Molecular Chains Research Articles

Soybean protein “mechanically interlocked” bonding of polysaccharide and MXene to improve the strength and toughness of biomass adhesive

Simultaneously improving the strength and toughness of soybean protein adhesives is a huge challenge. The multi-scale enhancement strategy proposed in this study introduced MXene nanosheets and oxidized sodium alginate (OSA) to improve mechanical properties. The polymer network framework with high crosslink density dissipates energy by restricting the slip of the SPI molecular chains, and MXene act as stress dispersers in the polymer network in order to solve the challenge of the strength-toughness balance. The prepared biomass-based adhesives with high adhesion (dry/wet shear strength 1.93 MPa/1.33 MPa), high toughness (adhesion work 810.9 mJ), high thermal stability, high residual rate (92.53 %), low moisture absorption rate (11.18 %), and long storage time (12 d). Additionally, the application of SOM-5 adhesive reduces the burden of petrochemical resource extraction for adhesive production and contributes to the sustainable development of the wood industry. Most importantly, it presents an adoptable strategy for resolving the tension between strength and toughness of composite materials.

Research insight into the change of aggregation structure of BOPP films and its influence on electrical properties under accelerated thermal aging

AbstractBiaxially oriented polypropylene (BOPP) film used in pulse film capacitors withstands high temperatures for a long time. This leads to frequent faults in pulse film capacitors, affecting the reliability of the pulse system. In this paper, the thermal aging tests of BOPP films at 100°C for 10–80 days are carried out in this paper, and the physicochemical and electrical properties of the aging materials are characterized. The results show that more deep and shallow traps to BOPP films are introduced during the thermal aging process. With the increase in aging time, the breakdown field strength gradually decreases, and the conductivity decreases first and then increases. Under the action of thermal aging for a long time, the recrystallization of materials and the destruction of molecular chains by thermal aging are the main reasons for the increase of traps and the decrease of breakdown field strength. The former is dominant in the early stage of aging, and the latter is dominant in the late stage of aging. Therefore, the conductivity shows the law of slow decrease first and then rapid increase. The relevant research provides a theoretical foundation for the process improvement and life prediction of BOPP films.

Improved high temperature energy storage density and efficiency of polyimide nanocomposites via hindering charge and molecular motions

Electric vehicles and renewable energy consumption have huge demands for high-performance polymer dielectric capacitors. However, the resistivity and breakdown strength of existing polymer dielectrics deteriorate significantly at high temperatures, reducing the energy storage density and charge-discharge efficiency of capacitors below service requirements. The charge transport and molecular chain motion characteristics in linear polymers determine their conductivity, breakdown, and energy storage properties, but the quantitative relationship between them is not clear. An in-situ polymerization method was used to prepare polyimide/Al2O3 nanocomposites (PI/Al2O3 PNCs). Experimental results show that the resistivity, breakdown strength, energy storage density, and charge-discharge efficiency of PNCs increase initially and then decrease with increasing doping content, peaking at 3 wt%. The discharged energy density of PI/Al2O3-3 wt% PNCs at 180°C is 207.52 % higher than pure PI. A conductance-breakdown-energy storage co-simulation model based on charge transport and molecular chain displacement was used to simulate the voltage-current, breakdown, and energy storage characteristics of PNCs. The simulation results are consistent with the experiments. Comparative studies between simulation and experiments show that the independent interface zone between nanofillers and PI hinders charge transport and molecular chain movement, reducing electric field distortion and molecular chain spacing, thereby improving high-temperature breakdown and energy storage performance of PNCs.

