Structure and properties of semiinterpenetrating polymer networks based on polyurethane and nitrochitosan

Two semiinterpenetrating polymer networks (semi‐IPNs) based on trihydroxyl methylpropane–polyurethane (T‐PU) or castor oil–polyurethane (C‐PU) were prepared by curing the mixed solution of the polyurethane prepolymer and nitrochitosan (NCH). During the curing process, crosslinking and grafting reaction between the molecules of the PU prepolymer and NCH occurred, because of the high reactivity of remaining hydroxyl groups in the NCH with ? NCO groups of PU. The structure of the original semi‐IPN sheets and the sheets treated with acetone were studied by infrared, ¹³C‐NMR, scanning electron microscopy, and dynamic mechanical analysis, showing interpenetration of NCH molecules into the PU networks. When nitrochitosan content (C_NCH) was lower than 10 wt %, the semi‐IPN sheets T‐PU and C‐PU had higher density and tensile strength (σ_b) than the systems with C_NCH more than 20%. The trihydroxymethyl propane‐based PU reacted more readily with nitrochitosan to form the semi‐IPNs than castor oil‐based PU. The semi‐IPN coatings T‐PU and C‐PU were used to coat cellophane, resulting in intimate interfacial bonding. The mechanical strength and water resistivity of the cellophane coated with T‐PU coating were improved remarkably. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3109–3117, 2001     

Interpenetrating polymer networks of poly(butyl methacrylate) and poly(α‐terpineol‐co‐styrene): Synthesis and characterization

Simultaneous interpenetrating polymer networks (IPNs) based on poly(butyl methacrylate) and poly(α‐terpineol‐co‐styrene) were synthesized with azobisisobutyronitrile (AIBN) as the initiator and divinyl benzene as the crosslinking agent in xylene under an inert nitrogen atmosphere. Fourier transform infrared spectra provided structural evidence for the IPNs, indicating characteristic frequencies of ester groups of butyl methacrylate at 1723 cm^?1 and alcoholic groups of α‐terpineol at 3436 cm^?1. Scanning electron microscopy revealed threadlike network structures. Properties such as percentage swelling and average molecular weight between crosslinks were direct functions of the copolymer and initiator (AIBN) concentrations and inverse functions of the monomer (butyl methacrylate) and crosslinking agent (divinyl benzene) concentrations. Differential scanning calorimetry showed an IPN glass‐transition temperature at 80.2°C. The thermal decompositions of the IPNs were established with the help of thermogravimetric analysis. The value of the activation energy, calculated from thermogravimetric analysis with the Coats and Redfern equation, was 23 kJ/mol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 343–352, 2006     

Study on the properties,morphology, and applications of castor oil polyurethane—poly(methyl methacrylate) IPNs

A series of castor oil polyurethane—poly(methyl methacrylate) interpenetrating polymer networks (IPN COPU/PMMA) were produced from castor oil, toluene diisocyanate, and methyl methacrylate. The properties and morphology of the IPNs were estimated. The adhesives based on the IPN COPU/PMMA prepolymer were prepared and the influence of the composition on the adhesion strength was studied. The experimental results showed that the adhesives have an effective adhesive power for metals and these adhesives have good prospects in a practical project. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1393–1401, 1997     

Synthesis and Characterization of Interpenetrating Biopolyester Networks Using Naturally Available Renewable Resources

Biodegradable crosslinked biopolyesters and interpenetrating networks (IPN) were prepared with poly(cardanol fumarate) (MCFR) and poly(castor oil fumarate) (CFR). In addition, polymerization and crosslinking with styrene-free vinyl monomers, vinyl acetate (VA), and n-vinyl pyrrolidone (VP) were adopted to prepare these materials. The IPNs have higher thermal stability and mechanical properties in comparison with the crosslinked biopolyesters. The improved characteristics of IPNs are due to the synergistic effect of physical and chemical crosslinking. These IPNs undergo gradual degradation in various media in comparison with crosslinked biopolyesters.     

