Polyurethane–poly(methyl methacrylate) interpenetrating polymer networks. I. Synthesis,characterization, and preliminary blood compatibility studies

Simultaneous polyurethane–poly(methyl methacrylate) (PU–PMMA) interpenetrating polymer networks (IPNs) were synthesized with the PMMA polymerization initiated at room temperature. Transparent IPNs with better miscibility and synergism of mechanical properties were obtained. Dynamic mechanical analysis data indicated that up to 30% PMMA can be incorporated into PU networks without substantial phase separation. The PU–PMMA 90/10 IPNs elicit less than 2% hemolysis, suggesting that these materials could be used as blood contacting materials. © 1996 John Wiley & Sons, Inc.     

Semi‐interpenetrating polymer networks based on polyurethane and poly(vinyl pyrrolidone) obtained by photopolymerization: Structure‐property relationships and bacterial adhesion

A range of semi‐interpenetrating polymer networks (semi‐IPNs) based on polyurethane (PU) and poly(vinyl pyrrolidone) (PVP) have been synthesized and characterized with respect to their thermodynamic characteristics, morphology, mechanical properties, surface properties, water sorption and bacterial adhesion. The free energies of mixing of PU and PVP in semi‐IPNs have been determined by the vapor sorption method and were shown to be positive for all compositions. The surface properties of semi‐IPNs were investigated using the dynamic contact angle analysis. It was shown that the advancing contact angle changes from 83.1° to 65.3° with increasing PVP from 7.05% to 57.38%. Scanning electron microscopy demonstrated that the semi‐IPNs are two‐phase systems with incomplete phase separation. The mechanical properties reflect the changes in structure of semi‐IPNs with increasing of amounts of PVP in the system. Incorporation of PVP into the semi‐IPN with PU restricts the ability of PVP to sorb water. As infection is likely to be caused by bacterial adherence to biomedical implants, the bacterial adhesion data suggests that the semi‐IPNs with PVP content below 22.52% may be useful for biomedical material applications. Polym. Eng. Sci. 44:940–947, 2004. © 2004 Society of Plastics Engineers.     

Synthesis and characterization of interpenetrating polymer networks from polyurethane and poly(ethylene glycol) diacrylate

Interpenetrating polymer networks (IPNs) combining polyurethane (PU) and poly(ethylene glycol) diacrylate (PEGDA) networks were prepared with simultaneous polymerization. PU was synthesized from biocompatible and biodegradable poly(ε-caprolactone) diol, and the hydroxyl group of poly(ethylene glycol) was substituted with a crosslinkable acrylate group. The effects of the PU/PEGDA compositions and the crosslink density of PU and PEGDA on the thermal properties, swelling ratio, surface energy, mechanical properties, and morphologies were investigated. The mechanical properties of PEGDA networks were improved by the presence of PU networks, particularly in the 75% PU/25% PEGDA IPNs. All PU/PEGDA IPNs showed a microphase-separated structure with cocontinuous morphology, as observed by atomic force microscopy, which was in agreement with the results of swelling ratio and dynamic mechanical thermal analysis measurements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of polyurethane/poly(vinylidene chloride) interpenetrating polymer networks

A series of polyurethane (PU)/poly(vinylidene chloride) (PVDC) interpenetrating polymer networks (IPNs) were synthesized through variations in the amounts of the prepolyurethane and vinylidene chloride monomer via sequential polymerization (80/20, 60/40, 50/50, 40/60, 30/70, and 20/80 PU/PVDC). The physicomechanical and optical properties of the IPNs were investigated. Thermogravimetric analysis (TGA) studies of the IPNs were performed to establish their thermal stability. TGA thermograms showed that the thermal degradation of the IPNs proceeded in three steps. Microcrystalline parameters, such as the crystal size and lattice disorder, of the PU/PVDC IPNs were estimated with wide‐angle X‐ray scattering. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1375–1381, 2007     

Damping properties of interpenetrating polymer networks of polyurethane‐modified epoxy and polyurethanes

Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU)‐modified epoxy with different molecular weight of polyol and polyurethanes based on the mixture of polydiol and polytriol by a one‐shot method. Two types of PU‐modified epoxy: PU‐crosslinked epoxy and PU‐dangled epoxy were synthesized, and the effects of the different molecular weights of polyol in the PU‐modified epoxy/PU IPNs on the dynamic mechanical properties, morphology, and damping behavior were investigated. The results show that the damping ability is enhanced through the introduction of PU‐modified epoxy into the PU matrix to form the IPN structure. As the molecular weight of polyol in PU‐modified epoxy increases, the loss area (LA) of the two types of the IPNs increases. PU‐dangled epoxy/PU IPNs exhibit much higher damping property than that of the PU‐crosslinked epoxy/PU IPNs with 20 wt % of PU‐crosslinked epoxy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 328–335, 1999     

Miscibility and thermal and dynamic mechanical behaviour of semi‐interpenetrating polymer networks based on polyurethane and poly(hydroxyethyl methacrylate)

The thermodynamic miscibility and thermal and dynamic mechanical behaviour of semi‐interpenetrating polymer networks (semi‐IPNs) of crosslinked polyurethane (PU) and linear poly(hydroxyethyl methacrylate) (PHEMA) have been investigated. The free energies of mixing of the semi‐IPN components have been determined by the vapour sorption method and it was established that the parameters are positive and depend on the amount of PHEMA in the semi‐IPN samples. Thermal analyses glass transition temperatures evidenced two in the semi‐IPNs in accordance with the investigation of the thermodynamic miscibility of these systems. Dynamic mechanical analysis revealed a pronounced change in the viscoelastic properties of the PU‐based semi‐IPNs with different amounts of PHEMA in the samples. The semi‐IPNs have two distinct tan δ maxima related to the relaxations of the two polymers in their glass temperature domains. The temperature position of PU relaxation maximum tan δ is invariable but its amplitude decreases in the semi‐IPNs with increasing amount of PHEMA in the systems. The tan δ maximum of PHEMA is shifted to a lower temperature and its amplitude decreases with increasing amount of PU in the semi‐IPNs. The segregation degree of components α was calculated using the viscoelastic properties of semi‐IPNs. It was concluded that the studied semi‐IPNs are two‐phase systems with incomplete phase separation. The different levels of immiscibility lead to the different degree of phase separation in the semi‐IPNs with compositions. Copyright © 2004 Society of Chemical Industry     

Studies on interpentrating polymer networks of polyurethane and polybismaleimide. I. Polyurethane and bismaleimide-urethane copolymer

The interpenetrating polymer networks (IPNs) of polyurethane (PU) and the mixture of bismaleimide (BMI) and the 2-hydroxylethyl methacrylate (HEMA)-terminated PU prepolymer (HPU) were prepared by using a simultaneous polymerization technique. The effects of the PU molecular weight and the amounts of the PU on the mechanical properties, thermal stability, and dynamic mechanical properties are discussed. The IPNs exhibited superior ultimate tensile strength as the polyol of PU and HPU in the IPNs is based on poly(tetramethylene oxide) (PTMO) glycol of molecular weight 1000 (PTMO1000). Izod impact property of the IPNs indicated that the PU(PTMO1000)/BMI-HPU(PTMO1000) IPNs had much more significant improvement than that of the PU(PTM02000)/BMI-HPU(PTMO2000) IPNs. Better thermal stability was shown by the IPNs as compared with the components of the networks, i.e. PU or BMI-HPU copolymers. The dynamic mechanical analysis (DMA) indicates that these IPNs show various shifts in the loss moduli(E) at the high and low temperature transition peaks for various molecular weight of the polyol employed in the PU. Better compatibility between BMI and PU was found as the PU(PTMO1000) was employed.To whom all correspondence should be addressed.     

