Introduction Of PEG Research Articles

PEG-assisted synthesis of highly dispersed Cs/Zr-SiO2 catalyst for aldol condensation of methyl acetate with formaldehyde

The dispersion of active sites plays an imperative role in the promotion of catalytic performance on methyl acrylate synthesis via direct vaporous aldol condensation. Herein, a novel PEG-assisted impregnation method was proposed to synthesize Cs/Zr-SiO2 catalyst with high dispersion of acid and base sites. A series of characterization techniques including NMR, TEM, physical N2 adsorption isotherms, XRD, XPS, NH3-/CO2-TPD, and Py-IR were used to investigate the physico-chemical properties of these prepared catalyst series. The introduction of PEG improved the specific surface area, dispersion of active sites, and density of acid and base sites, resulting in superior catalytic performance of Cs/PEG@Zr-SiO2 by comparison with that of Cs/SiO2 and Cs/Zr-SiO2. The kinetic experiments revealed that the activation energy of aldol condensation was 80.8 kJ/mol over the Cs/PEG@Zr-SiO2 catalyst. The deactivation behavior derived from carbon deposition was discovered, and the spent catalyst could be regenerated by simple thermal treatment.

Using Dynamic Laser Speckle Imaging for Plant Breeding: A Case Study of Water Stress in Sunflowers.

This study focuses on the promising use of biospeckle technology to detect water stress in plants, a complex physiological mechanism. This involves monitoring the temporal activity of biospeckle pattern to study the occurrence of stress within the leaf. The effects of water stress in plants can involve physical and biochemical changes. Some of these changes may alter the optical scattering properties of leaves. The present study therefore proposes to test the potential of a biospeckle measurement to observe the temporal evolution in different varieties of sunflower plants under water stress. An experiment applying controlled water stress with osmotic shock using polyethylene glycol 6000 (PEG) was conducted on two sunflower varieties: one sensitive, and the other more tolerant to water stress. Temporal monitoring of biospeckle activity in these plants was performed using the average value of difference (AVD) indicator. Results indicate that AVD highlights the difference in biospeckle activity between day and night, with lower activity at night for both varieties. The addition of PEG entailed a gradual decrease in values throughout the experiment, particularly for the sensitive variety. The results obtained are consistent with the behaviour of the varieties submitted to water stress. Indeed, a few days after the introduction of PEG, a stronger decrease in AVD indicator values was observed for the sensitive variety than for the resistant variety. This study highlights the dynamics of biospeckle activity for different sunflower varieties undergoing water stress and can be considered as a promising phenotyping tool.

Two-dimensional MXene-based nano-prodrug for synergistic chemo-photothermal therapy on cancer treatment

In cancer treatment, although prodrugs have been developed to overcome obstacles such as undesirable pharmacokinetic performance and serious off-target toxicity of most chemotherapeutics, the combination of prodrugs with nanotechnology could be used to overcome the shortcomings of conventional prodrug strategies and facilitate more efficient drug delivery and accumulation of anticancer prodrugs at specific sites/tissues. Phototherapy is a method that uses near-infrared (NIR) light to achieve local and non-invasive tumor therapy. The combination of chemotherapy and phototherapy has shown many therapeutic advantages, including synergistic therapeutic effects and the reduction of toxic and side effects of drugs through dose reduction. In this work, a hydrazone linkage was reported to conjugate Ti3C2Tx MXene nanosheets with doxorubicin hydrochloride (DOX) and methoxy poly(ethylene glycol) benzaldehyde (mPEG-CHO) through a chemical surface modification to form a two-dimensional (2D) nano-prodrug Ti3C2Tx-DOX/PEG (TDP) for synergistic chemo-photothermal therapy. First, hydrazide functionalized Ti3C2Tx was obtained. Then, the carbonyl group of DOX and the aldehyde group of mPEG-CHO can form a pH-responsive hydrazone bond with hydrazide-functionalized Ti3C2Tx. The high surface area of Ti3C2Tx could overcome the reduced drug loading caused by conjugation. Aqueous stability and biocompatibility were enhanced by the introduction of PEG, making the material capable of prolonged circulation in the body's bloodstream. By achieving excellent antitumor results with this nano-prodrug, we have added another brick to the edifice of Ti3C2Tx MXene as an anticancer drug carrier, and given new vitality to the study of anticancer prodrugs combined with nanotechnology.

