Polymer Phase Research Articles

Performance and mechanism of bio-oil "chain-pyrolytic" crumb rubber and SBS composite modified asphalt

To enhance the high-temperature performance of bio-oil degraded crumb rubber (CR) modified asphalt, a "chain-pyrolysis" treatment of CR was conducted using waste frying oil. This involved adding the CR in batches to the high-temperature waste oil to increase the CR-to-oil ratio, and control the degree of CR degradation. The effects of pyrolysis batch on the physicochemical properties of CR were evaluated through solubility, particle size analysis, thermal analysis, and scanning electron microscope. The performance and mechanism of "chain-pyrolytic" crumb rubber/Styrene-Butadiene-Styrene composite modified asphalt (PCR/SBSCMA) were investigated using conventional performance tests, rheological tests, Fourier transform infrared spectroscopy, fluorescence microscopy, and atomic force microscope. Results show that during the "chain-pyrolysis" process of CR, the sol content decreases, reaching a plateau after 3 batches and decreasing after 7 batches, indicating a decline in degradation degree. The particle size increases, whereas the rubber hydrocarbon content marginally rises, and the surface texture complexity diminishes with each batch. With an escalation in pyrolysis batch of CR, the penetration of the PCR/SBSCMA hits a minimum, the ductility gradually diminishes and the softening point slowly increases after 3 batches. The phase angle and non-recoverable creep compliance decrease, while the complex shear modulus and recovery rate enhance, significantly boosting the elasticity of the modified asphalt. The preparation of PCR and modification of PCR/SBSCMA contain the cleavage of sulfur bonds, the formation of oxygen functional groups, and the CR swelling. The uniform dispersion of polymer phases, presence of fine carbon black, and establishment of a stable colloidal system contribute the high-temperature mechanical properties and stability of the PCR/SBSCMA. The reduction of light components in the PCR/SBSCMA caused by swollen CR results in diminished surface roughness, disappeared "bee-like" structure, and improved homogeneity, which is conducive to low-temperature ductility. Overall, the PCR/SBS composite modification method promotes the high-quality and sustainable development of the utilization of waste tires and biomass in asphalt pavement.

Photonics of High-Entropy Polymers Revealing Molecular Dispersion via Polymer Mixing.

Blending multiple polymers together to form the so-called "high-entropy polymers (HEPs)" can generate the effects of molecular dispersion in addition to suppressing polymer phase separation. We embedded a semiconducting polymer (conjugated polymers, CPs) in an optically inert matrix composed of n polymer species and found that a molecule-level dispersion is attained in HEPs defined as n ≥ 5. In the regime of dilute CP concentrations, the photonic properties vary widely in the n = 1 matrices owing to diverse solubility parameters, but the distribution narrows with n, and the CP starts to exhibit behaviors of molecule-level dispersion at n ≥ 5, where the matrix polymers compete with each other to exert direct influences on the embedded CP. Specifically, for MEH-PPV, increasing n reduces the fluorescence redshift and spectral width from diminishing aggregation. For the rigid PFO molecules, increasing n creates a dilution effect facilitating formation of the low-energy planar β-phase. For the flexible regioregular P3HT-rr, HEPs offer well-dispersed amorphous chains highly susceptible to chain environments, thus influencing ηR's in the quasi-fixed amorphous-crystalline energy transfer landscape. The HEP effects continue for greater CP concentrations, consistent with the matrix dispersing behaviors in the dilute regime. This work demonstrates a molecular-level dispersion by HEPs, offering a method of molecular tailoring for polymer research and applications via simple mixing.

