Thermal Transition Research Articles

Surface Passivation of Polymer Based Redistribution Layers for Area Selective Deposition of an Oxygen Barrier

Heterogeneous 3D integration is being hailed as the driver for new technologies due to its stacked device architecture. This increases functionality as the number and length of interconnecting wires decreases, in turn decreasing power consumption. In these advanced packaging technologies, the metal redistribution layers (RDLs) and the insulating polymer surrounding them are crucial components on which stringent reliability requirements are placed. The metal RDL’s are necessary to reroute signals from device level to packaging level. The polymer insulator, used as an alternative to traditional dielectric materials, must (i) be photosensitive to be compatible with lithography processing steps, (ii) possess high mechanical strength, (iii) exhibit good electrical performance, (iv) have a high thermal stability and glass transition temperature, and crucially (v) it must not be hygroscopic. Low or no moisture uptake of the polymer is essential as any moisture can cause mechanical and electrical reliability issues. Absorbed moisture can cause oxidation of Cu lines leading to the well-known problem of Cu diffusion resulting in voids, contact issues, delamination, electromigration and higher leakage currents.Area selective deposition (ASD) could greatly benefit these RDL’s by preferentially depositing an oxygen barrier to stop the oxidation of the Cu lines. The proprietary polymer used in this work is part of the WPR series by JSR Corporation and is a thermosetting phenol-based polymer which displays a high mechanical stability as it contains rubber nanoparticles, 70 nm in diameter. These are added to the polymer to increase the toughness and to prevent cracks and fractures forming and propagating through the film. However, achieving ASD with this polymer is difficult as the polymer is designed to have good adhesion properties so it will easily adhere to the Cu in the metal lines, and there are two materials of interest to passivate, the polymer itself and the rubber nanoparticles.In this work the surface is passivated by utilizing a polymerizing octafluorocyclobutane (C4F8) plasma which creates a Teflon-like film on the surface. The surface morphology and hydrophobicity are investigated to assess the best plasma exposure time, which was found to be 30 s. Surface chemistry from XPS analysis reveals surface modification through the deposition of fluorine rich groups from the 30 s C4F8 plasma exposure, Figure 1(a). Water contact angle measurements reveal an initial hydrophobic surface (~94°) but this hydrophobicity decreases over the course of several seconds. Following the 30 s C4F8 plasma exposure, the hydrophobicity increases significantly to above 110° and remains stable as shown in Figure 1(b). Surface morphology studies carried out by AFM demonstrates no increase in surface roughness following plasma exposure, Figure 1(c) and (d). ALD tests show the process to be selective to the tetrachloride family of ALD precursors. No selectivity was observed with tetrakis (dimethylamino) or isopropoxide based precursors. This process has the capability to block approximately 2 nm of TiO2 and HfO2 from these tetrachloride precursors. Studies of the same process on Cu substrates show that the metal surface is only temporarily modified, and ALD growth can still take place. Reliability stress and corrosion tests were performed to assess if the selectively deposited barriers could prevent Cu oxidation.Figure 1(a) C 1s XPS spectra showing difference before and after plasma treatment, (b) WCA value increases following plasma treatment, and AFM images in (c) and (d) show no change in the surface following plasma exposure. Figure 1

Using carboxyl groups to improve the compatibility of XNBR/lignin composites

AbstractThe paper and pulp industry produces lignin as a byproduct, which could be a bio‐based reinforcing filler for rubber. Carboxylated nitrile rubber (XNBR) contains carboxyl groups that form ionic bonds with zinc oxide, potentially increasing compatibility with lignin, compared to usual nonpolar rubbers. This study employed the traditional mixing method, two‐roll mill, to incorporate hardwood Kraft lignin without chemical or physical modification as a reinforcing filler in commercial XNBR. A mixture design of experiments was used to explore the effect on rubber/lignin interaction of the carboxyl group content (from 1% to 7% in blends of XNBR) and the amount of lignin (from 0 to 40 phr). Adding 40 phr of lignin increased stress at 100% in XNBR 7% from 1.7 to 6.3 MPa. In XNBR 1%, the increase was from 1.2 to 1.9 MPa. Lignin showed better interaction and dispersion with XNBR 7%, determined from response surface of G′ at high deformations and SEM, respectively. Loss of thermal transition in DMA indicates interaction through ionic groups. These results show that the presence of carboxyl groups enhances the rubber/lignin interaction. This research open possibilities of compatibilization of lignin, offering guidance for future studies and technologies involving lignin in technical applications.Highlights Lignin dispersion increased as the carboxyl group content increased to 7% (w/w). Stress at 100% elongation increased 370% with 40 phr of lignin and 7% carboxyl. Rubber/lignin interaction as per G′ increased with carboxyl groups. Loss of thermal transition suggests lignin/carboxy/zinc oxide interaction. Lignin can be used as a reinforcing filler in nitrile carboxylated rubber.

