Enhanced dynamic mechanical and shape‐memory properties of a poly(ethylene terephthalate)–poly(ethylene glycol) copolymer crosslinked by maleic anhydride

Dimethyl terephthalate (DMT) and ethylene glycol (EG) were used for the preparation of poly(ethylene terephthalate) (PET), and poly(ethylene glycol) (PEG) was added as a soft segment to prepare a PET–PEG copolymer with a shape‐memory function. MWs of the PEG used were 200, 400, 600, and 1000 g/mol, and various molar ratios of EG and PEG were tried. Their tensile and shape‐memory properties were compared at various points. The glass‐transition and melting temperatures of PET–PEG copolymers decreased with increasing PEG molecular weight and content. A tensile test showed that the most ideal mechanical properties were obtained when the molar ratio of EG and PEG was set to 80:20 with 200 g/mol of PEG. The shape memory of the copolymer with maleic anhydride (MAH) as a crosslinking agent was also tested in terms of shape retention and shape recovery rate. The amount of MAH added was between 0.5 and 2.5 mol % with respect to DMT, and tensile properties and shape retention and recovery rate generally improved with increasing MAH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 27–37, 2002     

Water vapor permeability and mechanical properties of fabrics coated with shape‐memory polyurethane

Water vapor permeable fabrics were prepared by coating shape‐memory polyurethane (PU), which was synthesized from poly(tetramethylene glycol), 4,4′‐methylene bis(phenylisocyanate), and 1,4‐butanediol, onto polyester woven fabrics. Water vapor permeability and mechanical properties were investigated as a function of PU hard‐segment content or polymer concentration of the coating solution. Water vapor permeability of PU‐coated fabrics decreased dramatically with increased concentration of coating solution, whereas only a slight change was observed with the control of PU hard‐segment content. The coated fabric showed the clear appearance of a nonporous PU surface according to SEM measurements. Attainment of high water permeability in PU‐coated fabrics is considered to arise from the smart permeability characteristics of PU. Mechanical properties of coated fabrics, although there was some variation depending on the concentration of coating solution, were primarily affected by PU hard‐segment content. Fabrics coated with PU hard‐segment content of 40% showed the lowest breaking stress and modulus as well as the highest breaking elongation, which could be interpreted in terms of the dependency of mechanical properties of coated fabrics on PU hard‐segment content and the yarn mobility arising from a difference in penetrating degree of coating solution into the fabric. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2812–2816, 2004     

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

Biodegradable and photocurable multiblock copolymers of various compositions were synthesized by the high‐temperature solution polycondensation of poly(ε‐caprolactone) (PCL) diols of molecular weight (M_n) = 3000 and poly(ethylene glycol)s (PEG) of M_n = 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 > 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     

Preparation and characterization of poly(ethylene terephthalate) fabrics treated by blends of cellulose nanocrystals and polyethylene glycol

In this study, the coating based on the blends of low molecular weight polyethylene glycol (PEG) and cellulose nano‐crystals (CNC) was introduced to immobilize on the surface of polyethylene terephthalate (PET) fabrics to modify the surface properties of fabrics, and to fabricate comfortable fabrics for formidable climate. Field‐emission scanning electron microscope, attenuated total reflectance Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC) were employed to study the topography, superficial ingredients, and thermal activity of the finished fabrics. The observation of field‐emission scanning electron microscope and attenuated total reflectance Fourier transform infrared spectroscopy confirmed that the surface of PET fabrics was covered by CNC/PEG1000/PEG600 coating. The transition onset temperature and phase change enthalpy of PET fabrics treated with CNC/PEG1000/PEG600 were at 7.06°C and 11.41 kJ/kg, respectively. Dimensional memory measurement demonstrated that the introduction of CNC caused the deformation percent to decrease by about 41% for PET fabrics covered with CNC/PEG1000/PEG600 coating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Properties of crosslinked blends of pellethene and multiblock polyurethane containing poly(ethylene oxide) for biomaterials