Maltodextrin polymer nanospheres as a filtrate reducer for filtration control in water-based drilling fluids

With the development of deep and ultra-deep wells, there is a need to enhance the rheological and filtration properties of water-based drilling fluids under high temperature and salinity conditions. In this study, maltodextrin polymer nanospheres (MDPN) were synthesized through cross-linking maltodextrin and methylene bisacrylamide (MBA) via inverse emulsion polymerization. Then, the polymer MDPN-DAN was synthesized via aqueous solution polymerization, using maltodextrin polymer nanospheres, N, N-dimethylacrylamide (DMAA), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), and N-vinylpyrrolidone (NVP) as raw materials. Structural characterization confirmed the successful synthesis of the polymer MDPM-DAN, with a median particle size of 234.4 nm. Thermogravimetric analysis revealed a thermal decomposition temperature of 242 °C for MDPM-DAN. This polymer demonstrated excellent settling stability at 220 °C in high-temperature and weakly alkaline environments. Rheological assessments demonstrated a 754 % enhancement in the drilling fluid’s rheological properties when MDPM-DAN was added compared to the base mud. MDPM-DAN demonstrated significant reduction in filtration loss, with polymer mud aged at 220 °C showing only 5.6 mL of loss, and polymer mud aged at 220 °C with 15 wt% NaCl exhibiting 8.9 mL loss. The filtration loss reduction mechanism elucidated that MDPM-DAN could adsorb onto bentonite particles via hydrogen bonds, while nanoparticles filled the micropores of the filter cake, promoting the formation of a dense filter cake. Furthermore, plugging experiments showcased MDPM-DAN’s ability to block nano-pore throats, with the molecular chain’s amide groups reinforcing the plugging through hydrogen bonding with rocks, while bentonite coats the micro-pore throats.

Characteristics and competitive mechanisms of polycondensation and cyclization induced by end‐groups in polyamide 6 melt

AbstractPolycondensation and ring‐formation reactions are the main factors that cause instability in the molecular structure of commercial polyamide 6 (PA6) during melting. In this study, the mechanisms and interactions of the ring‐formation and polycondensation reactions induced by various factors were thoroughly investigated. The findings suggest that the average molecular weight of PA6 increased by 20.4% during melting. The total monomer and oligomer content increased by 79.2%, and the ring‐forming reaction was promoted with an increase in temperature. Moreover, a high concentration of the end‐amino in PA6 promoted the ring‐forming reaction, whereas similar concentrations of the end‐amino and end‐carboxyl groups were more conducive to the polycondensation reaction. In short, the nitrogen atoms in the end‐amino group on the PA6 molecular chain attack the carbonyl carbon at different sites, including the carbonyl carbon in the amide bond and the carbonyl carbon in the end‐carboxyl group, which is the key to the strength of the ring‐formation and polycondensation reactions.

Nonempirical Prediction of the Length-Dependent Ionization Potential in Molecular Chains.

The ionization potential of molecular chains is well-known to be a tunable nanoscale property that exhibits clear quantum confinement effects. State-of-the-art methods can accurately predict the ionization potential in the small molecule limit and in the solid-state limit, but for intermediate, nanosized systems prediction of the evolution of the electronic structure between the two limits is more difficult. Recently, optimal tuning of range-separated hybrid functionals has emerged as a highly accurate method for predicting ionization potentials. This was first achieved for molecules using the ionization potential theorem (IPT) and more recently extended to solid-state systems, based on an ansatz that generalizes the IPT to the removal of charge from a localized Wannier function. Here, we study one-dimensional molecular chains of increasing size, from the monomer limit to the infinite polymer limit using this approach. By comparing our results with other localization-based methods and where available with experiment, we demonstrate that Wannier-localization-based optimal tuning is highly accurate in predicting ionization potentials for any chain length, including the nanoscale regime.

One-dimensional Dexter-type excitonic topological phase transition

The concept of the Su-Schrieffer-Heeger model, which was successfully introduced in topological photonics, can also be applied to the study of topological excitonics. Here we study the topological properties of a one-dimensional excitonic tight-binding model formed by two-level systems by taking into account the charge transfer and local excitations. The interactions between the two types of excitons give rise to a rich spectrum of physics, including the nontrivial topological phase in the uniform chain, unlike the conventional Su-Schrieffer-Heeger model, the topologically nontrivial flat bands, and, most importantly, the excitonic topological phase transition assisted by the Dexter electron exchange process. The excitonic topological phase leads to the development of “chiral superposition.” The topological edge states are robust because they are protected by the inversion symmetry. Based on our calculations, experiments for observing the edge states optically in a molecular chain are proposed. Published by the American Physical Society 2024

Application of Hydrothermal Synthesized Titanium Dioxide-Doped Multiwalled Carbon Nanotubes on Filtration Properties-Response Surface Methodology Study.

