Increasing PEG Content Research Articles

Effects of annealing and the addition of PEG on the PVA based hydrogel by gamma ray

Poly(vinyl alcohol) (PVA) is an interesting material with good biocompatibility, high elasticity and hydrophilic characteristics. PVA hydrogels have been formed through chemical crosslinking with aldehyde, photopolymerization and physical crosslinking with freeze-thawing. In this study, crosslinked hydrogels based on PVA, and poly(ethylene glycol) (PEG) were prepared by gamma-ray irradiation, and then annealed at 120°C. The properties of a hydrogel such as gel fraction, swelling behavior, gel strength as a function of PEG content and annealing time were investigated. Also, the thermal behaviors were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The gel fraction decreases with an increase in PEG content and decrease in annealing time. The tensile strength increases with an increase in annealing time. The thermal behaviors have shown different patterns according to the annealing time. The improved properties suggest that PVA/PEG blend hydrogel can be a good candidate for applications in the articular cartilage.

Orientation behavior and mechanical properties of poly(butylene 2,6-naphthalate)/poly(ethylene glycol) copolymer filament under uniaxial elongation

Poly(butylene 2,6-naphthalate) (PBN)/poly(ethylene glycol) (PEG) copolymers for a thermoplastic elastomer utilizing an aromatic polyester and a hydrophilic PEG were synthesized by condensation polymerization, and the copolymer filaments were then fabricated by using a melt spinning method. The copolymer filaments produced had different PEG contents and molecular weights. The effects of PEG content and molecular weight on the orientation behavior and mechanical properties of the copolymer filaments under uniaxial elongation were investigated. The orientation, elongation at the break, and instantaneous elastic recovery of the PBN/PEG copolymer filaments were found to be significantly improved compared with pure PBN, while their tensile strength decreased with increasing PEG content and molecular weight. Open image in new window

Improvement of hemocompatibility on materials by photoimmobilization of poly(ethylene glycol)

PEGylation of biomaterials is a common way to effectively enhance hemocompatibility of a substrate. In this study, photoimmobilization of poly(PEGMA) was applied to prepare an anti-fouling substrate for improving biomaterials' hemocompatibility. Poly(ethylene glycol) methacrylate (PEGMA) was firstly copolymerized with acrylic acid (AA), which was then used for conjugation with photosensitive azidoaniline molecules. The synthesized copolymers were coated onto several substrates, such as tissue culture polystyrene, polyurethane, and polydimethylsiloxane, and then covalently immobilized on the substrates by exposure to UV radiation. The crosslinked poly(PEGMA-co-AA) coated surfaces revealed excellent blood compatibility. Platelet adhesion and fibrinogen adsorption to the PEGylated substrates were reduced significantly compared to the untreated substrate. The ability to inhibit platelet adhesion was increased with increasing PEG content in the copolymer. The UV-crosslinked PEG was very stable in both the acid and alkaline conditions and could be applied to various materials. Therefore, we demonstrate that this approach is considered an effective method for the preparation of bioinert surfaces to improve hemocompatibility of biomaterials.

Nonisothermal crystallization behavior, and morphology of poly(trimethylene terephthalate)/polyethylene glycol copolymers

Poly(trimethylene terephthalate)/polyethylene glycol (PTT/PEG) copolymers, with PEG content ranging from 27.2 to 47.4 wt%, were synthesized by melt copolycondensation. Wide-Angle X-ray diffractometer revealed that all copolymers had the same crystal structure of homo-PTT at room temperature. All copolymers could form ring-banded spherulites, and band spacing increased with increasing PEG content at a given crystallization temperature. Nonisothermal crystallization morphology of copolymers was greatly influenced by cooling rate. When the cooling rate was 2.5 °C/min or lower, banded patterns were absent, whereas when the cooling rate was 20 °C/min or higher, a novel crystal morphology composed of non-banded spherulites (central part) and ring-banded spherulites with decreasing band spacing along the radial growth direction was observed. Moreover, the size of the non-banded spherulitic part decreased with increasing cooling rate. Finally, the nonisothermal crystallization kinetics of copolymers were analyzed and only the Mo method was satisfactory to accurately describe this system.