A series of multiblock polyurethanes, containing various poly(ethylene oxide) (PEO; number‐average molecular weight = 400–3400) contents (0–80 wt %) and prepared from hexamethylene diisocyanate/PEO/poly(dimethylsiloxane) diol/polybutadiene diol/1,4‐butanediol, were used as modifying additives (30 wt %) to improve the properties of biomedical‐grade Pellethene. Different molecular weights of PEO were used to keep poly(ethylene glycol) at a fixed molar content, if possible, although the PEO content, related to the PEO block length in the multiblock polyurethanes, was varied from 0 to 80 wt %. The hydrophilic PEO component was introduced through the addition of PEO‐containing polyurethanes and dicumyl peroxide as a crosslinking agent in a Pellethene matrix. As the PEO content (PEO block length) increased, the hydrogen‐bonding fraction of the crosslinked Pellethene/multiblock polyurethane blends increased, and this indicated an increase in the phase separation with an increase in the PEO content in the crosslinked Pellethene/multiblock polyurethane blends. According to electron spectroscopy for chemical analysis, the ratio of ether carbon to alkyl carbon in the crosslinked Pellethene/multiblock polyurethane blends increased remarkably with increasing PEO content. The water contact angle of the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased with increasing PEO content. The water absorption and mechanical properties (tensile modulus, strength, and elongation at break) of the crosslinked Pellethene/multiblock polyurethane blend films increased with increasing PEO content. The platelet adhesion on the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased significantly with increasing PEO content. These results suggest that crosslinked Pellethene/multiblock polyurethane blends containing the hydrophilic component PEO may have potential for biomaterials that come into direct contact with blood. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2348–2357, 2004     

Preparation and characterization of genistein containing poly(ethylene glycol) microparticles

The purpose of this study was to prepare, characterize, and evaluate genistein‐containing microparticles with enhanced dissolution profile using poly(ethylene glycol) (PEG) as polymer matrix. Genistein loaded microparticles were prepared by a solvent evaporation process and their surface, thermal, chemical, and dissolution properties were analyzed by microscopy, differential scanning calorimetry, ATR‐FTIR spectroscopy, and USP dissolution apparatus II, respectively. The wettability index was also determined. Genistein exhibited an elongated crystal habit. However, the drug containing PEG microparticles were discrete and quasispherical. The ATR‐FTIR studies performed on the formulation suggested hydrogen bonding between the drug and the polymer matrix. Thermal analysis indicated a conversion of the crystalline form of the drug to an amorphous form. Genistein, exhibiting low solubility and high permeability, is a Class II drug of the Biopharmaceutical Classification Scheme. However, there was a ～9‐fold increase in the rate of dissolution of genistein in the case of all formulations as compared to native genistein. This study showed that genistein could be effectively encapsulated into PEG microparticles using an emulsion‐solvent evaporation technique, therefore avoiding the potential disadvantages of other solid dispersion techniques. This approach provided a significant enhancement in the drug dissolution profile. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2070–2078, 2006     

Synthesis of bismaleimide resin containing the poly(ethylene glycol) side chain: Curing behavior and thermal properties

Two maleimido end‐capped poly(ethylene glycol) (m‐PEG) of different molecular weights were synthesized and blended at various proportions with bismaleimide resin (4,4′‐bismaleimido diphenylmethane) (BDM). The curing behavior and the thermal properties of the m‐PEG/BDM blends were studied and presented here. It was found that the addition of m‐PEG enhanced the processability of the BDM resin significantly. The processing window of the BDM resin was increased from approximately 20 to 80°C. The addition of m‐PEG modified resins, however, resulted not only in the reduction in the thermal stability of the blended BDM resin but also elevation of the coefficients of thermal expansion. The changes in thermal/mechanical properties of the blends were found to be proportional to the amounts of m‐PEG incorporated. It was observed that the curing behavior, and thermal and mechanical properties, of the blends were independent of the molecular weight of the PEG segment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2935–2945, 2002     

Shape memory effect of poly(methylene‐1,3‐cyclopentane) and its copolymer with polyethylene

Poly(methylene‐1,3‐cyclopentane) (PMCP) cyclopolymerized from 1,5‐hexadiene by metallocene catalyst, rac‐(ethylenebis(1‐indenyl))Zr(N(CH₃)₂)₂ is partially crystalline and has a value of elongation at break of more than 400% in the temperature range 25–85 °C. The shape memory effect of PMCP with moderate molecular weight is enhanced by sequentially polymerized polyethylene segments, the crystalline phase of which seems to strengthen the fixed structure which memorizes the original shape. The glass transition temperature or melting temperature of PMCP can be selectively used as shape recovery temperature when an appropriate deformation temperature is chosen. © 2002 Society of Chemical Industry     

Preparation and characterization of poly(ethylene glycol) crosslinked chitosan films