The success of any drilling activity mainly depends on the characteristics of the drilling fluid. Therefore, a high-performance drilling fluid is substantial for any drilling operation. During overbalance drilling operations, the drilling mud invades the permeable formations and causes the loss of circulation, which is responsible for nonproductive time events. Hence, the filtration characteristics of the drilling mud are an imperative property. The purpose of this study is to evaluate the filtration characteristics of water-based mud systems in the presence of polyanionic cellulose (PAC) and multiwalled carbon nanotubes (MWCNTs)/TiO2 nanoparticles. The nanoparticles were synthesized by using the hydrothermal technique. For the first time, a composite of MWCNTs and TiO2 has been utilized as a fluid loss control additive in the petroleum sector, marking a significant development in the field. The filtration properties of water-based mud were assessed at two concentrations (0.35 g and 3.5 g). Furthermore, based on the two levels (concentrations) and two factors (particles), the novel application of the central composite response surface design of experiment (CCD) was implemented. The results showed that the predicted model from CCD was in good agreement with the filter press experimental result with R 2 = 0.8446. Furthermore, based on the ANOVA analysis, the concentration of MWCNTs/TiO2 nanoparticles was the most significant parameter with p-value < 0.05. In addition, 10 out of 13 experimental points fall under the ±10% error window, thus indicating a higher accuracy of the regression model. The 2D interactive plots further show that the concentration of PAC is insignificant and has no considerable influence on fluid loss control, which was also validated by p-value > 0.05. The performance of MWCNTs/TiO2 nanoparticles is superior to PAC because these nanodimension particles plug the pore-spacing and block the permeation channels on the filter paper. However, the PAC, because of its long molecular chain, entangles around the pore spaces and plugs the microsize pores, which eventually reduces the filtration loss volume up to some extent. By observing the synergistic interaction between MWCNTs/TiO2 nanoparticles and PAC, this study develops valuable insights that assist in improving the performance of drilling fluid and minimizes the wellbore instability issues in the oil and gas sector.

New insights on the degradation of polystyrene and polypropylene by larvae of the superworm Zophobas atratus and gut bacterial consortium enrichments obtained under different culture conditions

This study aims to deepen knowledge of the biodegradation of plastics, focusing on polypropylene (PP) fabric from surgical masks and polystyrene (PS) by larvae of Zophobas atratus as well as of specialized bacterial consortia from their gut, which were obtained in different enrichment conditions (aerobic, anaerobic, presence or absence of combined nitrogen). Plastics ingested by larvae obtained in Spain did not show any signs of oxidation but only limited depolymerization, preferably from the lowest molecular weight chains. Gut microbiota composition changed as an effect of plastic feeding. Such differences were more evident in bacterial enrichment cultures, where the polymer type influenced the composition more than by culture conditions, with an increase in the presence of nitrogen-fixers in anaerobic conditions. PS and PP degradation by different enrichment cultures was confirmed under aerobic and anaerobic conditions by respirometry tests, with anaerobic conditions favouring a more active plastic degradation. In addition, exposure to selected bacterial consortia in aerobiosis induced limited surface oxidation of PS. This possibly indicates that different biochemical routes are being utilized in the anaerobic gut and in aerobic conditions to degrade the polymer.

Self-Healing Flexible Sensor Based on Epoxidized Natural Rubber with the Synergistic Effect of Coordination and Hydrogen Bonds.