Synthesis and characterization of high performance,transparent interpenetrating polymer networks with polyurethane and poly(methyl methacrylate)

Transparent, interpenetrating polymer network (IPN) materials were synthesized using polyurethane (PU) and poly(methyl methacrylate) (PMMA). PMMA contributed to the transparency and rigidity necessary for use in impact‐resistant applications, whereas PU contributed to toughness. Several factors affecting the physical properties, such as the ratio of PU to PMMA, curing profile, inclusion of different isocyanates for the PU phase, and use of an inhibitor in the PMMA phase, were investigated. Full‐IPNs were synthesized so that the two polymer networks would remain entangled with one another, and domain sizes of each system were reduced, mitigating phase separation. Both simultaneous IPNs, polymerization of monomers occurring at the same time, and sequential IPNs, polymerization of monomers occurring at different temperatures, were synthesized for studying the reaction kinetics and final morphologies. The phase morphology and the final thermal and mechanical properties of the IPNs prepared were evaluated. Findings suggest that samples containing ～80 wt% PMMA, 1,6‐diisocyanatohexane 99+% (DCH), and an inhibitor with the MMA monomer created favorable results in the thermo‐mechanical and optical properties. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers     

Studies on physico‐mechanical and optical properties,and WAXS of castor oil based polyurethane/polyacrylates interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) of polyurethane (PU)/polyacrylates have been synthesized by sequential polymerization of castor oil, methylene diisocyanate (MDI), and acrylate monomers such as methyl acrylate (MA), methyl methacrylate (MMA), and ethyl acrylate (EA); with benzoyl peroxide (BPO) and ethylene glycol dimethyl acrylate (EGDM) as an initiator and crosslinker, respectively. The physico‐mechanical properties, such as density, surface hardness, tensile strength, percentage elongation at break, and tear strength; and the optical properties, like total transmittance and haze, of PU/polyacrylate IPNs have been reported. Microcrystalline parameters of IPNs have been computed by using wide angle X‐ray scattering (WAXS) recordings. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 764–773, 2005     

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     

Drug releasing characteristics of thermo- and pH-sensitive interpenetrating polymer networks based on poly (N-isopropylacrylamide)

Interpenetrating polymer networks (IPNs) of poly(N-isopropylacrylamide)/polyurethane (PNIPAAm/PU) and poly(N-isopropylacrylamide)/poly(acrylic acid) (PNIPAAm/PAA) were synthesized to investigate the swelling and drug releasing behavior. The presence of urethane network in PNIPAAm/PU IPNs improved the mechanical strength, but reduced the swelling and drug releasing rates because of its hydrophobic characteristics. The swelling transition temperatures of PNIPAAm gels were little affected by the incorporation of PU networks in IPN structures. The drug releasing process was analyzed with a simple exponential expression of time dependent fractional drug release. The swelling and drug releasing behavior of PNIPAAm/PAa IPNs was significantly affected by the variation of PAA compositions. The drug release process changed from anomalous to dual type via zero-order mode with increasing PAA concentration due to the competitive swelling rates between PNIPAAm and PAA during release process. The releasing rate decreased in the buffer solution of pH 7.4, but increased in that of pH 5.0 with increasing PAA concentration at both 28 and 37°C because the swelling power of PAA in pH 5.0 was much less than that in pH 7.4. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2647–2655, 1997     

Mechanical property and swelling behavior of semi-interpenetrating polymer networks based on polyvinyl alcohol and polyurethane

We have studied the mechanical property and swelling behavior of semi-interpenetrating polymer networks (semi-IPNs) of poly(vinyl alcohol) (PVA) and polyurethane (PU) with reactive groups under different experimental conditions. Tensile strength and elongation of these semi-IPNs are strongly dependent on the composition of IPNs and degree of PU crosslinking. It is clear that the composition of PVA and PU forms different IPNs morphology, which would determine the final mechanical property. The experimental results also demonstrate that the degree of crosslinking, which is controlled by heat treating temperature time, and amount of reactive groups, affects the swelling behavior of IPNs. With a change in the degree of crosslinking, the degree of swelling of IPNs is also different. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 473–479, 1998     