Poly(ethylene glycol) (PEG) crosslinked chitosan films with various PEG to chitosan ratio and PEG molecular weight were successfully prepared via the epoxy‐amine reaction between chitosan and PEG‐epoxy. The thermal and mechanical properties and swelling behavior were studied for the PEG crosslinked chitosan films. The mechanical strength of chitosan films were greatly enforced by the introduction of PEG‐epoxy, achieving an elongation of about 80%. It was found that the crosslinked chitosan films form hydrogel in water, achieving a swelling ratio higher than 20 times of original weight. The swelling behavior of chitosan films relied greatly on the molecular weight of the crosslinker PEG‐epoxy and the weight percent of PEG‐epoxy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

ABA triblock copolymers from poly(p‐dioxanone) and poly(ethylene glycol)

Poly(p‐dioxanone)–poly(ethylene glycol)–poly(p‐dioxanone) ABA triblock copolymers (PEDO) were synthesized by ring‐opening polymerization from p‐dioxanone using poly(ethylene glycol) (PEG) with different molecular weights as macroinitiators in N₂ atmosphere. The copolymer was characterized by ¹H NMR spectroscope. The thermal behavior, crystallization, and thermal stability of these copolymers were investigated by differential scanning calorimetry and thermogravimetric measurements. The water absorption of these copolymers was also measured. The results indicated that the content and length of PEG chain have a greater effect on the properties of copolymers. This kind of biodegradable copolymer will find a potential application in biomedical materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1092–1097, 2006     

Shape‐memory effects of radiation crosslinked poly(ϵ‐caprolactone)

Poly(?‐caprolactone) (PCL) with different molecular weight were crosslinked by γ‐radiation. The radiation crosslinking features were analyzed by Soxhlet extraction with toluene and the Charlesby–Pinner equation. The crosslinking degree is relative to molecular weight and radiation dose; the relation between sol fraction and dose follows the Charlesby–Pinner equation. All the samples were crystalline at room temperature, and the radiation crosslinking had a little effect on the crystallinity and the melting behavior of PCL. The shape‐memory results indicated that only those specimens that had a sufficiently high crosslinking degree (gel content is higher than about 10%) were able to show the typical shape‐memory effect, a large recoverable strain, and a high final recovery rate. The response temperature of the recovery effect (about 55°C) was related to the melting point of the samples. The PCL shape‐memory polymer was characterized by its low recovery temperature and large recovery deformation that resulted from the aliphatic polyester chain of PCL. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1589–1595, 2003     

Influence of poly(ethylene glycol)‐containing additives on extrusion of ultrahigh molecular weight polyethylene/polypropylene blend

The influence of poly(ethylene glycol) (PEG)‐containing additives on the extrusion behavior of ultrahigh molecular weight polyethylene/polypropylene (UHMWPE/PP) blend was studied. It was found that the addition of small amounts of PEG to UHMWPE/PP blend resulted in significant reduction of die pressure and melt viscosity, and obvious increase of the flow rate at a given die pressure, while PEG/diatomite binary additives enhanced the improvement in the processability of UHMWPE/PP blend. When pure HDPE was extruded with the die through which UHMWPE/PP/PEG blend was previously extruded, the extrusion pressure of HDPE increased with the extrusion time gradually. This meant that PEG might migrate to the die wall surface and coat it in the extrusion of UHMWPE/PP/PEG blend. FTIR spectra and SEM micrographs of the UHMWPE/PP/PEG extrudates indicated that PEG located not only at the surface but also in the interior of the extrudates. So, the external lubrication at the die wall, combined with the internal lubrication to induce interphase slippage of the blend, was proposed to be responsible for the reduction of die pressure and viscosity. In addition, an ultrahigh molecular weight polysiloxane and a fluoropolymer processing aid were used as processing aids in the extrusion of UHMWPE/PP as control, and the results showed that only minor reduction effects in die pressure and melt viscosity were achieved at their suggested loading level. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1282–1288, 2006     

Development of shape memory polyurethane based on polyethylene glycol and liquefied 4,4′‐diphenylmethane diisocyanate using a bulk method for biomedical applications

In this study, a series of shape memory polyurethanes (SMPUs) were synthesized successfully by the bulk polymerization method from liquefied 4,4′‐diphenylmethane diisocyanate (L‐MDI), 1,4‐butanediol (BDO) and polyethylene glycol (PEG). The influence of the hard segment content (HSC) on the structure, morphology, properties and biocompatibility of PEG based SMPUs (PEGSMPUs) was carefully investigated. The results show that a microphase separation structure composed of a semicrystalline soft phase and an amorphous hard phase is formed in the PEG6000/L‐MDI/BDO system. Crystallization of the PEG soft segment is influenced by the hard segments. The PEG semicrystalline soft phase serves as a reversible phase while the L‐MDI?BDO hard segment acts as physical netpoints. Finally, a cyclic tensile test shows that all PEGSMPUs have good shape recovery (e.g. above 80%), whereas good shape fixity can only be achieved when the HSC is less than 35 wt%. The Cell Counting Kit 8 assay also demonstrates that only PEGSMPUs containing less than 40 wt% HSC have low cytotoxicity. It is thus concluded that PEGSMPUs bearing both good shape memory effects and good biocompatibility can be used as shape memory materials for biomedical applications when the HSC is less than 35 wt%. © 2014 Society of Chemical Industry     