Improvement of biocompatibility and biodegradability of poly(ethylene succinate) by incorporation of poly(ethylene glycol) segments

Poly(ethylene glycol) (PEG) segments were incorporated into poly(ethylene succinate) (PES) by chain-extension reaction of PEG with PES using 1,6-hexamethylene diisocyanate as a chain-extender, forming a poly(ester ether urethane) (PEEU). The chemical structures and molecular weights of the PEEUs were determined by 1H NMR and GPC, respectively. The composition dependence of thermal transitions, crystallization, hydrophilicity, in vitro biocompatibility, in vitro biodegradation and tensile properties of the PEEUs were systematically investigated. The glass transition temperature and degree of crystallinity of PEEU decreased with increase of PEG content. The hydrophilicity increased with PEG content as proved by the decreased water contact angle and increased water absorption. The results of cell culturing suggested that the in vitro biocompatibility increased with PEG content. Hydrolytic degradation demonstrated that degradation rate of PEEU increased with PEG content, which was caused by the increased hydrophilicity and decreased degree of crystallinity with increase of PEG content. The tensile results proved that the tensile strength and modulus decreased while elongation at break increased with PEG content.

Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone), on the gelation of aqueous micellar solutions of Pluronic copolymer F127

The micellization of F127 (E98P67E98) in dilute aqueous solutions of polyethylene glycol (PEG6000 and PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic radius (rh,app) obtained from the dynamic light scattering technique increased with increase in PEG concentration but decreased on addition of PVP, results which are consistent with interaction of the micelles with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion was used to determine the onset of gelation. The critical concentration of F127 for gelation increased on addition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scattering (SAXS) was used to show that the 30wt% F127 gel structure (fcc) was independent of polymer type and concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elastic modulus (Gmax′) of 30wt% F127 decreased from its value for water alone as PEG was added, but was little changed by adding PVP. These results are consistent with the packed-micelles in the 30wt% F127 gel being effectively isolated from the polymer solution on the microscale while, especially for the PEG, being mixed on the macroscale.

Porcine pancreatic Lipase Immobilized in Amino-Functionalized Short Rod-Shaped Mesoporous Silica Prepared Using Poly(ethylene glycol) and Triblock Copolymer as Templates

Mesoporous materials have large ratio surface areas, an average pore diameter, and ordered pore arrangement, showing promising application in the fields of catalysis, adsorption, separation, and functional materials. In this study, short rod-shaped mesoporous silica (SRSMS) were prepared using poly(ethylene glycol) (PEG) and P123 as dual templates and functionalized with (3-aminopropyl)triethoxysilane (APTES) by a postsynthesis-grafting method. The synthesis conditions, including PEG chain length and PEG concentration, when the dual templates were added to the reaction system are discussed. The results show that the d100 increased continuously with the increase of PEG concentration and molecular weights (MW). When PEG with different MW was added, the pore size of SRSMS changed a little, while it increased with increasing PEG content. Pore volumes and surface areas of SRSMS decreased, while the two-dimensional hexagonal p6mm mesoscopic structure remained after functionalization. Porcine pancreatic lipase (PPL) was used as a model enzyme for studying the effect of amino-functionalization on loading amount and enzymatic activity. As a result, functionalized SRSMS immobilized PPL showed the better reusability, higher catalytic activity, and thermal stability.

