Bio-Based Polyurethane Networks Containing Sunflower Oil Based Polyols.

This work focused on the preparation and investigation of polyurethane (SO-PU)-containing sunflower oil glycerides. By transesterification of sunflower oil with glycerol, we synthesized a glyceride mixture with an equilibrium composition, which was used as a new diol component in polyurethanes in addition to poly(ε-caprolactone)diol (PCLD2000). The structure of the glyceride mixture was characterized by physicochemical methods, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), nuclear magnetic resonance spectroscopy (NMR), and size exclusion chromatography (SEC) measurements. The synthesis of polyurethanes was performed in two steps: first the prepolymer with the isocyanate end was synthesized, followed by crosslinking with an additional amount of diisocyanate. For the synthesis of the prepolymer, 4,4'-methylene diphenyl diisocyanate (MDI) or 1,6-hexamethylene diisocyanate (HDI) were used as isocyanate components, while the crosslinking was carried out using an additional amount of MDI or HDI. The obtained SO-PU flexible polymer films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The so-obtained flexible SO-PU films were proved to be suitable for the preparation of potentially biocompatible and/or biodegradable scaffolds. In addition, the stress versus strain curves for the SO-PU polymers were interpreted in terms of a mechanical model, taking into account the yield and the strain hardening.

Molecular dynamics simulations in pre-polymerization mixtures for peptide recognition.

CONTEXT: Molecularly imprinted polymers (MIPs) have promising applications as synthetic antibodies for protein and peptide recognition. A critical aspect of MIP design is the selection of functional monomers and their adequate proportions to achieve materials with high recognition capacity toward their targets. To contribute to this goal, we calibrated a molecular dynamics protocol to reproduce the experimental trends in peptide recognition of 13 pre-polymerization mixtures reported in the literature for the peptide toxin melittin. METHODS: Three simulation conditions were tested for each mixture by changing the box size and the number of monomers and cross-linkers surrounding the template in a solvent-explicit environment. Fully atomistic MD simulations of 350 ns were conducted with the AMBER20 software, with ff19SB parameters for the peptide, gaff2 parameters for the monomers and cross-linkers, and the OPC water model. Template-monomer interaction energies under the LIE approach showed significant differences between high-affinity and low-affinity mixtures. Simulation systems containing 100 monomers plus cross-linkers in a cubic box of 90 Å3 successfully ranked the mixtures according to their experimental performance. Systems with higher monomer densities resulted in non-specific intermolecular contacts that could not account for the experimental trends in melittin recognition. The mixture with the best recognition capacity showed preferential binding to the 13-26-α-helix, suggesting a relevant role for this segment in melittin imprinting and recognition. Our findings provide insightful information to assist the computational design of molecularly imprinted materials with a validated protocol that can be easily extended to other templates.

Development of Macromolecular Cryoprotectants for Cryopreservation of Cells.

Cryopreservation is a common way for long-term storage of therapeutical proteins, erythrocytes, and mammalian cells. For cryoprotection of these biosamples to keep their structural integrity and biological activities, it is essential to incorporate highly efficient cryoprotectants. Currently, permeable small molecular cryoprotectants such as glycerol and dimethyl sulfoxide dominate in cryostorage applications, but they are harmful to cells and human health. As acting in the extracellular space, membrane-impermeable macromolecular cryoprotectants, which exert remarkable membrane stabilization against cryo-injury and are easily removed post-thaw, are promising candidates with biocompatibility and feasibility. Water-soluble hydroxyl-containing polymers such as poly(vinyl alcohol) and polyol-based polymers are potent ice recrystallization inhibitors, while polyampholytes, polyzwitterions, and bio-inspired (glyco)polypeptides can significantly increase post-thaw recovery with reduced membrane damages. In this review, the synthetic macromolecular cryoprotectants are systematically summarized based on their synthesis routes, practical utilities, and cryoprotective mechanisms. It provides a valuable insight in development of highly efficient macromolecular cryoprotectants with valid ice recrystallization inhibition activity for highly efficient and safe cryopreservation of cells.

