyrolysis of polyolefin raw materials must be carried out is for HDLP - 400-430 °С (the maximum output of the gasoline fraction at 420 °С); for PP - 350-370 °C (maximum yield of gasoline fraction at 365 °C). By controlling the duration of thermal pyrolysis, it is possible to increase the yield of the gasoline fraction by an average of 15-17%, which must be taken into account during the industrial implementation and further operation of pyrolysis plants for polymer raw materials. Increasing the temperature of the end of boiling of the gasoline fraction from 150 °С to 210 °С allows to increase its output by 9% (for HDLP) and by 12% (for PP). But at the same time, there is also an increase in the content of olefins in it (by 13-14%), which is a positive point from the point of view of resistance to detonation of the gasoline fraction, and a negative point - in view of its low chemical stability. The conducted studies showed that secondary polyolefin raw materials should be considered as an alternative to classic raw materials (oil and gas condensate), and the pyrolysis process as the main technological process for obtaining the gasoline fraction - the basis for obtaining commercial automobile gasoline. Prospective places for the implementation of this technology are both production sites of oil refineries and sites located in close proximity to places of accumulation of raw materials - ports, city landfills, special landfills.

Acetylation and Phosphorylation Regulate the Role of Pyruvate Kinase as a Glycolytic Enzyme or a Protein Kinase in Lamb.

Protein post-translational modifications (PTMs) play an essential role in meat quality development. However, the effect of specific PTM sites on meat proteins has not been investigated yet. The characteristics of pyruvate kinase M (PKM) were found to exhibit a close correlation with final meat quality, and thus, serine 99 (S99) and lysine 137 (K137) in PKM were mutated to study their effect on PKM function. The structural and functional properties of five lamb PKM variants, including wild-type PKM (wtPKM), PKM_S99D (S99 phosphorylation), PKM_S99A (PKM S99 dephosphorylation), PKM_K137Q (PKM K137 acetylation), and PKM_K137R (PKM K137 deacetylation), were evaluated. The results showed that the secondary structure, tertiary structure, and polymer formation were affected among different PKM variants. In addition, the glycolytic activity of PKM_K137Q was decreased because of its weakened binding with phosphoenolpyruvate. In the PKM_K137R variant, the actin phosphorylation level exhibited a decrease, suggesting a low kinase activity of PKM_K137R. The results of molecular simulation showed a 42% reduction in the interface area between PKM_K137R and actin, in contrast to wtPKM and actin. These findings are significant for revealing the mechanism of how PTMs regulate PKM function and provide a theoretical foundation for the development of precise meat quality preservation technology.

Using RAFT Polymerization Methodologies to Create Branched and Nanogel-Type Copolymers.

This review aims to highlight the most recent advances in the field of the synthesis of branched copolymers and nanogels using reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerization is a reversible deactivation radical polymerization technique (RDRP) that has gained tremendous attention due to its versatility, compatibility with a plethora of functional monomers, and mild polymerization conditions. These parameters lead to final polymers with good control over the molar mass and narrow molar mass distributions. Branched polymers can be defined as the incorporation of secondary polymer chains to a primary backbone, resulting in a wide range of complex macromolecular architectures, like star-shaped, graft, and hyperbranched polymers and nanogels. These subcategories will be discussed in detail in this review in terms of synthesis routes and properties, mainly in solutions.

The Kinetic Study of the Influence of Common Modifiers on the Curing Process of Epoxy Vitrimers.

An analysis of the influence of common modifiers on the kinetics of the curing process of epoxy-anhydride vitrimers was carried out. As common modifiers to enhance the "vitrimeric" nature of the material, zinc acetylacetonate as a transesterification catalyst and glycerol as a modifier of hydroxyl group content were chosen. The curing process of all obtained compositions was studied by differential scanning calorimetry (DSC) followed by the application of the isoconversional approach. It was shown that additives significantly affect the curing process. The resulting cured polymers were shown to be chemically recyclable by dissolution in the mixture of ethylene glycol and N-methylpirrolidone in a volume ratio of nine to one. The introduction of both zinc acethylacetonate and glycerol to the neat formulation led to a decrease in the dissolution time by 85.7% (from 35 h for the neat epoxy-anhydride formulation to 5 h for the modified formulation). In order to show the opportunity of the secondary use of recyclates, the mixtures based on the basic composition containing 10 wt. % of secondary polymers were also studied. The introduction of a recycled material to neat composition led to the same curing behavior as glycerol-containing systems.