Thermal behavior of polymers and copolymers based on plant oils with differing saturated and monounsaturated content

AbstractPlant oil‐based acrylic monomers from hydrogenated sunflower (HFM), palm (PMM) and castor (CSM) oils were polymerized to investigate the effect of chemical composition on polymer phase transitions at temperatures relevant to physiological range. While HFM and PMM possess a highly differing content of saturated palmitic and stearic acids combined with unsaturated fatty acids, CSM contains primarily fragments based on monounsaturated ricinoleic hydroxy acid (up to 90%). Differential scanning calorimetry (DSC) measurements indicate that polymers from PMM and HFM are both semicrystalline (with Tm = −6 and −13 °C, respectively), while poly(CSM) appears to be amorphous (Tg = −49 °C). Considering the similarity in polymers' molar mass (Mn = 16 000–20 000 g mol−1), the observed thermal transitions can be explained by the formation of ordered morphological domains due to the presence of saturated palmitic and stearic acid fractions in poly(PMM) and poly(HFM). For copolymers of CSM, PMM and HFM (80 wt% of monomer feed) with styrene, DSC data show two transitions corresponding to the mobility of long alkyl fatty acid side fragments and the macromolecular backbone. For copolymers of PMM and HFM, comparable values (−52.8 and −55.5 °C, respectively) were obtained, while the second transition for poly(CSM‐co‐styrene) appears at 35 °C. We attribute this higher value to the presence of hydroxyl groups in ricinoleic acid fragments of CSM serving as additional chain transfer sites and the formation of macromolecular fractions enriched with polystyrene fragments. We expect that the temperature transitions obtained can be relevant to the future use of these polymers for biomedical applications, including the synthesis of polymer brushes. © 2024 Society of Chemical Industry.

Solid-state solvatochromism of oxazolidine in multi-functionalized copolymer nanoparticles: Development of advanced materials with multi-color fluorescence

Investigating the solvatochromism of stimuli-chromic compounds such as oxazolidine in polymer matrices with various polarities or functionalities is a unique approach to developing advanced materials for anticounterfeiting, sensor, optoelectronic, and displayers. In a novel strategy, multi-functionalized copolymer nanoparticles were synthesized by copolymerization of methyl methacrylate (MMA) with various functional comonomers in emulsion media for post-polymerization modification with oxazolidine and investigation of its solvatochromism in both colloidal solution and solid phase. The particle size and morphology of nanoparticles were influenced significantly by the polarity of functional groups, and the morphology evolution from sphere to anisotropic shapes was observed by increasing the polarity of functional groups. Investigation of oxazolidine solvatochromism in colloidal solution and solid polymer powders indicated different mechanisms for solvatochromism, in which the polarity of media is the main effective parameter in colloidal solution and the polarity of functional groups in the polymer structure is the main effective parameter in solid polymer phase. The solvatochromism of oxazolidine was confirmed by observed red shift and blue shift in UV–Vis and fluorescence spectra, in which the intensity of absorbance and emission peaks was changed as a function of the polarity of functional groups. Solvatochromic photoluminescent polymer nanoparticles were used for several advanced applications such as solid anticounterfeiting inks to information encryption, dual-mode visualization of latent fingerprints, and also development of organic light-emitting diodes (OLEDs). For the first time, the results indicate a significant effect of polymer chain local polarity induced by functional groups on the tuning of optical properties of the oxazolidine by the solid-state solvatochromic phenomenon. Solvatochromism of oxazolidine in functionalized polymer nanoparticles is an interesting approach to developing novel intelligent materials that have advanced applications in different fields such as anticounterfeiting and information encryption, optoelectronic, polarity sensor, and visualization of latent fingerprints.

