Lamellar Crystalline Structure Research Articles

Role of Annealing with Electric Field Toward Improvement of Ferroelectric and Electroactive Properties of PVDF Copolymer and Terpolymer Thin Films.

The present study elucidates the role of annealing with electric field on lamellar crystalline structure and molecular orientation of polymer chains in ferroelectric copolymer (P(VDF-TrFE)) and ferroelectric terpolymer (P(VDF-TrFE-CFE)) spin-coated thin films. The ferroelectric polymer thin films annealed under an electric field support the growth of nanostructure with an "edge-on" lamellar crystalline structure having in-plane molecular chain orientation. The poled P(VDF-TrFE) thin films have higher remnant polarization (Pr) ≈6.2µCcm-2 and saturation polarization (Ps) ≈8.2µCcm-2 at an applied electric field of 250 MV/m compared to unpoled thin films having Pr ≈4.7 and Ps ≈6.2µCcm-2. Also, poled P(VDF-TrFE) thin films show lower coercive field (Ec) ≈94 MV/m compared to an unpoled thin film having Ec ≈105 MV/m. Similarly, poled PVDF-TrFE-CFE thin film shows better ferroelectric properties having Pr ≈0.4 and Ps ≈5.7µCcm-2 at an applied electric field of 200 MVm-1 compared to unpoled thin films having Pr ≈0.4 and Ps ≈4.1µCcm-2. The storage energy efficiency of unpoled and poled P(VDF-TrFE-CFE) thin films is measured to be ≈75% and 80%. Annealing of ferroelectric P(VDF-TrFE) polymer thin films under an electric field demonstrates improved ferroelectric and electroactive properties.

Characteristics of in-situ automated fiber placement carbon-fiber-reinforced low-melt polyaryl ether ketone laminates part 1: Manufacturing influences

This study presents an investigation into mechanical and thermal properties, as well as the microstructure of Automated Fiber Placement-manufactured laminates using a novel carbon fiber-reinforced low-melt polyaryl ether ketone polymer material. The material’s lower melting temperature and lower melt viscosity as compared to established high-temperature thermoplastic materials as PEEK, promises favourable characteristics for the Automated Fiber Placement process. This work aims at in-situ consolidation and the influence of a heated tooling and a post process tempering step, which both turned out to be promising in previous investigations. Laminates were manufactured using a cold tooling, a heated tooling configuration, a cold tooling with a subsequent tempering process step and a hot-pressed reference laminate. Differential Scanning Calorimetry showed that crystallinity values more than doubled for the heated tooling and post process tempering configurations, compared to the cold tooling, reaching 24% and 30%, respectively. Mechanical strength values showed an increase in interlaminar shear strength and compression strength but did not increase to the same extent as was expected from the increase in crystallinity. With Scanning Electron Microscopy differences in the microscopic structure of the polymer matrix could be detected. While the post process tempering step leads to a mostly lamellar crystalline structure, the heated tooling configuration and the post process hot pressing induce a predominance of crystalline spherulites, which might positively affect the mechanical performance. Computed Tomography scans revealed a high amount of porosity in the in-situ-manufactured samples and unprocessed tape material, which likely mitigated the positive effect of increased crystallinity.

Lamellar Microphase Separation and Phase Transition of Hydrogen-Bonding/Crystalline Statistical Copolymers: Amide Functionalization at the Interface.

Microphase separation of random copolymers, as well as that of high χ-low N block copolymers, is promising to construct sub-10-nm structures into materials. Herein, we designed statistical copolymers consisting of 2-hydroxyethyl acrylate (HEA) and N-octadecylacrylamide (ODAAm) to produce crystallization and hydrogen bond-assisted lamellar structure materials. The copolymers not only formed a crystalline lamellar structure with 3-4 nm domain spacing but also maintained an amorphous lamellar structure via phase transition above the melting temperature up to approximately 100 °C. The key is to introduce hydrogen-bonding amide junctions between the octadecyl groups and the polymer backbones, by which the polymer chains are physically fixed at the interface of lamellar structures even above the melting temperature. The stabilization of the lamellar structure by the amide units is also supported by the fact that the lamellar structure of all-acrylate random copolymers bearing hydroxyethyl and crystalline octadecyl groups is disordered above the melting temperature. By spin-coating on a silicon substrate, the HEA/ODAAm copolymer formed a multilayered lamellar thin film consisting of a hydrophilic hydroxyethyl/main chain phase and a hydrophobic octadecyl phase. The structure and order-disorder transition were analyzed by neutron reflectivity.