Soft, strong, and breathable polylactic acid/polyethylene glycol microfibrous membranes with a fluffy alignment structure for skin contactor

Polylactic acid (PLA) microfibrous membranes, having high comfort and wearability features, have attracted considerable research interest for applications involving skin contactors. However, the poor softness and low strength of these membranes are the major challenges that prevent their large-scale fabrication and application. Herein, an advanced strategy for preparing a soft, strong, and breathable polylactic acid/polyethylene glycol (PLA/PEG) microfibrous membrane using an in situ drafting-assisted melt-blowing process has been developed. The introduction of PEG significantly improved the crystallization and plasticization of the PLA chain molecules, thus promoting the perfect crystallinity of the PLA phase. Benefiting from the synergy of the PEG and the drafting process, the prepared PLA/PEG microfibrous membranes exhibited a fluffy structure wherein the air permeability increased to 142.5 mm/s with the increase in DCD to 37 cm. Meanwhile, the PLA/PEG microfibrous membranes exhibit optimized anisotropic softness performance: a smaller maximum resistance of 0.13 N in the machine direction and a larger maximum resistance of 1.8 N in the cross direction were obtained in comparison with conventional membranes. This suggests the tremendous potential for using the fabricated membranes in flexible, breathable, and wearable skin contactors.

Synthesis of Biodegradable Polyester-Polyether with Enhanced Hydrophilicity, Thermal Stability, Toughness, and Degradation Rate.

Novel poly(butylene succinate-butylene furandicarboxylate/polyethylene glycol succinate) (PBSF-PEG) was synthesized using two-step transesterification and polycondensation in the melt. There are characterized by intrinsic viscosity, GPC, 1H NMR, DSC, TGA, tensile, water absorption tests, and water degradation at different pH. GPC analysis showed that PBSF-PEG had high molecular weight with average molecular weight (Mw) up to 13.68 × 104 g/mol. Tensile tests showed that these polymers possessed good mechanical properties with a tensile strength as high as 30 MPa and elongation at break reaching 1500%. It should be noted that the increase of PEG units improved the toughness of the polyester material. In addition, the introduction of PEG promoted the water degradation properties of PBSF, and the copolymer showed a significantly faster water degradation rate when the PEG unit content was 20%. This suggests that the amount of PEG introduced could be applied to regulate the water degradation rate of the copolymers. Hence, these new polymers have great potential for application as environmentally friendly and sustainable plastic packaging materials.

Interfacial Engineering Based on Polyethylene Glycol and Cuprous Thiocyanate Layers for Efficient and Stable Perovskite Solar Cells

AbstractCuprous thiocyanate (CuSCN) is an ideal inorganic hole transport material for perovskite solar cells (PSCs). However, polar solvents for film deposition of CuSCN run a risk of destroying the perovskite light‐absorbing layer. There is also a poor contact between perovskites and CuSCN, restricting photovoltaic performance and operational stability of PSCs. In this work, a polyethylene glycol (PEG‐10000) is employed as an interlayer to effectively overcome the obstacles mentioned above. By introducing this ultra‐thin layer at the interface between (MAFA)Pb(IBr)3 and CuSCN, the power conversion efficiency (PCE) and operational stability of the related PSCs are both greatly improved. The results confirm that the insertion of PEG cannot only prevent the destruction of bulk perovskites but also reduce the traps/defects at the interface through its strong chemical bonding with undercoordinated ions, which significantly lowers the potential barrier between the perovskite and the hole transport layer. An improved PCE of 19.2% can be achieved in the CuSCN‐based PSCs by interface engineering with PEG. The introduction of PEG can also protect the perovskite film from moisture attack, and greatly enhance device stability. The PEG‐treated PSCs without encapsulation maintain more than 90% of the initial efficiency after 1860 h in the ambient air.