Antifouling ultrafiltration membranes made from PAN-b-PEG copolymers: Effect of copolymer composition and PEG chain length

Antifouling ultrafiltration membranes were prepared by polyacrylonitrile-block-polyethylene glycol (PAN-b-PEG) copolymers through immersion precipitation phase inversion method. The effect of copolymer composition and PEG chain length on the structure and property of the block copolymer membranes were investigated. Compared with PAN membranes, PAN-b-PEG copolymer membranes possessed excellent hydrophilic surface due to the enrichment of PEG segments, which was confirmed by X-ray photoelectronic spectroscopy (XPS) and contact angle measurements. SEM images showed these PAN-b-PEG copolymer membranes had a typical asymmetric structure similar with PAN membranes, but the thinner skin layer was helpful for the membrane resistance reduction. The PAN-b-PEG copolymer membranes exhibited better antifouling ability for BSA than PAN membranes. The BSA absorption amount on the copolymer membrane could reduce 45% than that on the PAN membrane, and its irreversible fouling extent could lower 7 times. The hydrophilicity and antifouling ability of the copolymer membranes increased with increasing PEG content in the copolymer. While the chain length of PEG had little effect on the hydrophilicity and antifouling ability of the copolymer membrane.

Determining the optimal model for improving seed germination and seedling vigor of perennial grasses

در اصلاح و احیاء مراتع توجه به مرحله جوانه زنی و استقرارگراس های پایا که حساس به تنشهای محیطی می باشد ضروری به نظر می رسد. بدین منظور تکنیک پرایمینگ بذر جهت بهبود سرعت جوانه زنی و بنیه گیاهچه پنج گراس چند ساله فصل سرد مرتعی شامل Bromus confinis، Elymus elongatum، Agropyron pectiniform، Festuca ovinaو Festuca arundinaceae با استفاده از ماده اسمتیک پلی اتیلن گلایکول (PEG 8000) در غلظتهای 0، 5/0 ، 1، 5/1 ، 2 و 5/2 مگاپاسکال (MP) برای دوره­های نگهداری صفر، 2، 4، 6 و 8 روز (D) مورد ارزیابی قرار گرفت. این آزمایش به صورت فاکتوریل در قالب طرح کاملا تصادفی در 4 تکرار اجرا شد. نتایج تجزیه واریانس نشان داد که تفاوت بین تمامی عوامل مورد مطالعه و اثرات متقابل آنها برای سرعت جوانه زنی و اجزاء گیاهچه بسیار معنی داربود (P<0.01). تاثیر پرایمینگ بذر بر افزایش سرعت جوانه زنی نسبت به شاهد (بذر پرایم نشده) مثبت بود و به طور خاص برای گونه های B. confinis، pectiniforme .A و E. elongatum (2 روز نگهداری و 2 مگاپاسکال) به ترتیب 9/127، 8/77 و 5/66 درصد افزایش و برای گونه F. arundinaceae (6 روز و 5/1 مگاپاسکال) 5/96 % افزایش را سبب شد و کمترین تاثیر در گونه F. ovina ( 4 روز و 5/2 مگاپاسکال) با 15 % افزایش نسبت به شاهد مشاهده شد. روابط رگرسیونی نشان داد که با افزایش غلظت PEG وزن خشک ریشه­چه و ساقه­چه برای تمامی گونه­ها به جز F. arundinaceaeو F. ovinaکاهش یافت. همچنین بیشترین کاهش وزن خشک ریشه­چه و ساقه­چه را دو گونه دانه درشت E. elongatum و B. confinesبا افزایش دوره نگهداری بذر (بیشتر از دو روز) و کاهش غلظت PEG نشان دادند. به طورکلی نتایج این تحقیق نشان داد که افزایش غلظت PEG تا حدود 2 و 5/2 مگاپاسکال و کاهش مدت نگهداری بذر تا 2 روز می­تواند در موفقیت تکنیک پرایمینگ بذر گراس­ها نقش موثرتری ایفا کند و شاید گونه­های دانه ریز پاسخ بهتری به پرایمینگ بذر جهت بهبود جوانه زنی و استقرار نسبت به دانه درشت نشان دهند.