The use of highly tensile and self-healing conductive composites has gained considerable interest due to their wide range of applications in healthcare, sensors, and robotics. Epoxidized natural rubber (ENR), known for its ability to undergo highly reversible deformation, can be utilized in strain sensors to effectively transmit a broader range of signal changes. In this study, we introduced a self-healing ENR composite specifically designed for high-strain sensors. The rubber molecular chains were enhanced with hydrogen bonds and metal coordination bonds, allowing the matrix material to autonomously repair itself through these interactions. Following a repair period of 12 h at 45 °C, the composites achieve a repair efficiency exceeding 90%. Furthermore, by incorporating conductive fillers into the matrix using multistage layering, the resulting composite has good electrical conductivity, thermal conductivity, and hydrophobicity. In addition, this composite presents good sensitivity even at large strain (strain in the range of 50-200%, GF = 7.65). In conclusion, this self-healing nanocomposite, characterized by its high strain sensitivity, holds immense potential for various strain sensor applications.

The intrinsic flame retardant multifunctional composite phase change material with phosphorus pentoxide for battery thermal safety system

The temperature distribution has severely affected the performance of lithium-ion battery modules in electric vehicles (EVs), composite phase change material (CPCM) with excellent temperature controlling function as a passive battery thermal management system is essential to ensure the safety of battery module. In this study, the polyethylene glycol phosphate ester (PEGP) has been synthesized by esterification of phosphorus pentoxide and polyethylene glycol through the reaction of PEGP and melamine (MA), the network crosslinking structure has been built to greatly improve the anti-leakage performance. The flame-retardant CPCM containing PEGP/expanded graphite /epoxy resin/MA (PPEM) has been successfully designed and prepared. The results indicate that PPEM2 containing 20 wt% melamine and 7 wt% epoxy resin exhibit excellent antileakage and prominent flame retardant properties comprehensively. It should be noted that the peak heat release rate of PPEM2 has been reached to 352.41 KW/m2, which is obviously decreased by 47.55 % comparing with pure PEG. The main reason is that the grafting flame retardant elements (P) and melamine onto polyethylene glycol molecular chain by chemical reaction. In addition, it can maintain the operating temperature below 36 °C at 23 A discharge current. The battery module with PPEM2 can transfer the heat timely and promptly, exhibiting outstanding flame-retardant effect to avoid thermal runaway. With these prominent performances, this intrinsic flame-retardant CPCM can not only exhibit an excellent thermal management effect but also provide a promising approach to inhibit the thermal runaway propagation.

Magnetic polyacrylamide-based gel with tunable structure and properties and its significance in conformance control of oil reservoirs

The polyacrylamide-based gel used for oilfield conformance control exhibits poor temperature and salt resistance. This paper proposes the use of inorganic-organic core-shell materials as chemical crosslinkers for the polyacrylamide-polyethyleneimine (PAM-PEI) gel system to regulate and design its gel structure, enabling it to withstand harsh reservoir conditions. To achieve this, Fe3O4@PEI nanoparticles were prepared using a facile one-pot method and employed as chemical crosslinkers for the PAM-PEI gel. Herein, the Fe3O4 "core" provides strong stability derived from the inorganic material, and the PEI "shell" reacts with the PAM molecular chain in a transamidation reaction, so that the Fe3O4@PEI nanoparticles are riveted inside the gel by chemical crosslinking, which greatly enhances the gel structure. The Fe3O4@PEI nanoparticles exhibit a nearly spherical shape with an average diameter of approximately 75.6 nm and demonstrate excellent dispersion in water, possessing a zeta potential of 40.8 mV. In comparison to the control PAM-PEI gel, the PAM-PEI-Fe3O4@PEI gel exhibited significantly enhanced gel strength, rheological properties, long-term thermal stability, and anti-salt properties. It demonstrated a tan(δ) value of 0.12, indicative of its behavior as a nearly robust gel. Even after 360 days of placement at 90 °C in a 20 g/L NaCl solution, the gel maintained its Sydansk code at code I. Moreover, NaCl was observed to act as a retarder for this gel, while its Sydansk strength remained unaffected. In addition, the PAM-PEI-Fe3O4@PEI gel is magnetically responsive, so it can be utilized with a magnet generator to enhance its plugging performance and control its directional movement. By monitoring the magnetization rate of the gel in the reservoir, high permeability layers can be accurately identified, thus providing important practical applications in reservoir management.