Ring‐opening polymerization of epoxy end‐terminated poly(ethylene oxide) as a route to highly crosslinked materials with exceptional swelling behavior (II)

Highly swellable poly(ethylene oxide) (PEO) gels were prepared by anionic ring‐opening polymerization of diepoxy end‐capped PEO (3400 g mol^?1) and PEO (8000 g mol^?1) using dianionic glycerol and glycolic acid initiators at scales of up to 50 g diepoxide. The glycerol‐derived materials swell to almost 20 times their mass in water. The driving force for rapid swelling appears to arise during ‘crystallization’, as segments between crosslinks are forced to pack under conditions that create high‐energy domains within the material. Solvation and therefore swelling are driven by the release of the resulting packing energy. These observations may offer insight into methods for designing other highly swellable materials. When the polyfunctional initiators have groups with different reactivities (e.g. alkoxide versus carboxylate), as might be expected, the more nucleophilic functional group appears to dominate the ring‐opening polymerization process. Copyright © 2007 Society of Chemical Industry     

Surface and adhesion properties of poly(ethylene glycol) on polyester(polyethylene terephthalate) fabric surface: Effect of air‐atmospheric plasma treatment

The surface and adhesion properties of different molecular weight poly(ethylene glycol) (PEG) (400, 1500, and 3000 g/mol) on untreated and air‐atmospheric plasma‐treated PET woven fabrics were studied, with the aim of developing durable hydrophilic PET fibrous structures. PEG application was carried out by padding of the PET fabric in aqueous solution of PEG followed by curing and drying. The surface properties of the PEG‐coated PET fabrics were then characterized using wicking test to measure the water contact angle (θ°) and capillary weight (W_c), and using atomic force microscopy (AFM) images in the tapping mode. Results showed that without a prior air‐atmospheric plasma treatment of the PET fabric, the water contact angle decreased and capillary weight increased with the three PEGs, implying an increase in the hydrophilicity of both inner and outer PET fabric fiber surface. Air‐plasma treatment of the PET fabrics before PEG coating increases further the hydrophilicity of the inner fabric fiber surface: the capillary weight was almost doubled in the case of the three PEGs. Best results were obtained with PEG 1500: water contact angle decreasing from 82° to 51°, and the capillary weight increasing from 11 mg to 134 mg. Moreover, wash fastness test at room temperature and at 80°C confirms improved adhesion of PEG‐1500 to the plasma‐treated PET woven fabric surface, while under the same conditions the plasma‐treated PET without PEG loses completely its hydrophilic character. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

The study of rapid curing crease‐resistant processing on cotton fabrics. II. Effect of poly(ethylene glycol) on physical properties of processed fabrics

This study aimed to examine the effects of the addition of poly(ethylene glycol) (PEG) on the physical properties of processed cotton fabrics in a rapid heat‐curing crease‐resistant process. Our results show that this addition influences the moisture absorbency, crease resistance in both dry and wet conditions, and tensile strength preservation rate of the processed fabrics. Moreover, with such addition, the use of higher temperature in the process would enhance the moisture absorbency and dry–wet crease resistance but reduce the tensile strength preservation rate. The optimum condition for processing cotton fabric is to use PEG with a molecular weight of 1000 at a concentration of 10%, heated at 200°C for 30 s. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1008–1012, 2002     

Bifunctional poly(ethylene glycol) based crosslinked network polymers as electrolytes for all‐solid‐state lithium ion batteries