Properties of linear poly(lactic acid)/polyethylene glycol blends

AbstractPoly(lactic acid) (PLA) has great potentials to be processed into films for packaging applications. However, film production is difficult to carry out due to the brittleness and low melt strength of PLA. In this investigation, linear PLA (L‐PLA) was plasticized with poly(ethylene glycol) (PEG) having MW of 1000 g mol−1 in various PEG concentrations (0, 5, 10, 15, and 20 wt%). In relation to plasticizer content, the impact resistance and crystallinity of L‐PLA was increased, whereas a decrease in glass transition temperature and lower stiffness was observed. Nevertheless, the phase separation has been found in samples which contained PEG greater than 10 wt%. The dynamic and shear rheological studies showed that the plasticized PLA possessed lower viscosity and more pronounced elastic properties than that of pure PLA. Both storage and loss moduli decreased with PEG loading at all frequencies while storage modulus exhibited weak frequency dependence with increasing PEG content. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Plasticised polymer electrolytes based on PMMA grafted natural rubber–LiCF3SO3–PEG200

Polymer electrolyte membranes that consist of 70 wt-% natural rubber grafted with 30 wt-% poly(methyl methacrylate) (MG30) and 30 wt-% lithium trifluoromethane sulphonate (LiTf) salt have been investigated with various concentrations of poly(ethylene glycol) 200 (PEG200). The formation of polymer–salt complexes has been confirmed by Fourier transform infrared spectral studies. X-ray diffraction studies further confirmed that all the samples prepared are amorphous. The highest conducting sample has the composition of 63 wt-%MG30–27 wt-%LiTf–10 wt-%PEG with conductivity of 3·65×10−4 S cm−1 at 298 K. From differential scanning calorimetry studies, the glass transition temperature Tg is found to increase from −63 to −54°C with the increase in PEG concentration at 30 wt-%PEG200. The ionic transference number of mobile ions has been estimated using Wagner’s polarisation method, and the results reveal that the conducting species are mainly ions.

Formulation and evaluation of mucoadhesive glipizide films

Glipizide is mainly absorbed in the proximal areas of the gastrointestinal tract. The purpose of this study was formulation and evaluation of mucoadhesive films to prolong the stay of drug in its absorption area. Glipizide was formulated in a mucoadhesive film that could be retained in the stomach for prolonged intervals. Polymeric films were designed with various compositions of hydroxypropyl cellulose and polyethylene glycol 400 (PEG 400). Properties of the mucoadhesive film such as tensile strength, percentage elongation, swelling index, moisture content, pH and viscosity of polymeric dispersion, film thickness, content uniformity and mucoadhesion in a simulated gastric environment were characterized. In addition, percentage drug retained in stomach mucosa was estimated using a simulated dynamic stomach system as a function of time. Increase in hydroxypropyl cellulose concentration resulted in a higher tensile strength and elongation at break, while increase in concentration of PEG 400 was reflected in a decrease in tensile strength and increase of elongation at break. Glipizide/hydroxypropyl cellulose/PEG 400 (2.5:1:0.5) (GF5) was found to be the optimal composition for a novel mucoadhesive stomach formulation that showed good peelability, relatively high swelling index, moderate tensile strength, and stayed on rat stomach mucosa up to 8 h. In vivo testing of the mucoadhesive films with glipizide demonstrated a potential hypoglycemic effect.

Absorption of dilute sulfur dioxide in aqueous poly-ethylene glycol 400 solutions at T = 308.15 K and p = 122.60 kPa

Isothermal (gas + liquid) equilibrium (GLE) data at T = 308.15 K and p = 122.60 kPa are reported for the absorption of dilute SO 2 in various aqueous poly-ethylene glycol 400 (PEG) solutions, in which SO 2 partial pressures are in the range of (0.9 to 92) Pa. Measurements are carried out by a saturation method using a glass absorption apparatus, which was controlled at constant temperatures by a thermostatic circulation bath with a Beckmann thermometer. The GLE data were obtained with uncertainties within 0.02 K for temperature, 0.1 kPa for total pressures, 3% for SO 2 concentration in the gas phase, and 0.6% for SO 2 concentration in the liquid phase. The measurements show that the solubility of dilute SO 2 in the system of {PEG (1) + water (2)} increases with increasing PEG concentration in the mass fraction range of w 1 = (0.40 to 1.00), and the solubility of SO 2 in the system of {PEG (1) + water (2)} presents an extreme minimum at the mass fraction of w 1 = 0.40 of 190 mg · L −1 when SO 2 in the gas phase is designed at Φ SO 2 = 5 · 10 −4. The peculiarity of this work is used to provide important GLE data for the design and operation of the absorption and desorption process in flue gas desulfurization (FGD) with potential industrial application of the solutions containing PEG.