Unraveling the role of probiotics in affecting the structure of monoglyceride gelled emulsions: A low-field 1H NMR study

The capacity of monoglyceride (MG) gelled emulsions (MEs) in protecting probiotic cells of Lacticaseibacillus rhamnosus against stresses suffered during food processing, storage, and human digestion has been recently demonstrated. These findings open new perspectives on the possible participation of probiotics in the stabilization of emulsion structure. To unravel this aspect, rheological analysis and Low-Field 1H NMR investigations were performed on MEs having different aqueous phases (water or skimmed milk) and stored for increasing time (1 and 14 days) at 4 °C. Loaded and unloaded samples were considered. Results highlighted that probiotics initially hindered the ability of MG to self-assemble in the multiphase environment, interacting in some way with MG crystalline lamellar structure, as confirmed by rheological and 1H NMR analysis. During storage, an increase of proton compartmentation was observed in loaded MEs indicating the role of probiotics in stabilizing MG structure at a molecular level. Such a result was more evident when the system was composed of milk, suggesting that the presence of milk-native components (i.e., lactose, proteins, and minerals) favored the cell-structure interactions. Such preliminary results could open new perspectives in considering probiotic cells as having an active role in the stabilization of food structure.

A Mechanistic Study on the Fluidization and Enhancement Effects of Cineole Toward Stratum Corneum Intercellular Lamellar Lipids: A Liquid Crystalline Model Approach.

The stratum corneum (SC) serves as the primary barrier for permeation in human skin. Penetration enhancers, such as 1,8-cineole, are utilized to enhance the permeation of drugs. Cineole increases the permeation of chemicals through different mechanisms. However, its mechanism, particularly at high concentrations, has not been well-studied and is the subject of the present investigation. In continuation of our previous studies, the present investigation aims to elucidate the mechanism of action and concentration dependency of the effects of 1,8-cineole on the structure, diffusional properties, and partitioning behavior of the SC at high concentrations. This will be achieved through lamellar liquid crystalline models and ex-vivo skin studies. A lamellar liquid crystalline lipid matrix model in the presence (25 - 90%, w/w) and absence of cineole was prepared from SC lipids and characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and polarized light microscopy (PLM) studies. Release of the model lipophilic drug (diazepam) from cineole and cineole-treated matrices and the permeation of the drug from cineole and cineole-containing matrices (as a vehicle similar to the stratum corneum lipids) through excised rat skin were studied. Drug assay was performed by HPLC. The PLM, DSC, and X-ray studies showed that the model matrix had a lamellar gel-liquid crystalline structure, and cineole fluidized the structure concentration-dependently and created other mesomorphic textures, such as myelinic figures. Release experiments showed that diffusion coefficients remained almost constant at high cineole concentrations of 40-90%, suggesting similar fluidization states. Skin permeation studies indicated that the diffusion coefficient (estimated from lag-time) increased concentration-dependently and played a role in permeability coefficient (Kp) increments alongside the increased partitioning of the model drug into the skin. Data suggest that high concentrations of cineole at the skin surface might not provide enough cineole in the skin for full fluidization, despite the similarity of the vehicle to SC lipids and even at high concentrations. The enhancement effect of cineole is concentration-dependent and might reach maximum fluidization at certain concentrations, but this maximum might not be easily achievable when cineole is used in formulations as pure or in a vehicle.