Polymer electrolyte based lithium ion batteries represent a revolution in the battery community due to their intrinsic enhanced safety, and as a result polymer electrolytes have been proposed as a replacement for conventional liquid electrolytes. Herein, the preparation of a family of crosslinked network polymers as electrolytes via the ‘click‐chemistry’ technique involving thiol‐ene or thiol‐epoxy is reported. These network polymer electrolytes comprise bifunctional poly(ethylene glycol) as the lithium ion solvating polymer, pentaerythritol tetrakis (3‐mercaptopropionate) as the crosslinker and lithium bis(trifluoromethane)sulfonimide as the lithium salt. The crosslinked network polymer electrolytes obtained show low T_g, high ionic conductivity and a good lithium ion transference number (ca 0.56). In addition, the membrane demonstrated sterling mechanical robustness and high thermal stability. The advantages of the network polymer electrolytes in this study are their harmonious characteristics as solid electrolytes and the potential adaptability to improve performance by combining with inorganic fillers, ionic liquids or other materials. In addition, the simple formation of the network structures without high temperatures or light irradiation has enabled the practical large‐area fabrication and in situ fabrication on cathode electrodes. As a preliminary study, the prepared crosslinked network polymer materials were used as solid electrolytes in the elaboration of all‐solid‐state lithium metal battery prototypes with moderate charge–discharge profiles at different current densities leaving a good platform for further improvement. © 2018 Society of Chemical Industry     

Effect of poly(ethylene glycol) on the solid‐state polymerization of poly(ethylene terephthalate)

Poly(ethylene glycol) (PEG) and end‐capped poly(ethylene glycol) (poly(ethylene glycol) dimethyl ether (PEGDME)) of number average molecular weight 1000 g mol^?1 was melt blended with poly(ethylene terephthalate) (PET) oligomer. NMR, DSC and WAXS techniques characterized the structure and morphology of the blends. Both these samples show reduction in T_g and similar crystallization behavior. Solid‐state polymerization (SSP) was performed on these blend samples using Sb₂O₃ as catalyst under reduced pressure at temperatures below the melting point of the samples. Inherent viscosity data indicate that for the blend sample with PEG there is enhancement of SSP rate, while for the sample with PEGDME the SSP rate is suppressed. NMR data showed that PEG is incorporated into the PET chain, while PEGDME does not react with PET. Copyright © 2005 Society of Chemical Industry     

Dynamic mechanical properties of sandwich‐structured epoxy beam composites containing poly(ethyleneterephthalate)/poly(ethyleneglycol) copolymer with shape memory effect

To make smart vibration‐controlling composite laminate, a few poly(ethylene terephthalate) (PET) and poly(ethylene glycol) (PEG) copolymers with shape memory ability were prepared. After selecting the best composition of PET–PEG copolymer in mechanical properties, a crosslinking agent such as glycerine, sorbitol, or maleic anhydride (MA) was included for crosslinked copolymer, followed by analysis of its effect on mechanical, shape memory, and damping properties. The highest shape recovery was observed for copolymer with 2.5 mol % of glycerine, and the best damping effect indicating vibration control ability was from copolymer with 2.5 mol % of sorbitol. With the optimum copolymers in hand, sandwich‐structured epoxy beam composites fabricated from an epoxy beam laminate and crosslinked PET–PEG copolymer showed that impact strength increased from 1.9 to 3.7 times depending on the type of copolymer, and damping effect also increased as much as 23 times for the best case compared to epoxy laminate beam alone. The resultant sandwich‐structured epoxy beam composite can be utilized as structural composite material with vibration control ability, and its glass transition temperature can be controlled by adjustment of PET, PEG, or crosslinking agent composition. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3141–3149, 2003     

Crystallization and morphology of cholesterol end‐capped poly(ethylene glycol)

Crystallization and morphology of polyethylene glycol with molecular weight M_n = 2000 (PEG2000) capped with cholesterol at one end (CS‐PEG2000) and at both ends (CS‐PEG2000‐CS) were investigated. It is found that the bulky cholesteryl end group can retard crystallization rate and decrease crystallinity of PEG, especially for CS‐PEG2000‐CS. Isothermal crystallization kinetics shows that the Avrami exponent of CS‐PEG2000 decreases as crystallization temperature (T_c). The Avrami exponent of CS‐PEG2000‐CS increases slightly with T_c, but it is lower than that of CS‐PEG2000. Compared to the perfect spherulite morphology of PEG2000, CS‐PEG2000 exhibits irregular and leaf‐like spherulite morphology, while only needle‐like crystals are observed in CS‐PEG2000‐CS. The linear growth rate of CS‐PEG2000 shows a stronger dependence on T_c than PEG2000. The cholesterol end group alters not only the free energy of the folding surface, but also the temperature range of crystallization regime. The small angle X‐ray scattering (SAXS) results show that lamellar structures are formed in all these three samples. By comparing the long periods obtained from SAXS with the theoretically calculated values, we find that the PEG chains are extended in PEG2000 and CS‐PEG2000, but they are once‐folded in CS‐PEG2000‐CS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2464–2471, 2007