Polyurethane Interpenetrating Polymer Networks Research Articles

Synthesis and performance study of novel antibacterial and anticorrosive polyurethane IPN

Polyaniline has been extensively used for the corrosion protection of polymeric materials. However, there have been few studies on its combined antimicrobial activity when used in combination with silver molybdate. In this study, we synthesized silver molybdate (Ag2MoO4) crystals using a homogeneous precipitation method. Polyaniline-dodecylbenzenesulfonic acid/castor oil(PANI-DBSA/CO) mixtures were prepared in an encapsulated state by in situ polymerisation. Subsequently, PANI/Ag2MoO4-PU interpenetrating polymer network(IPN) composite coatings(P/A-PU) were produced by dispersing Ag2MoO4 and PANI-DBSA/CO in polyurethane using ultrasonic dispersion. The composite coatings were characterized using Fourier transform infrared spectroscopy(FTIR), X-ray diffraction analysis(XRD), and transmission electron microscopy(TEM). The study confirmed that composite coatings with uniformly dispersed nanoparticles of PANI and Ag2MoO4 encapsulated by CO and epoxy resin E-44 grease exhibit improved physico-mechanical characteristics. The research also evaluated the effect of nanoparticles on the corrosion behaviour of the coatings using electrochemical impedance spectroscopy and kinetic potential polarisation experiments. The study investigated the antimicrobial properties of P/A-PU composite coatings on Escherichia coli(E.coli) and Staphylococcus aureus(S.aureus) by conducting bacterial growth curves, protein leakage, and fluorescence staining experiments. The aim was to establish a causal connection between the coated surfaces and the observed antimicrobial properties. The study demonstrated that incorporating IPN of polyaniline polyurethane into the coating composites improved their anticorrosive properties. Furthermore, the addition of silver molybdate at a mass ratio of 0.3 % resulted in a remarkable 99 % antimicrobial activity against E.coli and S.aureus.

Suppressive Photochromism and Promotive Mechanochromism of Rhodamine Mechanophore by the Strategy of Poly(methyl acrylate)/Polyurethane Interpenetrating Polymer Network.

As molecular design and the structure-property relationships of photochemical molecules established in the literature serve as a convenient reference for mechanophore exploration, many typical mechanophores suffer undesired responses to UV light or even sunlight in bulk polymers. We developed a strategy of a poly(methyl acrylate)/polyurethane (PMA/PU) interpenetrating polymer network (IPN) to suppress the photochromic property of the mechanophore and promote its mechanochromic property. A widely used rhodamine mechanophore (Rh-2OH) was first incorporated into polyurethane (P1). Then P1 was swollen in methyl acrylate and photopolymerized to prepare a PMA2.8/PU IPN (P2). Different from photo/force-responsive P1, P2 selectively responded to force because the low free volume in IPN greatly hinders photoisomerization of the rhodamine spirolactam, suggesting that a simple IPN strategy successfully resolves the giant problem of nonselective response to photo/force for photochromic mechanophores. Moreover, PMA/PU IPN enhanced the mechanical property, resulting in a higher mechanochemical activation ratio than PU, and the prestretching effect of PMA/PU IPN promoted the force sensitivity of rhodamine mechanophores significantly. We believe that the strategy can be applied to other mechanophores, promoting their application in more complicated environments.

Mechanical performance of vinyl ester—polyurethane interpenetrating polymer network composites

AbstractIn this study, a carbon fiber/vinyl ester‐polyurethane interpenetrating polymer network (IPN) laminate composite was fabricated and characterized for the first time. The IPN matrix, consisting of a commercially available vinyl ester and polyurethane, was synthesized via a sequential method with vinyl ester as the rigid phase and polyurethane as the flexible phase. Good compatibility between the two phases in the matrix was achieved and confirmed via differential scanning calorimetry and dynamic mechanical analysis. The thermomechanical response of the IPN matrix was compared with that of an unmodified vinyl ester resin. The presence of the more ductile polyurethane in the IPN matrix depressed the glass transition temperature (from 94 to 84°C), but also served to improve damping response at all frequencies studied. Tensile and flexural tests were performed on the carbon fiber/IPN and carbon fiber/vinyl ester composites to determine their mechanical response. The IPN composite exhibited lower tensile properties than the vinyl ester composite. However, its flexural properties were on par with those of the vinyl ester composite.