Preparation of bacterial cellulose/acrylic acid-based pH-responsive smart dressings by graft copolymerization method

Conventional wound dressings used in trauma treatment have a single function and insufficient adaptability to the wound environment, making it difficult to meet the complex demands of the healing process. Stimuli-responsive hydrogels can respond specifically to the particular environment of the wound area and realize on-demand responsive release by loading active substances, which can effectively promote wound healing. In this paper, BC/PAA-pH responsive hydrogels (BPPRHs) were prepared by graft copolymerization of acrylic acid (AA) to the end of the molecular chain of bacterial cellulose (BC) network structure. Antibacterial pH-responsive ‘smart’ dressings were prepared by loading curcumin (Cur) onto the hydrogels. Surface morphology, chemical groups, crystallinity, rheological, and mechanical properties of BPPRHs were analyzed by different characterization methods. The drug release behavior under different physiological conditions and bacteriostatic properties of BPPRH-Cur dressings were also investigated. The results of structural characterization and performance studies show that the hydrogel has a three-dimensional mesh structure and can respond to wound pH in a ‘smart’ drug release capacity. The drug release behavior of the BPPRH-Cur dressings under different environmental conditions conformed to the logistic and Weibull kinetic models. BPPRH-Cur displayed good antimicrobial activity against common pathogens of wound infections such as E. coli, S. aureus, and P. aeruginosa by destroying the cell membrane and lysing the bacterial cells. This study lays the foundation for the development of new pharmaceutical dressings with positive health, economic and social benefits.

The adaptability of polycarboxylate superplasticizer in alkaline electrolyzed water (AEW)-based cement composites containing clay: Workability and mechanical properties

Improving the adaptability of polycarboxylate superplasticizers (PCE) in high-clay content mortar is of great significance in enhancing the workability and mechanical properties of mortar containing clay. In this study, the potassium-based alkaline electrolyzed water (AEW) was used as mixing water for cement mortar. The excellent properties of AEW enabled PCE to be more compatible in cement mortar containing montmorillonite (MT) or kaolin (GL), improving the performance of mortar containing clay. The results showed that compared with ordinary tap water (OTW), the adsorption rate of clay minerals on PCE decreased in the AEW environment, and the clay interlayer spacing of MT was also reduced. AEW can inhibit the intercalation and adsorption of PCE molecular side chains by clay minerals to some extent. However, due to its unique crystal structure, the adsorption of MT on PCE was still significantly higher than that of GL. At the same time, increasing the content of clay mineral led to a decrease in mortar performance. Compared with the GL series, the MT series had a more significant negative impact on mortar fluidity and strengths. AEW also can promote hydration reactions, release more hydration heat, and produce more hydration products to encapsulate clay particles, thereby improving the workability and mechanical properties of cement paste containing clay. Furthermore, the high-activity AEW is rich in positively charged metal ions that can interact with clay minerals preferentially over cement particles, which enables the clay interlayer structure to be quickly saturated by AEW water molecules, effectively hindering the adsorption of PCE by clay minerals. However, in both the OTW and AEW environments, the intercalation effect of GL on PCE molecular side chains was not significant. Therefore, AEW has great potential in improving the adaptability of PCE in muddy cement pastes, which can help to enhance the workability and mechanical properties of muddy cement composites. This study provides theoretical references for preparing high-performance anti-clay concrete.

Effect of ionic liquids on the polymerization behavior of acrylamide‐based copolymers

