Different Molecular Weights Of Poly Research Articles

Impact of Poly (Vinyl Alcohol) on The Thermogelation Property and Drug Release Profile of Ophthalmic Formulations Based on Poloxamer 407

AbstractIn this study, we have designed and assessed a Ketorolac tromethamine (KT) based thermally responsive in situocular gelling system. These gelling systems consist of a thermally responsive in situ gelling polymer, poloxamer 407 (PM) and different molecular weight of poly (vinyl alcohol) (PVA) as release retardant. The formulations were analyzed for sol‐gel transition temperature, gelling aptitude, viscosity and rheological studies, gel morphology study, gel dissolution property and in vitro drug release study. FTIR spectral analysis was performed to explore any polymer‐polymer or drug‐polymer association. In comparison to commercially available drugs, the new formulations present a longer‐lasting drug release profile.

Coupling Particle Ordering and Spherulitic Growth for Long-Term Performance of Nanocellulose/Poly(ethylene oxide) Electrolytes

Development of lithium-ion batteries with composite solid polymer electrolytes (CPSEs) has attracted attention due to their higher energy density and improved safety compared to systems utilizing liquid electrolytes. While it is well known that the microstructure of CPSEs affects the ionic conductivity, thermal stability, and mechanical integrity/long-term stability, the bridge between the microscopic and macroscopic scales is still unclear. Herein, we present a systematic investigation of the distribution of TEMPO-oxidized cellulose nanofibrils (t-CNFs) in two different molecular weights of poly(ethylene oxide) (PEO) and its effect on Li+ ion mobility, bulk conductivity, and long-term stability. For the first time, we link local Li-ion mobility at the nanoscale level to the morphology of CPSEs defined by PEO spherulitic growth in the presence of t-CNF. In a low-MW PEO system, spherulites occupy a whole volume of the derived CPSE with t-CNF being incorporated in between lamellas, while their nuclei remain particle-free. In a high-MW PEO system, spherulites are scarce and their growth is arrested in a non-equilibrium cubic shape due to the strong t-CNF network surrounding them. Electrochemical strain microscopy and solid-state 7Li nuclear magnetic resonance spectroscopy confirm that t-CNF does not partake in Li+ ion transport regardless of its distribution within the polymer matrix. Free-standing CSPE films with low-MW PEO have higher conductivity but lack long-term stability due to the existence of uniformly distributed, particle-free, spherulite nuclei, which have very little resistance to Li dendrite growth. On the other hand, high-MW PEO has lower conductivity but demonstrates a highly stable Li cycling response for more than 1000 h at 0.2 mA/cm2 and 65 °C and more than 100 h at 85 °C. The study provides a direct link between the microscopic dynamic, Li-ion transport, bulk mechanical properties and long-term stability of the derived CPSE and, and as such, offers a pathway towards design of robust all-solid-state Li-metal batteries.

Sub-Newtonian coalescence in polymeric fluids.

We present a theoretical framework for capturing the coalescence of a pendant drop with a sessile drop in polymeric fluids. The framework is based on the unification of various constitutive laws under a high Weissenberg creeping flow limit. Our results suggest that the phenomenon comes under a new regime, namely, the sub-Newtonian regime followed by the limiting case of arrested coalescence with the arrest angle θarrest ∝ Ec-1/2-1, where Ec-1 is the inverse of Elasto-capillary number. Furthermore, we propose a new time scale T* integrating the continuum variable Ec-1 and the macromolecular parameter Ne, the entanglement density to describe the liquid neck evolution. Finally, we validate the framework with high-speed imaging experiments performed across different molecular weights of poly(ethylene oxide) (PEO).

Optimizing the Molecular Weight of Poly(vinylidene Fluoride) for Competitive Perfluorosulfonic Acid Membranes

Homogeneous proton exchange membrane with high mechanical strength and low gas permeation is of paramount importance for the application of proton exchange membrane fuel cells (PEMFCs). Herein, the impact of different molecular weight of poly(vinylidene fluoride) (PVDF, Mw = 350 000–1 100 000 g mol−1) on the performance of the perfluorosulfonic acid (PFSA)/PVDF blend membrane is studied systematically for the first time. The mechanical strength of the PFSA/PVDF blend membrane increases and the H2 crossover of PFSA/PVDF blend membrane is decreased with increasing molecular weight of PVDF. Due to the fact that ultra‐high molecular weight PVDF has more long‐chain molecules which can enhance the adhesive strength between PVDF and PFSA, the tensile strength of 25 wt% PVDF5130–PFSA (Mw = 1 100 000) membrane reaches 33.5 MPa with the thickness of 15 μm, 200% higher than that of pure PFSA membrane and 60% higher than that of commercial Nafion 211. The H2 crossover of the blend membrane is 0.69 mA cm−2, much lower than that of commercial Nafion 211 (2.05 mA cm−2). When applied in PEMFCs, the blend membrane shows comparable power density to Nafion 211 with an output of 1.17 W cm−2.

Investigation of molecular weight effect on lignin flocculation induced by poly(diallyldimethylammonium chloride) (PDADMAC) through population balance modeling

In this research, population balance model was employed to investigated the effect of different molecular weights of poly(diallyldimethylammonium chloride) (PDADMAC) on flocculation process for lignin recovery. Results shows high molecular weight PDADMAC (1,100,000 g/mol) resulted in higher collision efficiency, higher restructure rate and stronger flocs than the lower molecular weight PDADMAC (200,000 g/mol). High molecular weight PDADMAC (1,100,000 g/mol) facilitated bridging while low molecular weight PDADMAC (200,000 g/mol) induced electrostatic patch flocculation mechanism. Polymer dosage, shear rate, temperature and electrolyte concentration affected both flocculation systems to different extents. Shear rate had more significant effect on the high molecular weight PDADMAC (1,100,000 g/mol) flocculation system than on low molecular weight PDADMAC (200,000 g/mol) flocculation system. The addition of a electrolyte had positive effect on the collision efficiency but negative effect on floc strength. More significant restructure at higher ionic strength was also observed.

Effect of molecular weight of poly(ethylene glycol) as humectant in interpenetrating polymer network hydrogels based on poly(sodium AMPS) and gelatin for wound dressing applications

Hydrogel composed of poly(sodium 2-acrylamido-2-methylpropane sulfonate) and gelatin containing different molecular weights of poly(ethylene glycol) (PEG) as a humectant were prepared via UV photopolymerization. The results indicated that the PEG slowed down evaporative water loss and water vapor transmission. Water transport, whether it was absorption, transmission or evaporation, and also tensile properties were found to be dependent to varying extents on the PEG molecular weight. These results could also be related to the amount of non-freezable water, as determined by differential scanning calorimetry. These properties and their relevance to the hydrogel’s potential use as a wound dressing are discussed.

Synthetic scheme to improve the solid content of biodegradable waterborne polyurethane by changing the association relationships of hydrophilic fragments.

A synthetic method was developed to prepare biodegradable waterborne polyurethanes (BHPUs) with a high solid content by introducing different molecular weights of poly(ethylene glycol) (PEG) into poly(ε-caprolactone) (PCL)-based polyurethanes. PCL is a semi-crystalline polymer that can be degraded in lipase to prepare biodegradable waterborne polyurethanes. The biodegradability of BHPUs was evaluated, and the results showed that BHPU samples could be degraded in a solution of phosphate-buffered saline (PBS)/lipase but not in PBS. Two different synthesis routes were used to prepare the BHPUs, which resulted in different association relationships between the ionic hydrophilic polymer dimethylol propionic acid (DMPA) and a nonionic hydrophilic polymer (PEG). The influence of the association relationship between DMPA and PEG on the solid content and other BHPU properties was investigated. The results showed that the method of associating all PEG molecules with DMPA increased the crystallization, tensile properties, and water and soil repellency of the BHPU samples. The solid content of the BHPU samples increased from 41% to 52.7%. In addition, PEG with molecular weights of 400 g mol−1 and 1000 g mol−1 had the best effect on the dispersibility and stability of BHPU samples when incorporated into a polyurethane backbone.

Effect of molecular weight on residual solvent and other parameters in polymer-polymer-solvent coatings: Poly(Styrene)-poly(methyl methacrylate)-ethylbenzene system

Homogeneous coatings of different molecular weights of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) were prepared using solution casting method. The effect of molecular weight on the residual solvent, change in coating thickness, polymer and solvent concentration of the coatings were extensively investigated. The dominance of molecular weight of poly(styrene) has a significant effect on the residual solvent as compared to the molecular weight of poly(methyl methacrylate). The residual solvent and coating thickness were least in the case of higher molecular weight poly(styrene).

Comparative Studies on Two-Electrode Symmetric Supercapacitors Based on Polypyrrole:Poly(4-styrenesulfonate) with Different Molecular Weights of Poly(4-styrenesulfonate).