Fabrication of hierarchically porous trabecular bone replicas via 3D printing with high internal phase emulsions (HIPEs)

Combining emulsion templating with additive manufacturing enables the production of inherently porous scaffolds with multiscale porosity. This approach incorporates interconnected porous materials, providing a structure that supports cell ingrowth. However, 3D printing hierarchical porous structures that combine semi-micropores and micropores remains a challenging task. Previous studies have demonstrated that using a carefully adjusted combination of light absorbers and photoinitiators in the resin can produce open surface porosity, sponge-like internal structures, and a printing resolution of about 150µm. In this study, we explored how varying concentrations of tartrazine (0, 0.02, 0.04, and 0.08 wt%) as a light absorber affect the porous structure of acrylate-based polymerized medium internal phase emulsions fabricated via vat photopolymerization. Given the importance of a porous and interconnected structure for tissue engineering and regenerative medicine, we tested cell behavior on these 3D-printed disk samples using MG-63 cells, examining metabolic activity, adhesion, and morphology. The 0.08 wt% tartrazine-containing 3D-printed sample (008 T) demonstrated the best cell proliferation and adhesion. To show that this high internal phase emulsion (HIPE) resin can be used to create complex structures for biomedical applications, we 3D-printed trabecular bone structures based on microCT imaging. These structures were further evaluated for cell behavior and migration, followed by microCT analysis after 60 days of cell culture. This research demonstrates that HIPEs can be used as a resin to print trabecular bone mimics using additive manufacturing, which could be further developed for lab-on-a-chip models of healthy and diseased bone.

L-Cysteine-Bonded Polymeric Monolithic Stationary Phase for Enantioseparation of Dansyl Amino Acids in Capillary Liquid Chromatography.

A chiral monolith stationary phase was fabricated by modifying the monolith surface using L-cysteine through a thiol-epoxy click reaction. L-cysteine-bonded polymer monolith was characterized by scanning electron microscopy/energy-dispersive X-ray and attenuated total reflectance Fourier-transformed infrared. The monomer content and modification temperature were carefully optimized to create a polymer monolith with excellent mechanical stability and permeability. Our findings revealed that the column morphology depended significantly on the porogen concentration and modification temperature for its morphology and efficiency. Adequate pores and binding sites were formed with the optimal porogen content, while a higher modification temperature improved the modification yield, enhancing peak shapes and increasing separation efficiency. The column demonstrated its capability for enantioseparation of dansyl glutamic acid, dansyl aspartic acid, dansyl methionine, and dansyl phenylalanine using a 60mM ammonium acetate buffer solution and acetonitrile in a 20:80 v/v ratio. It maintained good mechanical stability and repeatability with no relative standard deviation exceeding 7%. These results indicated that the L-cysteine-bonded polymer monolith has excellent potential as a chiral stationary phase.

Effects of Isocyanate Structure on the Properties of Polyurethane: Synthesis, Performance, and Self-Healing Characteristics.

Polyurethane (PU) plays a critical role in elastomers, adhesives, and self-healing materials. We selected the most commonly used aromatic isocyanates, 4,4'-methylene diphenyl diisocyanate (MDI) and tolylene-2,4-diisocyanate (TDI), and the most commonly used aliphatic isocyanates, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane-4,4'-diisocyanate (HMDI), as raw materials, combined with polytetramethylene ether glycol (PTMG) and 1,4-butanediol (BDO) to successfully synthesize five PU materials. The effects of isocyanate structure on polymerization rate, hydrogen bonding, thermal properties, phase separation, wettability, self-healing performance, adhesion, and mechanical properties were systematically investigated. The results show that isocyanates with higher symmetry facilitate hydrogen bonding, but excessive flexibility and crystallinity may inhibit its formation. MDI-based PU exhibits the highest hydrogen bonding index (HBI) of 4.10, along with the most distinct phase separation and the highest tensile strength of 23.4 MPa. HMDI-based PU demonstrates the best adhesion properties, with the highest lap shear strength of 7.9 MPa, and also exhibits excellent scratch healing ability. IPDI-based PU shows good self-healing performance, recovering 88.7% of its original tensile strength and 90.6% of its original lap shear strength after heating at 80 °C for 24 h. Furthermore, all the samples can be reprocessed by melt or solution methods, showing excellent recyclability.