A Mechanistic Study on the Fluidization and Enhancement Effects of Cineole Toward Stratum Corneum Intercellular Lamellar Lipids: A Liquid Crystalline Model Approach

Background: The stratum corneum (SC) serves as the primary barrier for permeation in human skin. Penetration enhancers, such as 1,8-cineole, are utilized to enhance the permeation of drugs. Cineole increases the permeation of chemicals through different mechanisms. However, its mechanism, particularly at high concentrations, has not been well-studied and is the subject of the present investigation. Objectives: In continuation of our previous studies, the present investigation aims to elucidate the mechanism of action and concentration dependency of the effects of 1,8-cineole on the structure, diffusional properties, and partitioning behavior of the SC at high concentrations. This will be achieved through lamellar liquid crystalline models and ex-vivo skin studies. Methods: A lamellar liquid crystalline lipid matrix model in the presence (25 - 90%, w/w) and absence of cineole was prepared from SC lipids and characterized by X-ray diffraction, differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA), and Polarized Light Microscopy (PLM) studies. The release of the model lipophilic drug (diazepam) from cineole and cineole-treated matrices and the permeation of the drug from cineole and cineole-containing matrices (as a vehicle similar to the stratum corneum lipids) through excised rat skin were studied. A drug assay was performed by HPLC. Results: The PLM, DSC, and X-ray studies showed that the model matrix had a lamellar gel-liquid crystalline structure, and cineole fluidized the structure concentration dependently and created other mesomorphic textures, such as myelinic figures. Release experiments showed that diffusion coefficients remained almost constant at high cineole concentrations of 40-90%, suggesting similar fluidization states. Skin permeation studies indicated that the diffusion coefficient (estimated from lag-time) increased concentration-dependently and played a role in permeability coefficient (Kp) increments alongside the increased partitioning of the model drug into the skin. Data suggest that high concentrations of cineole at the skin surface might not provide enough cineole in the skin for full fluidization, despite the similarity of the vehicle to SC lipids and even at high concentrations. Conclusions: The enhancement effect of cineole is concentration-dependent and might reach maximum fluidization at certain concentrations, but this maximum might not be easily achievable when cineole is used in formulations as pure or in a vehicle.

Ureido Hyperbranched Polymer Modified Urea-Formaldehyde Resin as High-Performance Particleboard Adhesive.

The performance of urea-formaldehyde (UF) resin and its formaldehyde emission is a natural contradiction. High molar ratio UF resin performance is very good, but its formaldehyde release is high; low molar ratio UF resin formaldehyde release is reduced, but the resin itself performance becomes very bad. In order to solve this traditional problem, an excellent strategy of UF resin modified by hyperbranched polyurea is proposed. In this work, hyperbranched polyurea (UPA6N) is first synthesized by a simple method without any solvent. UPA6N is then added into industrial UF resin in different proportions as additives to manufacture particleboard and test its related properties. UF resin with a low molar ratio has a crystalline lamellar structure, and UF-UPA6N resin has an amorphous structure and rough surface. The results show that internal bonding strength increased by 58.5%, modulus of rupture increased by 24.4%, 24 h thickness swelling rate (%) decreased by 54.4%, and formaldehyde emission decreased by 34.6% compared with the unmodified UF particleboard. This may be ascribed to the polycondensation between UF and UPA6N, while UF-UPA6N resin forms more dense three-dimensional network structures. Finally, the application of UF-UPA6N resin adhesives to bond particleboard significantly improves the adhesive strength and water resistance and reduces formaldehyde emission, suggesting that the adhesive can be used as a green and eco-friendly adhesive resource for the wood industry.

Microstructures and magnetic properties of PrNd-free (Ce, RE)-Fe-B (RE = Y, La) sintered magnets

The phase constitutions and microstructure characteristics of PrNd-free (Ce, RE)-Fe-B (RE = Y, La) sintered magnets were investigated, and the effects of Y and La substitution on the microstructures and magnetic properties of Ce-based magnets were discussed. It indicated that the Ce-Fe-B strip casting (SC) alloy has an inhomogeneous lamellar crystalline structure, the uniformity of lamellar crystalline was improved by Y substitution, and an obvious refined crystalline structure has been obtained in the Y and La co-substituted SC alloy. The experimental Ce-based SC alloys were mainly composed of RE2Fe14B and REFe2 phases. Some “small islands” existing in REFe2 regions were identified as intermediate products of the peritectic reaction. It inferred that a trace amount of α-Fe existed in all the Ce-based SC alloys. The Ce-Fe-B sintered magnet has a large-grain microstructure, and several main-phase grains often directly contact without the isolation of RE-rich phases. Therefore, the intrinsic coercivity of the Ce-Fe-B sintered magnet was very low, equal to that of a soft magnetic material. The grains were obviously refined by Y and La co-substitution, and the magnetic properties of the corresponding magnet have increased remarkably. A Br of 8.31 kG, Hcj of 0.92 kOe, and (BH)max of 5.30 MGOe were obtained in the PrNd-free (Ce, Y, La)-Fe-B sintered magnet.