Enhanced crystallization of poly(lactic acid) bioplastics by a green and facile approach using liquid poly(ethylene glycol)

AbstractPolylactic acid (PLA) bioplastics have attracted increasing attention from both academic and industrial researchers due to their biomass‐derived nature and low toxicity for the human body and environment. A major drawback of PLA is slow crystallization during processing, which considerably limits its commercial applications. In this study, a simple and low‐cost approach involving the addition of eco‐friendly low molecular weight poly(ethylene glycol) (PEG; 400 g/mole) as a green solvent was developed to enhance the PLA crystallization process. Differential scanning calorimetry and polarized optical microscopy data revealed that the introduction of PEG into PLA considerably increased the PLA crystallization rate. In particular, the isothermal crystallization rate of a system with a PLA/PEG mass ratio of 70/30 was more than seven times greater than that of neat PLA. In addition, the miscibility, thermal properties, and microstructures of various PLA/PEG blends were determined. A substantial reduction in the equilibrium melting temperature of PLA after PEG addition confirmed that these polymer blends were thermodynamically miscible in the melt, which strongly influenced the PLA crystallization rate. Furthermore, the addition of PEG increased the regularity of PLA crystals and induced the formation of ring‐banded PLA spherulites with periodic twisted lamellae.

A Multifunctional Anti-Proton Electrolyte for High-Rate and Super-Stable Aqueous Zn-Vanadium Oxide Battery

HighlightsThe introduction of PEG 400 additive in the aqueous electrolyte enables regulating the Zn2+ solvation structure and inhibiting the ionization of free water molecules.Such anti-proton electrolyte can not only reduce the lattice expansion of cathode hosts and inhibit the associated by-products, but also guide the uniform Zn deposition and inhibit the hydrogen evolution reaction.A high-rate Zn-V2O3/C battery with 18,000-cycle shelf-life can be demonstrated via the integrated synergetic modification mechanism.

Polyethylene glycol-grafted cellulose-based gel polymer electrolyte for long-life Li-ion batteries

Recently, highly abundant natural materials have been used in the fields of energy storage because of their environmental friendliness and low cost. However, use of some natural materials like cellulose as host matrices of gel polymer electrolytes (GPEs) is challenging owing to the strong intra- and inter-molecular hydrogen bonding. Herein, a green GPE film was prepared by chemically grafting soft chain-polyethylene glycol (PEG) onto the backbone of cellulose. The introduction of PEG significantly improved the toughness of cellulose from 118 × 103to 270 × 103kJ m−3, as well as raised the wettability in carbonate-based liquid electrolyte solutions from 22.6% to 141.7%. The first cycle coulomb efficiency stayed above 90%. The capacity retention of LiFePO4/Libatteries assembled with the as-obtained GPEreached 80.3% after 300 cycles at 0.2 C. In sum, the as-obtained cellulose-based GPEs look promising to replace separators and liquid electrolytes in Li-ion batteries.

Fabrication of super-hydrophilic and highly open-porous poly (lactic acid) scaffolds using supercritical carbon dioxide foaming.

Porous poly (lactic acid) (PLA)-based scaffolds have been widely used as a promising product in tissue engineering. However, it is still a challenge to prepare the PLA-based scaffolds with high expansion ratio, good hydrophilicity, and excellent cytocompatibility by a green and cost-effective fabrication approach. Herein, we prepared porous PLA-based scaffolds using carbon dioxide (CO2) as the physical foaming agent. To improve the hydrophilicity and foaming behavior of PLA, poly (ethylene glycol) (PEG) was selected as a good additive to blend with PLA. It revealed that the introduction of PEG could improve the foaming behavior of PLA and promote the formation of opening cells via reducing the matrix strength of PLA. The obtained 3D PLA/PEG scaffolds exhibited high expansion ratio (9.1), high open-cell content (95.2%), and super-hydrophilicity (water contact angle 0°). Additionally, the mouse fibroblast NIH/3T3 cells with live/dead cell fluorescence staining assay was utilized to examine the biocompatibility of PLA/PEG scaffolds. The result demonstrated that the proliferation ratio of NIH/3T3 cells on the surface of PLA/PEG scaffolds was higher than that of PLA scaffolds, indicating that the highly interconnected cell structure was conducive to cell adhesion and attachment. Consequently, such hydrophilic open-cell structure obtained by adding PEG into PLA possesses great potential for use in tissue engineering.