Feasibility of conducting semi‐interpenetrating networks based on a poly(ethylene oxide) network and poly(3,4‐ethylenedioxythiophene) in actuator design

A new type of synthetic pathway—the use of interpenetrating polymer networks (IPNs)—is proposed to design conducting polymer‐based actuators. Two types of materials with interesting conducting properties were prepared: (1) a semi‐IPN between poly(3,4‐ethylenedioxythiophene) (PEDOT) and branched poly(ethylene oxide) (PEO) network; (2) a tricomponent IPN between PEDOT and a PEO/polycarbonate (PC)–based network as the ionic conducting partner. In the first case, the influence of the amount of branching in the PEO network on the EDOT uptake and electrochemical properties was studied. A maximum conductivity (15 S cm^?1) was obtained for 60 wt % branched PEO in the material. Moreover, the dispersion profile of PEDOT in the material was shown by elemental analysis and energy dispersion spectroscopy to follow a gradient through the thickness of the film leading to a built‐in three‐layered device. With respect to PEO/PC materials, the best results were obtained for about 80 wt % PEO in the matrix where the material remains sufficiently elastomeric. In this case, the conductivity reaches about 1 S cm^?1 for a 10 to 30 wt % polycarbonate content. These materials are capable of reversible 45° angular deflections under a 0.5V potential difference. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3569–3577, 2003     

Poly(ethylene oxide)/polybutadiene based IPNs synthesis and characterization

Interpenetrating polymer networks (IPNs) were prepared from hydroxytelechelic polybutadiene (HTPB) and poly(ethylene oxide) (PEO) via an in situ process. The PEO network was obtained by free radical copolymerization of poly(ethylene glycol) methacrylate and dimethacrylate. Addition reactions between HTPB and a pluri-isocyanate cross-linker (Desmodur^® N3300) led to the HTPB network. Polymerization kinetics were followed by Fourier transform spectroscopy in the near and middle infrared. Mechanical properties and the IPN morphology were investigated by dynamic mechanical analysis and transmission electron microscopy. The relation between the formation rates of the two networks and the IPN final morphology is discussed.     

Shape memory properties and unusual optical behaviour of an interpenetrating network of poly(ethylene oxide) and poly(2‐hydroxyethyl methacrylate)

An interpenetrating polymer network (IPN) with shape memory properties was prepared by using poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(ethylene oxide) (PEO). PHEMA acts as a fixed phase and PEO as a switching phase. The switching action of PEO is due to the reversible process of melting and crystallization. It was observed that the shape recovery of the IPN increases with increasing crosslinker concentration up to an optimum value and decreases thereafter. In addition to the shape memory property, the IPNs show a reversible change in optical properties from translucent to opaque. The change in optical properties is quite different from that observed in a semicrystalline polymer system where the transparency increases as a result of the melting of crystals. This behaviour of the IPN is explained in terms of H‐bonding of PEO with PHEMA. Fourier transform infrared spectroscopy was used to study the H‐bonding between PEO and PHEMA. © 2019 Society of Chemical Industry     

Synthesis and properties of unsaturated polyoxyethylene and its graft copolymers with styrene

The unsaturated polyoxyethylene (PEO) was synthesized by copolymerization of ethylene oxide with allyl glycidyl ether in toluene using bimetallic-oxo-alkoxide as a catalyst. The effects of polymerization conditions on conversion and intrinsic viscosity of the copolymer were studied. The unsaturated copolymer was characterized with infrared spectra, ¹H NMR, and wide-angle X-ray diffraction. The relationship between crystallinity of the copolymers and conductivity of their LiClO₄ complexes were investigated. The copolymer with ∼ 65 wt % PEO content exhibits a room temperature conductivity of 1 × 10⁻⁴ S cm⁻¹ at a molar ratio of EO/Li = 20. The unsaturated PEO was graft-copolymerized with styrene using 2,2′-azobis(isobutyronitrile) as initiator in toluene, with grafting efficiency ∼ 50%. The purified graft copolymer was characterized with infrared spectra, ¹H NMR, and wide-angle X-ray diffraction, and was shown to have good emulsifying properties and a phase-transfer catalytic property. LiClO₄ complex of the graft copolymer with 70 wt % PEO content exhibits a room temperature conductivity approaching 1 × 10⁻⁴ S cm⁻¹ at molar ratio of EO/Li = 20/1. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2417–2425, 1998     

Morphological,infrared, and ionic conductivity studies of poly(ethylene oxide)–49% poly(methyl methacrylate) grafted natural rubber–lithium perchlorate salt based solid polymer electrolytes