AbstractTo explore the influence of reaction medium on the copolymerization behavior of acrylamide‐based copolymers, three types of copolymers (P(AM‐St)(ILs), P(AM‐MMA)(ILs), and P(AM‐AMPS)(ILs)) were synthesized by combining insoluble, slightly soluble, and easily soluble monomers with acrylamide in the 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF4) reaction medium. The reactivity ratio, Fourier transform infrared spectroscopy, 1H NMR spectroscopy, elemental analysis, and scanning electron microscopy were employed to characterize the copolymers' properties. The results indicated that in [BMIM]BF4 copolymerization, the reactivity ratio of AM and St in P(AM‐St)(ILs) decreased, the reactivity ratio of AM in P(AM‐MMA)(ILs) will increase. While the reactivity ratio of MMA will decrease. The reactivity ratio of AM in P(AM‐AMPS)(ILs) will increase and the reactivity ratio of AMPS will decrease. The distribution of AM and St segments in P(AM‐St)(ILs) molecular chains is more uniform and compact. When AM polymerizes with hydrophobic monomers (St) in [BMIM]BF4, its copolymer solution exhibits lower viscosity loss rates in temperature, shear, and salt resistance tests. Therefore, ionic liquids are more suitable as reaction media for the synthesis of hydrophobic‐modified polyacrylamides, which facilitate a more uniform distribution of hydrophobic monomers within the copolymer chains and exhibit enhanced resistance to temperature, salt, and shear stresses.

A Perspective on tellurium-based optoelectronics

Tellurium (Te) has been rediscovered as an appealing p-type van der Waals semiconductor for constructing various advanced devices. Its unique crystal structure of stacking of one-dimensional molecular chains endows it with many intriguing properties including high hole mobilities at room temperature, thickness-dependent bandgap covering short-wave infrared and mid-wave infrared region, thermoelectric properties, and considerable air stability. These attractive features encourage it to be exploited in designing a wide variety of optoelectronics, especially infrared photodetectors. In this Perspective, we highlight the important recent progress of optoelectronics enabled by Te nanostructures, which constitutes the scope of photoconductive, photovoltaic, photothermoelectric photodetectors, large-scale photodetector array, and optoelectronic memory devices. Prior to that, we give a brief overview of basic optoelectronic-related properties of Te to provide readers with the knowledge foundation and imaginative space for subsequent device design. Finally, we provide our personal insight on the challenges and future directions of this field, with the intention to inspire more revolutionary developments in Te-based optoelectronics.

Synthesis and properties of bio-based semi-aromatic heat-resistant copolymer polyamide 5T-co-6T

ABSTRACT Herein, poly(pentanediamine terephthalamide) (PA5T) homopolymer was synthesized via a salt-forming reaction+solid state polycondensation method using bio-based 1,5-pentanediamine and terephthalic acid as the primary raw materials. To address the issue of its narrower processing window, poly(hexamethylene terephthalamide)(PA6T), which also cannot be melt processed due to the processing window is negative, was introduced into its molecular chain to synthesize poly (pentanediamine/hexanediamine terephthaloyl) (PA5T-co-6T) copolymers. The structures were investigated by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance carbon spectroscopy (13C-NMR). Furthermore, the melting temperature, crystallization temperature, thermal stability, and crystal growth mode of the polymer were tested and analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide-angle x-ray diffraction (WAXD), respectively. The results demonstrate that the crystal growth mode gradually changes from three-dimensional spherical growth to two-dimensional disk-like or three-dimensional spherical growth with the increase of 6T chain segment content. Simultaneously, the crystallization temperature, melting temperature, and crystallization rate of the polymer all showed a trend of decreasing first and then increasing, which was due to the combined effects of the increase in the content of 6T chain segments on the molecular-chain structure and crystal structure of the polymer. Bio-based PA5T-co-6T has excellent heat resistance and a wider processing window than PA5T and PA6T, which possesses great application prospects in the fields of automotive, electronic appliances, and LED optics.

Viscoelastic Performance of Bagasse/Glass Fiber Hybrid Epoxy Composites: Effects of Fiber Hybridization on Storage Modulus, Loss Modulus, and Damping Behavior

Abstract This study aimed to investigate the viscoelastic properties of bagasse/glass fiber multilayered hybrid reinforced epoxy composites, focusing on how fiber hybridization affects dynamic mechanical performance. Epoxy composites with various layering sequences, including all-glass (AG), all-bagasse (AB), bagasse-glass-bagasse (BGB), and glass-bagasse-glass (GBG), were fabricated and analyzed using dynamic mechanical analysis (DMA) to measure storage modulus (E'), loss modulus (E''), and damping factor (tan δ). The results showed that hybrid composites (GBG and BGB) experienced a decrease in storage modulus by approximately 25% compared to AG, indicating enhanced polymer molecular chain mobility and improved interfacial adhesion between bagasse fibers and the epoxy matrix. The glass transition temperature (Tg) was slightly lower in hybrid composites, with GBG at 61 °C and BGB at 60 °C, compared to 62 °C for AG. In terms of energy dissipation, AG exhibited the highest loss modulus peak at 62 °C, while AB showed the lowest with a Tg at 53 °C. The damping factor analysis revealed that AB had the highest damping peak (tan δ = 0.9) at 61 °C, although this occurred at a lower temperature than the AG composite (tan δ = 0.7 at 76 °C). These findings suggest that bagasse and glass fiber hybrid composites offer tailored viscoelastic properties, making them suitable for applications in automotive components, aerospace structures, and sports equipment.

A method for synthesis of waterborne polyurethane using an eco-friendly surfactant

In general, waterborne polyurethane molecular chains containing hydrophilic groups usually require extended drying times to achieve sufficient film formation, thereby increasing energy consumption. The preparation of high-solid content waterborne polyurethane has attracted significant attention in both scientific research and industrial applications. The primary challenges associated with increasing the solid content of waterborne polyurethane are poor fluidity and inadequate storage stability. In this study, two surfactants, sodium lauryl sulfate and polyethylene glycol, were incorporated into the emulsification process of waterborne polyurethane to achieve a solid content of more than 50 %. The effect of different addition levels ranging from 1 to 5 wt% on viscosity, storage stability, physical and mechanical properties, thermal properties, and surface morphology of dried WPU films was further investigated. Waterborne polyurethane dispersion without surfactants solidified within a month, whereas those with surfactants remained stable for up to four months. Furthermore, the addition of sodium lauryl sulfate and polyethylene glycol significantly reduced the viscosity of waterborne polyurethane to 6–80 P and 3–17 P, respectively. Compared to SDS, PEG offers several advantages, including non-toxicity, biocompatibility, and solubility in various solvents. The addition of 1 wt% polyethylene glycol resulted in a stable waterborne polyurethane dispersion, achieving a solids content above 50 % with a viscosity of 17 P. This fundamental study establishes a pathway for preparing high solid content WPU using environmentally friendly surfactants.

Research on resin modified gelatin as environmental-friendly high temperature resistant wellbore stabilizer

In the development of deep shale oil and gas, the working temperature of the water-based drilling fluids is relatively high, which can cause wellbore instability due to the poor temperature resistance of the traditional environmental-friendly additives. To address this issue, this study presents a wellbore stabilizer called PMG, prepared by modifying gelatin (GT) with a resin synthesized by polyvinyl alcohol (PVA) and methacrylic acid (MA) through hydrothermal free radical polymerization, and it can withstand temperature up to 200 °C. The synthesis and thermal stability of PMG were confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The wellbore stability performance of PMG was evaluated by linear swelling test, rolling recovery test, core immersion experiment and point load test and the wellbore stability mechanism was also investigated. The results reveal that the swelling height of sodium-based bentonite (Na-BT) in 2.0 % PMG solution at 150 °C is only 0.97 mm; the hot-rolling recovery rate in 2.0 % PMG solution at 200 °C is 72 %; the artificial core still maintains its original appearance after being immersed in 2.0 % PMG solution at 200 °C for 16 h, and the compressive strength increases by 12 %, effectively strengthening the wellbore. In addition, the EC50 value of PMG is > 106 mg/L, and the BOD5/CODcr value is 31 %, indicating that it is non-toxic and biodegradable. PMG has excellent wellbore stability performance, in addition to being able to adsorb on the surface of Na-BT by electrostatic action and hydrogen bonding, the PMG micelles that precipitated from the aqueous solution due to the breaking of hydrogen bonds in the molecular chain at high temperature also form a film on the clay surface, aggregating and cementing the clay particles together, further enhancing the wellbore stability.