Novel lactoferrin-conjugated gallium complex to treat Pseudomonas aeruginosa wound infection

Pseudomonas aeruginosa is one of the leading causes of opportunistic infections such as chronic wound infection that could lead to multiple organ failure and death. Gallium (Ga3+) ions are known to inhibit P. aeruginosa growth and biofilm formation but require carrier for localized controlled delivery. Lactoferrin (LTf), a two-lobed protein, can deliver Ga3+ at sites of infection. This study aimed to develop a Ga-LTf complex for the treatment of wound infection. The characterisation of the Ga-LTf complex was conducted using differential scanning calorimetry (DSC), Infra-Red (FTIR) and Inductive Coupled Plasma Optical Emission Spectrometry (ICP-OES). The antibacterial activity was assessed by agar disc diffusion, liquid broth and biofilm inhibition assays using the colony forming units (CFUs). The healing capacity and biocompatibility were evaluated using a P.aeruginosa infected wound in a rat model. DSC analyses showed thermal transition consistent with apo-lactoferrin; FTIR confirmed the complexation of gallium to lactoferrin. ICP-OES confirmed the controlled local delivery of Ga3+. Ga-LTf showed a 0.57 log10 CFUs reduction at 24 h compared with untreated control in planktonic liquid broth assay. Ga-LTf showed the highest antibiofilm activity with a 2.24 log10 CFUs reduction at 24 h. Furthermore, Ga-LTf complex is biocompatible without any adverse effect on brain, kidney, liver and spleen of rats tested in this study. Ga-LTf can be potentially promising novel therapeutic agent to treat pathogenic bacterial infections.

Design of Experiments to Compare the Mechanical Properties of Polylactic Acid Using Material Extrusion Three-Dimensional-Printing Thermal Parameters Based on a Cyber-Physical Production System.

The material extrusion 3D printing process known as fused deposition modeling (FDM) has recently gained relevance in the additive manufacturing industry for large-scale part production. However, improving the real-time monitoring of the process in terms of its mechanical properties remains important to extend the lifespan of numerous critical applications. To enhance the monitoring of mechanical properties during printing, it is necessary to understand the relationship between temperature profiles and ultimate tensile strength (UTS). This study uses a cyber-physical production system (CPPS) to analyze the impact of four key thermal parameters on the tensile properties of polylactic acid (PLA). Layer thickness, printing speed, and extrusion temperature are the most influential factors, while bed temperature has less impact. The Taguchi L-9 array and the full factorial design of experiments were implemented along with the deposited line's local fused temperature profile analysis. Furthermore, correlations between temperature profiles with the bonding strength during layer adhesion and part solidification can be stated. The results showed that layer thickness is the most important factor, followed by printing speed and extrusion temperature, with very close influence between each other. The lowest impact is attributed to bed temperature. In the experiments, the UTS values varied from 46.38 MPa to 56.19 MPa. This represents an increase in the UTS of around 17% from the same material and printing design conditions but different temperature profiles. Additionally, it was possible to observe that the influence of the parameter variations was not linear in terms of the UTS value or temperature profiles. For example, the increase in the UTS at the 0.6 mm layer thickness was around four times greater than the increase at 0.4 mm. Finally, even when it was found that an increase in the layer temperature led to an increase in the value of the UTS, for some of the parameters, it could be observed that it was not the main factor that caused the UTS to increase. From the monitoring conditions analyzed, it was concluded that the material requires an optimal thermal transition between deposition, adhesion, and layer solidification in order to result in part components with good mechanical properties. A tracking or monitoring system, such as the one designed, can serve as a potential tool for reducing the anisotropy in part production in 3D printing systems.