The potential of poly(ethylene oxide) (PEO) and 49% poly(methyl methacrylate) grafted natural rubber (MG49) as a polymer host in solid polymer electrolytes (SPE) was explored for electrochemical applications. PEO–MG49 SPEs with various weight percentages of lithium perchlorate salt (LiClO₄) was prepared with the solution casting technique. Characterization by scanning electron microscopy, Fourier transform infrared spectroscopy, and impedance spectroscopy was done to investigate the effect of LiClO₄ on the morphological properties, chemical interaction, and ionic conductivity behavior of PEO–MG49. Scanning electron microscopy analysis showed that the surface morphology of the sample underwent a change from rough to smooth with the addition of lithium salts. Infrared analysis showed that the interaction occurred in the polymer host between the oxygen atom from the ether group (C? O? C) and the Li⁺ cation from doping salts. The ionic conductivity value increased with the addition of salts because of the increase in charge carrier up to the optimum value. The highest ionic conductivity obtained was 8.0 × 10^?6 S/cm at 15 wt % LiClO₄. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and ionic conductivity of solid polymer electrolyte based on polyacrylonitrile‐polyethylene oxide

The transparent and flexible solid polymer electrolytes (SPEs) were fabricated from polyacrylonitrile‐polyethylene oxide (PAN‐PEO) copolymer which was synthesized by methacrylate‐headed PEO macromonomer and acrylonitrile. The formation of copolymer is confirmed by Fourier‐transform infrared spectroscopy (FTIR) measurements. The ionic conductivity was measured by alternating current (AC) impedance spectroscopy. Ionic conductivity of PAN‐PEO‐LiClO₄ complexes was investigated with various salt concentration, temperatures and molecular weight of PEO (Mn). And the maximum ionic conductivity at room temperature was measured to be 3.54 × 10^?4 S/cm with an [Li⁺]/[EO] mole ratio of about 0.1. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 461–464, 2006     

Castor-oil-based interpenetrating polymer networks: Synthesis and characterization

Castor oil was polymerized and crosslinked with sulfur or diisocyanates to form the vulcanized and urethane derivatives, respectively. Both types were swollen with a plastic-forming monomer plus crosslinker, and a second polymerization was carried out in situ. Polyblends were also made by emulsion polymerization of styrene and methyl methacrylate employing hydrolyzed castor oil as the soap. In all three polymerizations, a wide range of compositions was obtained. The resulting interpenetrating polymer networks were characterized using electron microscopy, modulus–temperature measurements, and stress–strain analysis. The polystyrene phase size of the castor oil–urethane/polystyrene IPN was shown to decrease with increased crosslinking of the castor oil component and with increased polystyrene contents. The modulus–temperature study showed two distinct glass transitions in all cases, with evidence of significant mixing of the two components in many cases. The stress–strain results show that some of the IPN's behave as reinforced, highly extensible elastomers at low polystyrene levels, and a rubber-toughened plastics at high levels of polystyrene or crosslinking.     

Physical and electrochemical properties of low molecular weight poly(ethylene glycol)‐bridged polysilsesquioxane organic–inorganic composite electrolytes via sol–gel process

A new class of ionic conducting organic/inorganic hybrid composite electrolyte with high conductivity, better electrochemical stability and mechanical behavior was prepared through the sol–gel processing between ethylene‐bridged polysilsesquioxane and poly(ethylene glycol) (PEG). The composite electrolyte with 0.05 LiClO₄ per PEG repeat unit has the best conductivity up to 10^?4 S/cm at room temperature with the transference number up to 0.48 and an electrochemical stability window as high as 5.5 V versus Li/Li⁺. Moreover, the effect of the PEG chain length on the properties of the composite electrolyte has also been studied. The interactions between ions and polymer have also been investigated for the composite electrolyte in the presence of LiClO₄ by means of FTIR, DSC, and TGA. The results indicated the interaction of Li⁺ ions with the ether oxygen of the PEG, and the formation of transient crosslinking with LiClO₄, resulting in an increase of the T_g of the composite electrolyte. The VTF‐type behavior of the ionic conductivity implied that the diffusion of the charge carriers was assisted by the segmental motions of the polymer chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2752–2758, 2007     

Inorganic-organic interpenetrating polymer networks involving polyhedral oligomeric silsesquioxane and poly(ethylene oxide)

A novel organic-inorganic interpenetrating polymer network (IPN) was prepared via in situ crosslinking between octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) and 2,2-bis(4-hydroxyphenyl)propane in the presence of poly(ethylene oxide) (PEO). The miscibility and intermolecular specific interactions of the IPNs were investigated by means of differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. In view of the results of calorimetric analysis and morphological observation, it is judged that the components of the organic-inorganic IPNs are fully miscible. The FTIR spectroscopy shows that there are inter-component hydrogen bonding interactions between the POSS network and PEO. The measurements of static contact angle show that the hydrophilicity (and/or the surface free energy) of the organic-inorganic IPNs increased with the addition of the miscible and water-soluble polymer (i.e., PEO). Thermogravimetric analysis (TGA) shows that the thermal stability of the IPNs was quite dependent on the mass ratios of the POSS network to PEO.     

Conformational,thermal, and ionic conductivity behavior of PEO in PEO/PMMA miscible blend: Investigating the effect of lithium salt

In this research, influence of incorporating LiClO₄ salt on the crystallization, conformation, and ionic conductivity of poly(ethylene oxide) (PEO) in its miscible blend with poly(methyl methacrylate) (PMMA) is studied. Differential scanning calorimetry showed that the incorporation of salt ions into the blend suppresses the crystallinity of PEO. The X‐ray diffraction revealed that the unit‐cell parameters of the crystals are independent of the LiClO₄ concentration despite of the existence of ionic interactions between PEO and Li cations. In addition, the complexation of the Li⁺ ions by oxygen atoms of PEO is investigated via Fourier transform infrared spectroscopy. The conformational changes of PEO segments in the presence of salt ions are studied via Raman spectroscopy. It is found that PEO chains in the blend possess a crown‐ether like conformation because of their particular complexation with the Li⁺ ions. This coordination of PEO with lithium cations amorphize the PEO and is accounted for suppressed crystallinity of PEO in the presence of salt ions. Finally, electrochemical impedance spectroscopy is used to characterize the ionic conductivity of PEO in the PEO/PMMA/LiClO₄ ternary mixture at various temperatures. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermal,thermomechanical, and electrochemical characterization of the organic–inorganic hybrids poly(ethylene oxide) (PEO)–silica and PEO–silica–LiClO4

To study the effect of the silica content on the properties of the salt‐free and salt‐added hybrids based on poly(ethylene oxide) (PEO) and silica, two series of hybrids, PEO–silica and PEO–silica–LiClO₄ (O:Li, 9:1) hybrids were prepared via the in situ acid‐catalyzed sol–gel reactions of the precursors [i.e., PEO functionalized with triethoxysilane and tetraethyl orthosilicate (TEOS)]. The morphology of the hybrids was examined by scanning electron microscopy (SEM) of the fracture surfaces of the hybrid. The results indicated that the discontinuity develops with increasing the weight percent of silica in both hybrids. The differential scanning calorimetric (DSC) analysis indicated that effects of silica content on the glass transition temperatures (T_g) of the PEO phase were different in salt‐free and salt‐added hybrids. The T_g of PEO phase increased with increasing weight percent of silica in salt‐free hybrids, whereas the curve of T_g of PEO phase and silica content had a maximum at 35 wt % of silica content in salt‐added hybrids. For both salt‐free and salt‐added hybrids, peaks of the loss tangent, determined by dynamic mechanical analysis (DMA) were gradually broadened and lowered with increasing weight percent of silica. The storage modulus, E′, in the region above T_g increases with increasing silica content for both PEO–silica and PEO–silica–LiClO₄ hybrids. In the conductivity and composition curves for PEO–silica–LiClO₄ hybrids, the conductivity shows a maximum value of 3.7 × 10^?6 S/cm, corresponding to the sample with a 35 wt % of silica. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2471–2479, 2001     

Preparation and characterization of hydroxyl ion-conducting interpenetrating polymer network based on PVA and PEI

Novel interpenetrating polymer networks (IPNs) and semi-interpenetrating polymeric networks (sIPNs) based on polyethyleneimine (PEI) and poly(vinyl alcohol) (PVA) have been prepared via crosslinking reactions with respective crosslinking agent, 1,4-dibromobutane and glutaraldehyde (GA). IPNs, sIPNs and PEI/PVA blend membranes are characterized in detail by Fourier transform Infrared attenuated total reflection (FTIR-ATR) spectroscopy, mechanical properties, water uptake, swelling ratio, field emission scanning electron microscope (FE-SEM), hydroxide ion (OH^?) conductivity. Moderate water uptake and swelling ratio are obtained by the IPN derived from PEI:PVA (1:1), achieving 78.4 and 36.8 %, respectively. And the IPN also shows an acceptable OH^? conductivity of 4.87 mS/cm at 80 °C.     

Radiation synthesis and environmental responsiveness of semi‐interpenetrating polymer networks composed of poly(dimethyl–aminoethyl methacrylate) and poly(ethylene oxide)

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of poly(dimethyl–aminoethyl methacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) were synthesized by γ‐radiation; three semi‐IPNs with 80 : 20, 90 : 10, and 95 : 5 weight ratios of DMAEMA/PEO were obtained by use of this technique. The gel–dose curves showed that the hydrogels were characterized by a structure typical of semi‐IPNs and the results of elemental analysis supported this point. The temperature‐induced phase transition of semi‐IPNs with the composition of 95 : 5 was still retained, with the lower critical solution temperature of PDMAEMA shifting from 40 to 27°C. The temperature sensitivity of the other two semi‐IPNs gradually disappeared. The pH sensitivity of three semi‐IPNs was still retained but the pH shifted slightly to lower values with increasing PEO content in the semi‐IPNs. The effect of PEO content in semi‐IPNs on their environmental responsiveness was discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2995–3001, 2004     

Relations between the molecular aggregation state and ionic conductivity in photopolymerized crosslinking polymers with oligo(oxyethylene) chains

A mixture of a vinyl monomer and a crosslinking agent was photopolymerized to form a crosslinked polymer film. Methacrylate with pendant oligo(oxyethylene) chain and poly(ethylene glycol) dimethacrylate were used as the vinyl monomer and crosslinking agent, respectively. The ionic conductivity of the film increased with an increasing concentration of LiClO₄ and then decreased. The size of the quasicrystalline aggregation phase composed of pendant and crosslinking chains in the film decreased with an increasing concentration of LiClO₄. The amorphous pendant and crosslinking oxyethylene chains gave rise to increased segmental motion and conductivity. The dissolution was depressed for a decrease in the ionic conductivity at a high LiClO₄ concentration at which the interactions among ions became stronger and the crystal phase of LiClO₄ was formed. The amount of the dissolution of the aggregation phase increased with an increasing crosslinking agent concentration. The quasicrystalline aggregation phase became larger with an increasing length of the pendant chains, and an increase in the size of the aggregation phase resulted in a decrease in the ionic conductivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1272–1277, 2002     

Studies on castor oil–based polyurethane/polyacrylonitrile interpenetrating polymer network for toughening of unsaturated polyester resin

Tricomponent interpenetrating polymer network (IPN) systems involving castor oil, toluenediisocyanate (TDI), acrylonitrile (AN), ethylene glycol diacrylate (EGDA), and general‐purpose unsaturated polyester resin (GPR) were prepared with various compositions. The structures of the IPNs at various stages were confirmed using FTIR. The thermal stability of the IPNs was studied using TGA, which indicated that the polyurethane/polyacrylonitrile/GPR (PU/PAN/GPR) IPN underwent single‐stage decomposition, showing perfect compatibility at the IPN composition of 10 : 90 (PU/PAN : GPR). The mechanical properties such as tensile, flexural, impact, and hardness for the IPNs with various compositions were determined. It was found that the tensile strength of the GPR matrix was decreased and flexural and impact strengths were increased upon incorporating PU/PAN networks. The swelling properties in water and toluene were also studied. The morphology of the IPNs was studied using SEM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 817–829, 2004     

Vernonia oil–based acrylate and methacrylate polymers and interpenetrating polymer networks with epoxy resins

Acrylate and methacrylate monomers were obtained by reacting vernonia oil, a naturally epoxidized oil, with acrylic or methacrylic acid. The highest conversion (85–98%) of epoxy groups was obtained when the reaction was performed with an excess of the carboxylic acid at 100–120°C. The acrylate and methacrylate monomers of vernonia oil were characterized by IR and NMR spectroscopy. These monomers were then cured by sunlight in the presence of benzophenone to produce transparent films. In addition, interpenetrating polymer neworks (IPNs) were prepared in a two‐step technique from the sunlight‐cured methacrylate of vernonia oil, as the elastomeric component, in combination with a cured epoxy resin (a bisphenol A–type resin). Dynamic mechanical analysis showed good compatibility between the networks of the two cured polymers. An IPN with a 1 : 1 composition of the two polymer components exhibited the properties of a reinforced elastomer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3835–3843, 2004