Перспективи виробництва синтетичного бензину в Україні

DOI: 10.31081/1681-309X-2024-0-1-34-40 Specialty 161. U.D.C. 662.7 PROSPECTS FOR THE PRODUCTION OF SYNTHETIC PETROL IN UKRAINE © K.V. Shevchenko, Ph.D. in Technical Sciences, A.B. Grigorov, Doctor of Technical Sciences (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine) The article analyses the possibility of using various hydrocarbon feedstocks (including secondary ones) in the technology of synthetic motor petrol production, which, together with petrol produced by classical technology (from oil or gas condensate), can satisfy the existing demand for this type of motor fuel. It is shown that, taking into account the possible production volumes and demand for raw materials, as well as the complexity (energy intensity) of their technological processing, the most promising types of raw materials are biomass, solid fossil fuels and secondary polymers. Biomass (mainly agricultural waste) is a feedstock for biogas production, which is currently being used quite successfully in the European Union. The product of this production is methane, which can be used for energy purposes or processed into petrol and biomethanol. Another promising area in biomass processing is the direct production of alcohols (biomethanol and bioethanol), which can be used as a raw material for organic synthesis and for the production of blended petrol (e.g., grades E5, E7 and E10). Given Ukraine's reserves of various grades of coal, its processing into synthetic gasoline by gasification followed by synthesis using the Fischer-Tropsch method or hydrogenation can also be considered very promising. However, to date, these processes have not been widely used in industry due to their high energy intensity. It has been determined that secondary polymers - production and consumption wastes represented by polyethylenes (HPDE and LPDE) and polypropylene (PP) - are more promising for Ukraine than other types of raw materials. The main process for their processing is thermal or thermocatalytic pyrolysis, which produces both liquid petrol fractions (boiling point 30-210 °C) and gases, represented by ethylene, propylene and butylene. Given their conversion rate (70-90 % and 100 %, respectively), propylene and butylene can be processed into polymer gasoline, which, after purification, will be suitable for use in mixed or synthetic commercial motor gasoline. Keywords: natural gas, biomass, solid fossil fuels, polymers, processing, hydrogenation, synthesis, pyrolysis, methane, propylene, butylene, synthetic petrol. Corresponding author: A.B. Grigorov, e-mail: grigorovandrey@ukr.net

Insights into structure and activity of a UDP-GlcNAc 2-epimerase involved in secondary cell wall polymer biosynthesis in Paenibacillus alvei.

