Long Polymer Chains Research Articles

Review: Utilization of cellulose in food products

Cellulose is one of the most abundant natural materials in the world. It has a long-chain carbohydrate polymer made up of repeating glucose units. Reviewed literature shows that the material has been widely explored as a functional ingredient in foods, including meat products, emulsions, beverages, dairy products, bread, confectionery, and fillings. This carbohydrate polymer has many promising applications in the functional food and nutraceutical industries. Cellulose can be isolated through chemical, mechanical, and biological means to produce a variety of functional materials in the form of cellulose crystals with varying shapes and sizes, including microcrystalline cellulose, micro fibrillated cellulose, nanocrystalline cellulose, nanofibrillated cellulose, and bacterial cellulose, based on its production techniques and sources. This review highlights the utilization and functions of cellulose as a material in food products.

Expandable ELAST for super-resolution imaging of thick tissue slices using a hydrogel containing charged monomers

Hydrogels have been utilized extensively as a material for retaining position information in tissue imaging procedures, such as tissue clearing and super-resolution imaging. Immunostaining thick biological tissues, however, poses a bottleneck that restricts sample size. The recently developed technique known as entangled link-augmented stretchable tissue-hydrogel (ELAST) accelerates the immunostaining process by embedding specimens in long-chain polymers and stretching them. A more advanced version of ELAST, magnifiable entangled link-augmented stretchable tissue-hydrogel (mELAST), achieves rapid immunostaining and tissue expansion by embedding specimens in long-chain neutral polymers and subsequently hydrolyzing them. Building on these techniques, we introduce a variant of mELAST called ExELAST. This approach uses charged monomers to stretch and expand tissue slices. Using ExELAST, we first tested two hydrogel compositions that could permit uniform expansion of biological specimens. Then, we apply the tailored hydrogel to the 500-μm-thick mouse brain slices and demonstrated that they can be stained within two days and imaged with a resolution below the diffraction limit of light.

Glucose-Triggered Release of trans-N-p-Coumaroyltyramine from Zeolitic Imidazolate Framework-8 (ZIF8) Modified with Dioscorea opposita Thunb Polysaccharide.

A Dioscorea opposita Thunb polysaccharide (DOP)-modified ZIF8 material was developed in this study, which can be used as a "smart" glucose-responsive carrier to control the slow release of drugs. The 3-aminophenylboronic acid (APBA) functionalized carboxylated long-chain polymer poly(ethylene glycol) (PEG) segments, which were first modified on the surface of ZIF8 nanoparticles with a hydrogen bond and then chemically cross-linked with DOP through a borate ester bond, leading to the drugs loaded on ZIF8 being "closed" in PBS but being "open" via taking off the DOP coating in high concentrations of glucose; thus, leakage can be prevented in the drug loaded and a glucose-triggered release can effectively result. Moreover, the materials showed good biocompatibility and the released trans-N-p-coumaroyltyramine (NCT) could work synergistically with the DOP to improve insulin resistance and promote glucose consumption in insulin-resistant HepG2 cells.

Low-Temperature Self-Stacking Ink for Electrohydrodynamic Direct Writing

Flexible electronics have gained significant attention in various fields due to their widespread applications in production and daily life. The electrohydrodynamic direct writing (EDW) is a promising method for fabricating flexible electronics due to its high efficiency, low cost, and ability to produce high-resolution patterns. However, traditional metal-based inks used in the EDW often suffer from agglomeration and needle blockage, which negatively impacts the direct writing effect, especially on flexible substrates. To address these issues, this study proposes a particle-free ink formulation that is simple to prepare and exhibits excellent performance. Polyethylene oxide is a long-chain polymer, and its aqueous solution is a non-Newtonian fluid, which is often used as a thickener and complexing agent for inks. The ink is prepared using a one-pot method based on the silver-amine complexation mechanism, which enables low-temperature sintering without metal particle agglomeration. The fibers fabricated from the ink exhibit a remarkable sintering performance, achieving a resistance of 3.00 kΩ/cm at low temperature of 50 °C. Additionally, the ink produces fibers with self-stacking properties that can be utilized to control the resistance of the fiber. Overall, this ink formulation has significant potential for the preparation of flexible electronics.

Review and Design Overview of Plastic Waste-to-Pyrolysis Oil Conversion with Implications on the Energy Transition

Plastics are cheap, lightweight, and durable and can be easily molded into many different products, shapes, and sizes, hence their wide applications globally, leading to increased production and use. Plastic consumption and production have been growing since its first production in the 1950s. About 4% of global oil and gas production is being used as feedstock for plastics, and 3–4% is used to provide energy for their manufacture. Plastics have a wide range of applications because they are versatile and relatively cheap. This study presents an in-depth analysis of plastic solid waste (PSW). Plastic wastes can be technically used for oil production because the calorific value of the plastics is quite comparable to that of oil, making this option an attractive alternative. Oil can be produced from plastic wastes via thermal degradation and catalytic degradation, while gasification can be used to produce syngas. Plastic pyrolysis can be used to address the twin problem of plastic waste disposal and depletion of fossil fuel reserves. The demand for plastics has continued to rise since their first production in the 1950s due to their multipurpose, lightness, inexpensiveness, and durable nature. There are four main avenues available for plastic solid waste treatment, namely, reextrusion as a primary treatment, mechanical treatment as secondary measures, chemical treatment as a tertiary measure, and energy recovery as a quaternary measure. The pyrolysis oil has properties that are close to clean fuel and is, therefore, a substitute to fresh fossil fuel for power generation, transport, and other applications. The study showed that plastic wastes pyrolysis offers an alternative avenue for plastic waste disposal and an alternative source of fossil fuel to reduce the total demand of virgin oil. Through plastic pyrolysis, plastic wastes are thermally converted to fuel by degrading long-chain polymers into small complex molecules in the absence of oxygen, making it a technically and economically feasible process for waste plastic recycling. The process is advantageous because presorting is not required, and the plastic waste can be directly fed without pretreatment prior to the process. Products of plastic pyrolysis are pyrolysis oil, a hydrocarbon-rich gas, with a heating value of 25–45 MJ/kg, which makes it ideal for process energy recovery. Hence, the pyrolysis gas can be fed back to the process to extract the energy for the process-heating purpose, which substantially reduces the reliance on external heating sources.

Intermolecular ═C–H···O═C Hydrogen Bonding and Conformational Preference in Crystalline Poly(butylene 2,5-furandicarboxylate)

Besides maximizing packing efficiency, molecular interactions also play an indispensable role upon conformational ordering for crystallization of long-chain polymers. Herein, structural evolution upon heating of biobased poly(butylene 2,5-furandicarboxylate) (PBF) is followed by temperature-dependent infrared (IR) spectroscopy and wide-angle X-ray diffraction (WAXD) to elucidate the molecular interactions and conformational preference in its crystalline state. By estimating the group distances according to atomic coordinates of its crystal structure, the stronger intermolecular interaction than the van der Waals force is speculated to exist in crystalline PBF, which is fully confirmed by the changes of IR absorptions associated with ═C–H and C═O groups upon heating as an abnormal ═C–H···O═C hydrogen bonding. The combination of temperature-dependent ═C–H band position and crystal lattice expanding supports a good thermostability of this interaction up to melting, fully defining its nature as strong hydrogen bonding rather than the generally reported weak H···O═C bonding in biodegradable polyesters. By further analyzing the confirmational ordering in its crystalline state, it is believed that such intermolecular ═C–H···O═C hydrogen bonding stabilizes the energetically inaccessible syn–syn conformer of 2,5-furandicarboxylic moieties for PBF crystallization.

Stable preparation of highly water-soluble ammonium polyphosphate by ion regulation

Water-soluble ammonium polyphosphate (APP) is an ideal phosphorus source to replace conventional phosphate fertilizers and improve phosphorus utilization. The industrial preparation of highly water-soluble APP is currently difficult owing to the associated harsh operating conditions and high raw material costs. Thus, a new strategy to stabilize the preparation of highly water-soluble APP was developed based on the addition of Mg2+ and SO42− ions to the raw materials. Product characterization demonstrated that Mg2+ inhibited the formation of water-insoluble long-chain polymers and stabilized the formation of crystalline type-I oligomeric APP, while the addition of SO42− induced the transformation of this oligomeric APP to amorphous acidic APP or polyphosphoric acid, further improving the product solubility. These effects were further investigated using reaction kinetics and density functional theory calculations. Compared with the pure phosphoric acid–urea system, the addition of Mg2+ and SO42− stabilized the average degree of polymerization of the product and simplified control of the production process. A pilot test showed that the use of this approach with wet-process phosphoric acid (WPA) as a raw material yields a product with superior solubility than the prevalent 18-58-0 (N-P2O5-K2O). In addition, the solubility of Ca2+ was increased from 2.3 g to 7.3 g/100 g APP, and the process cost was reduced by 17.7%. This study achieved the low-cost and stable preparation of highly water-soluble APP products from WPA, which could promote the industrial production of agricultural polyphosphates.

Insight into the Effect of Stabilizers on Anticancer and Antibacterial Activity of AgBiS2 Nanomaterial.

The near-infrared (NIR) light-absorbing AgBiS2 nanoparticles can be excited by single-wavelength light, which is the primary characteristic of a photo responsive platform. Chemical synthesis of nanomaterials inevitably requires long-chain organic surfactants or polymers to stabilize them in the nano regime. These stabilizing molecules barricade the interaction of nanomaterials with biological cells. We have produced stabilizer-free (sf-AgBiS2 ) and polymer-coated (PEG-AgBiS2 ) nanoparticles; and assessed their NIR mediated anticancer and antibacterial activity to evaluate the effect of stabilizers. sf-AgBiS2 showed better antibacterial activity against Gram-positive Staphylococcus aureus (S. aureus) and displayed excellent cytotoxicity against HeLa cells and live 3-D tumour spheroids compared to PEG-AgBiS2 both in presence and absence of NIR radiation. The photothermal therapy (PTT) results illustrated the tumour ablation ability of sf-AgBiS2 , which converted light into heat effectively up to 53.3 °C under NIR irradiation. This work demonstrates the importance of synthesizing stabilizer-free nanoparticles to produce safe and highly active PTT agents.

Overexpression of a gibberellin 20-oxidase gene in poplar xylem led to an increase in the size of nanocellulose fibrils and improved paper properties

Cellulose, the major component of secondary cell walls, is the most abundant renewable long-chain polymer on earth. Nanocellulose has become a prominent nano-reinforcement agent for polymer matrices in various industries. We report the generation of transgenic hybrid poplar overexpressing the Arabidopsis gibberellin 20-oxidase1 gene driven by a xylem-specific promoter to increase gibberellin (GA) biosynthesis in wood. X-ray diffraction (XRD) and sum frequency generation spectroscopic (SFG) analyses showed that cellulose in transgenic trees was less crystalline, but the crystal size was larger. The nanocellulose fibrils prepared from transgenic wood had an increased size compared to those from wild type. When such fibrils were used as a reinforcing agent in sheet paper preparation, the mechanical strength of the paper was significantly enhanced. Engineering the GA pathway can therefore affect nanocellulose properties, providing a new strategy for expanding nanocellulose applications.

Performance improvement of a pump running as turbine for energy recovery considering the effects of polymer additives: An experimental study

Employing pumps as turbines (PAT) has proven to be a cost-effective and efficient method for producing clean electricity in various engineering applications. PATs are now being considered for use in pumped hydro storage plants (PHS) instead of using a series of separate pumps and turbines and also in oil, petrochemical, and refinery industries as pressure energy recovery. Therefore, it is highly desirable to improve the hydraulic and mechanical characteristics of PATs in such applications. In this study, the effects of polymer additives as drag reducing agents on the performance of a centrifugal pump running as turbine mode is experimentally investigated. Reducing the friction drag within a turbulent flow using additives such as long-chain flexible polymers has attracted considerable attention from an energy-saving perspective. For this purpose, a test rig including the feed pump and the main pump has been set up where aqueous solutions of polyacrylamide with concentrations of 150, 300, and 450 ppm are used as working fluid. In order to compare the turbine mode with the pump mode, the pump performance in direct operation is also evaluated. The findings reveal that compared to tap water, using polymer solutions increases the efficiency and output power of the PAT, which even further improves with increasing polymer concentration. In the turbine mode, the highest increase in efficiency occurred at 450 ppm, which represented an increase of 7.61%. On the other hand, in the pump mode, the maximum improvement in pump efficiency (8.30%) has been recorded when the 150 ppm solution is used instead of tap water. By increasing the flow rate of polymeric solutions, the percentage of increase in the pump’s efficiency, compared to tap water, is ascending. Conversely, the percentage of increase in the PAT’s efficiency declines as the flow rate of polymeric working fluid passing the turbine is increased. The degradation of the utilized polymer in solutions leads to a decrease in output power and efficiency of the PAT compared to its fresh state. Nevertheless, the PAT efficiency and generated power in the degraded condition of the solution are still higher than what can be achieved in presence of tap water as the working fluid. The results of this study generally show that the use of working fluids with viscoelastic properties, which contain additive polymers, significantly improves the performance of reverse and direct pumps. As such, it can be used as an alternative working fluid in the industries mentioned above.

Spectroscopic study on size-dependent optoelectronics of N-type ultra-high conductive polymer PBFDO

Single-molecule plasmas are widely used in spectroscopic studies and plasma devices, and the organic conjugated molecular chain of poly (benzodifurandione) (PBFDO) has excellent electrical conductivity and unique electronic structure. Therefore, an in-depth theoretical study of the spectroscopic, charge transfer and electron transport properties of PBFDO polymers and the analysis of physical mechanisms are essential. In this work, the absorption spectra of neutral and charged PBFDO polymers of different sizes and periodic systems of PBFDO polymers are studied theoretically. The charge transfer modes of the different absorption peaks are also given. The Raman and resonance Raman properties of long-chain PBFDO polymers under 514 nm laser were revealed. The electron transport properties and Current-Voltage Characteristic (I-V) Curves of PBFDO devices were also investigated. This work will provide the necessary theoretical guidance for the application of PBFDO in the field of nanoscale optoelectronics and the design of devices.

Multiscale equilibration of highly entangled isotropic model polymer melts.

We present a computationally efficient multiscale method for preparing equilibrated, isotropic long-chain model polymer melts. As an application, we generate Kremer-Grest melts of 1000 chains with 200 entanglements and 25 000-2000 beads/chain, which cover the experimentally relevant bending rigidities up to and beyond the limit of the isotropic-nematic transition. In the first step, we employ Monte Carlo simulations of a lattice model to equilibrate the large-scale chain structure above the tube scale while ensuring a spatially homogeneous density distribution. We then use theoretical insight from a constrained mode tube model to introduce the bead degrees of freedom together with random walk conformational statistics all the way down to the Kuhn scale of the chains. This is followed by a sequence of simulations with carefully parameterized force-capped bead-spring models, which slowly introduce the local bead packing while reproducing the larger-scale chain statistics of the target Kremer-Grest system at all levels of force-capping. Finally, we can switch to the full Kremer-Grest model without perturbing the structure. The resulting chain statistics is in excellent agreement with literature results on all length scales accessible in brute-force simulations of shorter chains.

Biodegradability of polyethylene by efficient bacteria from the guts of plastic-eating waxworms and investigation of its degradation mechanism

Polyethylene (PE) has been regarded as non-biodegradable for decades, and the evidence for its degradation by bacteria remains unclear in the literature. Waxworms have recently gained attention for their ability to degrade natural long-chain polymers and synthetic plastic. This study aims to explore the potential of low-density polyethylene (LDPE)-degrading bacteria from the gut symbionts of lesser waxworm (Achroia grisella) larvae for the effective biodegradation of LEDP. Two bacterial isolates (LDPE-DB1 and LDPE-DB2) exhibited the greatest reduction in tensile strength among all isolates (P<0.0001), reaching 51.3% and 58.3%, respectively. The bacterial strains LDPE-DB1 and LDPE-DB2 stand for molecularly identified species, Citrobacter freundii and Bacillus sp., respectively. After 5 days of incubation, the cell density of LDPE-DB1 and LDPE-DB2 reached 2.20×108 and 1.8×108 CFU/mL, respectively. However, after 30 days of incubation, the cell density reached 7.3×108 and 5.9×108, respectively. The formed cavities indicate the high activity of the isolated bacteria from Achroia grisella larvae where the cavities reach a depth of up to 1.2µm. The findings of this study demonstrated the presence of LDPE-degrading bacteria in Achroia grisella and provide promising evidence for the biodegradation of plastic waste management in the environment.

Defect control for high-efficiency all-inorganic CsPbBr3 perovskite solar cells via hydrophobic polymer interface passivation

All-inorganic CsPbBr3-based perovskite solar cells (PSCs) have been proved to possess upgraded humidity and thermal stability. However, the CsPbBr3-based PSCs with a typical device configuration without hole transport layer (HTL) suffer from serious carrier recombination as a result of high interfacial defect density, which limits the enhancement of photoelectric conversion efficiency (PCE). To settle this issue, an interfacial engineering methodology is imported by utilizing polymethyl methacrylate (PMMA) as a passivation layer between the CsPbBr3 film and the carbon electrode. Through the interaction within the uncoordinated Pb2+ ions and oxygen atoms of carbonyl (CO) in the PMMA molecule chains, the trap sites existed in the modified CsPbBr3 interface can be greatly suppressed, beneficial for a faster extraction and transportation of photogenerated carriers. Besides, the PMMA interlayer can raise the valence band of the CsPbBr3 surface for a better energy level alignment, and simultaneously portray as a protective layer against moisture owing to the hydrophobic nature of long-chain polymers. Ultimately, the PMMA modified device exhibited a champion PCE of 9.60 % with a high open-circuit voltage (VOC) of 1.58 V, as well as showcasing ignorable PCE loss enduring over 400 h of aging.

Ordered and disordered microstructures of nanoconfined conducting polymers.

We probe the microstructural differences of conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives under geometrical nanoconfinement using a high-resolution electron microscopy (HRTEM) technique. Highly ordered domains of poly(3,4-ethylenedioxythiophene):tosylate PEDOT:Tos, which is polymerized within alumina nanochannels, are observed. These features are in contrast to those of the polymer blend poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) PEDOT:PSS inserted into the nanopores. The extent of the order-disorder parameter in terms of surface crystallization and the number of ordered domains of the long-chain polymers strongly depends on the dopant environment, processing conditions and structural confinement. Atomic force spectroscopy of individual PEDOT nanochannels highlights counterion-dependent surface adhesive factors. The molecular dynamics (MD) simulation of these systems reveals similar polymer chain configurations and the resulting morphology.

Effects of polybutylene terephthalate molecular weight and nanostructure size of copper surface on replication quality of nano-injection molding under practical condition: A molecular simulation study

Understanding the effects of the molecular weight of the polymers and the pore size of the adherend surface on the mechanical interlocking of polymer/substrate interfaces is central for enhancing the corresponding adhesion strength. In the present study, we comprehensively investigated the effects of the molecular weight of polybutylene terephthalate and the nanostructure size on the replication quality by molecular dynamics simulations. Under practical pressures and temperatures, polymers of various molecular weights infiltrated to the bottom of the nanopores; the filling rate was > 90 %. The high filling rate and infiltration depth were attributable to the large external pressure (which can overcome the increased viscosity) and the semi-spherical nature of the nanopores (beneficial for polymer infiltration). The nanostructure size weakly corresponded to the filling rate and interfacial energy, but substantially affected the infiltration of the polymer chains. The entanglements of long-chain polymers remained during the filling and increased the joint strength, by enhancing the internal friction and the interfacial friction between the polymer and copper substrate. The current findings provide new insights into the effects of the nanostructure size and the molecular weight of the polymer on the replication quality of nanoinjection molding.

Engineering Electrodes with Robust Conducting Hydrogel Coating for Neural Recording and Modulation.

Coating conventional metallic electrodes with conducting polymers has enabled the essential characteristics required for bioelectronics, such as biocompatibility, electrical conductivity, mechanical compliance, and the capacity for structural and chemical functionalization of the bioelectrodes. However, the fragile interface between the conducting polymer and the electrode in wet physiological environment greatly limits their utility and reliability. Here, a general yet reliable strategy to seamlessly interface conventional electrodes with conducting hydrogel coatings is established, featuring tissue-like modulus, highly-desirable electrochemical properties, robust interface, and long-term reliability. Numerical modeling reveals the role of toughening mechanism, synergy of covalent anchorage of long-chain polymers, and chemical cross-linking, in improving the long-term robustness of the interface. Through in vivo implantation in freely-moving mouse models, it is shown that stable electrophysiological recording can be achieved, while the conducting hydrogel-electrode interface remains robust during the long-term low-voltage electrical stimulation. This simple yet versatile design strategy addresses the long-standing technical challenges in functional bioelectrode engineering, and opens up new avenues for the next-generation diagnostic brain-machineinterfaces.

Development of temperature-responsive suspension stabilizer and its application in cementing slurry system

To solve the problem of cement slurry suspension instability caused by a geothermal gradient in low-pressure and leakage formation, a hydrophobically associating long-chain polymer (PSAN) was designed as a suspension stabilizer by introducing hydrophilic monomer acrylamide (AM), temperature-resistant monomer 2-acrylamide-2-methyl propane sulfonic acid (AMPS), hydrophobic monomer styrene (St) and temperature-sensitive monomer N-vinyl caprolactam (NVCL). The synthesis conditions of PSAN were optimized by orthogonal response surface method. The structure and performance of PSAN were characterized and tested by IR, 1H NMR, GPC, SEM, TG, high-temperature rheology, and fluorescent probes. The research and analysis showed that PSAN had a good temperature response. At 30–65 ℃, the apparent viscosity of PSAN aqueous solution increased with the increase of temperature. At 65 ℃, the hydrophobically associating ability of PSAN was enhanced, and the retention rate of the apparent viscosity of its aqueous solution at 65–110 ℃ was still more than 83%. The good temperature response of PSAN was conducive to the suspension stability of cement slurry under the condition of large temperature differences. When 1% bwoc (percentage of cement mass) was added to the cement slurry, the free liquid of the cement slurry was 0, the water loss was less than 90 mL, and the density difference between the upper and lower sections of the cement stone column was less than 0.01 g/cm3. SEM analysis showed that there was a network structure formed by hydrophobic association between PSAN molecules in cement. In a word, under the condition of 30–110 ℃ (80 ℃ large temperature difference), the suspension stabilizer PSAN can effectively alleviate the floating of light materials and the sinking of heavy materials in cementing slurry through the hydrophobic association between molecules, and ensure the suspension stability of cementing slurry, thus contributing to the safety of cementing construction and improving the quality of cementing.

Inorganic Polyphosphate: Coacervate Formation and Functional Significance in Nanomedical Applications.

Inorganic polyphosphates (polyP) are long-chain polymers of orthophosphate residues, which, depending on the external conditions, can be present both physiologically and synthetically in either soluble, nanoparticulate or coacervate form. In recent years, these polymers have received increasing attention due to their unprecedented ability to exhibit both morphogenetic and metabolic energy delivering properties. There are no other physiological molecules that contain as many metabolically utilizable, high-energy bonds as polyP, making these polymers of particular medical interest as components of advanced hydrogel scaffold materials for potential applications in ATP-dependent tissue regeneration and repair. However, these polymers show physiological activity only in soluble form and in the coacervate phase, but not as stable metal-polyP nanoparticles. Therefore, understanding the mechanisms of formation of polyP coacervates and nanoparticles as well as their transformations is important for the design of novel materials for tissue implants, wound healing, and drug delivery and is discussed here.

Toughening Modification of Polylactic Acid by Long-Chain Hyperbranched Polymers Containing Polycaprolactone end Groups

The hyperbranched polyester (HBPEs) were synthesized by the "one-step method" and grafted with caprolactone (ε-Cl) to obtain long-chain hyperbranched polymers (LCHBPs-Cl). In this study, LCHBPs-Cl with Cl long chain end groups were used for the first time to toughen and strengthen polylactic acid (PLA) by melt blending. Compared with pure PLA, the most significant toughening effect was obviously when the addition amount of LCHBPs-Cl was 2.0 phr. The tensile strength increased from 37.00 to 62.61 MPa. The impact strength was increased from 14.88 to 18.50 kJ. The elongation at break increased from 1.80% to 2.50%. The scanning electron microscope (SEM) images showed the impact section of the blends became rough, the brittle-ductile fracture transition occurred, and a large number of white wire drawing phenomena were produced. Due to the formation of topological entanglement and cohesive entanglement between the long-chain substituents of LCHBPs-Cl and PLA molecular chains, the plastic deformation of PLA was successfully improved, and the toughness of polylactic acid was highly improved.