Biodegradable and photocurable multiblock copolymers with shape‐memory properties from poly(ε‐caprolactone) diol, poly(ethylene glycol), and 5‐cinnamoyloxyisophthalic acid

AbstractBiodegradable and photocurable multiblock copolymers of various compositions were synthesized by the high‐temperature solution polycondensation of poly(ε‐caprolactone) (PCL) diols of molecular weight (Mn) = 3000 and poly(ethylene glycol)s (PEG) of Mn = 3000 with a dichloride of 5‐cinnamoyloxyisophthalic acid (ICA) as a chain extender, followed by irradiation by a 400 W high‐pressure mercury lamp (λ &gt; 280 nm) to form a network structure. The gel contents increased with photocuring time, reaching a level of over 90% after 10 min for all copolymers without a photoinitiator. The thermal and mechanical properties of the photocured copolymers were examined by DSC and tensile tests. In cyclic thermomechanical tensile tests, the photocured ICA/PCL/PEG copolymer films showed good shape‐memory properties at 37–60°C, with both shape fixity ratio and shape recovery ratio over 90% at a maximum tensile strain of 100–300%. The water absorption of these copolymers and their rate of degradation in a phosphate buffer solution (pH 7.0) at 37°C increased significantly with increasing PEG content. The novel photocured ICA/PCL/PEG multiblock copolymers are potentially useful in biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effect of PEG stress on plantlets of Chrysanthemum morifolium induced by endophytic Botrytis sp. (C1) and Chaetomium globosum(C4)

The effect of the endophytic fungi Botrytis sp. (C1) or Chaetomium globosum (C4) on the drought resistance of Chrysanthemum morifolium was studied. Ch. morifolium plantlets were inoculated with C1, C4 and cultured in the pots for 60 days, then the plantlets were stressed by 0%, 10%, 20%, 30%, 40% PEG6000 respectively in order to simulate different drought conditions. Biomass, the activities of SOD, POD, PAL, the contents of MDA and soluble protein of each group were determined. The results showed that endophytic fungi groups grew better than the control (without inoculation endophytic fungi). With the increasing of the concentration of PEG6000, the biomass of Ch. morifolium of each groups decreased, while the biomass of fungi groups was significantly higher than that of control, moreover C4 group higher than C1 group. With the concentration of PEG increasing, the content of MDA of each group increased too, while POD activity and soluble protein content of all treatments increased at first and then decreased. SOD activity and PAL activity of the control were increased with the increase of PEG concentration, but SOD activity of the two fungi groups were stable. After been stressed by different concentrations of PEG, MDA content of two fungi groups were always lower than the control, while SOD activity, POD activity, PAL activity and soluble protein content were higher. In conclusion, endophytic fungi can increase the drought resistance of Ch. morifolium.

Compatibility and Accelerated Degradation of L-Tyrosine Derived Biodegradable Polycarbonate/PEG Blends

In the present study, the compatibility and degradability of L-tyrosine derived polycarbonate(PC)/Poly(ethylene glycol) blend were investigated. The PC was synthesized in our laboratory. Blends of the polymers with compositions 95/5, 85/15, 75/25,50/50 and 25/75 w/w were prepared by solution-casting. The blends were characterized by FT-IR,DSC,XRD,SEM. No obvious two phases were observed. Analysis of water absorption revealed that the combination of PC and PEG improved the hydrophilicity of PC. DSC and SEM analysis implied that all those components in consideration were compatible well in the blend formulation systems.Tg of the blends decreased with increasing PEG content. With the increase of the soft segment PEG content, the water retention ratio increases from 37% to 83%.