Polypy: A Framework to Interpret Polymer Properties from Mass Spectroscopy Data.

Mass spectroscopy (MS) is a robust technique for polymer characterization, and it can provide the chemical fingerprint of a complete sample regarding polymer distribution chains. Nevertheless, polymer chemical properties such as polydispersity (Pd), average molecular mass (Mn), weight average molecular mass (Mw) and others are not determined by MS, as they are commonly characterized by gel permeation chromatography (GPC). In order to calculate polymer properties from MS, a Python script was developed to interpret polymer properties from spectroscopic raw data. Polypy script can be considered a peak detection and area distribution method, and represents the result of combining the MS raw data filtered using Root Mean Square (RMS) calculation with molecular classification based on theoretical molar masses. Polypy filters out areas corresponding to repetitive units. This approach facilitates the identification of the polymer chains and calculates their properties. The script also integrates visualization graphic tools for data analysis. In this work, aryl resin (poly(2,2-bis(4-oxy-(2-(methyloxirane)phenyl)propan) was the study case polymer molecule, and is composed of oligomer chains distributed mainly in the range of dimers to tetramers, in some cases presenting traces of pentamers and hexamers in the distribution profile of the oligomeric chains. Epoxy resin has Mn = 607 Da, Mw = 631 Da, and polydispersity (Pd) of 1.015 (data given by GPC). With Polypy script, calculations resulted in Mn = 584.42 Da, Mw = 649.29 Da, and Pd = 1.11, which are consistent results if compared with GPC characterization. Additional information, such as the percentage of oligomer distribution, was also calculated and for this polymer matrix it was not possible to retrieve it from the GPC method. Polypy is an approach to characterizing major polymer chemical properties using only MS raw spectra, and it can be utilized with any MS raw data for any polymer matrix.

Effect of Thermal Shock Conditions on the Low-Cycle Fatigue Performance of 3D-Printed Materials: Acrylonitrile Butadiene Styrene, Acrylonitrile-Styrene-Acrylate, High-Impact Polystyrene, and Poly(lactic acid).

3D printing technology is becoming a widely adopted alternative to traditional polymer manufacturing methods. The most important advantage of 3D printing over traditional manufacturing methods, such as injection molding or extrusion, is the short time from the creation of a new design to the finished product. Nevertheless, 3D-printed parts generally have lower strength and lower durability compared to the same parts manufactured using traditional methods. Resistance to the environmental conditions in which a 3D-printed part operates is important to its durability. One of the most important factors that reduces durability and degrades the mechanical properties of 3D-printed parts is temperature, especially rapid temperature changes. In the case of inhomogeneous internal geometry and heterogeneous material properties, rapid temperature changes can have a significant impact on the degradation of 3D-printed parts. This degradation is more severe in high-humidity environments. Under these complex service conditions, information on the strength and fatigue behavior of 3D-printed polymers is limited. In this study, we evaluated the effects of high humidity and temperature changes on the durability and strength properties of 3D-printed parts. Samples made of commonly available materials such as ABS (Acrylonitrile Butadiene Styrene), ASA (Acrylonitrile-Styrene-Acrylate), HIPS (High-Impact Polystyrene), and PLA (Poly(lactic acid)) were subjected to temperature cycling, from an ambient temperature to -20 °C, and then were heated to 70 °C. After thermal treatment, the samples were subjected to cyclic loading to determine changes in their fatigue life relative to non-thermally treated reference samples. The results of cyclic testing showed a decrease in durability for samples made of ASA and HIPS. The ABS material proved to be resistant to the environmental effects of shocks, while the PLA material exhibited an increase in durability. Changes in the internal structure and porosity of the specimens under temperature changes were also evaluated using microcomputed tomography (microCT). Temperature changes also affected the porosity of the samples, which varied depending on the material used.

Rapid and sensitive detection of etomidate based on functionalized copper nanoclusters fluorescent probe.