PEG-Induced Controllable Thin-Thickness Gradient and Water Retention: A Simple Way to Programme Deformation of Hydrogel Actuators.

Building the differential growth through the thickness is a promising and challenging approach to design the morphing structures of hydrogel actuators. Besides retaining the size of the hydrogel actuators under environmental stimuli still remains a big challenge. Herein, a facile and universal approach is developed to address both issues by introducing PEG during the polymerization of N-isopropylacrylamide (NIPAm) via one step method using asymmetric mold. Both composition gradient and pore gradient are obtained in micro level along the thickness direction of the final hydrogel, while thin-thickness gradient in macro level. The thickness gradient and water retention can be controllably adjusted by changing PEG concentration. The introduction of PEG effectively improves both responsive and non-shrunken performance by the interaction with PNIPAm. The resultant anisotropic PNIPAm/PEG hydrogel respond quickly and reach maximum deformation (360°) within 10 s at low temperature (40 °C).The various 3D shape and biomimetic movement can be programmed by simply controlling the PEG concentration and mold shape. This strategy can provide new insights into the design intelligent soft materials with 3D morphing for bioinspired and biomedical applications.

Preparation and Evaluation of Eudragit L100-PEG Proliponiosomes for Enhanced Oral Delivery of Celecoxib.

PEGylated Eudragit L100 (ELP)-containing proliponiosomes (PLNs) were developed for improved oral delivery of celecoxib (CXB). The successful introduction of PEG 2000 or 5000 to Eudragit L100 (EL) was confirmed via proton nuclear magnetic resonance analysis of which calculated molar substitution ratio of PEG to EL was 36.0 or 36.7, respectively. CXB, ELP, phospholipid, and non-ionic surfactants were dissolved in dimethyl sulfoxide and lyophilized to produce CXB-loaded PLNs (CXB@PLNs). The physical state of CXB@PLNs was evaluated using differential scanning calorimetry and powder X-ray diffractometry, which revealed that crystalline CXB was transformed into amorphous form after the fabrication procedure. The reconstitution of CXB@PLNs in aqueous media generated CXB-loaded liponiosomes with nano-sized mean diameters and spherical morphology. CXB@PLNs displayed enhanced dissolution rate and permeability compared to CXB suspension. In vivo pharmacokinetic studies performed on rats demonstrated the improved oral bioavailability of CXB@PLNs compared to that of CXB suspension. No serious systemic toxicity was observed in the blood biochemistry tests performed on rats. These results suggest that the developed PLNs could be promising oral delivery systems for improving the bioavailability of poorly water-soluble drugs, such as CXB.

Comprehensive investigation of in vitro hemocompatibility of surface modified polyamidoamine nanocarrier.

Polyamidoamine (PAMAM) dendrimers have been investigated for decades and currently applied in various areas throughout nanomedicine, including gene therapy, drug delivery, anti-bacteria and imaging. It is therefore necessary to assess cytotoxicity of PAMAM dendrimers systematically. Because blood component is usually the initial step of contact with any therapeutic agent, comprehensive hemocompatibility study is needed. The triblock dendrimer: polyamidoamine-polyethylene glycol-cyclic RGD (PAMAM-PEG-cRGD), was successfully synthesized. Various in vitro assays to characterize hemocompatibility of both PAMAM (Generation 4.0) and PAMAM-PEG-cRGD were performed, including hemolytic assay, platelet activation examination, platelet counting, assessment of coagulating pathways and evaluation of complement system activation. The hemolytic ratio of PAMAM-PEG-cRGD maintained below 5%. Surface engineering of PEG and cRGD to PAMAM attenuated hemolysis and RBC aggregation as compared with unmodified PAMAM. PAMAM (Generation 4.0) reduced platelet counting in a dose-dependent manner, and the platelet number dropped dramatically at a relatively low incubating dose (1 μM). Such surface modifications also alleviated platelet activation and platelet reduction mediated by PAMAM polycationicity. Finally, high concentration (10 μM) of PAMAM interfered the coagulation system, prolonging prothrombin time significantly. Surface modification of PEG and cRGD to PAMAM (Generation 4.0) improves hemocompatibility. Introduction of PEG and cRGD significantly mitigates hemolytic and RBC aggregation effects as compared with unmodified PAMAM. Similarly, these modifications alleviate platelet activation and platelet reduction mediated by PAMAM polycationicity.