Physicochemical, Rheological, and Thermal Properties of Pot-Honey from the Stingless Bee Melipona beecheii

The availability of data on physicochemical properties is crucial to direct efforts towards identifying the quality standards of the Neotropical stingless bee Melipona beecheii’s pot-honey. In this vein, other properties apart from those typically considered for Apis mellifera could also be relevant in characterizing the honey of this stingless bee. The physicochemical, rheological, and thermal properties of pot-honey from Melipona beecheii (Yucatán, México) were analyzed. Samples were collected from two annual harvests (2018 and 2019) and from a rural and an urban location. Free acidity, moisture, total reducing sugars, diastase activity, hydroxymethylfurfural content, and electrical conductivity were measured using standard techniques. The rheological and thermal behaviors were determined via Couette rheometry and differential scanning calorimetry, respectively. The physicochemical properties of Melipona beecheii pot-honey can be incorporated into a general quality specification for honey of the Neotropical Melipona genus, or as the basis for a regional (Mesoamerican) standardization of honey from this particular bee species. The rheological analyses indicated the Newtonian behavior of Melipona honey in the full studied range of 10-40 °C (7,545-244 cp), showing dynamic viscosities significantly lower than those expected for Apis mellifera honey, primarily due to its high water content. Two main endothermic transitions were detected via differential scanning calorimetry: at 96-162 °C and at 169-230 °C. The Apis mellifera honey samples showed the same thermal transitions but differed from Melipona beecheii honey in their peak temperatures and enthalpies.

Enhanced electrochemical and thermal stability of CdS:Pb2+, Cu2+ co-doped nanoparticles on energy storage applications

For the first time, we prepared the Pb2+, Cu2+ co-doped CdS nanoparticles that were prepared by a simple chemical precipitated method. Structural and lattice parameters were determined by XRD. It was found that mixed cubic-hexagonal crystal structure for the co-doped nanoparticles. Polyvinylpyrrolidone (PVP) was used as a surfactant to control particle size. The organic functional group's presence in the surfactant was identified by FT-IR. Two distinct morphologies were found for the co-doped sample that was studied by TEM. TG–DTA was used to study thermal stability and phase transition of the sample. CV analysis was used to determine the potential window of oxidation and reduction of the sample. In addition, VSM exhibits diamagnetic behavior for CdS:Pb:Cu nanoparticles. We found that the excellent electrochemical, thermal and magnetic properties of the co-doped CdS nanoparticles can be used for electrochemical energy storage applications.

Understanding the link between fragile-to-strong kinetics and β-relaxation in chalcogenide glasses

β-relaxation has been a universal behavior in various glasses with bond kinds of covalent and metallic, as well as the metavalent, which is the typical bonding of chalcogenide phase-change materials (PCMs). Recently, the fragile-to-strong (F–S) transition kinetics has been a significant feature in supercooled liquids of PCMs, to alleviate the contradiction between good thermal stability nearby glass transition temperature and fast crystallization speed around melting temperature. By analyzing the results from the measurements of powder mechanical spectroscopy and flash differential scanning calorimetry, in this work, we revealed the link between β-relaxation and F–S crystallization kinetics in GeTe-GeSe chalcogenide glass system. It was found a positive correlation between β-relaxation and F–S transition, which is accompanied by the results of resistance drift, crystallization temperature, as well as the maximum crystal growth rate. However, the GeTe component, which has large β-relaxation behavior but no F–S transition, does not obey the positive correlation because of the large activation energy of α-relaxation. These findings are expected to build a foundation and illustrate the microscopic mechanism between F–S crystallization kinetics and β-relaxation behavior in chalcogenide glasses.

Preparation of High-Transparency Phosphenanthrene-Based Flame Retardants and Studies of Their Flame-Retardant Properties.