S-layer anchoring in Paenibacillus alvei is enabled by a non-covalent interaction between an S-layer homology domain trimer and a secondary cell wall polymer (SCWP), ensuring the structural integrity of the bacterial cell wall. Within the SCWP repeat, pyruvylated ManNAc serves as the ligand and the UDP-GlcNAc-2-epimerase MnaA supplies UDP-ManNAc to SCWP biosynthesis. To better understand SCWP biosynthesis and identify strategies for inhibiting pathogens with comparable cell wall architecture, like Bacillus anthracis, MnaA and rational variants were produced in E. coli and their kinetic constants determined. The effect of UDP-GlcNAc as a predicted allosteric activator and tunicamycin as a potential inhibitor of MnaA was tested in vitro supported by molecular docking experiments. Additionally, wild-type MnaA was crystallized. We present the crystal structure of unliganded P. alvei MnaA resolved at 2.20 Å. It adopts a GT-B fold consistent with other bacterial non-hydrolyzing UDP-GlcNAc 2-epimerases. A comparison of amino acid sequences reveals conservation of putative and known catalytic and allosteric-site residues in MnaA, which was confirmed through analysis of Q42A, Q69A, E135A and H241A MnaA variants. The kinetic parameters K M and k cat of MnaA were determined to be 3.91 mM and 33.44 s-1 for the forward, and 2.41 mM and 6.02 s-1 for the reverse reaction. While allosteric regulation by UDP-GlcNAc has been proposed as a mechanism for enzyme activation, UDP-GlcNAc was not found to be essential for UDP-ManNAc epimerization by P. alvei MnaA. However, the reaction rate doubled upon addition of 5% UDP-GlcNAc. Unexpectedly, the UDP-GlcNAc analog tunicamycin did not inhibit MnaA. Molecular docking experiments comparing tunicamycin binding of P. alvei MnaA and Staphylococcus aureus MnaA, which is inhibited by tunicamycin, revealed different residues exposed to the antibiotic excluding, those at the predicted allosteric site of P. alvei MnaA, corroborating tunicamycin resistance. The unliganded crystal structure of P. alvei MnaA reveals an open conformation characterized by an accessible cleft between the N- and C-terminal domains. Despite the conservation of residues involved in binding the allosteric activator UDP-GlcNAc, the enzyme is not strictly regulated by the substrate. Unlike S. aureus MnaA, the activity of P. alvei MnaA remains unaffected by tunicamycin.

Modern Technologies and Trends in the Secondary Polymer Market

Modern Technologies and Trends in the Secondary Polymer Market

Characterization of Polypropylene Composite Reinforced on Bio-waste from the Production of Tung Oil

The aim of the conducted study was to develop wood-polymer composites (WPCs) using secondary polymer waste and agricultural technology waste materials, which would have lower environmental impacts than WPCs made from virgin resources. The study focused on developing WPCs based on polypropylene filled with finely dispersed powders of waste products from tung oil production (PP+TOPW composites). Finely scattered powder (with an average grain size of 0.5–1.5 mm) was obtained from crushing and grinding the outer pericarp of tung fruit waste, which resulted from tung oil extraction. Tung oil is produced in Georgia from tung fruit that is grown in Tsalenjikha district, Georgia. In addition, to modify the properties of the WPCs, organic silicon oligomer tetraethoxysilane and powdered aluminum hydroxide were used as additives. The study found that the strength properties of the PP+TOPW composites can be optimized by modifying them with tung oil and other mineral additives. The optimal strength properties were observed at a filler content of 40 wt.%, where the compression and bending strength limits were 63.5 and 36.7 MPa, respectively. The water absorption of the PP+TOPW composites was reduced by modifying them with tung oil. The PP+TOPW composites with a filler content of 30 wt.% showed 0% water absorption, and the water absorption of composites with a filler content of 40 and 50 wt.% (modified with tung oil) was very low, ranging from 0.2–0.8%. The study also investigated the effect of modifying PP+TOPW composites with tetraethyl orthosilicate (TEOS), which increased all the strength parameters, including impact strength, and reduced water absorption, although not as much as when modified with tung oil. The introduction of a flame retardant, aluminum hydroxide, into the composite composition in the amount of 25–30 wt.% made the composites flame-retardant and low-combustible materials, expanding their potential applications, particularly in construction. Overall, the study successfully developed WPCs using waste materials with optimized properties, which have potential for various applications, including in construction, due to their flame retardant and low-combustible properties.