Degradable Poly(ether-ester-urethane)s Based on Well-Defined Aliphatic Diurethane Diisocyanate with Excellent Shape Recovery Properties at Body Temperature for Biomedical Application.

The aim of this study is to offer a new class of degradable shape-memory poly(ether-ester-urethane)s (SMPEEUs) based on poly(ether-ester) (PECL) and well-defined aliphatic diurethane diisocyanate (HBH) for further biomedical application. The prepolymers of PECLs were synthesized through bulk ring-opening polymerization using ε-caprolactone as the monomer and poly(ethylene glycol) as the initiator. By chain extension of PECL with HBH, SMPEEUs with varying PEG content were prepared. The chemical structures of the prepolymers and products were characterized by GPC, 1H NMR, and FT-IR, and the effect of PEG content on the physicochemical properties (especially the shape recovery properties) of SMPEEUs was studied. The microsphase-separated structures of the SMPEEUs were demonstrated by DSC and XRD. The SMPEEU films exhibited good tensile properties with the strain at a break of 483%–956% and an ultimate stress of 23.1–9.0 MPa. Hydrolytic degradation in vitro studies indicated that the time of the SMPEEU films becoming fragments was 4–12 weeks and the introduction of PEG facilitates the degradation rate of the films. The shape memory properties studies found that SMPEEU films with a PEG content of 23.4 wt % displayed excellent recovery properties with a recovery ratio of 99.8% and a recovery time of 3.9 s at body temperature. In addition, the relative growth rates of the SMPEEU films were greater than 75% after incubation for 72 h, indicating good cytocompatibility in vitro. The SMPEEUs, which possess not only satisfactory tensile properties, degradability, nontoxic degradation products, and cytocompatibility, but also excellent shape recovery properties at body temperature, promised to be an excellent candidate for medical device applications.

Modification of poly(ethylene glycol) on the microstructure and mechanical properties of calcium silicate hydrates

With the aim of creating more sustainable building materials, calcium silicate hydrate (C-S-H), the primary binding phase in modern concrete, was integrated with poly(ethylene glycol) (PEG). At the crystal lattice scale, synchrotron radiation-based high-pressure X-ray diffraction (HP-XRD) reveals that the incorporation of PEG increases the ab-planar stiffness of C-S-H leading to a higher bulk modulus, while molecular simulation results indicate polymers are not likely intercalated into the interlayer region. At a higher length scale, nanoindentation measurements show the introduction of PEG lowers the packing density of C-S-H particles and, thus, decreases the indentation modulus. However, a high creep resistance of the C-S-H/PEG sample is still maintained, which suggests a meso-composite may form to restrict the rapid translation between neighboring calcium silicate sheets. Furthermore, 29Si nuclear magnetic resonance (NMR) shows that the presence of PEG shortens the mean chain length of C-S-H, making dimer the predominant structure.

An electrode-supported fabrication of thin polybenzimidazole membrane-based polymer electrolyte membrane fuel cell

H3PO4-doped polybenzimidazole (PBI) membranes have been employed for high temperature polymer electrolyte membrane fuel cell (HT-PEMFC). Although a thinner PBI membrane is beneficial in enhancing power performance, the use of thin PBI membrane has been hindered by its poor mechanical property and consequent difficulty in membrane handling during membrane electrode assembly (MEA) fabrication. Here, novel fabrication route to realize a thin PBI membrane (∼35 μm)-based HT-MEA is presented. The key feature of the process is to fabricate thin blend membrane of PBI and poly(ethylene glycol) (PEG) and laminate the blend membrane to anode gas diffusion electrode (GDE) followed by H3PO4 doping. The introduction of PEG to PBI film enables the tight bonding of the membrane to the GDE at a mild lamination temperature and mitigates the membrane expansion with the doping, preserving the tight interfacial bonding. Due to the lowered membrane thickness, the corresponding MEA exhibits a high power density of 264 mW cm-2 at 0.6 V. Therefore, the new fabrication strategy based on the blend of PBI/PEG is highly effective in improving both process and power performance of HT-MEA.