Transparency is an important property for polymer flame retardants, especially epoxy resin (EP) flame retardants, and flame-retardant epoxy resins that maintain a high transparency and low chromatic aberration play important roles in the optical, lighting, and energy industries. Herein, a DOPO-based flame retardant 6,6'-((sulfonylbis(4,1-phenylene))bis(oxy))bis(dibenzo[c,e][1,2]oxaphosphinine 6-oxide) with a high transparency and low chromatic aberration was prepared via the classical Atherton-Todd reaction and named SBPDOPO. Its chemical structure was characterized with Fourier IR spectroscopy and NMR spectroscopy. An EP loaded with 7 wt% SBPDOPO passed the UL-94 V-0 rating with an LOI value of 32.1%, and the peak heat release rate, total heat release, and total smoke production were reduced by 34.1%, 31.6%, and 27.7%, respectively, compared with those of pure EP. In addition, the addition of SBPDOPO improved the thermal stability, residual mass, and glass transition temperature of the EP. On this basis, the EP containing 7 wt% SBPDOPO maintained a high transparency and low color aberration, with a transmittance of 94% relative to that of pure EP and a color aberration ΔE of 1.63. Finally, the flame-retardant mechanism of SBPDOPO was analyzed, which demonstrated that it exerted both gas-phase and condensed-phase flame-retardant effects, and that SBPDOPO/EP had high potential for application scenarios in which both flame retardancy and transparency are needed. SBPDOPO/EP has great potential for applications requiring both flame retardancy and transparency.

Effects of Para‐ or Meta‐Aromatic Amide Units on the Microstructure, Thermal, Mechanical, Rheological, and Dielectric Properties of Thermotropic Liquid Crystalline Poly(ester amide)s

AbstractThe impact of para‐ and meta‐aromatic amide repeat units on the microstructure, thermal behavior, mechanical properties, rheological characteristics, and dielectric properties of thermotropic liquid crystalline poly(ester amide)s (TPEAs) is reported. For this purpose, two distinct series of TPEAs are synthesized using 75.0 mol% of 4‐hydroxybenzoic acid (HBA) and 25.0–17.5 mol% of 6‐hydroxy‐2‐naphtoic acid (HNA) with 0.0–7.5 mol% terephthalic acid/para‐acetylaminophenol (TPA/PAP) or isophthalic acid/para‐acetylaminophenol (IPA/PAP) are synthesized via bulk polycondensation reaction. Infrared and electron microscopic data reveal the existence of intermolecular hydrogen bonds and associated fibrillar structures of TPEAs with TPA/PAP‐ or IPA/PAP‐based aromatic amide units. Accordingly, the glass transition temperatures, dynamic storage moduli, and melt viscosities of TPEAs increased with the increment of the aromatic amide units, although they are higher for TPEAs with IPA/PAP‐derived units, compared to TPEAs with TPA/PAP‐derived units. The melting temperatures of TPEAs increase with the para‐aromatic amide unit owing to the intermolecular hydrogen bonding and the rigid linearity, whereas the melting points decrease with the meta‐aromatic amide unit due to the structural nonlinearity. Interestingly, the dielectric constants and losses of TPEAs decrease with the aromatic amide unit content, which is even dominant for TPEAs with IPA/PAP‐based repeat units. TPEAs can be thus utilized as super‐engineering plastics, industrial fibers, printed circuit board materials, etc., requiring enhanced mechanical and thermal transition properties but lower dielectric constants and losses.

The structural origin and boundaries of thermal transitions in stillwellite-type LnBSiO5

Stillwellite-type borosilicates, LnBSiO5 represent a family of promising non-linear optical materials. The incorporation of different rare earths into the Ln sites results in complicate patterns of phase transitions. We herein analyze the high-temperature (HT) structural transformations of LnBSiO5 (Ln = Nd, Ce, La) using a suite of in situ HT methods: single-crystal structural study, powder X-ray diffraction and Raman spectroscopy, accompanied by thermal analysis. It is shown that phase transitions between the low- and high-temperature polymorphs of LnBSiO5 originate from the order-disorder in borate chains and are greatly dependent on the nature of the rare earth in the Ln sites. We showed that the high-temperature polymorphs of LnBSiO5 (Ln = Nd, Ce, La) are always metastable at ambient conditions, regardless of lanthanide cation type.

Synthesis of Calamitic Fluorinated Mesogens with Complex Crystallization Behavior.