STUDY OF NON-FUEL APPLICATION OF BROWN COAL DERIVATIVES FOR BITUME MODIFICATION

The article shows research into the non-fuel use of brown coal derivatives for the modification of bitumen. The work used petroleum road grade bitumen BND 60/90 with a flash point in an open crucible of 260 °C, a softening temperature (using the ring and ball method) of 48 °C, resin after lignite thermal destruction and rubber waste. and powder. Based on the fact that the most relevant technologies for the non-fuel use of brown coal concern areas aimed at obtaining wax, humane preparations, adsorbents, obtaining valuable derivatives in the form of resins, GR, etc., an assessment was made of the non-fuel use of brown coal derivatives for modification bitumen. Analysis of the experimental results showed that the studied quality indicators of the composition samples, which include waste rubber powder, have an increased complex of both thermophysical and physical-mechanical characteristics. This is obviously due to the fact that, as a result of thermal destruction of rubber powder, the swelling process occurs faster compared to crumb rubber with a size of 2.5–4.5 mm. However, the process of destruction and dispersion in both cases does not occur completely, of course, and the volume of edematous rubber particles contains resins and polyaromatic components that affect the value of both thermophysical and physical-mechanical characteristics. Thus, it has been established that the optimal composition for creating effective polymer-modified bitumens with an increased complex of thermo-physical and physical-mechanical characteristics is 40 % by weight of rubber powder and 5 % by weight. brown coal resins after thermal destruction. It is shown that the results of laboratory studies have proven the prospects of using brown coal tar after thermal destruction for the modification of road bitumen. Summarizing research into the direction of non-fuel use of brown coal derivatives in the form of liquid products – tar resins of brown coal after thermal destruction for the modification of bitumen materials, it should be noted that the results obtained are moderate in comparison with existing directions for the production of polymer-modified bitumens. Modification of bitumen with primary and secondary polymers makes it possible to significantly improve their adhesion and performance characteristics compared to brown coal resins after thermal destruction. The use of brown coal resins after thermal destruction is much less effective in improving the elasticity, heat resistance and reducing the fragility of bitumen compositions compared to the use of thermoplastic and thermoelastomer modifiers in the production of polymer-modified bitumens.

Gellan gum-based bi-polymeric hydrogel scaffolds loaded with Rosuvastatin calcium: A useful tool for tendon tissue regeneration

Statins have been long used in tissue engineering, besides their marketed hypolipidemic benefits. The aim of this research was to sustain the release of rosuvastatin calcium from bi-polymeric hydrogel scaffolds. A bi-polymer blend technique was used to enhance the mechanical properties of the fabricated hydrogels. Briefly, hydrogels were prepared via crosslinking gellan gum as the main polymer together with a secondary polymer in the presence of Ca2+. The fabricated hydrogels were assessed in terms of % swelling capacity, hydrolytic degradation and % drug released to determine the most efficient carrier system. The selected hydrogel exhibited a swelling capacity of 131.45±1.49 % following 3 weeks in an aqueous environment with a % weight loss of 15.73±1.86 % after 4 weeks post-equilibrium in aqueous medium. The results ensure a proper window for adequate drug diffusion and nutrient exchange. Sustained release was attained where 94.61±2.77 % of rosuvastatin was released at the 4-week mark. Later, FT-IR and DSC, were carried out and suggested the successful crosslinking and formation of new matrix. SEM images demonstrated the porous surface of the hydrogel while a Young's modulus of 888.558±73.549 kPa indicated the suitability of the hydrogel for soft tissue engineering. In-vivo testing involved implanting the selected hydrogel at precisely surgical cuts in the Achilles tendon of male Wistar Albino rats. Upon visual and microscopic evaluation, enhanced rates of fibrous tissue formation, vascularization and collagen expression were clearly noticed in the treatment group.

Densely crosslinked protein bioplastics with superior stretchability and desirable wet stability via quality protein restoration

We have demonstrated that dithiol-based crosslinkers are most suitable for protein materials with high contents of cysteine. Crosslinking is always the effective approach to improvement in properties of protein materials. However, most crosslinking technologies damage structures of protein materials due to harsh crosslinking conditions, or form uncontrollable and unstable crosslinkages. In this work, we selected dithiols with different chain lengths and flexibility to form disulfide crosslinkages via reduction and oxidation at room temperature. Sustainable dithiols were screened by computational simulation for bioplastic uses. Since the reactions were performed at room temperature, keratin backbone structures were intact. Our developed model indicates that number of sigma bonds in crosslinkages and retention of crosslinking, dominated by sigma bonds in crosslinkages, quantitatively controlled mechanical properties of regenerated keratin films. Wet-stable keratin films with excellent stretchability were developed without any plasticizers and secondary polymers. Some properties of our bioplastics via quality restoration were similar to some petroleum-based products. For example, feather-derived bioplastics had dry stress, wet stress, dry breaking elongation, and wet elongation of 35 MPa, 10.2 MPa, 70%, and 105%, respectively. After seven days in water, the stress retention of films was as high as 85%. This work promoted the application of keratin bioplastics in food, pharmaceutical and cosmetic industries.