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     

Interpenetrating polymer networks from castor oil based polyurethanes,XI

Under different experimental conditions, various liquid polyurethanes (PU) were synthesized from castor oil and isophorone diisocyanate varying NCO/OH ratio. These polyurethanes were then subsequently interpenetrated with n-butyl acrylate (nBA) monomer and ethylene glycol di-methacrylate as crosslinker by radical polymerization using benzoyl peroxide as an initiator. This leads to the formation of novel PU/PnBA interpenetrating polymer networks (IPNs) by transfer molding. These IPNs were characterized by their resistance to chemical reagents, thermal behavior (TGA), mechanical properties, namely; tensile strength, Young's modulus, elongation at break (%) and hardness (Shore A). The morphology of the IPNs was studied by Scanning Electron Microscopy. The dielectric behavior was computed in terms of electrical conductivities, dielectric constant (ε′), loss tangent (tan δ) and dielectric loss (ε″).     

Electrical behavior of chitosan and poly(hydroxyethyl methacrylate) hydrogel in the contact system

Semi‐interpenetrating polymer networks (semi‐IPNs), as polymer hydrogels composed of chitosan and poly(hydroxyethyl methacrylate) (PHEMA), exhibiting electrical‐sensitive behavior, were prepared. The swelling behavior of the chitosan/PHEMA hydrogels was studied by immersing the gels in various concentrations of aqueous NaCl solution. The electrical responses of the semi‐IPN hydrogel, in applied electric fields, were also investigated. When the semi‐IPN hydrogels were swollen, where one electrode was placed in contact with the gel and the other fixed 30 mm apart from one, they exhibited bending behavior on the application of an electric field on a contact system. The electroresponsive behavior of the present semi‐IPN was also affected by the electrolyte concentration of the external solution. The semi‐IPN also showed various degrees of increased bending behavior depending on the electric stimulus. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 915–919, 2004     

Interpenetrating polymer network from castor oil-based polyurethanes and poly(methyl acrylate). XIV

Castor oil containing hydroxyl functionality was reacted with 4,4′-diphenylmethanediisocyanate under different stoichiometric ratios of NCO/OH to obtain liquid polyurethanes. These polyurethanes were subsequently interpenetrated with methyl acrylate monomer using ethylene glycol dimethacrylate as a crosslinker by radical polymerization using benzoyl peroxide as an activator. The polyurethane/poly(methyl acrylate) interpenetrating polymer networks (PU/PMA IPNs) were obtained as tough films by transfer molding techniques. All IPNs were characterized by their resistance to chemical reagents, optical properties, thermal behavior, and mechanical properties: tensile strength, Young's modulus, elongation at break (%) and hardness Shore A. The morphology of the IPNs was studied by scanning electron microscopy and dielectric properties: electrical conductivity (σ), dielectric constant (?′), dielectric loss (?″), and loss tangent (tan δ) at different temperatures.     

Semi‐interpenetrating polymer networks based on polyurethane and polyvinylpyrrolidone. II. Dielectric relaxation and thermal behaviour

Semi‐interpenetrating polymer networks (semi‐IPNs) based on crosslinked polyurethane (PU) and linear polyvinylpyrrolidone (PVP) were synthezised, and their thermal and dynamic mechanical properties and dielectric relaxation behavior were studied to provide insight into their structure, especially according to their composition. The differential scanning calorimetry results showed the glass transitions of the pure components: one glass‐transition temperature (T_g) for PU and two transitions for PVP. Such glass transitions were also present in the semi‐IPNs, whatever their composition. The viscoelastic properties of the semi‐IPNs reflected their thermal behavior; it was shown that the semi‐IPNs presented three distinct dynamic mechanical relaxations related to these three T_g values. Although the temperature position of the PU maximum tan δ of the α‐relaxation was invariable, on the contrary the situation for the two maxima observed for PVP was more complex. Only the maximum of the highest temperature relaxation was shifted to lower temperatures with decreasing PVP content in the semi‐IPNs. In this study, we investigated the molecular mobility of the IPNs by means of dielectric relaxation spectroscopy; six relaxation processes were observed and indexed according the increase in the temperature range: the secondary β‐relaxations related to PU and PVP chains, an α‐relaxation due to the glass–rubber transition of the PU component, two α‐relaxations associated to the glass–rubber transitions of the PVP material, and an ionic conductivity relaxation due to the space charge polarization of PU. The temperature position of the α‐relaxation of PU was invariable in semi‐IPNs, as observed dynamic mechanical analysis measurements. However, the upper α‐relaxation process of PVP shifted to higher temperatures with increasing PVP content in the semi‐IPNs. We concluded that the investigated semi‐IPNs were two‐phase systems with incomplete phase separation and that the content of PVP in the IPNs governed the structure and corresponding properties of such systems through physical interactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1191–1201, 2003     