Functional grading of IPN parts: plates with single and multiple cracks

Functional grading (FG) around the crack tip is studied to improve the load capacity in parts made of graded interpenetrating polymer networks (IPN). To calculate the capacity, the stress intensity factor at the crack tip is calculated by blending the displacement correlation technique and finite element solutions. This process is integrated into an optimization process that uses linear scaling to obtain optimal material grading in a fixed domain around the crack tip. The process is demonstrated using a known poly(methyl methacrylate)/polyurethane IPN system for the case of internal and edge cracks. The FG-IPN parts obtained by this optimization show substantially improved load capacity compared to both optimal uniform plates, and plates with simple toughening of the region around the crack.

Self-gradient mechanism, morphology and damping analysis of a thickness continuous gradient epoxy–polyurethane interpenetrating polymer network

A simple and affordable gradient-distributing interpenetrating polymer network (IPN) composite was created that takes advantage of the relatively poor compatibility and the curing rate discrepancy between epoxy (EP) and polyurethane (PU) resins. Organic element content analysis (CHNS/O) and attenuated total reflection infrared spectroscopy (ATR-FTIR) reveal that the PU content is a gradient that changes along the direction of the thickness. Morphology analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) proves that it has a continuously changing modulus with no stratified structure. Dynamic thermomechanical analysis (DMA) and fatigue testing demonstrate that the composite has better performances than traditional homogeneous IPNs with the same compositions.

Evaluating the mechanical properties of E-Glass fiber/carbon fiber reinforced interpenetrating polymer networks

A series of vinyl ester and polyurethane interpenetrating polymer networks were prepared by changing the component ratios of VER (Vinyl ester) and PU (Polyurethane) and the polymerization process was confirmed with Fourier Transform infrared spectroscopy. IPN (Inter Penetrating Polymer Network - VER/PU) reinforced Glass and carbon fiber composite laminates were made using the Hand lay up technique. The Mechanical properties of the E-glass and carbon fiber specimens were compared from tests including Tensile, Compressive, Flexural, ILSS (Inter Laminar Shear Strength), Impact & Head Deflection Test (HDT). The IPN Reinforced Carbon fiber specimen showed better results in all the tests than E-Glass fibre reinforced IPN laminate with same thickness of the specimen, according to ASTM standards. It was found that the combination of 60%VER and 40%PU IPN exhibits better impact strength and maximum elongation at break, but at the slight expense of mechanical properties such as tensile, compressive, flexural, ILSS properties. The morphology of the unreinforced and reinforced composites was analyzed with help of scanning electron microscopy.

Correlation between mechanical damping and interphase content in interpenetrating polymer networks

AbstractRecently, some interpenetrating polymer networks with good mechanical damping properties have been synthesized. However, the effect of morphology on this property has not yet been clearly elucidated. Herein, two polystyrene–polyurethane interpenetrating polymer networks, which were grafted using TMI [benzene‐1‐(1‐isocyanato‐1‐methyl ethyl)‐3‐(1‐methylenyl)] and HEMA (2‐hydroxyethyl methacrylate), respectively, have been investigated, as model samples, by modulated‐temperature differential scanning calorimetry and by dynamical mechanical thermal analysis. The results indicate that there is a correlation between mechanical damping and both interphase content and the distribution of composition in the interphase region. The findings should provide valuable information for the design of future damping materials. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2439–2442, 2001

Energy Transfer Studies of Interpenetrating Polymer Networks: Characterizing the Interface in Polyacrylate−Polyurethane IPNs