The influence of CuxS particles on the thermal decomposition of anion exchangers

AbstractDue to the versality, surface imperfections and diverse redox chemistry of CuxS, hybrid ion exchangers (HIXs) containing these particles are an interesting object of research, including thermal transformation. The composite materials used for testing were strongly basic anion exchangers, with macroreticular (M) and gel-type structure (G), containing in the poly (styrene/divinylbenzene) skeleton fine particles of covellite/brochantite (M1), covellite (M2), covellite/digenite/djurleite (G1) and covellite/digenite (G2). The prepared HIXs contained 12–16 mass% S + Cu. They were subjected to thermal analysis under air and N2 to identify the role of the inorganic phase in decomposition of the polymeric phase. The results were discussed on the basis of the TG/DTG curves and X-ray diffraction (XRD) patterns of the solid residues (CuO after combustion, carbon/Cu2S after pyrolysis). It was found that CuxS in the resin phase exhibited oxidative activity promoting the combustion process. The polymeric skeleton of HIXs decomposed in air at a much lower temperature compared to pure resins (400 vs 600 °C). The TG/DTG curves had a model shape, three separate conversions occurring in a narrow temperature range, which indicated sequential decomposition. The low consumption of hydrogen for the reduction of CuxS to Cu2S during pyrolysis was not conducive to condensation of alkyl radicals and increase of the mass of carbon matter. The results advance the understanding of the effect of copper/sulfur-containing fine particles on the thermal decomposition of anion exchanger and can be useful in preparation of multifunctional carbon-containing composite materials.

Soft Matter Electrolytes: Mechanism of Ionic Conduction Compared to Liquid or Solid Electrolytes

Soft matter electrolytes could solve the safety problem of widely used liquid electrolytes in Li-ion batteries which are burnable upon heating. Simultaneously, they could solve the problem of poor contact between electrodes and solid electrolytes. However, the ionic conductivity of soft matter electrolytes is relatively low when mechanical properties are relatively good. In the present review, mechanisms of ionic conduction in soft matter electrolytes are discussed in order to achieve higher ionic conductivity with sufficient mechanical properties where soft matter electrolytes are defined as polymer electrolytes and polymeric or inorganic gel electrolytes. They could also be defined by Young’s modulus from about Pa to Pa. Many soft matter electrolytes exhibit VFT (Vogel–Fulcher–Tammann) type temperature dependence of ionic conductivity. VFT behavior is explained by the free volume model or the configurational entropy model, which is discussed in detail. Mostly, the amorphous phase of polymer is a better ionic conductor compared to the crystalline phase. There are, however, some experimental and theoretical reports that the crystalline phase is a better ionic conductor. Some methods to increase the ionic conductivity of polymer electrolytes are discussed, such as cavitation under tensile deformation and the microporous structure of polymer electrolytes, which could be explained by the conduction mechanism of soft matter electrolytes.

Highly porous polycaprolactone microspheres for skeletal repair promote a mature bone cell phenotype in vitro.

Improving our ability to treat skeletal defects is a critical medical challenge that necessitates the development of new biomaterials. One promising approach involves the use of degradable polymer microparticles with an interconnected internal porosity. Here, we employed a double emulsion to generate such round microparticles (also known as microspheres) from a polycaprolactone-based polymerised high internal phase emulsion (polyHIPE). These microspheres effectively supported the growth of mesenchymal progenitors over a 30-day period, and when maintained in osteogenic media, cells deposited a bone-like extracellular matrix, as determined by histological staining for calcium and collagen. Interestingly, cells with an osteocyte-like morphology were observed within the core of the microspheres indicating the role of a physical environment comparable to native bone for this phenotype to occur. At later timepoints, these cultures had significantly increased mRNA expression of the osteocyte-specific markers dentin matrix phosphoprotein-1 (Dmp-1) and sclerostin, with sclerostin also observed at the protein level. Cells pre-cultured on porous microspheres exhibited enhanced survival rates compared to those pre-cultured on non-porous counterparts when injected. Cells precultured on both porous and non-porous microspheres promoted angiogenesis in a chorioallantoic membrane (CAM) assay. In summary, the polycaprolactone polyHIPE microspheres developed in this study exhibit significant promise as an alternative to traditional synthetic bone graft substitutes, offering a conducive environment for cell growth and differentiation, with the potential for better clinical outcomes in bone repair and regeneration.