Etomidate as a non-barbiturate sedative, has central inhibitory effect and addiction and has been listed as a controlled drug in some countries due to the abusing trend nowadays. Therefore, rapid and sensitive detection of etomidate is of great significance. In this work, a novel fluorescent sensing probe (CuNCs@MIPs) based on copper nanoclusters (CuNCs) and molecular imprinted polymers (MIPs) has been firstly reported. CuNCs was environment-friendly synthesized using poly(vinylpyrrolidone) as a template and ascorbic acid as a reducing agent. After functionalized with molecular imprinting technique, the CuNCs@MIPs probe has special binding cavities on surface to target etomidate, causing the fluorescence intensity rapidly decrease, which confirmed it has excellent sensitivity, selectivity and stability. Under optimal conditions, the fluorescent sensing probe presented high precision linear relationship for etomidate in range of 10-500 ng/ml with detection limit of 10 ng/ml, and the whole detection process was completed within 10 min. This sensing method has also been applied to real samples detection, still demonstrated excellent feasibility in electronic cigarette liquids and urine. More importantly, compared with previous methods, this fluorescent sensing method has advantages such as rapid, simple and easy to operate. Collectively, the proposed CuNCs@MIPs sensing probe has good fluorescence characteristics and simple synthesis strategy, showed a great potential in etomidate detection and application.

Detection of Crude Oil in Subsea Environments Using Organic Electrochemical Transistors.

Current methods for detecting pipeline oil leaks depend primarily on optical detection, which can be slow and have deployment limitations. An alternative non-optical approach for earlier and faster detection of oil leaks would enable a rapid response and reduce the environmental impact of oil leaks. Here, we demonstrate that organic electrochemical transistors (OECTs) can be used as non-optical sensors for crude oil detection in subsea environments. OECTs are thin film electronic devices that can be used for sensing in a variety of environments, but they have not yet been tested for crude oil detection in subsea environments. We fabricated OECTs with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) as the channel and showed that coating the channel with a polystyrene film results in an OECT with a large and measurable response to oil. Oil that comes in contact with the device will adsorb onto the polystyrene film and increases the impedance at the electrolyte interface. We performed electrochemical impedance spectroscopy measurements to quantify the impedance across the device and found an optimal thickness for the polystyrene coating for the detection of oil. Under optimal device characteristics, as little as 10 µg of oil adsorbed on the channel surface produced a statistically significant change in the source-drain current. The OECTs were operable in seawater for the detection of oil, and we demonstrated that the devices can be transferred to flexible substrates which can be easily implemented in vehicles, pipelines, or other surfaces. This work demonstrates a low-cost device for oil detection in subsea environments and provides a new application of OECT sensors for sensing.

Harnessing Immunomodulatory Polymers for Treatment of Autoimmunity, Allergy, and Transplant Rejection.

Autoimmunity, allergy, and transplant rejection are a collection of chronic diseases that are currently incurable, drastically decrease patient quality of life, and consume considerable health care resources. Underlying each of these diseases is a dysregulated immune system that results in the mounting of an inflammatory response against self or an innocuous antigen. As a consequence, afflicted patients are required to adhere to lifelong regimens of multiple immunomodulatory drugs to control disease and reclaim agency. Unfortunately, current immunomodulatory drugs are associated with a myriad of side effects and adverse events, such as increased risk of cancer and increased risk of serious infection, which negatively impacts patient adherence rates and quality of life. The field of immunoengineering is a new discipline that aims to harness endogenous biological pathways to thwart disease and minimize side effects using novel biomaterial-based strategies. We highlight and discuss polymeric micro/nanoparticles with inherent immunomodulatory properties that are currently under investigation in biomaterial-based therapies for treatment of autoimmunity, allergy, and transplant rejection.

Electrosynthesis of Transition Metal Coordinated Polymers for Active and Stable Oxygen Evolution.