Microstructures of Starch Granules with Different Amylose Contents and Allomorphs as Revealed by Scattering Techniques.

In this study, as-is (ca. 12% moisture by mass) and hydrated (50% water by mass) granules of waxy potato (WP), waxy wheat (WW), waxy maize, normal maize, and high-amylose maize (HAM) starches were investigated by using small-angle neutron and X-ray scattering (SANS and SAXS), wide-angle X-ray scattering, and ultra-small-angle neutron scattering. The SANS and SAXS data were fitted using the two-phase stacking model of alternating crystalline and amorphous layers. The partial crystalline lamellar structures inside the growth rings of granules were analyzed based on the inter-lamellar distances, thicknesses of the crystalline lamellae and amorphous layers, thickness polydispersities, and water content in each type of layer. Despite having a longer average chain length of amylopectin, the WP and HAM starches, which had B-type allomorph, had a shorter inter-lamellar distance than the other three starches with A-type allomorph. The WP starch had the most uniform crystalline lamellar thickness. After hydration, the amorphous layers were expanded, resulting in an increase of inter-layer distance. The low-angle intensity upturn in SANS and SAXS was attributed to scattering from interfaces/surfaces of larger structures, such as growth rings and macroscopic granule surfaces. Data analysis methods based on model fitting and 1D correlation function were compared. The study emphasized─owing to inherent packing disorder inside granules─that a comprehensive analysis of different parameters was essential in correlating the microstructures with starch properties.

Constructions of special network structure in natural rubber composites for improved anti-fatigue resistance

Nature rubber (NR) as the most widely used rubber material with excellent comprehensive properties suffers the poor fatigue resistance, which seriously affects the serving life of NR products. Blending crystalline components with NR could improve the fatigue properties of NR. However, the desired structures constructed by the crystalline component in the NR based composites were not clear. Herein, three crystalline polymers including isotactic polybutene-1 (PB), trans-1,4-polyisoprene (TPI) and trans-1,4-poly(butadiene-co-isoprene) copolymer rubber (TBIR) with varied crystallinity and crosslinking ability were selected to blend with NR for various network structure construction. The influences of unvulcanized PB and crosslinkable TPI and TBIR on the polymer network structures, filler network structures and then properties of the final composites were studied. It was found, although the modulus and hardness of both filled and unfilled NR/PB (90/10) vulcanizate improved, while the dynamic properties like heat built-up and fatigue resistance decreased greatly when compared with that of NR vulcanizate. While, NR/TBIR (90/10) vulcanizate showed the highest fatigue life. The structures of unfilled and filled NR/TBIR vulcanizates were analyzed to acquire the desired structure for satisfied fatigue properties of NR based composites. The more homogeneous rubber matrix enhanced with nano-scale crystalline lamellar structures and having co-vulcanization crosslinking bonds between NR and TBIR contributed to the greatly improved fatigue resistance, as well as satisfied other mechanical properties.

Small-angle neutron scattering reveals basis for composition dependence of gel behaviour in oleic acid - sodium oleate oleogels

The relationship between gel strength and structure on the micro- and nano-scale has been investigated for oleogels prepared in a range of triglyceride (TAG) oils (sunflower, olive, medium chain triglyceride) using mixtures of oleic acid (OA) and sodium oleate (SO) as gelling agents. Microscopy indicated a reduction in crystal size with increasing SO content. Gel strength increased with SO concentration but, for a constant SO concentration, decreased with the addition of OA. Small-angle neutron scattering (SANS) and ultra-SANS was measured from the gels formed in the TAG oils, as well as in hexadecane oil, the latter employing solvent contrast variation, to study the structures formed in more detail. In both the TAG oils and in hexadecane, SO formed lamellar crystalline structures whose low q scattering was consistent with mass fractal-like behaviour (for 0:1 and 1:8 compositions). Further OA addition (1:4–2:1) resulted in the simultaneous presence of inverse micellar structures. We hypothesise that the negative effect of OA on gel strength is due to the partial dissolution of SO by OA and the loss of gel-mediating SO-based lamellar crystals. The variation in OA:SO ratio is demonstrated to provide control over mechanical properties via large-scale structure formation while the tunability of such gel properties using this mechanism potentially provides an alternative route to the use of solid fats for structuring food.