Graft interpenetrating polymer networks of polyurethane and epoxy containing rigid rods in side chain

The rigid rod‐like 4,4′‐bis(6‐hydroxyhexyloxy)biphenyl (BHHBP) units were distributed in either the epoxy or polyurethane to become SR‐epoxy and PU (with or without BHHBP) polymer matrices. The interpenetrating polymer networks (IPNs) of PU (with or without BHHBP) and SR‐epoxy were synthesized through simultaneous polymerization, and connected each other via the grafting reaction between the ? NCO groups of the PU polymer network and the ? OH groups on the side chains of SR‐epoxy network. The thermal and mechanical characteristics, compatibilities, and morphologies of these PU (with or without BHHBP)/SR‐epoxy graft‐IPNs were investigated. The polyether‐type PU(PPG series)/SR‐ epoxy graft‐IPNs exhibited two‐phased morphologies (i.e., phase separation occurred), and higher fracture energies (G_IC). Whereas the polyester‐type PU(PBA series)/SR‐ epoxy graft‐IPNs were homogeneous (no phase separation), and exhibited higher tensile and Izod impact strengths. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Semiinterpenetrating polymer networks based on polyurethane and polyvinylpyrrolidone. I. Thermodynamic state and dynamic mechanical analysis

Semiinterpenetrating polymer networks (semi‐IPNs) based on polyurethane (PU) and polyvinylpyrrolidone (PVP) have been synthesized, and their thermodynamic characteristics, thermal properties, and dynamical mechanical properties have been studied to have an insight in their structure as a function of their composition. First, the free energies of mixing of the two polymers in semi‐IPNs based on crosslinked PU and PVP have been determined by the vapor sorption method. It was established that these constituent polymers are not miscible in the semi‐IPNs. The differential scanning calorimetry results evidence the T_g of polyurethane and two T_g for PVP. The dynamic mechanical behavior of the semi‐IPNs has been investigated and is in accordance with their thermal behavior. It was shown that the semi‐IPNs present three distinct relaxations. If the temperature position of PU maximum tan δ is invariable, on the contrary, the situation for the two maxima observed for PVP is more complex. Only the maximum of the highest temperature relaxation is shifted to lower temperature with changing of the semi‐IPNs composition. It was concluded that investigated semi‐IPNs are two‐phase systems with incomplete phase separation. The phase composition was calculated using viscoelastic properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 852–862, 2001     

Damping analysis of polyurethane/polyacrylate interpenetrating polymer network composites filled with graphite particles

The graphite‐filled polyurethane/poly(methyl methacrylate‐butyl methacrylate) (PU/P(MMA‐BMA)) semi‐interpenetrating polymer networks (IPNs) were synthesized by sequential method. The influences of graphite particle content and size on the 60/40 PU/P(MMA‐BMA) IPNs were studied. The damping properties of IPN composites were evaluated by dynamic mechanical thermal analysis (DMA) and cantilever beam resonance methods. The mechanical performances were investigated using tensile and hardness devices. DMA results revealed that the incorporation of graphite particles improved damping properties of IPNs significantly. The 5% graphite‐filled IPN composite exhibited the widest temperature range and the highest loss factor (tan δ) when the test frequency was 1 Hz. As to the damping properties covering a wide frequency range from 1 to 3,000 Hz, the addition of graphite particles broadened the damping frequency range (Δf, where tan δ is above 0.3) and increased the tan δ value of IPNs. Among them, the composite with 7.5% graphite showed the best damping capacity. And the hardness and the tensile strength of IPN composites were also improved significantly. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers