Molecular Chains Research Articles

Unlocking the Potential of Liquid Plasma Polymer Films: Characterizing Aging Effects and Their Impact on the Wrinkling Phenomenon.

Here, we present the study of the intricate dynamics between the physicochemical properties of liquid propanethiol plasma polymer films (PPFs) and the formation of wrinkles in PPF/Al bilayers. The study investigates the effect of liquid PPF aging in the air before top Al layer deposition by magnetron sputtering on the wrinkling phenomenon for 4 days. Thanks to atomic force microscopy, the wrinkle dimensions were found to decrease by approximately 55% in amplitude and 66% in wavelength, correlated with an increase in the viscosity of the PPF over the aging duration (i.e., from less than 107 to 1010 Pa·s). This behavior is not linked to alterations in cross-linking degree as evidenced by time-of-flight secondary ion mass spectrometry experiments but rather to network densification driven by the inherent molecular chain mobility due to the viscous state of the PPF. X-ray photoelectron spectroscopy measurements emphasizing the absence of oxidation of the PPF over the aging duration support this, revealing a unique aging mechanism distinct from other plasma polymer families. Overall, this study offers valuable insights into the design and application of mechanically responsive PPFs involved in bilayer systems, paving the way for advancements in nanotechnology and related fields.

Modeling and tracing of polycarbonate (PC) degradation in soil microcosm with a PC microplastics quantification method based on pyrolysis GC–MS

Understanding the migration and transformation of polycarbonate (PC) plastic wastes in the natural environment is crucial for assessing their environmental impact and bioremediation. In this study, PC plastic degradation was modeled and traced in soil microcosm by investigating physiochemical properties changes of PC, the formation of microplastics, and changes in soil microbial communities. Notably, PC microplastics quantification method was also successfully devised by pyrolysis gas chromatography mass spectrometry and also applied herein. Through gel permeation chromatography analysis, the molecular weight of the naturally aged PC film obviously reduced, whereas no change for unaged ones. After 12 months of soil burial, the surface corrosion and holes formation were emerged on the surfaces of both PC films in the non-sterilized soil harboring indigenous microorganisms by scanning electron microscope. The worsened thermal stability of both PC films in non-sterilized soil was demonstrated by thermogravimetric analysis. Meanwhile, the presence of increased hydroxyl group absorption and decreased carbonyl peak highlighted molecular chain breakage in both PC films by Fourier transform infrared spectroscopy. In particular, all the changes were more significant in aged PC than unaged ones. Furthermore, the increase of quantified PC microplastics on the surface of PC film in the non-sterilized soil accompanied the decreasing of microbial diversity and the enrichment of potential functional microorganisms. These findings revealed that the combination of natural aging and indigenous microbes exhibited a noticeable performance in PC plastics degradation in soil microcosm, providing new insights into the degradation mechanism of PC plastic wastes in the natural environment.

The impact of nanoparticle surface topography on the interfacial mechanical behavior and microstructure of polyvinyl alcohol composites

The interfacial mechanical strength between nanoparticle and matrix is one of the key factors affecting the mechanical properties of nanoparticulate-polymer composites. Based on the structural composition of a nanoscale iron particle/polyvinyl alcohol composite, this study employed molecular dynamics simulations to investigate the stress-response behavior and microstructural evolution of Fe/PVA/Fe interface models with different surface morphologies under both tensile and shear deformations. The results indicate that when the particle surfaces exhibit different rough structures, the interfacial tensile strength significantly increases with the absolute value of the interfacial binding energy. The order of tensile strength is Type-cube > Type-pyramid > Type-plane. Furthermore, during the shearing process, the protruding structures on the particle surfaces significantly hinder the deformation and unfolding of the matrix molecular chains. As the volume of the protruding structures increases, the interfacial shear strength decreases markedly. The research findings illuminate the mechanisms by which nanoparticle surface morphology at the microscopic molecular scale influences the mechanical properties of nanoparticle-polymer composite materials. These discoveries aid in selecting nanoparticle fillers that enhance the mechanical performance of polymer nanocomposites to a measurable extent.

A Biodegradable, Stretchable, Healable, and Self-Powered Optoelectronic Synapse Based on Ionic Gelatins for Neuromorphic Vision System.

Optoelectronic synapses have gained increasing attentions as a fundamental building block in the development of neuromorphic visual systems. However, it remains a challenge to integrate multiple functions into a single optoelectronic synapse that can be widely applied in wearable artificial intelligence and implantable neuromorphic vision systems. In this study, a stretchable optoelectronic synapse based on biodegradable ionic gelatin heterojunction is successfully developed. This device exhibits self-powered synaptic plasticity behavior with broad spectral response and excellent elastic properties, yet it degrades rapidly upon disposal. After complete cleavage, the device can be fully repaired within 1min, which is mainly attributed to the non-covalent interactions between different molecular chains. Moreover, the recovery and reprocessing of the ionic gelatins result in optoelectronic properties that are virtually indistinguishable from their original state, showcasing the resilience and durability of ionic gelatins. The combination of biodegradability, stretchability, self-healing, zero-power consumption, ease of large-scale preparation, and low cost makes the work a major step forward in the development of biodegradable and stretchable optoelectronic synapses.

Strong and tough semi-crystalline poly(aryl ether nitrile) with low coefficient of thermal expansion

The crystallization of poly (aryl ether nitrile) (PEN) has an essential impact on improving heat resistance, mechanical properties, chemical resistance, and dielectric properties. However, during the synthesis process, high crystallinity PEN is prone to precipitate out, which makes it difficult to carry out the synthesis reaction, which poses a significant challenge to synthesizing high crystallinity and high molecular weight PEN. In this work, hydroquinone (HQ) as the main phenolic monomer and 4,4′-biphenol (BP) as the second phenolic monomer were used to solve the technical difficulties in synthesis by copolymerization. The crystalline PEN with high molecular weight and significant crystallinity was obtained by regulating the molar ratio of BP to HQ. The effects of isothermal heat treatment on its crystalline, mechanical, and thermal properties were investigated. The influence laws of molecular chain structure and heat treatment process on the properties of PEN films were revealed. Among them, when the isothermal treatment temperature was 270 °C and the HQ: BP was 85:15, the mechanical strength reached 130 MPa, and the elongation at break could be up to an astonishing 50 %. Besides, the CTE value from 50 °C–150 °C is 40.84 ppm/°C, which is lower than most thermoplastics. Therefore, PEN with the HQ to BP molar ratio of 85:15 is suitable for large-scale production, providing new crystalline plastic specifications for high-performance special engineering plastics. A crystal bridge-tie chain model is summarized by the properties of HQ/BP-PEN films under different crystallization conditions, which provides an idea for preparing stiff and tough films.

Enhanced carbon black exfoliation through elongational flows for faster and higher value-added rubber recycling

The recycling of rubber featuring intricate three-dimensional crosslinked networks necessitates the application of cutting-edge technology and specialized machinery. In this study, the rubber was recycled by mechanochemistry under elongational flow field. The crosslink bonds in the rubber were rapidly broken through the high extension of molecular chains, without the need for additives or additional refinements. At 200 °C, the waste rubber is devulcanized in only 2 min so that the sol molecular weight reached an impressive 3.3 × 104 g/mol, and the mechanical properties of the reclaimed rubber were significantly enhanced, reaching a tensile strength of 17.44 MPa. The elongational flow field devulcanizes the waste rubber while simultaneously achieving rapid refinement of rubber particles and exfoliating the carbon black from the crosslinked network. These making reclaimed rubber forms a micro-nano microstructure in natural rubber (NR), which makes particle reinforcement of the NR-matrix. Faster and high-value-added rubber recycling achieved successfully through elongational flows.

PH-Responsive, Wide Color Gamut Dynamic Color Display Enabled by PDMAEMA Brush-Based Fabry-Perot Resonant Cavity.

Dynamic color-changing materials have attracted broad interest due to their widespread applications in visual sensing, dynamic color display, anticounterfeiting, and image encryption/decryption. In this work, we demonstrate a novel pH-responsive dynamic color-changing material based on a metal-insulator-metal (MIM) Fabry-Perot (FP) cavity with a pH-responsive poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) brush layer as the responsive insulating layer. The pH-responsive PDMAEMA brush undergoes protonation at a low pH value (pH < 6), which induces different swelling degrees in response to pH and thus refractive index and thickness change of the insulator layer of the MIM FP cavity. This leads to significant optical property changes in transmission and a distinguishable color change spanning the whole visible region by adjusting the pH value of the external environment. Due to the reversible conformational change of the PDMAEMA and the formation of covalent bonds between the PDMAEMA molecular chain and the Ag substrate, the MIM FP cavity exhibits stable performance and good reproducibility. This pH-responsive MIM FP cavity establishes a new way to modulate transmission color in the full visible region and exhibits a broad prospect of applications in dynamic color display, real-time environment monitoring, and information encryption and decryption.

Discrete polyketones: synthesis, derivatization, and potential applications

Abstract The present account reviews recent progress in the synthesis, functionalization, and application of discrete polyketones. Whereas most polyketones are synthesized as polydisperse polymers with various molecular chain lengths and sizes, discrete polyketones are obtained in chemically pure forms. This allows precise structural analysis using nuclear magnetic resonance and X-ray diffraction. Discrete polyketones have been used to determine the critical chain length that distinguishes the crystallization behaviors of small molecules from those of macromolecules. Calix[3]pyrrole, which is a ring-contracted analogue of porphyrinogen, was first obtained from a cyclic hexaketone. The discovery of the strain-induced ring expansion reaction of calix[3]pyrroles has provided an important insight into solving a long-standing enigma in porphyrin synthesis. Chemical derivatization of discrete polyketones using ketone-derived transformations has resulted in the generation of various functional molecules for potential applications. These molecules have been used to develop several materials, including luminescent chromophores, ion adsorbents, drug–drug conjugates, and microfluidic devices for cancer diagnosis.

Enhancing the foamability of poly(L-lactide-co-ε-caprolactone) through formation of stereocomplex crystal by introducing of poly(D-lactic acid)

The bio-elastomer poly (L-lactide-co-ε-caprolactone) (PLCL) with linear random molecular chain structure exhibits low viscosity and melt strength, resulting in poor foamability, cell merging, or collapse during the foaming process. Consequently, PLCL foams have large cell sizes and low cell densities, limiting their use as biodegradable elastomeric foams. To enhance the foamability of PLCL, poly (D-lactic acid) (PDLA) was incorporated into the PLCL matrix. Stereocomplex crystals (Sc-crystals) formed between the L-LA segments of PLCL and the molecular segments of PDLA. The effects of varying PDLA content on the basic properties and foaming behavior of the blends were investigated. Results indicate that optimal Sc-crystal formation occurs in the PLCL/PDLA-10 blend. The presence of Sc-crystals enhances melt strength and facilitates cell nucleation, reducing cell size from 351.2 to 11.8 μm and increasing cell density from 1.4 × 104 to 1.7 × 108 cells/cm³. Consequently, the mechanical properties of the foam are significantly improved. The Sc-crystal formation between PLCL and PDLA provides an effective method to enhance the processability of linear chain copolymers containing L-lactide.

Enhanced EMI shielding effectiveness of green Eucommia ulmoides gum composites through heterogeneous and crystalline structures

In order to mitigate the increasing severity of electromagnetic interference (EMI), it is imperative to develop advanced rubber composites. Despite recent advancements in structural design and filler hybridization for enhancing their EMI shielding performance, challenges persist in terms of suboptimal mechanical properties and intricate processing techniques. To overcome these limitations, bio-based Eucommia ulmoides gum (EUG) composites with segregated network structures were fabricated by simple mechanical blending, capitalizing on the characteristics of highly cross-linked rubbers with restricted molecular chains. Highly cross-linked EUG (HCE) effectively segregated the conductive fillers into the EUG phase, while the crystallization of EUG promoted the dispersion of fillers within the amorphous region of the EUG. Therefore, a highly efficient 3D conductive network was formed due to the segregated structure and crystallization, enabling the EUG/HCE/CNT composite to achieve an exceptional shielding effectiveness (SE) value of 83.0 dB with a high absorption loss ranging from 8.2 GHz to 12.4 GHz.

Creation of fully degradable and mechanically robust poly(4-hydroxybutyrate) films by filling modified starch

Chemically synthesized poly(4-hydroxybutyrate) (P4HB) is a new generation of biomass-derived and degradable semi-crystalline polymer with good comprehensive properties, but high costs limit its application. Starch, as an inexpensive natural polymer, can reduce the cost of P4HB products. However, starch lacks thermoplastic behavior and has poor compatibility with P4HB, thus its extensive use will inevitably impair the mechanical properties of P4HB. In this study, the ball-milling starch grafting process is adopted, which can simultaneously solve the two major deficiencies of starch, and the prepared ball-milling starch-g-polycaprolactone (BSt-g-PCL) has thermoplasticity and better compatibility with P4HB. BSt-g-PCL can melt near 55 °C, and the interweaving of its molecular chains with P4HB reduces the binding energy (Einteraction) of both, making the phase interface blurred or even disappear. Therefore, the elongation at break retention (REB) of P4HB/BSt-g-PCL can increase from 37.1 % to 74.3 % compared to P4HB/starch at the same filling (70 Phr). Additionally, BSt-g-PCL can exert the effect of accelerating P4HB degradation and still make it maintain excellent anti-aging ability. The ball-milling starch graft process provides a simple and effective method for the preparation of inexpensive fully biodegradable P4HB composite films with excellent mechanical properties.

LNMR analysis of the retention of different guar gum structure in sandstone: Based on a new characterization method

The adsorption and retention damage of guar gum to reservoirs are important factors affecting the effectiveness of hydraulic fracturing. Accurately understanding and evaluating the adsorption and retention of guar gum can better support the research of low-damage fracturing fluid. However, previous indoor evaluation methods have some limitations in studying the adsorption and retention characteristics of guar gum. The analysis object of low-field nuclear magnetic resonance (LNMR) is water rather than guar gum, which cannot achieve visualization of guar gum retention. In addition, Ordinary guar gum (GG), hydroxypropyl guar gum (HPG), and carboxymethyl guar gum (CMG) are commonly used in the hydraulic fracturing of sandstone gas reservoirs, but there are very few studies that focus on the differences in the adsorption and retention damage of the three guar gums from a microscopic perspective. In this study, a new characterization method for evaluating the retention of polymer in fracturing fluid based on the principles and properties of LNMR was proposed. This method can quantitatively evaluate the amount of guar gum adsorption retention and achieve a visual evaluation of the adsorption and retention of guar gum in cores. The aggregation characteristics of guar gum in porous media can be reflected. The dynamic retention process of GG, HPG, and CMG in sandstone cores was directly characterized through this method. The aggregation and entanglement characteristics of the three types of guar gum in sandstone were analyzed from the structure of guar gum. The experimental results show that the difference in molecular weight and modified groups of guar gum has an impact on its adsorption and retention. The molecular chain after the gel-breaking of GG was longer due to the large molecular weight. Long chains and intramolecular hydrogen bonds caused a larger curling degree of GG molecules. The entanglement degree of guar gum increased due to the introduction of non-ionic long-chain hydroxypropyl. The introduction of anionic carboxymethyl made CMG molecules more stretched due to electrostatic repulsion. The median particle size of the gel breaking liquid of GG was 10.65 μm, HPG was 8.8 μm, and CMG was 5.88 μm. A larger molecular particle size after guar gum gel breaking would aggravate the retention in sandstone porous media. After 150 min of displacement, the adsorption and retention amount of GG in the core was 4.59 mg/g, HPG was 4.17 mg/g, and CMG was 3.86 mg/g. The compactness of aggregates formed by guar gum in the core was HPG > GG > CMG. The gas flooding can relieve the adsorption and retention of guar gum. The higher the degree of entanglement of guar gum molecules, the more difficult to remove them from the core. The flowback degree of gas flooding of GG was 10.2%, HPG was 6.8%, and CMG was 21.9%. This research provides an experimental strategy for the microscopic evaluation of polymer adsorption and retention in rock porous media. The research results provide a deep understanding of the microscopic characteristics of guar gum adsorption and retention from the perspective of guar gum structure, which has some significance for guiding the optimization of fracturing fluid and the study of low-damage fracturing fluid.

Silk fibroin wetting stability film induced by polyamide-amine-epichlorohydrin (PAE) for intelligent sensing system

Protein materials gain new functions and applicability through redesigns in protein structure and engineering confer. However, the application and development of proteins for use in flexible devices that fit in flexible devices that fit the surface of human skin is hindered by their poor wet stability. Here, we described the design of wet-stable materials based on the reconstruction of silk fibroin (SF). The combination of polyamide-amine-epichlorohydrin (PAE) was used as a traction rope to bring SF molecular chains closer to each other, to facilitate the self-assembly of SF through branching and lengthening of molecular chains, and change its crystalline structure. SF/PAE composite films that exhibited huge improvement in ductility and wet stability were combined with flexible SF substrates via patterning and ion sputtering to prepare flexible sensors. In addition, the SF/PAE sensing system equipped with a microprocessor and Bluetooth module enabled the real-time remote acquisition of human health signals such as vocal cords, joints, pulse and meridians. This reconfiguration of the SF structure will advance the systematic exploration of protein structures and the development of protein materials for intelligent device applications.

Structural characterization and in vitro digestibility of rice starch processed with the combination of ultra‐high pressure homogenization, debranching, and temperature‐cycled crystallization

AbstractThis study examined the structural characterization and in vitro digestibility of rice starch processed with the combination of ultra‐high pressure homogenization (UHPH), debranching, and temperature‐cycled crystallization under various pressures (0–160 MPa). After UHPH treatment, the degree of branching (DB) of processed starches (0.65%–2.03%) was lower than that of the native rice starch (NS, 2.96%). Assessment of chain length distribution suggested that the considerable amylose was produced after treatments. Processed starches exhibited an irregular fragmented structure, and the crystalline structure was transformed from A‐type (native rice starch) into B + V‐type (processed starches). Moreover, the relative crystallinity (RC) and the absorbance ratio of 1047/1022 cm−1 (R1047/1022) of processed starches decreased from NS (RC, 22.99%; R1047/1022, 0.79) to 13.47%–18.21% (RC) and 0.51–0.78 (R1047/1022), respectively. Iodine binding curves revealed that processed starches possessed the higher degree of polymerization (DP). Furthermore, the contents of slowly digestible starch (SDS) and resistant starch (RS) increased in all processed starches, and the RS content of starch treated under 160 MPa (35.33%) was notably greater than that of native starch (9.37%). These results suggested that the UHPH can be used as a pretreatment strategy to reduce the digestibility of starch products.Practical applicationsUHPH pretreatment disrupts starch molecular chains to produce the large amounts of short linear amylose. Debranching followed by temperature‐cycled crystallization can increase the content of resistant starch (RS), yielding a raw material suitable for boosting the health of the digestive system and overall health. Therefore, UHPH pretreatment has a high application value in the field of starch modification.

Scalable Fabrication of Quasi-One-Dimensional van der Waals Ta2Pt3Se8 Nanowire Thin Films via Solution Processing for NO2 Gas Sensing over Large Areas.

Solution-based processing of van der Waals (vdW) one- (1D) and two-dimensional (2D) materials is an effective strategy to obtain high-quality molecular chains or atomic sheets in a large area with scalability. In this work, quasi-1D vdW Ta2Pt3Se8 was exfoliated via liquid phase exfoliation (LPE) to produce a stably dispersed Ta2Pt3Se8 nanowire solution. In order to screen the optimal exfoliation solvent, nine different solvents were employed with different total surface tensions and polar/dispersive (P/D) component (P/D) ratios. The LPE behavior of Ta2Pt3Se8 was elucidated by matching the P/D ratios between Ta2Pt3Se8 and the applied solvent, resulting in N-methyl-2-pyrrolidone (NMP) as an optimal solvent owing to the well-matched total surface tension and P/D ratio. Subsequently, Ta2Pt3Se8 nanowire thin films are manufactured via vacuum filtration using a Ta2Pt3Se8/NMP dispersion. Then, gas sensing devices are fabricated onto the Ta2Pt3Se8 nanowire thin films, and gas sensing property toward NO2 is evaluated at various thin-film thicknesses. A 50 nm thick Ta2Pt3Se8 thin-film device exhibited a percent response of 25.9% at room temperature and 32.4% at 100 °C, respectively. In addition, the device showed complete recovery within 14.1 min at room temperature and 3.5 min at 100 °C, respectively.

Cross-linking affecting properties and in-vitro digestibility of starch-sucrose ester complexes

This study investigated the effects of cross-linking on the characteristics and in-vitro digestibility of starch-sucrose ester (SE) complexes. To achieve this, corn starch (CS) was cross-linked with various concentrations of sodium trimetaphosphate /sodium tripolyphosphate (5 %, 10 %, and 15 %). Subsequently, cross-linked starches (CLS) were complexed with SE through hydrothermal treatment. X-ray diffraction analysis revealed that V-type amylose-lipid complexes formed by the interaction between CS and SE. The resultant CS-SE complex significantly reduced CS digestibility, increasing its resistant starch (RS) content from 10.19 % to 22.71 %. The cross-linking modification did not alter the crystalline pattern of the CS-SE complex. Several CLS-SE complexes demonstrated higher enzymatic resistance compared to the CS-SE complex. The CLS10-SE complex exhibited the highest RS content of 39.37 % when the cross-linking agent concentration was 10 %. This phenomenon may be attributable to the cross-linking reaction having enhanced the interaction between starch molecular chains, reducing the solubility and swelling power, thereby hindering the accessibility of starch chains to digestive enzymes. These findings indicate that cross-linking modification is a practical approach to improving the anti-digestion performance of starch-lipid complexes.

Laboratory investigations on influence of thermoplastic polyurethane and its hard segment content on pavement performance of asphalt mixture

ABSTRACT Thermoplastic polyurethane (TPU) is an excellent asphalt modifier, which is consisted of hard and soft segments in the TPU molecular chain. In this paper, The conventional road performances (high and low temperature performance, water stability, fatigue performance and aging resistance) of TPU modified asphalt mixture (TPU-AM) with different hard segment content were evaluated. The results proved that the hard segment of TPU can effectively improve the high temperature performance of asphalt. Compared with TPU-AM with high hard segment content, using TPU with low hard segment content as modifier, the low temperature flexibility and fatigue resistance of TPU-AM are significantly improved. TPU-AM with hard segment content of 40% has excellent high temperature performance, while the TPU-AM with hard segment content of 10% has the best fatigue ability and low temperature performance. The water stability of TPU-AM is obviously stronger than that of base asphalt mixture, although the content of TPU hard segment has little influence on the water stability of TPU-AM. The aging results show that TPU-AM has the best aging resistance when the hard segment content is 30%. Based on the above analysis, the high performance of TPU-AM can be designed by changing the hard segment content.

