A Phase-Changing Polymer Film for Broadband Smart Window Applications.

Smart windows (SWs) with tunable opacity are sought to regulate solar-irradiation and privacy protection. A new smart window material based on a phase-changing polymer that can be reversibly switched between a semicrystalline, opaque state and an amorphous, transparent state is introduced. The polymer film is a network of the phase-changing poly(stearyl acrylate) crosslinked with a poly(ethylene oxide) oligomer. The two constituent polymers show strong phase separation. The transmission switching of the resulting copolymer film is resulted from the combination of three different mechanisms: reversible phase changing of the poly(stearyl acrylate) component, phase separation between the two distinct constituent polymers, and a large change of refractive index of the phase-changing polymer during the amorphous-to-semicrystalline transition. The opaqueness switching can be reversed and repeated for more than 500 cycles of heating and cooling. A silver nanowire (AgNW)-based transparent heater is combined with the SW film to control the semicrystalline-to-amorphous phase transition. The resulting smart window exhibits a high infrared transmittance modulation (ΔTIR ) of 80.4% and solar transmittance modulation (ΔTsolar ) of 70.2%, which significantly outperform existing thermochromic smart windows.

Thermal properties and crystallite morphology of nylon 66 modified with a novel biphenyl aromatic liquid crystalline epoxy resin.

In order to improve the thermal properties of important engineering plastics, a novel kind of liquid crystalline epoxy resin (LCER), 3,3',5,5' -Tetramethylbiphenyl-4,4' -diyl bis(4-(oxiran-2-ylmethoxy)benzoate) (M1) was introduced to blend with nylon 66 (M2) at high temperature. The effects of M1 on chemical modification and crystallite morphology of M2 were investigated by rheometry, thermo gravimetric analysis (TGA), dynamic differential scanning calorimetry (DSC) and polarized optical microscopy (POM). TGA results showed that the initial decomposition temperature of M2 increased by about 8 °C by adding 7% wt M1, indicating the improvement of thermal stability. DSC results illustrated that the melting point of composites decreased by 12 °C compared to M2 as the content of M1 increased, showing the improvement of processing property. POM measurements confirmed that dimension of nylon-66 spherulites and crystallization region decreased because of the addition of liquid crystalline epoxy M1.

Folate Decoration Supports the Targeting of Camptothecin Micelles against Activated Hepatic Stellate Cells and the Suppression of Fibrogenesis.

As the central cellular player in fibrogenesis, activated hepatic stellate cells (aHSCs) are the major target of antifibrotic nanomedicines. Based on our finding that activated HSCs increase the expression of folate receptor alpha (FRα), we tried to apply folic acid (FA) decoration to generate an active drug-targeting at aHSCs and suppress hepato-fibrogenesis. FA-conjugated poly(ethylene glycol)-poly(ε-caprolactone) copolymers (PEG-PCL) were synthesized and self-assembled into the spherical micelles that owned a uniform size distribution averaging at 60 nm, excellent hemo- and cyto-compatibility, and pH-sensitive stability. These FA-modified micelles were preferentially ingested by aHSCs as expected and accumulated more in acutely CCl4 injured mouse livers compared to nondecorated counterparts. Such an aHSC targetability facilitated the loaded medicinal camptothecin (CPT) to achieve a greater therapeutic efficacy and inhibition of MF phenotypic genes in aHSCs. Encouragingly, though free CPT and nontargeting CPT micelles produced negligible curative outcomes, FA-decorated CPT micelles yielded effectively remedial effects in chronically CCl4-induced fibrotic mice, as represented by a significant shrinkage of aHSC population, suppression of fibrogenesis, and recovery of liver structure and function, clearly indicating the success of the folate decoration-supported aHSC-targeted strategy for antifibrotic nanomedicines in fibrosis resolution.

Stretchable Photodiodes with Polymer-Engineered Semiconductor Nanowires for Wearable Photoplethysmography.

Healthcare systems worldwide have been stressed to provide sufficient resources to serve the increasing and aging population in our society. The situation became more challenging at the time of pandemic. Technology advancement, especially the adoption of wearable health monitoring devices, has provided an important supplement to current clinical equipment. Most health monitoring devices are rigid, however, human tissues are soft. Such a difference has prohibited intimate contact between the two and jeopardized wearing comfortableness, which hurdles measurement accuracy especially during longtime usage. Here, we report a soft and stretchable photodiode that can conformally adhere onto the human body without any pressure and measure cardiovascular variables for an extended period with higher reliability than commercial devices. The photodiode used a composite light absorber consisting of an organic bulk heterojunction embedded into an elastic polymer matrix. It is discovered that the elastic polymer matrix not only improves the morphology of the bulk heterojunction for obtaining the desired mechanical properties but also alters its electronic band structure and improves the electrical properties that lead to a reduced dark current and enhanced photovoltage in the stretchable photodiode. The work has demonstrated high fidelity measurements and longtime monitoring of heat rate variability and oxygen saturation, potentially enabling next-generation wearable photoplethysmography devices for point-of-care diagnosis of cardiovascular diseases in a more accessible and affordable way.