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and polyacrylate (PA) were prepared to give very small domains (ca. 20 nm) of PA dispersed in a PU matrix. In these samples the PU phase is labeled with phenanthrene, a donor for energy transfer experiments, and the PA phase is labeled with anthracene, the corresponding acceptor. Direct nonradiative energy transfer from phenanthrene to anthracene was used to study the IPN morphology. The interface and mixing between the microphases were analyzed in terms of a Helfand and Tagami (H−T) profile, which is commonly used to describe the interface in polymer blend systems. Exact fluorescence theoretical decay profiles were calculated according to the H−T profiles in a restricted geometry. Experimental fluorescence decays were compared to the theoretical decays, and the interface thickness was recovered. At the level of the model we used in our analysis, we found strong similarities between these IPNs and traditional polymer blends.

Effect of cross-link density and hydrophilicity of PU on blood compatibility of hydrophobic PS/hydrophilic PU IPNs

To investigate the effect of the hydrophilic and hydrophobic microdomain structure on blood compatibility, a series of interpenetrating polymer networks (IPNs) composed of hydrophilic polyurethane (PU) and hydrophobic polystyrene (PS) was prepared. One series was prepared with varying cross-link densities of each network, the other with varying hydrophilicity of the PU component. All PU/PS IPNs exhibited microphase-separated structures that had dispersed PS domains in the continuous PU matrix. The domain size decreased with decreasing the hydrophilicity of the PU component and increasing the cross-link density of each network. As the cross-link density and hydrophobicity of the PU component was increased, an inward shift of Tgs was observed, which was due to the decrease in phase separation between the hydrophobic PS component and hydrophilic PU component. In the in vitro platelet adhesion test, as the microdomain size of PU/PS IPN surface decreased, the number of adhered platelets on the PU/PS IPN surface was reduced and deformation of the adhered platelets decreased. It could be concluded that blood compatibility of PU/PS IPN was mainly affected by the degree of mixing between PU and PS component, which was reflected by the domain size of PS rich phase.

Modulated differential scanning calorimetry: 13. Analysis of morphology of poly(ethyl methacrylate)/polyurethane interpenetrating polymer networks

The phase structure of poly(ethyl methacrylate)–polyurethane (PEMA/PUR) interpenetrating polymer networks (IPNs) has been investigated by means of modulated-temperature differential scanning calorimetry (M-TDSC), dynamic mechanical thermal analysis (DMTA) and small-angle X-ray scattering (SAXS). Experimental data from both M-TDSC and SAXS indicate that the morphologies of all the PEMA/PUR IPN samples (90 : 10 to 10 : 90 PUR/PEMA) are multi-phase structures. The scattering peaks from SAXS are quite broad, thereby indicating a distribution of microdomain sizes from 5 to 12 nm. This structure formation in IPNs is a competitive process between phase separation and the formation of cross-links which restricts segmental diffusion. An M-TDSC-based characterization method for IPNs has been developed using the differential of heat capacity signal, d C p/d T, to analyze phase structure and calculate the weight fraction of each component.

Small-angle x-ray scattering and pulsed NMR studies of polyurethane interpenetrating polymer networks

Simple mixtures, semi-interpenetrating polymer network (semi-IPN), and interpenetrating polymer networks (IPN) of polystyrene and polyurethane which were synthesized at different high pressures were studied. It was found that, with increasing pressure, mixing of the components was enhanced. This was evidenced by the reduction in the size scale of the phases and/or the extent of mixing within the phases. In general, it was found that increasing the amount of cross-linking enhanced the mixing. Temperature-dependent SAXS studies showed that the enhanced mixing of the linear chains could be reversed at elevated temperatures

The effects of functional azo initiator on PMMA and polyurethane IPN systems. I. Synthesis, characterization, and thermal effects