Synthesis and properties of novel biobased poly(hexamethylene 2,5-furandicarboxylate)-b-poly(diethylene glycol 2,5-furandicarboxylate) multiblock copolyesters

Two poly(hexamethylene 2,5-furandicarboxylate)-b-poly(diethylene glycol 2,5-furandicarboxylate) multiblock copolyesters were synthesized using two hydroxyl-terminated poly(hexamethylene 2,5-furandicarboxylate) (PHF-diol) and poly(diethylene glycol 2,5-furandicarboxylate) (PDEGF-diol) prepolymers in the presence of a chain extender hexamethylene diisocyanate. A series of techniques were employed to fully characterize the thermal, mechanical, and crystallization properties of the obtained multiblock copolyesters. 1H NMR results confirmed the expected multiblock structures. The combination of the two segments significantly improved the elongation at break of PHF without sacrificing the tensile strength. Moreover, the melt crystallization temperatures and melt points of the multiblock copolyesters only slightly decreased, due to the excellent crystallizability of the PHF segment. In addition, the PDEGF segment significantly influenced the tensile strength and hydrophilicity by forming hydrogen bonds between the adjacent molecular chains.

Unlocking interfacial synergies: In situ multi-step reaction-induced control for high-performance and functional polybutylene terephthalate/polyolefin blends from recycled sources

This investigation employed free radical melt grafting technology for the synthesis of (POE/R-LLDPE)-g-(GMA-co-St) graft copolymers. Subsequently, this graft copolymer was applied as a modifier for poly (butylene terephthalate) (PBT) resin. The effects of varying recycled linear low-density polyethylene (R-LLDPE) contents in the graft on the rheological behavior, thermal properties, mechanical properties, and toughening mechanism of PBT/(POE/R-LLDPE)-g-(GMA-co-St) blends were exhaustively explored. The findings revealed that glycidyl methacrylate (GMA) and styrene (St) were effectively grafted onto the poly (ethylene-octene) (POE) and R-LLDPE molecular chains. This process enabled the epoxy groups in the GMA of the graft to react with the terminal groups of the PBT resin, thereby enhancing its compatibility with PBT. The use of R-LLDPE-g-(GMA-co-St) or POE-g-(GMA-co-St) as singular modifiers did not produce optimal modification results. Conversely, the most effective modification of the PBT resin was observed when both were combined, indicating a pronounced synergistic modification effect. The optimal overall performance of the blend was noted when the R-LLDPE content in the graft copolymer was 50 wt%. This method significantly enhanced the toughness of the blend while preserving excellent thermal stability and mechanical strength, concurrently reducing the product cost. At this point, a high concentration of voids was observed in the stress-whitening area of the impact specimens. The PBT matrix displayed conspicuous shear yielding with a notably rough impact fracture surface, manifesting highly significant tough fracture characteristics.

Single‐step preparation of intrinsic solid–solid phase change materials with excellent anti‐leakage and form‐stable performance

AbstractPhase change materials (PCM) often encounter severe problems of leakage and shape collapse concerns. Chemical modification methods, utilizing chemical bonds to bind phase change molecular chains, have the potential to address the above‐mentioned problems radically. However, this approach often entails the use of expensive raw materials and complex processes. Therefore, a simple one‐pot preparation method had been reported using earth‐abundant and inexpensive octadecyl methacrylate (OMA) and 1,6‐hexanediol diacrylate (HD) as raw materials to prepare PCM with a molecular structure of cross‐linked polymer main chains and phase change side chains through free radical polymerization. Owing to the three‐dimensional polymer main chain structure, it exhibited excellent leakage‐proof performance, maintaining its form‐stable nature at 70°C with no obvious leakage observed during the phase change process, confirming it to be an excellent intrinsic solid–solid PCM (SSPCM). Additionally, the introduction of the cross linking segment significantly improves its thermal stability, and the 50% degradation temperature increased significantly from 228.8 to 355.9°C. Moreover, the latent heat increased with the decrease of the crosslinking density until the molar ratio of HD/OMA was reduced to 1/40 and then tended to reach constant. At the optimal ratio the latent heat of SSPCM can reach 88.23 J g−1. Excessive crosslinking density will affect the stacking tightness of molecular chains during the crystallization process, thereby reducing the latent heat.