Investigation of the LiBH4 Modification Effect on Cycling Stability and High-Rate Capacity of LiCoO2 Cathodes

A LiCoO2 (LCO) cathode with LiBH4 modification (LBH-LCO) was obtained in a facile condition using a fast wet-chemical synthesis method. X-ray photon spectroscopy analysis indicates that B3+ in LiBH4 with high oxygen affinity can quickly incorporate onto the LCO surface accompanied by Co3+ reduction. Meanwhile, XRD characterization shows that the modified samples have a clear crystalline lamellar structure. After being modified by LiBH4, LBH-LCO present increased cycling stability [with near 95%/85% capacity retention at 1 C/5 C (1 C = 180 mA g–1) rates after 100/300 cycles] and better rate performance from 0.2 to 5 C under 4.6 V operation, compared to the pristine LiCoO2 (P-LCO). Electrochemical testing also shows that the LBH-LCO cathode retains a much higher Li+ chemical diffusion coefficient and smaller charge transfer impedance increases than the P-LCO. Even after being exposed to moist air for 48 h, the discharge capacity of the LBH-LCO can still reach 202 mA h g–1, which has a strong commercial application prospect.

Role of Chemical Functionality in the Adhesion of Aluminum and Isotactic Polypropylene

In the direct melt bonding of isotactic polypropylene (iPP) to aluminum (Al), the blending of a small amount of maleic anhydride-grafted PP (PPgMA) with iPP was found to induce a dramatic improvement of the strength of adhesion. The effect of blending PPgMA was, however, limited, maximizing at ∼20 wt % PPgMA. Incorporation of larger amounts of PPgMA reduced the strength of adhesion. We studied the mechanism of adhesion between Al and iPP by incorporating chemical functionality to the polymer side. The fracture surfaces produced by peeling off the interfaces were investigated by replicating the surface topographic features on a platinum thin film and analyzing them by scanning transmission electron microscopy (STEM) as well as by reconstructing three-dimensional (3D) surface structures with STEM tomography. The replica-STEM technique enabled us to visualize PP surface crystalline lamellar structures and their deformation upon the failure in 3D. We found that polymer/metal interfaces produced surface features in the failure that were similar to those associated with failure of entanglement-based polymer/polymer adhesion via chain pullout. A fractography study by replica-STEM suggested that the formation of a low-molecular-weight layer with low crystallinity at the interfacial region was responsible for the improvement of adhesion. The adhesion strength depended on the toughness of the "soft layer" and did not depend on the chemical bonding between PPgMA and Al. The interfacial chemical reaction between MA and the Al surface yielded PP with a grafted carboxylic acid (-COOH) group, which may have been excluded from the PP crystalline lamellae. We concluded that chemical bonding was not the primary reason for the improvement of adhesion, but it was necessary to induce the segregation of PPgMA in the interfacial region and the formation of the soft layer.

Formation of Flat‐on Lamellar Crystals in Absence of Nanoconfinement

AbstractFlat‐on lamellar crystals are crucial for gas‐barrier polymer films. The formation of this lamellar crystalline structure with chains perpendicular to the substrate is currently understood as the result of confined crystallization, e.g., in block copolymers and ultrathin polymer films. In this paper, it is demonstrated that these flat‐on lamellar crystals of various thermoplastic polymers may form on stainless steel and silicon wafer surfaces without the presence of confined crystallization. Atomic force microscopy, high‐resolution scanning electron microscopy, and polarized light hot‐stage microscopy are used to characterize the formation of the lamellar crystals. Further results show that the surface physicochemical properties of the substrates strongly influence the formation of these lamellar crystals. A hypothesis, based on the heterogeneous crystallization theory, is proposed to explain the formation of such flat‐on lamellar crystals. These results are crucial for a fundamental understanding of the formation of lamellar crystals and may provide a new approach to fabricate such structures.