Nitrosyl hemoglobin formation from nitrite in normal and sickle blood

Sickle cell anemia is caused by a single mutation in the gene encoding the beta subunit of hemoglobin. Due to this mutation, sickle cell hemoglobin (HbS) polymerizes under hypoxic conditions, decreasing red blood cell deformability and leading to multiple pathological effects that cause substantial morbidity and mortality. Several pre-clinical and human studies have demonstrated that the anion nitrite has potential therapeutic benefits for patients with sickle cell disease. Nitrite is reduced to nitric oxide (NO) by deoxygenated hemoglobin contributing to vasodilation, decreasing platelet activation, decreasing cellular adhesion to activated endothelium, and decreasing red cell hemolysis; all of which could ameliorate patient morbidities. Previous work on extracellular hemoglobin has shown that solution phase HbS reduces nitrite to NO faster than normal adult hemoglobin (HbA), while polymerized HbS reduces nitrite slower than HbA. In this work, we compared the rate of nitrite reduction to NO measured by the formation of nitrosyl hemoglobin in sickle and normal red blood cells at varying hemoglobin oxygen saturations. We found the overall rate of nitrite reduction between normal and sickle red blood cells was similar and confirmed this result under partially oxygenated conditions, but normal red blood cells reduced nitrite faster than sickle red blood cells under anoxia where HbS polymerization is maximal. These results are consistent with previous work using extracellular hemoglobin where the rate of reduction by solution phase HbS makes up for the slower reduction by polymer phase HbS under partially oxygenated conditions, but the polymer phase kinetics dominates in the complete absence of oxygen.

Carboxymethyl Cellulose Enhanced Polymeric Form Stable Phase Change Materials with Reversible Transparency for Energy Storage

Carboxymethyl Cellulose Enhanced Polymeric Form Stable Phase Change Materials with Reversible Transparency for Energy Storage

Poly(4‐methoxyaniline) composites: Investigating structure–property relationship towards semiconducting applications

ABSTRACTConjugated polymers are essential materials for the organic optoelectronic industry, serving a pivotal role in cutting‐edge technologies. In this study, we conducted an integrated characterization approach, including spectroscopic techniques coupled with X‐ray diffraction analysis to explore the structure–property relationship of poly(4‐methoxyaniline), commonly referred to as poly(p‐anisidine) or PPA, along with two distinct ceramic composites: PPA/α‐Al2O3 and PPA/Eu2O3. From powder X‐ray diffraction analysis, a triclinic unit cell in space group P1 is proposed, after the whole powder pattern decomposition (WPPD) refinement is employed for the semicrystalline regions of the polymeric phases. Fractal‐like structures are observed, following analysis of small‐angle X‐ray scattering (SAXS) data and scanning electron microscopy (SEM) from which we could infer the approximate sizes of the fractal clusters. Pure PPA displays a glass transition temperature (Tg) of approximately 80°C and an electrical conductivity slightly above 10−5 S/cm. In contrast, the composite materials do not exhibit a glass transition temperature but perform better in terms of crystallinity and thermal stability. PPA/Eu2O3 present conductivity enhancement exceeding tenfold, surpassing 10−4 S/cm. These findings provide the baseline for further explorations on the development of organic electronic devices and sensors.