Hardening mechanism of waste polyolefin mixtures in the presence of modified bentonite clay

The aim of the work is to obtain and study polymer composite materials based on mixtures of secondary polyolefins and modified polydisperse bentonite clay. The formation features of the structure of mixtures of waste polyolefins in the presence of this-type filler are studied. The data on the changes in the mechanical strength of mixed composites, as well as the results of physico-chemical studies are presented. Mixtures based on waste polymers in the presence of highly dispersed particles of modified polydisperse bentonite are characterized by the improvement of the strength of composites due to increased interfacial interaction in them and by the formation of structure uniformity of the material. This to some extent compensates for the loss of cohesive strength of secondary polymers due to thermal degradation processes. The following conclusions are made: at the phase boundaries, the molecular mobility of polymer chains decreases, which leads to changing the crystallization conditions and to appearing a nonequilibrium stress state; introducing bentonite increases crystalline due to the initiation of physico-chemical interaction; the strength grows due to increased interfacial interaction and structure uniformity; the formation mechanism of a complex of properties of composites consists of two-level adsorption – a modifier on filler particles and active polymer groups on the modified filler surface.

Controlled Noncovalent Synthesis of Secondary Supramolecular Polymers.

Dynamic supramolecular polymers, with their functional similarities to classical covalent polymers and their adaptive and self-repairing nature reminiscent of biological assemblies, have emerged as highly promising systems for the design of smart soft materials. Recent advancements in mechanistic investigations and novel synthetic strategies, such as living supramolecular polymerization, have significantly enhanced our ability to control the primary structure of these supramolecular polymers. However, realizing their full functional potential requires expanding their topological diversity in a manner akin to classical polymers as well as achieving precise molecular organization at higher hierarchical levels of self-assembly. In this paper, we present a remarkable advancement in this field, introducing an unprecedented and controlled synthesis of secondary supramolecular polymers. Our innovative strategy combines chirality-controlled surface-catalyzed secondary nucleation and a bioinspired peptide design, effectively stabilizing higher-order assembly. Furthermore, by harnessing this stereoselective nucleation process, we demonstrate the successful synthesis of racemic supramolecular polymers featuring parallelly stacked conglomerate microstructures─a previously unreported topology in synthetic self-assembled systems. Additionally, we elucidate that the extent of secondary supramolecular polymers can be regulated by modulating the enantiomeric excess of the chiral monomers. Consequently, our study unveils new topologies that exhibit enhanced higher-order structural complexity in the realm of supramolecular polymers.

Fabrication, Characterization and in vitro Evaluation of Prednisolone Sustained Release Multiparticulate System for Colonic Targeting

Background: Prednisolone (PRD) is orally prescribed for inflammatory bowel syndrome (IBS) as the upper GIT is the main site of absorption; therefore, long-term PRD dosing decreases therapeutic effectiveness through systemic side effects. Objective: This work focused on formulating sustained-release alginate beads as a multiparticulate system for colon targeting using prednisolone (PRD) to be filled in an HPMC capsule. Methods: PRD beads were prepared by the ionotropic gelation technique using sodium alginate as the primary polymer and inulin, guar gum, and pectin as secondary polymers. In addition to the impact of polymer type and quantity, other factors were investigated: The CaCl2 concentration and tween 80 addition Thirteen formulations were successfully prepared, and their properties, such as bead size, morphology, percentage of encapsulation efficiency, yield, DL, in vitro release study in GIT buffer media, IBS media, SEM, and FTIR, were assessed. Results: The study showed that the beads were close in size, and the size was not an obstacle for loading the beads in HPMC capsules. Further, yield%, EE%, and DL% increased according to the bead’s content increase. Conclusions: The optimum formula was F3 that coated HPMC capsules with Eudragit S-100, which gave sustained release profiles in GIT and IBS simulating media, and F13 that could last the release in different pH media, pH 1.2, 6.8, and 7.4.