Transition metal coordination polymers (TM-CP) are promising inexpensive and flexible electrocatalysts for oxygen evolution reaction in water electrolysis, while their facile synthesis and controllable regulation remain challenging. Here we report an anodic oxidation-electrodeposition strategy for the growth of TM-CP (TM = Fe, Co, Ni, Cr, Mn; CP = polyaniline, polypyrrole) films on a variety of metal substrates that act as both catalyst supports and metal ion sources. An exemplified bimetallic NiFe-polypyrrole (NiFe-PPy) features superior mechanical stability in friction and exhibits high activity with long-term durability in alkaline seawater (over 2000 h) and anion exchange membrane electrolyzer devices at current density of 500 mA cm-2. Spectroscopic and microscopic analysis unravels the configurations with atomically distributed metal sites induced by d-π conjugation, which transforms into a mosaic structure with NiFe (oxy)hydroxides embedded in PPy matrix during oxygen evolution. The superior catalytic performance is ascribed to the anchoring effect of PPy that inhibits the metal dissolution, the strong substrate-to-catalyst interaction that ensures good adhesion, and the Fe/Ni-N coordination that modulates the electronic structures to facilitate the deprotonation of *OOH intermediate. This work provides a general strategy and mechanistic insight into building robust inorganic/polymer composite electrodes for oxygen electrocatalysis.

Temporal changes in microalgal biomass and species composition on different plastic polymers in nutrient-enriched microcosm experiments.

Marine plastic debris (MPD) is a potential threat to marine ecosystems, but its function as a vector for the transportation of harmful microalgae and its impact on the habitats of other marine organisms are uncertain. To address this gap in knowledge, we performed month-long experiments in 30 L microcosms that contained plates made of six different plastic polymers (polypropylene [PP], low-density polyethylene [LDPE], high-density polyethylene [HDPE], polyvinyl chloride [PVC], polyethylene terephthalate [PET], and polystyrene [PS]), and examined the time course of changes in planktonic and periphytic microalgae. There were no significant differences in the composition of periphytic microalgae or biomass among the different plastic polymers (p > 0.05). Nutrient depletion decreased the abundance of planktonic microalgae, but increased the biomass of attached periphytic microalgae (p < 0.05). In particular, analysis of the plastic plates showed that the abundance of benthic species that are responsible for harmful algal blooms (HABs), such as Amphidinium operculatum and Coolia monotis, significantly increased over time (days 21-28; p < 0.05). Our findings demonstrated that periphyton species, including benthic microalgae that cause HABs, can easily attach to different types of plastic and potentially spread to different regions and negatively impact these ecosystems. These observations have important implications for understanding the potential role of MPD in the spread of microalgae, including HABs, which pose a significant threat to marine ecosystems.

Beyond Lipids: Exploring Advances in Polymeric Gene Delivery in the Lipid Nanoparticles Era.

The recent success of gene therapy during the COVID-19 pandemic has underscored the importance of effective and safe delivery systems. Complementing lipid-based delivery systems, polymers present a promising alternative for gene delivery. Significant advances have been made in the recent past, with multiple clinical trials progressing beyond phase I and several companies actively working on polymeric delivery systems which provides assurance that polymeric carriers can soon achieve clinical translation. The massive advantage of structural tunability and vast chemical space of polymers is being actively leveraged to mitigate shortcomings of traditional polycationic polymers and improve the translatability of delivery systems. Tailored polymeric approaches for diverse nucleic acids and for specific subcellular targets are now being designed to improve therapeutic efficacy. This review describes the recent advances in polymer design for improved gene delivery by polyplexes and covalent polymer-nucleic acid conjugates. The review also offers a brief note on novel computational techniques for improved polymer design. The review concludes with an overview of the current state of polymeric gene therapies in the clinic as well as future directions on their translation to the clinic.

Electrochemiluminescence enhanced by molecular engineering linear π-conjugated polymer: An ingenious ECL emitter for the construction of exosome sensing platform.