Phase solubility behavior of hydrophilic polymer/cyclodextrin/lansoprazole ternary system studied at high polymer concentration and by response surface methodology

Evaluation of polymer/cyclodextrin (CD)/drug ternary systems has been performed at low polymer levels to date, and the cross-interaction of polymers and CDs has not been well studied. In this study, the effects of PVP K30 and PEG 6000 on the complexation ability of β-CD and 2-hydroxypropyl-β-cyclodextrin (HPCD) with lansoprazole (LSP) was investigated. The phase solubility of polymer/CD/LSP ternary systems was first studied at polymer levels of 0%, 2% and 6%, respectively. A response surface methodology was then employed to investigate the cross-interaction of polymers/CDs on phase solubility at polymer levels up to 10%. Results indicated AL-type inclusion for both β-CD and HPCD. Increase in PEG concentration leads to improved complexation efficiency, whereas increase of PVP lead to decreased CE, which is attributable to the strong interaction between PVP and LSP. Second-order polynomial equations were well employed to estimate the relationship between LSP solubility and the two independent variables. The response surface showed that PVP and PEG had no significant effects on LSP/CD complexation, while a synergistic effect on LSP solubility was observed at higher concentrations of HPCD and PEG. It is concluded that high levels of polymer lead to increased LSP solubility but not significant increase in CE.

Compatibility of L-Tyrosine Derived Biodegradable Polycarbonate/Chitosan Blends

In the present study, the compatibility and degradability of L-tyrosine derived polycarbonate(PC)/Chitosan（CTS）blend were investigated. The PC was synthesized in our laboratory. Blends of the polymers with compositions 4/1, 3/1, 1/1,1/3 and 1/4 w/w were prepared by solution-casting. The blends were characterized by FT-IR,DSC,XRD,SEM. No obvious two phases were observed. DSC and SEM analysis implied that all those components in consideration were compatible well in the blend formulation systems.Tg of the blends decreased with increasing PEG content. With the increase of the CTS content, the water retention ratio increases from 15% to 61%.

Sodium Alginate and Poly(ethylene glycol) Blends: Thermal and Morphological Behaviors

Sodium alginate (SA) was blended with varying amounts of poly(ethylene glycol) (PEG) viz., 10, 20, 30, 40 and 50 wt % by using water as a solvent. The obtained SA/PEG blends have been characterized for thermal behavior by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and surface morphology by scanning electron microscopic (SEM) methods. DSC analysis indicates the increase in glass transition temperature (Tg) of the blends with an increase in PEG content in the blend, which is due to chain entanglement. TGA results reveal the enhancement of thermal stability of SA/PEG blends in terms of the onset of degradation and percentage of weight loss. SEM photomicrographs shows the two phase morphology. This result indicates the immiscible nature of the SA/PEG blends.

Synthesis and in vitro characterization of freeze-dried doxorubicin-loaded silica/PEG composite

Freeze-dried doxorubicin-loaded silica/poly(ethylene glycol) composites have been prepared by a two-step acid/base catalyzed sol–gel process from tetraethylorthosilicate in the presence of poly(ethylene glycol) (PEG). PEG was used as a pore-forming agent, followed by liberation process of PEG during the in vitro doxorubicin release study. Simulated body fluid (SBF, Kokubo solution) at 37 °C with ion concentrations nearly equal to those of human blood plasma (pH 7.4) was used for in vitro evaluation. The characteristics of these composites before and after drug release, including the infrared absorption spectra, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) in combination with IR and nitrogen gas adsorption/desorption, were measured and analyzed. The relationship between the liberation process of PEG and rate of drug release is discussed mainly in terms of molecular and structural features of the silica composites before and after drug release study. It was shown that an increase in the proportion of PEG in the silica network was associated with an increase in degree of hydration (higher hydrophilicity) and average pore size, and with a decrease in bulk density, specific surface area, and also degree of polymerization of silica. The rate of drug release increases with an increase in PEG content. These results are in line with the increase in specific surface area and mesopore size of these composites and also correspond to a more polymerized and thermally stable silica network obtained after drug release study.