The efficacy of parecoxib in improving pain after total knee or total hip arthroplasty: Systematic review and meta-analysis.

BACKGROUND: The cyclooxygenase-2 (COX-2) selective inhibitor parecoxib is widely used in the treatment of pain and inflammation. Parecoxib has been adopted for use for postoperative analgesia following a range of surgical procedures (orthopedic, general, gynecological, and dental surgery). Total knee or total hip arthroplasty (THA) surgery is mostly done in older patients, so postoperative analgesics need to be used more carefully, and the safety and efficacy of parecoxib in this type of surgery need to be further verified. The aim of this study was to investigate the effects of parecoxib on patient safety, cumulative morphine consumption and was at 24 and 48 hours in the analgesic treatment of total knee or THA for meta-analysis and systematic review, with few studies in this area so far. METHODS: We searched the Online Database Cochrane Library, PubMed, Web of Science, EMBASE, and CBM (SinoMed), CNKI, VIP, WANFANG up to January 2021. According to the value of I2, the random-effect model or fixed-effect model was supposed to combine data from studies, respectively. Publication bias was assessed through funneling plot and Beggs test. Review Manager 5.3 and Stata 16.0 software were applied to perform the statistical analyses. RESULTS: Eleven RCTs which involved 1690 participants were included in this study. The meta-analysis indicated parecoxib sodium could not significantly reduce the incidence of adverse events after total knee or THA compared with placebo. There was no statistical significance in incidence of nausea and vomiting. 24 hours resting VAS score was statistically significant between the group. The 48-hour resting VAS scores did not indicate a significant difference between the groups. CONCLUSION: Parecoxib can reduce the incidence of adverse events after total knee or total hip surgery to some extent but cannot reduce the incidence of nausea and vomiting. Twenty-four hour postoperative analgesia is better than placebo, but 48 hours after operation analgesia is the same as placebo.

Synthesis and dissipative particle dynamics simulation of cross-linkable fluorinated diblock copolymers: self-assembly aggregation behavior in different solvents.

Developing microstructures, such as low molecular aggregates, spherical micelles and multi-compartment micelles, is an expanding area of research in Materials Science. By applying an atom transfer radical polymerization (ATRP) process to cross-linkable fluorinated diblock copolymers and analyzing the data we are able to demonstrate the potential for developing films with different micro-structures for additional biological research. Applying the Dissipative Particle Dynamic (DPD) Method, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) techniques to cross-linkable fluorinated diblock copolymers of (methyl methacrylate-co-hydroxyethyl methacrylate-co-butyl methacrylate)-b-2-(perfluoroalkyl)ethyl methacrylate (MMA-co-HEMA-co-BMA-b-FMA) we were able to analyze the structures and their relationships to the aggregation of various microstructure formations through the use of various solvents in the process. For the self-assembly of the cross-linkable diblock copolymer in solutions, the DPD simulation results are only in qualitative agreement with experimental data of aggregate morphologies and sizes. This suggests an improved approach to creating materials and methods necessary for studying microstructures in films used in other research areas. Our work examines whether using selective solvents can be easily extended to prepare aggregates with different morphologies, which is an effective shortcut to obtain films with different microstructures. DPD simulation can be considered as an adjunct to experiments and provides other valuable information for the experiment.

Construction of antimicrobial and biocompatible cotton textile based on quaternary ammonium salt from rosin acid.

Antimicrobial cotton textiles (CT) show great promise for wound dressings. However, modifying CTs to have antimicrobial properties requires balancing the killing of microbes while protecting normal cells. In this study, the surface of CT was modified using maleopimaric acid quaternary ammonium cations (MPA-N+) from rosin acid. The surfaces morphology and chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), which confirmed that the MPA-N+ modified CT (CT-g-MPA-N+) was prepared. CT-g-MPA-N+ shows strong and broad spectrum antimicrobial activities against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). It also exhibits prominent durability of antimicrobial capability even after soaking in PBS for 6 days, and can effectively inhibit bacterial biofilm formation. Most importantly, the excellent biocompatibility of CT-g-MPA-N+ was verified by hemocompatible and cytotoxic assays. This work is believed to be promising method to prepare antimicrobial cotton textiles by surface modification and suggest the great potential application in wound dressing.