Preparation of plasticized poly (lactic acid) and its influence on the properties of composite materials.

Plasticized poly (lactic acid) (PPLA) was prepared by melt blending poly (lactic acid) (PLA) with 10 wt% of poly (ethylene glycol) (PEG), with varied molecular weights range from 400 to 4000. The structure, thermal property, morphology, and surface free energy of the PPLA were investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and contact angles (CA). The resulting PPLA results indicated that the introduction of PEG to the blend systems resulted in a ductile fracture, a decrease in the melt temperature (Tm) and glass transfer temperature (Tg), and an increase in the degree of crystallization (χc), which indicated an improved flexibility. In addition, the polarity of the PPLA increased and the surface free energy decreased. The resulting PPLA was subsequently used as matrix to blend with wood flour to prepare composites. The mechanical strength, melting behavior, thermal stability, and microscopy of the PPLA/wood flour composites were also evaluated. These results illustrated that the plasticized PPLA matrix was beneficial to the interfacial compatibility between the polar filler and the substrate.

Thermal, crystallization, mechanical and decomposition properties of poly(lactic acid) plasticized with poly(ethylene glycol)

In order to modify the brittleness of poly(lactic acid) (PLA), a series of PLA/poly(ethylene glycol) (PEG) blends were prepared by the solution‐cast technique using PEG as a plasticizer. The thermal, crystallization, mechanical, and hydrophilic properties of the PLA/PEG blends were compared with those of neat PLA. It is concluded that the PLA/PEG blends change from miscible to partially miscible at the critical PEG content of 10 wt%. Above 10 wt% PEG content, the miscible PLA/PEG blends occur the phase separation, and the PEG component does not co‐crystallize with PLA component with PLA and PEG crystallizing separately. The introduction of PEG reduces the intermolecular force and enhances the mobility of PLA chains, thus improving the crystallization capacity and flexibility of PLA. The PLA/PEG blends show plastic fracture behavior, yielding higher elongation and lower modulus values compared with neat PLA. Below 30 wt% PEG content, blending with PEG significantly decreases the modulus and yield stress and increases the fracture strain of PLA with an increase in the PEG content. Whereas above 30 wt% PEG content, the crystallization of PEG component results in an increase in modulus and a corresponding decrease in elongation at break of the blends. The thermal degradation temperature is in the range of 320–330°C for PLA/PEG blends, in comparison with 375°C for neat PLA. At ambient temperature, the desired mechanical properties are achieved by blending PLA with 30 wt% PEG. The PEG plasticizer is compatible with the PLA matrix and has a relatively low migration rate toward the blend surfaces with a low PEG content (≤30 wt%). J. VINYL ADDIT. TECHNOL., 24:E154–E163, 2018. © 2018 Society of Plastics Engineers

In situ synthesis of PAA-b-PSt nano-assemblies via dispersion RAFT polymerization: effects of PEG in the medium

A facile and efficient approach was proposed to adjust BCP assemblies in PISA by introduction of PEG in the medium. Both PEG amount and molecular weight have significant effects on PAA-b-PSt micelles.

Preparation and Properties of 2, 4-2-Isocyanic Acid Methyl Ester/Poly(ϵ-caprolactone)/Diethylene Glycol Hydrogels

ABSTRACTThe hydrophilic polyurethane (PU) hydrogels have become attractive in the biomedical field for drug delivery. In this work 2, 4-2-isocyanic acid methyl ester (TDI), poly(ϵ-caprolactone) (PCL), and poly(ethylene glycol) (PEG) were used to prepare a prepolymer and then diethylene glycol (DEG) was used as a chain extender to prepare a novel hydrophilic polyurethane, TDI/PCL-PEG/DEG. The obtained PU hydrogels were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM). By varying the ratio of PCL to PEG in the copolymer, modulations of hydrophilicity and drug release behavior were observed. FT-IR analysis confirmed the successful synthesis of the TDI/PCL-PEG/DEG hydrogels. The introduction of PEG into the PU hydrogels led to a porous structure. The water contact angle and swelling ratio results confirmed that the hydrophilicity increased with increasing amounts of the PEG segments. The introduction of PEG also increased the release rate of chloramphenicol, used as model drug, from the PU hydrogels.