Linear π-conjugated polymers (LCPs) with π-electron conjugation system have many remarkable optical characteristics such as fluorescence and electrochemiluminescence (ECL). However, the extremely strong interchain interaction and π-π stacking limit the luminescence efficiency. In this work, 1H-1,2,4-triazole-3,5-diamine was chosen as the polymer monomer and reacted with terephthalaldehyde via simple Schiff base condensation to synthesize LCPs. Subsequently, molecular engineering strategy was adopted to construct zirconium-based LCPs (MLCPs), which not only prevented π-π stacking but also ensured that extended π-coupling was maintained in the LCPs, thus effectively promoting charge transport and achieving strong luminescence. Second, the coreactant polyethyleneimine (PEI) was assembled onto the MLCPs (MLCPs@PEI) to further promote the emission of ECL. To further explore the potential of the obtained MLCPs@PEI as emerging ECL emitter, colorectal cancer exosome was chosen as model biomarker, and an innovative ECL ratiometric system based on MLCPs@PEI and luminol was designed to improve the validity and accuracy of the sensors. This research provides a fresh nanoplatform for exosome detection and broadens the application of LCPs in ECL immunoassay.

Spiderweb-Shaped Iron-Coordinated Polymeric Network as the Novel Coating on Microneedles for Transdermal Drug Delivery Against Infectious Wounds.

Coated microneedles (CMNs) are a minimally invasive platform for immediate-release transdermal drug delivery. However, the practical applications of CMNs have been significantly hindered by the challenges associated with complex formulations, single function, and limited drug loading capacity. In this study, we have developed a spiderweb-shaped iron-coordinated polymeric nanowire network (Fe-IDA NWs). The resulting Fe-IDA NWs are endowed with a certain viscosity due to the synergy of multiple supramolecular interactions. This allows them to replace traditional polymeric thickeners as microneedle coatings. The Fe-IDA NWs-coated microneedles (Fe-IDA MNs) display rapid disintegration in the skin model, which also enables the swift diffusion of Fe-IDA NWs and their payloads into the deeper skin layers. Additionally, Fe-IDA MNs exhibit desirable enzymatic activity and potential antibacterial ability. Thus, Fe-IDA MNs can enhance the therapeutic efficacy against wound infection through synergistic effects, and avoid the overly complicated formulation and the release of non-therapeutic molecules of conventional CMNs. As a proof-of-concept, Fe-IDA MNs loaded with chlorin e6 showed a synergistic chemodynamic-photodynamic antibacterial effect in a methicillin-resistant Staphylococcus aureus-infected wound model in mice. Collectively, this work has significant implications for the future of CMNs-based transdermal drug delivery systems and expands the application fields of metal coordination polymer materials. This article is protected by copyright. All rights reserved.

Rational Design of NIR-II Emitting Conjugated Polymer Derived Nanoparticles for Image-Guided Cancer Interventions.

Due to the reduced absorption, light scattering, and tissue autofluorescence in the NIR-II (1000-1700 nm) region, significant efforts are underway to explore diverse material platforms for in vivo fluorescence imaging, particularly for cancer diagnostics and image-guided interventions. Of the reported imaging agents, nanoparticles derived from conjugated polymers (CPNs) offer unique advantages to alternative materials including biocompatibility, remarkable absorption cross-sections, exceptional photostability, and tunable emission behavior independent of cell labeling functionalities. Herein, the current state of NIR-II emitting CPNs are summarized and structure-function-property relationships are highlighted that can be used to elevate the performance of next-generation CPNs. Methods for particle processing and incorporating cancer targeting modalities are discussed, as well as detailed characterization methods to improve interlaboratory comparisons of novel materials. Contemporary methods to specifically apply CPNs for cancer diagnostics and therapies are then highlighted. This review not only summarizes the current state of the field, but offers future directions and provides clarity to the advantages of CPNs over other classes of imaging agents.

Biomimetic nanoporous oxygenation membranes with high hemocompatibility and fast gas transport property.