This work presents the synthesis and self-organization of the calamitic fluorinated mesogen, 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-4-iodobutoxy)ethanesulfonic acid, a potential model for perfluorosulfonic acid membranes (PFSA). The compound is derived in three steps from 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-iodoethoxy)ethanesulfonyl fluoride, achieving a 78% overall yield. The resulting compound exhibits intricate thermal behavior. At 150 °C, a crystal-to-crystal transition is observed due to the partial disordering of calamitic molecules, which is followed by isotropization at 218 °C. Upon cooling, sample ordering occurs through the formation of large smectic liquid crystalline phase domains. This thermotropic state transforms into a layered crystal phase at lower temperatures, characterized by alternating hydrophilic and hydrophobic layers. Using X-ray diffraction, crystalline unit cell models at both room temperature and 170 °C were proposed. Computer simulations of the molecule across varying temperatures support the idea that thermal transitions correlate with a loss of molecular orientation. Importantly, the study underscores the pivotal role of precursor self-organization in aligning channels during membrane fabrication, ensuring controlled and oriented positioning.

Synthesis and Fabrication of Betulin-Derived Polysulfide and Polysulfoxide Electrospun Fibers for Fruit Preservation.

Plant-derived biocompounds play a crucial role in the field of renewable materials due to their sustainability as they can be converted into monomers for polymerization, comparable to numerous monomers obtained from petroleum. In this work, betulin, a triterpene derivative with antibacterial properties obtained from birch tree bark, was esterified to produce two varieties of α,ω-diene derivatives with different lengths of methylene spacers. These derivatives were then copolymerized with 2,2'-(ethylenedioxy)diethanethiol using thiol-ene photopolymerization. We optimized and confirmed the polymerization parameters such as solvents, catalysts, and monomer concentrations. These analyses allowed for the obtainment of polysulfides with a high molar mass of up to 38.9 kg/mol under the optimized conditions. Furthermore, the polysulfides were converted into polysulfoxides by using a dilute hydrogen peroxide solution. Thermal analysis of the obtained polymers revealed excellent thermal stability (up to 300 °C) and tunable glass transition temperatures depending on their molar mass and composition. We successfully produced fibers with a diameter of approximately 3.9 μm by using the electrospinning technique. The morphology and hydrophobicity of the fibers were analyzed by using scanning electron microscopy and water contact angle analysis. Plant-derived polymeric fibers exhibited good cellular biocompatibility and broad-spectrum antibacterial activity, making them promising candidates for applications in fruit preservation.

Cycloaliphatic epoxy-functionalized polydimethylsiloxanes for comprehensive modifications of epoxy thermosets

Polydimethylsiloxane (PDMS) are known as a class of efficient modifiers for epoxy thermosets, but the simultaneous improvement in thermal stability, thermomechanical and mechanical properties remain a challenge. Herein, we report a cycloaliphatic epoxy-functionalized polydimethylsiloxane (PDMS-CE) with a designed epoxy value for comprehensive modifications of diglycidyl ether of bisphenol A (DGEBA)/methylhexahydrophthalic anhydride (MeHHPA) thermosets. Compared to neat epoxy thermoset, the 4 wt% PDMS-CE modified epoxy thermoset showed a 79 %, 120 % and 503 % increase in flexural strength, impact strength and fracture toughness, respectively, as well as a slight increase in the initial thermal decomposition temperature (Td5%) and glass transition temperature (Tg), and a desirable decrease in the dielectric constant and water absorption rate. This comprehensive modification performance was caused by the combined effects of crosslinking density improvement, rigid cycloaliphatic structure, as well as the flexible PDMS chains.

Strong and ultrafast stimulus-healable lignin-based composite elastomers with excellent adhesion properties

With the increased environmental issues, advanced high-performance and multifunctional polymeric materials derived from biomass have tremendous attention due to the great potential to replace their traditional petroleum-based counterparts. In this work, a series of lignin graft copolymers, lignin-graft-poly(n-butyl acrylate-co-acrylic acid) (Lig-g-P(BA-co-AA)), were rationally prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. These lignin-based copolymers demonstrate good thermal stability and tunable glass transition temperature (Tg) values. The mechanical performance, including tensile strength, extensibility, Young's modulus, and toughness can be facilely adjusted by the BA/AA feed ratio and lignin content during polymerization. Owing to the extraordinary photothermal conversion ability of lignin, the Lig-B550 copolymer, containing 11.8 wt% lignin content, shows excellent stimulus-healing behavior within 1 min with a 97.1 % healing efficiency under near-infrared (NIR) laser irradiation. Moreover, the Lig-g-P(BA-co-AA) copolymers exhibit remarkable adhesion property, broadening their potential applications in the adhesive area. This grafting strategy is versatile and efficient, conferring the resultant lignin-based composite elastomers with dramatically enhanced mechanical properties and unprecedented photothermal behavior, which can inspire the further development of strong lignin-based sustainable elastomers.