Poly(4-styrenesulfonate)-conducting polymer (PSS-CP) is advantageous for thin-film electrode manufacturing due to its high conductivity, high charge storage, structural stability, and excellent ink dispersion. In this work, comparative studies of two-electrode symmetric supercapacitors using Polypyrrole:Poly(4-styrenesulfonate) (PPy:PSS), with different molecular weights (Mw’s) of Poly(4-styrenesulfonate) (PSS) as the electrodes, were performed. PPy:PSS can be easily prepared using a simple solution process that enables the mass production of thin-film electrodes with improved electrical and electrochemical properties. As-prepared PPy:PSS, with different PSS molecular weights, were assembled into two-electrode supercapacitors based on coin cell structures. It was confirmed that the electrical and electrochemical properties of PPy:PSS were improved with increasing PSS molecular weight. The coin cell, using PPy:PSS with a PSS molecular weight of 1.0 × 106 g/mol, exhibited higher areal capacitance (175.3 mF/cm2), higher volumetric capacitance (584.2 F/cm3), and longer cycling stability (86.3% after 5000 cycles) compared to those of PPy:PSS with PSS molecular weights of 2.0 × 105 and 7.0 × 104 g/mol. This work provides an efficient approach for producing cost-effective and miniaturized supercapacitors with high conductivity and high specific capacitance for practical applications in a variety of electronic devices.

Novel nanosuspension-based dissolving microneedle arrays for transdermal delivery of a hydrophobic drug.

A nanosuspension (NS) was formulated from the lipophilic molecule cholecalciferol (CL) for enhanced transdermal delivery by embedding this NS into hydrophilic polymer‐based dissolving microneedles (DMNs). First, the NS was prepared by sonoprecpitation with different molecular weights of poly (vinyl alcohol) and poly (vinyl pyrrolidone) as stabilizers and using two different solvents for particle size and zeta potential optimization. DMN arrays were then prepared by centrifugation‐assisted micromoulding and subsequently dried. Poly (vinyl alcohol) (10 kDa) produced a NS with the lowest particle size ( ~ 300 nm). These particles yielded DMN with good mechanical properties when combined with aqueous blends of high molecular weight poly (vinyl pyrrolidone) (360 kDa). The particle size remained similar before and after MN preparation, as confirmed by scanning electron microscope. The CL was in the amorphous state in the free particles as well as in the DMN and, hence, no characteristic CL peak was observed in differential scanning calorimetry or X‐ray diffraction. DMN arrays were found to be strong enough to bear a 32 N force, showed efficient skin insertion, and penetrated down to the third layer (depth ≈ 375 μm) of the validated skin model Parafilm M®. An ex vivo porcine skin permeation study using Franz diffusion cells compared the permeation of CL from CL‐NS‐loaded DMN arrays and MN‐free CL‐NS patches. It was observed that CL‐NS‐loaded DMN arrays showed significantly higher (498.19 μg ± 89.3 μg) ex vivo skin permeation compared with MN‐free CL‐NS patches (73.2 μg ± 26.5 μg) over 24 h. This is the first time a NS of a hydrophobic drug has been successfully incorporated into dissolving MN and suggest that NS‐containing DMN systems could be a promising strategy for transdermal delivery of hydrophobic drugs.

Hemocompatibility, cytotoxicity, and genotoxicity of poly(methylmethacrylate)/nanohydroxyapatite nanocomposites synthesized by melt blending method

ABSTRACTThe aim of this study was to show the hemocompatibility, cytotoxicity, and genotoxicity of nanocomposites that were synthesized with different molecular weights of poly(methyl methacrylate) (PMMA) and different concentrations of nanohydroxyapatite (nHAp). Different techniques to characterize the nanocomposites were used. The cytotoxicity and genotoxic effects of the polymers and nanocomposites on human lymphocytes were determined by acid phosphatase assay, viability test, and comet assay. Moreover, hemocompatibility test was performed. It was found that all of the PMMA/nHAp nanocomposites are highly hemocompatible and biocompatible, none of the nanocomposites showed a cytotoxic effect, and nHAp addition decreased the genotoxicity.

Clean-up of oily liquids, fuels and organic solvents from the contaminated water fields using poly(propylene glycol) based organogels

Organogels with high and fast absorption properties, as well as reusability functions, were successfully prepared through the condensation reactions of different molecular weights of poly(propylene glycol)s (PPG)s and tris[3-(trimethoxysilyl) propyl] isocyanurate (ICS). The characterization of these organogels was determined by solid-state 13C and 29Si cross polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). Thermal gravimetric analysis (TGA) was used to describe the thermal behavior of the prepared organogels. Obtained organogels are reusable and can absorb a large amount of oils, such as dichloromethane (DCM), tetrahydrofuran (THF), methyl tert-butyl ether (MTBE), toluene, benzene, acetone, and gasoline. The capacity of the synthesized organogels did not change in either pure organic liquids or in organic liquid/water mixtures, these can be used at least ten times without loss of capacity.

Cross-linked poly(tetrahydrofuran) as promising sorbent for organic solvent/oil spill

In this study, a series of different molecular weights of poly(tetrahydrofuran) (PTHF), which is one of the most important commercial polymers around the world, was condensed with tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS) to generate a cross-linked 3-dimensional network in order to obtain organic solvent/oil sorbents having high swelling capacity. The prepared sorbents show high and fast swelling capacity in oils such as dichloromethane (DCM), tetrahydrofuran (THF), acetone, t-butyl methyl ether (MTBE), gasoline, euro diesel, and crude oil. The recovery of the absorbed oils from contaminated surfaces, especially from water, and the regeneration of the sorbents after several applications are effective. The characterization and thermal properties of the sorbents are identified by Fourier transform infrared spectroscopy (FTIR), solid-state 13C and 29Si cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and thermal gravimetric analyses (TGA), respectively. The new usage area of PTHF is emerged by the preparation of PTHF-based network structure with high oil absorption capacity and having excellent reusability as an oil absorbent for the removal of organic liquids from the spill site.

Preparation and characterization of poly(ethylene glycol) stabilized nano silver particles by a mechanochemical assisted ball mill process

ABSTRACTNano silver particles with an average mean crystallite size of between 10 and 12 nm were synthesized from different molecular weights of poly(ethylene glycol) as a stabilizing agents, through solid state oxidation of silver nitrate using a higher energy planetary ball mill. Ultraviolet‐Visible spectra were used to confirm the synthesis of nano silver particles. The surface plasmon resonance bands were observed around 410 nm. Fourier transformed infrared spectrum, X‐ray diffraction, and transmission electronic microscopy techniques were used to characterize the nano silver particles synthesized. Thermal stability was determined using thermogravimetic analysis and the elemental composition of the sample was determined by energy dispersive X‐ray analysis. The nano silver particles synthesized, exhibited very good antibacterial activity against Gram‐positive bacteria (Bacillus) and Gram‐negative bacteria (Pseudomonas aeruginosa). Based on the obtained results, it was additionally explored that the size and the stabilization of the nano silver particles synthesized, strongly depend on the molecular weight of poly(ethylene glycol). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43027.

Effects of soft segments on the waterproof of anionic waterborne polyurethane

To study the waterproof of coating materials, a series of waterborne polyurethanes were prepared with different kinds and molecular weight of polyols. IR spectroscopy was used to check the end of polymerization reaction and characterization of polymer. The study was carried out by increasing the waterproof of various coating agents through variations of soft segments. We introduced laser-scattering equipment, Brookfield digital viscometer, JC2000C instrument, scanning electron microscope (SEM), and atomic force microscope (AFM) to investigate the particle size, viscosity, contact angle, and morphology of the coated fabric. In short, results displayed waterproof as follows: 3146~8200 mm H2O (IPDI = 30 %) in various polyols and 5421~8748 mm H2O (R = 1.6) of different molecular weight of poly(butylene adipate) (PBA). The higher water resistance belonged to PTMG-WBPU and WBPU-1000, respectively. Experimental results indicated that water resistance may be controlled by not only the types of soft segments, but also the molecular weight.

Low glass transition temperature polymer electrolyte prepared from ionic liquid grafted polyethylene oxide

In this contribution, we report a new type of poly (ionic liquids) prepared by imidazolium ionic liquids directly grafting onto polyethylene oxide backbone. Different molecular weights of poly (ionic liquids) are obtained with a low glass transition temperature up to −14 °C. The materials as polymer electrolyte achieve a high conductivity around 10−5 S cm−1 at 30 °C and close to 10−3 S cm−1 at 90 °C. High viscosity up to 4000 Pa s at room temperature would minimize the electrolytes leaking in electrochemical devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2104–2110

Thermal and structure properties of biobased cellulose nanowhiskers/poly (lactic acid) nanocomposites

Cellulose nanowhiskers were used to improve the performance of poly (lactic acid) (PLA). The nanocomposites mixed with three different molecular weight of poly (ethylene glycol) (PEG) were characterized by mechanical testing, thermal gravimetry and differential scanning calorimetry. The tensile test showed an increase in tensile strength and elongation at break with the addition of PEG to PLA/CNW nanocomposites, the thermal analysis results showed an increase of crystallization temperature (T c) and crystallization compatibility (larger crystallization and melting areas), which indicated that the cellulose nanowhiskers (CNW) and PEG or CNW alone should not be considered as nucleating agents for the PLA matrix; The CNW was homo-dispersed which contributed to decreasing mobility of polymer chain segments. The compatibility between hydrophobic PLA matrix and the hydrophilic CNW was improved by the addition of different molecular weight polymeric-PEG. The thermo gravimetric analysis indicated that the thermal stability of the different composites were reflected well in the region between 25 °C and 245 oC. The structure of the PLA/CNW/PEG composites was characterized by AFM, which showed that the CNW dispersed in the PLA matrix evenly.

Hydrophilic–hydrophobic copolymer nano-sized particle gels: Swelling behavior and dependence on crosslinker chain length

Poly N-isopropylacrylamide-co-ethylacrylate [P(NIPAM-co-EA)], Poly N-isopropylacrylamide-co-2-hydroxyethylmethacrylate [P(NIPAM-co-HEMA)], and Poly N-isopropylacrylamide-co-2-hydroxyethylacrylate [P(NIPAM-co-HEA)] nano-sized particle copolymer hydrogels were synthesized to investigate their volume phase transition behavior. Increasing the hydrophobic or hydrophilic monomer content of hydrogels led to uniform changes in transition temperature and swelling ratio. Different statistical thermodynamic models are presented to describe the swelling behavior of copolymer gels. The classical interaction energy parameter in the thermodynamic model, which is not suitable for accurately representing the equilibrium swelling of a copolymer hydrogel, was modified semi-empirically in order to reflect the individual contribution of each hydrogel constituent. In addition, we investigated the volume phase transition of PNIPAM gels as a function of crosslinker chain length. The crosslinkers used in this study were N,N′-methylenebisacrylamide (BIS) and two different molecular weights of Poly(ethyleneglycol) diacrylate (PEGDA, 575 and 700). Interestingly, the use of a long chain crosslinker resulted in a decreased volume change compared to that of a short chain crosslinker without any significant changes in transition temperature. To understand this unexpected result, we used a molecular dynamics simulation for BIS and PEGDA 575 to demonstrate the micro-scale conformation change of crosslinker chain mixed with water or ethanol. The proposed thermodynamic models represent the swelling behavior of the copolymer hydrogels and PNIPAM gels with different length crosslinkers.

Chemical cross-linking of conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) using poly(ethylene oxide) (PEO)

Hybrid films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were prepared with different molecular weights of poly(ethylene oxide) (PEO). The cross-linking reaction between PEO and PEDOT:PSS was performed at high temperature and confirmed by using differential scanning calorimeter (DSC), contact angle measurement, and solid-state 1H NMR. The effect of chemical reaction on the conductivity and morphology of these hybrid films was studied by using 4-point probe and atomic force microscope (AFM), respectively. As-spun PEO/PEDOT:PSS films have lower electric conductivity due to the addition of nonconductive PEO, and exhibits no molecular weight dependence on conductivity. After chemical cross-linking reaction at high temperature, only PEDOT:PSS films with lowest molecular weight PEO additives show enhanced conductivity with increasing reaction time. AFM result indicates that the heat-treated PEO/PEDOT:PSS hybrid films show grain-like morphology compared to ethylene glycol treated PEDOT:PSS films which shows continuous PEDOT domain. In the present work we demonstrate that the cross-linking reaction can be used to improve the wet stability of PEDOT:PSS nanofiber, showing good water resistance and excellent dimensional stability.

Effect of Soft Segment Polydispersity on the Elasticity of Polyurethane Elastomers

A family of copolyurethane elastomers was synthesized, based on 1,4-butanediol (BDO) or diethylene glycol (DEG) and hard segments of 4,4′-dibenzyl diisocyanate (DBDI) of constant uniform length. The materials had comparable molecular weights. The soft-segment (SS) polydispersity was varied. A broad polydispersity was achieved by blending polyols of different molecular weights of poly(oxytetramethylene) (PTMO650, PTMO1000, and PTMO2000). To obtain a narrow soft segment molecular weight distribution, fractionated samples of PTMO1546 were prepared. The tensile and thermomechanical properties were determined. Results were related to microstructural changes, on the basis of evidence from wide-angle X-ray scattering (WAXS). Increasing the SS polydispersity from 1.1 to 1.72 resulted in an improvement of the mechanical properties. Inelastic effects were most pronounced when the hard segment crystallized and in the case of the materials achieved with a narrow SS polydispersity.