Towards a Low-Carbon Plastic Waste Recycling in Finland: Evaluating the Impacts of Improvement Measures on GHG Emissions

The use of plastics in products and packaging is growing. At the same time, the lifespan of packaging is short and consequently plastic waste volumes are growing in Finland and globally. Although separate collection and recycling of plastic packaging waste exists in Finland, it needs to be strengthened to reach the European Union’s targets. The separately collected plastic waste is mechanically recycled, but the recycling capacity is small, as is the process’s yield of secondary polymers. Hence, a large share of plastic packaging waste remains being recovered for energy. In our study, we first apply material flow analysis (MFA) to identify different routes of plastic packaging waste in Finland, and then we apply life cycle assessment (LCA) to quantify greenhouse gas (GHG) emissions of the current system and of alternative scenarios based on improvement measures. Domestic GHG emissions of the studied system were estimated to be 178 kt CO2e. Net GHG emissions including exports and credits from avoided production were estimated to be 155 kt CO2e. The results of the scenario assessment indicate that combining more measures offer significantly greater potential to reduce the system’s climate impacts, compared to individual measures. The results are complemented by a sensitivity analysis, helping with the interpretation of the results, understanding modelling challenges, and supporting robust decision-making. The study contributes to academic literature in two ways; it presents a robust, yet flexible way to integrate scenario-based, future-oriented modelling techniques into decision-making, and it assesses the various possibilities to improve the plastic recycling system to identify the quantitative improvement potential.

Amine Chemistry of Porous CO2 Adsorbents.

ConspectusAs renewable energy and CO2 utilization technologies progress to make a more significant contribution to global emissions reduction, carbon capture remains a critical component of the mission. Current CO2 capture technologies involve operations at point sources such as fossil fuel-based power plants or source-agnostic like in direct air capture. Each strategy has its own advantages and limitations, but in common, they all employ sorption-based methods with the use of sorbents strongly adhering to CO2. Amine solutions are the most widely used absorbents for industrial operations due to the robust chemical bonds formed between amines and CO2 under both dry and humid conditions, rendering excellent selectivity. Such strong binding, however, causes problematic regeneration. In contrast, purely physisorptive porous materials with high surface areas allow for the confinement of CO2 inside narrow pores/channels and have a lower regeneration energy demand but with decreased selectivity and capacity. The most promising solution would then be the unification of both types of sorbents in one system, which could bring about a practical adsorption-desorption process. In other words, the development of porous solid materials with tunable amine content is necessary to leverage the high contact surface of porous sorbents with the added ability to manipulate amine incorporation toward lower CO2 binding strength.To answer the call to uncover the most feasible amine chemistry in carbon capture, our group has devoted intense effort to the study of amine-based CO2 adsorbents for the past decade. Oriented along practicality, we put forth a principle for the design of our materials to be produced in no more than three synthetic steps with economically viable starting materials. Porous organic polymers with amine functionalities of various substitutions, meaning primary, secondary, and tertiary amines, were synthesized and studied for CO2 adsorption. Direct synthesis proved to be feasibly applicable for secondary and tertiary amine-incorporated porous polymers whereas primary-amine-based sorbents would be conveniently obtained via postsynthetic modifications. Sorbents based on tertiary amines exhibit purely physical adsorption behavior if the nitrogen atoms are placed adjacent to aromatic cores due to the conjugation effect that reduces the electron density of the amine. However, when such conjugation is inhibited, chemisorptive activity is observed. Secondary amine adsorbents, in turn, express a higher binding strength than tertiary amine counterparts, but both types can merit a strengthened binding by the physical impregnation of small-molecule amines. Sorbents with primary-amine tethers can be obtained via postsynthetic transformation of precursor functionalities, and for them, chemical adsorption is mainly at work. We conclude that mixed-amine systems could exhibit unprecedented binding mechanisms, resulting in exceptionally specific interactions that would be useful for the development of highly selective sorbents for CO2.