Crystalline Lamellar Structure of Thermosetting Urea–Formaldehyde Resins at a Low Molar Ratio

Reducing formaldehyde emission from cured urea–formaldehyde (UF) resins forced us to synthesize UF resins at a low formaldehyde to urea (F/U) molar ratio (≤1.0), resulting in low emission and poor adhesion by forming crystalline domains instead of building a three-dimensional network in cured resins. For the first time, we report a crystalline lamellar structure of thermosetting UF resins at a low molar ratio and compare it with highly amorphous UF resins at a high F/U molar ratio (1.6). Films of crystalline and amorphous UF resins were prepared using a spin-coater and characterized using atomic force microscopy. In addition, transmission electron microscopy, gel permeation chromatography, and X-ray diffraction were also employed for their characterization. The results showed that 1.0 UF resins had a low molecular weight with a lamellar structure of the crystalline domain, whereas 1.6 UF resins exhibited a high molecular weight with an amorphous structure and had a lower surface roughness. Fourier transform infrared and carbon-13 nuclear magnetic resonance spectroscopy also proved that linear molecules and hydrogen bonding were responsible for the formation of crystalline lamellar structures in thermosetting UF resins at a low molar ratio.

Effect of moist and dry-heat treatment processes on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid complexes

Herein, we investigated the impact of moist (steaming and boiling) and dry (baking and microwaving)-heat treatment processes on the structure and physicochemical properties of wheat starch (WS) supplemented with lauric acid (LA). Elemental composition analysis revealed the interplay between WS and LA. Scanning electron microscopy (SEM) and iodine staining revealed that lamellar crystalline structure of WS-LA complexes was improved after moist-heat treatment (relative to samples without any heat treatments); the finding which is at variance to dry-heat treatment process. Additionally, high resistance to thermal decomposition and a lower 1022/995 cm−1 absorbance ratio were observed in moist-heat treated WS-LA compared with dry-heat samples. Moreover, the V-type diffraction peak intensity and resistance to in vitro enzymatic hydrolysis of samples treated with moist-heat were increased to a greater extent than the dry-heat treated counterparts. In sum, this study would facilitate the application of functional starch-lipid complexes in food necessitated heat treatments.

An insight on the MoS2 tribo-film formation to determine the friction performance of Mo-S-N sputtered coatings

Amorphous Mo-S-N coatings are known to provide excellent tribological properties in diverse environments due to easy sliding under the influence of MoS 2 tribo-films. However, the role of nitrogen incorporation, the formation mechanism of MoS 2 tribo-film at the sliding interface and the changes in the friction behaviour under different environments are not fully understood. In this study, an amorphous coating with 30 at. % N was deposited in a semi-industrial reactive direct current magnetron sputtering (DCMS) system, using a single MoS 2 target in combination with a secondary plasma source. The coating was predicted to have either a Mo-S-N phase with N filling some of the S sites or a MoS 2 (N 2 ) structure where the gas molecules prevent the formation of a crystalline lamellar structure. Tribological studies performed in vacuum and ambient air resulted in steady-state COF values of 0.03 and 0.15, respectively. High-resolution transmission electron microscopy (HRTEM) analysis performed on the wear-tracks revealed that the low coefficient of friction (COF) in vacuum was attributed to the formation of a thick and continuous lamellar tribo-film with a low amount of nitrogen. Contrarily, in ambient air, the surface oxidation disturbed the formation of a continuous MoS 2 tribo-film from the amorphous coatings, leading to an increase in the COF and wear rate. This study shows through indirect measurements of the chemical composition of the as-deposited coating and wear debris that nitrogen is stored in gaseous form (N 2 ) within the amorphous matrix and is released from the contact during sliding. • Amorphous Mo-S-N coatings with 30 at. % N deposited with high adhesion to steel. • Tribo-film formation and role of N on the lubricating behaviour of Mo-S-N coatings. • COF in vacuum (10 −2 Pa) of 0.03 and in ambient air (24 °C, 20–30% RH) of 0.15. • Low friction in vacuum due to formation of a MoS 2 tribo-layer at the sliding interface. • Higher friction in ambient air due to a surface oxide formed at the interface.