Faraday waves on a nematic liquid crystal, and its coupling with Marangoni convection about the thermal phase transition.

Using a linear hydrodynamic theory, we demonstrate that Faraday waves occur in liquid crystalline fluids. The use of already experimentally known material parameters of a N-(4-methoxybenzylidene)-4-butylaniline liquid crystal allows us to confirm and realize the predictions of this theory. It provides the critical wave number and necessary driving acceleration at instability wave onset. Additionally, these observables experience an abrupt change originated by Marangoni convection due to the temperature gradient at the isotropic-nematic phase transition temperature. Correspondingly, the Marangoni number versus temperature also shows a sharp change in the transition temperature.

The structure and in vitro starch digestibility of wheat starch-glycerol monopalmitin complexes: the effect of heating conditions and water content

The effects of the heating conditions and water content on the structure and digestibility of wheat starch (WS)-glycerol monopalmitin (GMP) complexes were investigated. The results showed that the higher water content and the heating conditions of 90°C for 60 min after 100°C for 10 min favor the formation of more WS-GMP complexes with the greater short-range order, although the thermal transition temperatures of GWS-GMP-100 complexes are not significantly affected by the water content. Only the type I complexes were formed under the heating conditions of 90°C for 60 min. The heating conditions of 90°C for 60 min after 100°C for 10 min facilitates the formation of type II complexes, and the amounts of type II complexes increased with increasing water content. The digestion rates of WS-GMP complexes decreased slightly with increasing water content, and the extent of starch amylolysis of WS-GMP complexes significantly decreased after heating further at 90°C compared with that only heating at 100°C. The digestibility of complexes is mainly related to structural order rather than the number of complexes. This study is helpful to further understand starch-lipid complexes by showing that heating conditions and water content influence the formation of WS-GMP complexes.

Mild Quantitative One Step Removal of Macrophages from Cocultures with Human Umbilical Vein Endothelial Cells Using Thermoresponsive Poly(Di(Ethylene Glycol)Methyl Ether Methacrylate) Brushes.

The authors report on a mild, label-free, and fast method for the separation of human umbilical vein endothelial cells (HUVEC), which are relevant cells, whose use is not limited to studies of endothelial dysfunction, from cocultures with macrophages to afford HUVEC in ≈100% purity. Poly(di(ethylene glycol)methyl ether methacrylate) (PDEGMA) brushes with a dry thickness of (5±1)nm afford the highly effective one-step separation by selective HUVEC detachment, which is based on the brushes' thermoresponsive behavior. Below the thermal transition at 32 °C the brushes swells and desorbs attached proteins, resulting in markedly decreased cell adhesion. Specifically, HUVEC and macrophages, which are differentiated from THP-1 monocytes, are seeded and attached to PDEGMA brushes at 37°C. After decreasing the temperature to 22°C, HUVEC shows a decrease in their cell area, while the macrophages are not markedly affected by the temperature change. After mild flushing with a cell culture medium, the HUVEC can be released from the surface and reseeded again with ≈100% purity on a new surface. With this selective cell separation and removal method, it is possible to separate and thereby purify HUVEC from macrophages without the use of any releasing reagent or expensive labels, such as antibodies.