Implant dynamics, inner structure, and their impact on drug release of in situ forming implants uncovered through CT imaging

In situ forming implants (ISFIs) composed of biodegradable polymers and biocompatible solvents are generally designed for sustained drug release. In this study, a non-invasive computed tomography (CT) imaging approach is used to achieve real time imaging of ISFIs in vivo and in vitro using leuprolide acetate in situ forming implant as a model drug product. The process of implant formation, inner structure change and their impact on drug release were elucidated. Real-time drug distribution was unveiled by the CT contrast agent, iohexol, where it shows a core-shell structure of the deposition. The incorporation of leuprolide acetate (LA) led to a reduced extent of burst release, prolongated release profile, and extended implant size expansion. LA was found to interact with the solvent and slowed down the polymer phase inversion, thus significantly changed the drug distribution in the implant and reduced the drug release. The implant inner structure identified through SEM, implant size change, and polymer degradation along with the CT real time imaging all consistently support the implant formation differences and their implant on the drug release. Similar patterns of implant size expansion and iohexol distribution in the implants were observed both in vitro and in vivo for the implants with and without LA. The comprehensive understanding of the impact of implant formation on drug release through real time CT imaging facilitates the ISFI product development and evaluation.

Rapid Analysis of Sterols in Blood-Derived Samples.

Dysregulations of cholesterol biosynthesis are known to be associated with several pathologies. Due to the rapid growth of clinical investigations in this research area, a specific, fast, and valid method for analyzing cholesterol, its precursors, and metabolites is required. Here, we describe a rapid method for sample preparation, separation, and quantification of sterols in blood-derived samples using polymeric solid phase extraction followed by gas chromatography-mass spectrometry. The validated method demonstrates a reliable quantification of cholesterol, its precursors, and metabolites.

Structural modulation in colored polymer bands of methacrylic acid-based frontal polymerization

The periodic colored polymer bands have been investigated in frontal polymerization (FP) reaction containing methacrylic acid (MAA), hydroquinone, Benzoyl peroxide (BP), and N, N Dimethyl aniline (DMA) system. The MAA acts as a monomer, which was diluted adequately with methanol (MeOH), ethanol (EtOH), and butanol (BuOH) separately to observe the patterning characteristics in different reaction schemes. The structural modulations that include the periodicity of colored polymer bands, morphological changes, and spacings between two adjacent layers were studied. The colored variations of polymer bands and their dependency on the concentration of BP, hydroquinone and alcoholic compositions have been studied. The highly consistent pink-white colored polymer bands, loosely-packed band structures, and perfectly ordered band structures resulted in MeOH, EtOH, and BuOH systems, respectively, as discussed. The evolution of tiny bubbles and convection-type instability has been observed in different conditions of the FP reactions that significantly affect the planar movement of the polymer fronts. The hot spots, which usually represent the high-temperature regions of a typical frontal surface, have also been demonstrated in all reacting systems, which may cause spin mode propagation of the fronts and change the surface geometry, as described. The materials characterization was carried out using UV-visible spectrophotometer, NMR, FTIR, and FESEM techniques, providing information about the polymer phases involved in band structures, composition, and surface properties. The analytical data and results obtained during the study further emphasized that two different coloured polymers, namely 1, 4-dihydroxy anthraquinone methacrylic acid and poly-methacrylic acid dihydroxy, anthraquinone produced simultaneously and crystallized periodically, results in the development of a coloured polymer band structures. The possible reactions and associated chemical mechanisms concerning the observations, the nature of the monomer, and solvent characteristics have been proposed, which show a close agreement with the analytical data and results obtained during the study

Microalgae aggregation induced by thermoresponsive polymers

Algal biomass harvesting is one of key technical hurdles impeding the commercialization of algae-based biorefinery. The goal of this work is to develop an innovative technology for algae cell harvesting. Thermoresponsive polymers (TRPs) such as poly(N-isopropylacrylamide) (PNIPAM) and its derivatives were studied on their properties and potential applications for microalgae harvesting. Various PNIPAM was synthesized, and the effects of charge, molecular weight (MW), amine content, and polymer concentration on the polymer phase transition temperature, the degree of phase separation, and the harvesting of microalgae (Chlorella vulgaris) were investigated. The lower critical solution temperature (LCST) of PNIPAM decreased with the increase of polymer concentration, while the decline rate reduced under high MW. The amine content didn’t significantly affect the LCST of TRPs. Approx. 92 % of algae cells were harvested by PNIPAM-300 kDa. Modified TRPs showed few benefits in enhancing algae harvesting. TRPs are a promising class of polymers for microalgae harvesting.

Multifunctional polymeric stationary phases with enhanced hydrophilicity grafted with polyethyleneimine and polyglycidol

Two methods for increasing the degree of hydrophilization and screening of the sorbent matrix based on a copolymer of styrene and divinylbenzene grafted with polyethyleneimine quaternized with glycidol are proposed. The first method involves the polymerization of glycidol in the functional layer by varying the pH of the reaction medium, and the second method involves modifying the matrix by oxidizing the double bonds on its surface to obtain anchor epoxy groups. It was demonstrated that in the first method, the optimal approach is the twofold addition of glycidol before and after the addition of alkali, as in this case, the first addition of glycidol is consumed for the quaternization of polyamine, and the second for polymerization in ion-exchange centers. The new method of matrix modification, combined with the developed method of creating hydrophilic layers, significantly reduced the retention of oxyhalides, haloacetic acids, and polarizable anions in ion chromatography with suppressed background conductivity and amino acids in hydrophilic chromatography up to the point of changing the elution order. The obtained stationary phases are suitable for the simultaneous determination of standard inorganic anions, oxyhalides, and anions of haloacetic or alkylphosphonic acids in ion chromatography, as well as for the separation of amino acids, sugars, and vitamins in hydrophilic chromatography.

EIS Behavior of Polyethylene + Graphite Composite Considered as an Approximation to an Ensemble of Microelectrodes

The electrical percolation of alternating current through two-phase polyethylene/graphite composite electrodes with different contents of graphite microparticles immersed in aqueous KCl solutions has been studied. Above the graphite content of the first percolation threshold, the electrochemical impedance response of this electrode is associated with an equivalent circuit of resistance Ru in series with a constant phase element (CPE). An insulator material + conducting filler model is proposed in which the electroactive surface is considered as the intersection of the percolation cluster through the solid and the cluster associated with the interfacial region. CPE is analyzed assuming a distribution of microcapacitors of the graphite particles in contact with the dielectric solution and inside the dielectric polymeric phase.

Heat transfer mechanism of superabsorbent polymers phase change energy storage cold-formed steel wall under fire

The superabsorbent polymer phase change materials (SAP materials) exhibit exceptional water absorption and retention properties, offering substantial potential for fire protection in steel structures, thereby reducing the need for sheathing boards and fire-retardant coatings, while minimizing energy consumption. Understanding the heat-mass exchange theory of SAP materials is crucial for enhancing their application in the building industry. This study develops a comprehensive theoretical model for heat-mass exchange in cold-formed steel (CFS) walls incorporating SAP materials. An equilibrium phase change model and a simplified thermal radiation model were developed to capture the water loss and dynamic heat exchange processes in SAP materials. These models were integrated into a transient fluid-solid-thermal coupling model using Ansys Fluent and User Defined Functions. In the case study, the newly developed numerical models can accurately predict temperature field changes in CFS walls with SAP materials, demonstrating the heat transfer mechanisms of hot and cold flanges at different temperature rise stages. The developed numerical model was used to investigate the effects of factors such as the moisture content of the SAP material, web depth, and flange width on the fire resistance of the CFS wall. Results indicated that increasing the wall stud height improves fire resistance, while increasing flange width has little effect on hot flange temperature. These findings provide a theoretical foundation and practical guidelines for the application of SAP phase change insulation materials in the building industry, promoting energy reduction and supporting sustainable construction practices.