Allylated chitosan-poly(N-isopropylacrylamide) hydrogel based on a functionalized double network for controlled drug release.

Smart hydrogels with dual network were presented since a new allylated chitosan was conceived. As a double network hydrogel, its first network consisted of poly(N-isopropylacrylamide) worked as the gel matrix, and its second network with Schiff base bond enabled itself function as a molecular switch through the formation and break of the bond. When only the intestinal fluid was used, the second network could provide efficient protection for the loaded drug, and the drug release mechanism conformed to the non-Fickian type diffusion. While pre-treated with simulated gastric fluid, the switch would be opened and the mechanism was the Fickian type, which increased the cumulative percentage of drug release by about 25% and the release time by about 300 min. Besides, the hydrogel was characterized by 1H NMR, FT-IR and SEM. The effects of allylated chitosan, pH and crosslinker on the swelling ratio and morphology of hydrogel were also studied.

Synthesis of composite particles through emulsion polymerization based on silica/fluoroacrylate-siloxane using anionic reactive and nonionic surfactants.

The composite particles with core/shell structure resulting from the combination of silica seed and hydrophobic copolymer (dodecafluoroheptyl methacrylate (DFMA), gamma-methacryloxypropyltriisopropoxidesilane (MAPTIPS), methyl methacrylate, butyl acrylate) were synthesized by emulsion polymerization. The amount of the silica seeds, concentration of reactive surfactant, as well as the addition of DFMA and MAPTIPS, have strong influences on the morphology of composite particles. It has been shown that it would be possible to produce stable organic/inorganic composite particles with inhomogeneous core/shell structure encapsulated by hydrophobic fluorinated acrylate even though using unmodified silica particles and admixture of anionic and nonionic surfactants. However, there was an obvious difference on the morphologies of core-shell structure whether the DFMA and MAPTIPS were added or not. It was concluded that two kinds of polymerization approaches might coexist in the presence of DFMA and MAPTIPS for raw silica. One clear advantage of this process is that there is only one silica bead for each composite particle. This kind of stable core-shell structural hybrid latex is useful for preparing high performance hydrophobic coating.

Durably Antibacterial and Bacterially Antiadhesive Cotton Fabrics Coated by Cationic Fluorinated Polymers.

Considerable attention has been devoted to producing antibacterial fabrics due to their very wide applications in medicine, hygiene, hospital, etc. However, the poor antibacterial durability and bad bacterial antiadhesion capacity of most existing antibacterial fabrics limit their applications. In this work, a series of antibacterial and polymeric quaternary ammonium monomers with different alkyl chain length were successfully synthesized to copolymerize with fluorine-containing and other acrylic monomers to generate cationic fluorinated polymer emulsions and durably antibacterial and bacterially antiadhesive cotton fabrics. The relation between antibacterial constituent and its antibacterial activity was investigated. The study indicated that the alkyl chain length and contents of the antibacterial monomers, as well as the add-on percentage of polymer greatly influenced the antibacterial activities of the fabrics. In addition, it was found that incorporation of fluorine component into the polymer greatly enhanced the antibacterial activity and bacterial antiadhesion of the treated fabrics due to the low surface energy induced hydrophobicity. Finally, antibacterial and antiadhesive models of action of the obtained fabrics were illustrated.

Inspired by Stenocara Beetles: From Water Collection to High-Efficiency Water-in-Oil Emulsion Separation.

Inspired by the water-collecting mechanism of the Stenocara beetle's back structure, we prepared a superhydrophilic bumps-superhydrophobic/superoleophilic stainless steel mesh (SBS-SSM) filter via a facile and environmentally friendly method. Specifically, hydrophilic silica microparticles are assembled on the as-cleaned stainless steel mesh surface, followed by further spin-coating with a fluoropolymer/SiO2 nanoparticle solution. On the special surface of SBS-SSM, attributed to the steep surface energy gradient, the superhydrophilic bumps (hydrophilic silica microparticles) are able to capture emulsified water droplets and collect water from the emulsion even when their size is smaller than the pore size of the stainless steel mesh. The oil portion of the water-in-oil emulsion therefore permeates through pores of the superhydrophobic/superoleophilic mesh coating freely and gets purified. We demonstrated an oil recovery purity up to 99.95 wt % for surfactant-stabilized water-in-oil emulsions on the biomimetic SBS-SSM filter, which is superior to that of the traditional superhydrophobic/superoleophilic stainless steel mesh (S-SSM) filter lacking the superhydrophilic bump structure. Together with a facile and environmentally friendly coating strategy, this tool shows great application potential for water-in-oil emulsion separation and oil purification.