Preparation and characterization of hemicellulose films reinforced with amino polyhedral oligomeric silsesquioxane for biodegradable packaging

Biomass is one of the powerful alternatives to petroleum-based packaging materials. Herein, carboxymethyl hemicellulose (CMH) based films (CPF) were prepared using a convenient strategy. The chains of CMH provided the necessary supporting matrix, and the aminopropyl polyhedral oligomeric silsesquioxane (POSS-NH2) regulated the thermal and barrier properties of the CPF. The secondary amide groups and hydrogen bond were appeared in chemical structure, and SEM-EDS results indicated the preferable dispersion and compatibility of POSS-NH2 in CPFs. The thermal degradation temperature (Tonset > 260 °C), the coefficient of linear thermal expansion and glass transition temperature (Tg > 130 °C) have been improved by introduction of POSS-NH2. The tensile strength of CPF showed a higher level of 39.43 MPa with the POSS-NH2 loading of 20 wt%, which was 18.8 % higher than that of CMH film. More importantly, water vapor barrier property of films almost improved by two times, and its value is reduced to 18.82 g m−2 h−1. The shelf life of blueberry was effectively extended by the CPF coating for one week compared with commercial PE film. Therefore, CPF films displayed effective thermal performances, water vapor barrier characteristic and biodegradability, which might be exploited in packaging material for food application.

In Vitro Antioxidant Activity, Bioaccessibility, and Thermal Stability of Encapsulated Strawberry Fruit (Fragaria × ananassa) Polyphenols.

Bioactive compounds in red fruits, such as strawberries, are vulnerable to digestion, and encapsulation has become an alternative for their protection. This study aims at encapsulating strawberry juice (SJ) by freeze-drying with pea protein and okra mucilage (SJPO), pea protein and psyllium mucilage (SJPP), and pea protein, psyllium mucilage, and okra mucilage (SJPPO) and investigating the in vitro release. The highest encapsulation efficiency was observed in capsule SJPPO (95.38%) and the lowest efficiency in SJPO (82.45%). Scanning electron microscopy revealed an amorphous glassy structure for the structure of the strawberry microcapsules, and X-ray diffraction confirmed that observation. However, X-ray diffraction further showed that SJPPO was crystalline, indicating a tighter crosslinking density than the other microcapsules. Fourier transform infrared spectroscopy showed peaks at 3390 and 1650 cm-1, confirming the presence of polyphenols and polysaccharides in the strawberry microcapsules. Thermal stability was higher for SJPPO, and the observed thermal transitions were due to the bonds formed between the polymers and polyphenols. Pelargonidin 3-glucoside, cyanidin 3-glucoside, cyanidin, delphinidin, malvidin 3-glucoside, ellagic acid, chlorogenic acid, catechin, and kaempferol were identified in the strawberry microcapsules. Digestion affected the compounds' content; the bioaccessibility for SJ was 39.26% and 45.43% for TPC and TAC, respectively. However, encapsulation improved the bioaccessibility of both TPC (SJPP, 51.54%; SJPO, 48.52%; and SJPPO, 54.39%) and TAC (SJPP, 61.08%; SJPO, 55.03%; and SJPPO, 71.93%). Thus, encapsulating pea protein isolate, psyllium mucilage, and okra mucilage is an effective method to facilitate targeted release and preserve the biological activities of fruits.

Conduction Mechanism Switching from Coulomb Blockade to Classical Critical Percolation Behavior in Disordered Nanoparticle Array

AbstractLarge, open‐gate transistors made from metal nanoparticle arrays offer possibilities to build new electronic devices, such as sensors. A nanoparticle necklace network (N3) of Au particles from 300 K to cryogenic temperatures exhibit a nonohmic I–Vd behavior, I ≈ (Vd–VT)ζ, where VT is a conduction gap and ζ is a constant critical exponent. The conduction gap in N3, made from disordered networks of 1D chains of 10 nm diameter Au particles exhibits room temperature (RT) gating. Although the I–Vd behavior at RT is identical to Coulomb blockade, the conduction is modulated by field‐assisted tunneling exhibiting classical critical behavior. In this study, based on three results, invariance of VT on gating, invariance of VT on temperature, and zero–bias conductance, a sharp transition temperature at ≈140 K is discovered where the conduction mechanism switches from Coulomb blockade to classical critical percolation behavior. The N3 architecture allows the reconciliation of the Coulomb blockade versus activation process as a sharp thermal transition to serve as a model system to study the exotic behavior in nanogranular‐metallic materials. The novel global critical behavior to local Coulomb blockade governed transition in these N3 architectures may potentially lead to novel sensors and biosensors.