Ocular lamellar crystalline gels for sustained release and enhanced permeation of resveratrol against corneal neovascularization

Corneal neovascularization (CNV) is the major cause of blindness after eye injury; however, only several drugs can be applied and the invasive administration ways (i.e., intravitreal injection and subconjunctival injection) are used. Resveratrol is a highly effective anti-VEGF agent against CNV. However, its applications are limited due to its strong hydrophobicity and instability. Here, we developed a resveratrol-loaded ocular lamellar crystalline gel (ROLG) for high inhibition of CNV. ROLGs were composed of resveratrol, glyceryl monooleate (GMO), ethanol, and water, and their lamellar crystalline structures were identified by polarizing light microscopy and small-angle X-ray scattering. High drug loading (4.4 mg/g) of ROLGs was achieved due to the hydrogen bonding between GMO and resveratrol. Resveratrol showed sustained release with 67% accumulative release in 7 h, which was attributed to the slow erosion of gels. Resveratrol in ROLGs had a high corneal permeation 3 times higher than resveratrol in hyaluronic acid suspensions (RHSs). ROLGs were administered to rats only once a day because of their strong retention on the cornea surface. ROLGs were safe due to the very little contact of ethanol in ROLGs to the cornea. CNV post-rat corneal alkaline injury was highly inhibited by ROLGs, resulting from the attenuation of corneal VEGF expression and then corneal healing was improved. The ROLG was a promising ocular medicine for the prevention of CNV.

Influence of the Polymer Interphase Structure on the Interaction between Metal and Semicrystalline Thermoplastics

It is demonstrated that a lamellar crystalline structure may form near the metal–polymer interface during the comolding of metal–thermoplastic joints. The influence of the crystalline morphology near the interface on the rupture behavior of the joint is studied experimentally. High‐resolution scanning electron microscopy (HR–SEM), atomic force microscopy (AFM), and optical microscopy are used to characterize the microstructure of the metal–thermoplastic interface. The results show that a lamellar crystalline structure at the interface promotes cohesive failure, i.e., the crack runs in the polymer. Additional experiments show that a transcrystalline polymer structure at the interface results in failure at the interface. Herein, two methodologies have been developed to characterize the formation of the transcrystalline polymer interphase structure based on X‐ray diffraction and polarized light hot stage microscopy. The results show the importance of the polymer interphase structure for metal–thermoplastic interactions. Understanding of the formation of the polymer interphase and its influence on the interfacial bonding strength are vital for thermoplastic applications such as fiber‐reinforced thermoplastic composites, tool surface design for processing of thermoplastics, and their composites as well as for metal–polymer hybrid joints.

Rheological fingerprinting as an effective tool to guide development of personal care formulations

Conventional rheological techniques in the linear viscoelastic region provide insights about the spatial configuration of the microstructural components of personal care formulations in their 'at-rest' state. However, they fail to describe the textural experience associated with large and fast deformations during daily consumer application. In this study we present a non-conventional rheological technique-large amplitude oscillatory shear (LAOS)-for probing the transformation of a material during its application. This technique is proposed a practical tool for formulators in their efforts to design products with desired textural attributes. A non-linear rheological technique termed LAOS was utilized to capture the textural expression perceived by consumers. Lissajous plots (stress vs. strain or strain rate) provide a fingerprint of the formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry, molecular properties, colloidal parameters and processing conditions. In this study, we showcased several approaches for modifying the texture of personal care formulations and show the influence of various parameters on the characteristics of the Lissajous curves and their relation to sensorial perception. This fingerprinting technique shows that increasing the molecular weight or hydrophobic modification boosts the elasticity and thickening efficiency of a given polymer. Differences in the chemistry of rheological ingredients also influence the characteristic Lissajous fingerprint. In high concentration surfactant systems, which tend to form worm-like micelles, their unique Lissajous fingerprints indicate structure rebuild because of fast kinetics at large but slow deformations. Analysis of lamellar gel-based hair conditioner formulations demonstrates the unique high yield stress of these types of materials, accompanied by the fast breakdown transition from a solid to viscous structure because of their crystalline lamellar gel structure. The LAOS technique presented in this article is intended to better capture the textural expression perceived by consumers. Lissajous plots-generated from the LAOS experimental data-provide a fingerprint of the tested formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry and molecular weight of the thickener, pH of the formula medium and influence of other ingredients in the formula (surfactants, emulsifiers, etc.).