Membrane technology holds great potential for separation applications and also finds critical needs in biomedical fields, such as blood oxygenation. However, the bottlenecks in gas permeation, plasma leakage, and especially hemocompatibility hamper the development of membrane oxygenation. It remains extremely challenging to design efficient membranes and elucidate underlying principles. In this study, we report biomimetic decoration of asymmetric nanoporous membranes by ultrathin FeIII-tannic acid metal-ligand networks to realize fast gas exchange with on plasma leakage and substantially enhance hemocompatibility. Because the intrinsic nanopores facilitate gas permeability and the FeIII-catechol layers enable superior hydrophilicity and electronegativity to original surfaces, the modified membranes exhibit high transport properties for gases and great resistances to protein adsorption, platelet activation, coagulation, thrombosis, and hemolysis. Molecular docking and density functional theory simulations indicate that more preferential adsorption of metal-ligand networks with water molecules than proteins is critical to anticoagulation. Moreover, benefiting from the better antiaging property gave by biomimetic decoration, the membranes after four-month aging present gas permeances similar to or even larger than those of pristine ones, despite the initial permeation decline. Importantly, for blood oxygenation, the designed membranes after aging show fast O2 and CO2 exchange processes with rates up to 28-17 and 97-47 mL m-2 min-1, respectively, accompanied with no detectable thrombus and plasma leakage. We envisage that the biomimetic decoration of nanoporous membranes provide a feasible route to achieve great biocompatibility and transport capability for various applications.

Design and Fabrication of a Biomimetic Smart Material for Electrochemical Detection of Carbendazim Pesticides in Real Samples with Enhanced Selectivity.

Agricultural products are vitally important for sustaining life on earth and their production has notably grown over the years worldwide in general and in Brazil particularly. Elevating agricultural practices consequently leads to a proportionate increase in the usage of pesticides that are crucially important for enhanced crop yield and protection. These compounds have been employed excessively in alarming concentrations, causing the contamination of soil, water, and air. Additionally, they pose serious threats to human health. The current study introduces an innovative tool for producing appropriate materials coupled with an electrochemical sensor designed to measure carbendazim levels. The sensor is developed using a molecularly imprinted polymer (MIP) mounted on a glassy carbon electrode. This electrode is equipped with multi-walled carbon nanotubes (MWCNTs) for improved performance. The combined system demonstrates promising potential for accurately quantifying carbendazim. The morphological characteristics of the synthesized materials were investigated using field emission scanning electron microscopy (FESEM) and the Fourier-transform infrared (FTIR) technique. The analytical curve was drawn using the electrochemical method in the range of 2 to 20 ppm while for HPLC 2-12 ppm; the results are presented as the maximum adsorption capacity of the MIP (82.4%) when compared with NIP (41%) using the HPLC method. The analysis conducted using differential pulse voltammetry (DPV) yielded a limit of detection (LOD) of 1.0 ppm and a repeatability of 5.08% (n = 10). The results obtained from the analysis of selectivity demonstrated that the proposed electrochemical sensor is remarkably efficient for the quantitative assessment of carbendazim, even in the presence of another interferent. The sensor was successfully tested for river water samples for carbendazim detection, and recovery rates ranging from 94 to 101% were obtained for HPLC and 94 to 104% for the electrochemical method. The results obtained show that the proposed electrochemical technique is viable for the application and quantitative determination of carbendazim in any medium.

Impact of Sub-Ambient Temperature on Aging Rate and Gas Separation Properties of Polymers of Intrinsic Microporosity.

Aging in polymers of intrinsic microporosity has slowed exploitation due to a decay in performance over time since densification makes them unsuitable for industrial applications. This work aimed to study the impact of the operation and storage temperature on the gas separation properties and aging rates of PIM-1 self-standing films. The permeability, diffusivity, and solubility of the tested membranes were monitored through permeation tests for pure carbon dioxide and nitrogen at a maximum upstream pressure of 1.3 bar for temperatures ranging from -20 °C to 25 °C. This study found significant benefits in the operation of glassy polymeric membranes at low temperatures, resulting in a favourable trade-off in separation performance and a reduction in the aging rate by three orders of magnitude. This brings new opportunities for the industrial application of PIMs in innovative carbon capture processes.

Characterization of the Chemical Resistance of Two Non-Vulcanized Styrene-Butadiene Rubbers (SBR).

The objective of this series of tests is to characterize the alkali and water resistance of two non-vulcanized formulations based on co-polymerizing styrene-butadiene rubbers (SBR1 and SBR2). The relative merits of the two polymer systems as impregnating agents for alkali-resistant glass reinforcement in cementitious binders are assessed. For this purpose, polymer films were synthesized and then chemically conditioned for up to half a year at temperatures of 23 °C and 50 °C in sodium hydroxide and potassium hydroxide solutions as well as in salt and distilled water. Changes in mass, tensile strength, and material hardness were evaluated to assess the chemical resistance of the two polymer systems. The different test liquids generally led to swelling (increase in mass) and degradation (reduction in mass) of the polymer structures. These two processes occurred simultaneously. The liquid absorption capacity of the SBR1 impregnation system was between 25.05% and 51.60% by weight, depending on the test liquids. In contrast, the SBR2 impregnation system exhibited a lower liquid absorption capacity, with a weight increase from 21.19% to 42.90%. The chemical conditioning resulted in a maximum mass reduction of the polymer structure SBR1 of 8.82% by weight. The polymer SBR2, on the other hand, only lost up to 2.88% by weight. The tensile strengths of the unconditioned samples of the polymer systems SBR1 and SBR2 were 55.49 ± 7.47 N and 80.87 ± 15.96 N, respectively. The test liquids caused a reduction in strength over the storage period which was accelerated by increased temperatures. The loss of strength of the polymer structure SBR2 was lower over the entire conditioning period. In this context, a correlation was found between strength and material hardness. Overall, the polymeric impregnation system SBR2 had a lower liquid absorption capacity and a lower degree of damage caused by the degrading test liquids. Furthermore, the tensile strength was generally higher and more robust over the entire conditioning period. The results of the durability tests indicate that the SBR2 polymer system is more suitable for use in cementitious binders, as it exhibits less degradation of the polymer structure in response to chemical aging processes.

Advancing sustainability in the green engineering of nanocomposites based on marine-derived polymers and their applications.

Nanocomposites are sophisticated materials that incorporate nanostructures into matrix materials, such as polymers, ceramics and metals. Generally, the marine ecosystem exhibits severe variability in terms of light, temperature, pressure, and nutrient status, forcing the marine organisms to develop variable, complex and unique chemical structures to boost their competitiveness and chances of survival. Polymers sourced from marine creatures, such as chitin, chitosan, alginate, sugars, proteins, and collagen play a crucial role in the bioengineering field, contributing significantly to the development of nanostructures like nanoparticles, nanocomposites, nanotubes, quantum dots, etc. These nanostructures offer a wide array of features involving mechanical strength, thermal stability, electrical conductivity, barrier and optical characteristics compared to traditional composites. Notably, marine nanocomposites have distinctive roles in a wide spectrum of applications, among them anti-cancer, anti-microbial, antioxidant, cytotoxic, food packing, tissue engineering and catalytic actions. Sol-gel, hot pressing, chemical vapor deposition, catalytic decomposition, dispersion, melt intercalation, in situ intercalative polymerization, high-energy ball milling and template synthesis are common processes utilized in engineering nanocomposites. According to our literature survey and the Web of Science, chitosan, followed by cellulose, chitin and MAPs emerge as the most significant marine polymers utilized in the construction of nanocomposites. Taken together, the current manuscript underscores the biogenesis of nanocomposites, employing marine polymers using eco-friendly processes. Furthermore, significant emphasis in this area is needed to fully explore their capabilities and potential benefits. To the best of our knowledge, this manuscript stands as the first comprehensive review that discusses the role of marine-derived polymers in engineering nanocomposites for various applications.