AbstractThe use of functional azo initiators and the thermal history of the materials have been shown to exert significant effects on the properties of interpenetrating polymer networks (IPNs). The IPNs prepared with a reactive azo initiator from MDI and 1,2‐PBD (1,2‐polybutadiene diol) with PMMA have been found to exhibit greater ductility, lower rigidity, and lower moduli than IPNs prepared with AIBN. This probably resulted from the attached PMMA blocks modifying the properties of the PU matrix phases. Increasing thermal treatment of IPNs prepared from either the reactive or the normal azo initiators exhibited increased Tg values in both DSC and DMTA scans. These results have been explained by increased association from chemical reactions between the hard segments of the polyurethane and poly(methyl methacrylate) ester groups.

The effects of functional azo initiator on PMMA and polyurethane IPN systems. II. The influence of the interface and the matrix structure on the mechanical properties

AbstractThe mechanical properties of materials prepared by a new method for modifying the structure of polyurethane/poly(methyl methacrylate) (PU/PMMA) interpenetrating polymer networks (IPNs) by using a reactive azo initiator were investigated by means of tensile test, tear test, and dynamic mechanical thermal analysis (DMTA) measurement. The structures of these IPNs were similar to the particulate filled elastomers. It was found that the reactive initiator, which could form blocks of PMMA within the PU matrix (rubber), changed both the filler‐matrix interface and the matrix structure. The mechanical properties of these IPNs were dominated by the matrix structure and the interface.

Studies on the effect of degree of hydrophilicity on tissue response of Polyurethane interpenetrating polymer networks

Interpenetrating polymer networks of polyurethane and vinyl monomers such as polyacrylamide, polyvinyl pyrrolidone, poly(hydroxyethy) methacrylate) and poly (methyl methacrylate) were implanted intramuscularly in rabbits. Attempts were made to correlate the morphological aspects of the interpenetrating polymer networks to their histological response. A relatively increased hydrophilicity of hydrophobicity of the interpenetrating polymer networks as in the case of polyurethane-polyvinyl pyrrolidone and polyurethane-poly(methyl methacrylate) interpenetrating polymer networks, respectively, could elicit an inert response whilst degradation of materials promoted reactivity.

Polyamide–polyurethane interpenetrating polymer networks prepared by synthesis in the melt

AbstractTwo types of interpenetrating polymer networks based on polyamide (nylon 12) and a polyurethane formed in the polyamide melt were prepared. The first type (A), which could be regarded as a semi‐2‐IPN, consisted of a polyurethane component crosslinked with trimethylolpropane whereas for the second type (B), which would meet the definition of a thermoplastic IPN, the polyurethane component was chain‐extended with butane‐1,4‐diol only. The phase morphologies of these IPNs were investigated using electron microscopy, dynamic mechanical analysis, tensile testing, and sonic velocity measurements. Electron micrographs were compared by using the conventional TEM technique and a Robinson‐type backscattered electron detector in combination with a SEM. It was concluded that the materials are phase separated, but with a fine continuous‐dispersed phase structure. For a 44 wt % polyurethane IPN a cocontinuous phase structure with a subcellular texture was indicated. One physically blended sample was compared with the analogous IPN‐type sample.

Polyurethane interpenetrating polymer networks (IPN's) synthesized under high pressure. 4. Compositional variation of polyurethane-polystyrene IPN's and linear blends

Le module dynamique complexe suit le modele de Budiansky montrant une inversion de phase lorsque l'IPN est synthetise a pression atmospherique, et suit le modele de Dickie avec une matrice vitreuse pour une pression de synthese de 10000 kg/cm 2

Polyurethane interpenetrating polymer networks (IPN's) synthesized under high pressure. 3. Morphology and Tg behavior of polyurethane-polystyrene semi-IPN's and linear blends

Polyurethane interpenetrating polymer networks (IPN's) synthesized under high pressure. 3. Morphology and Tg behavior of polyurethane-polystyrene semi-IPN's and linear blends

Polyurethane interpenetrating polymer networks (IPN's) synthesized under high pressure. 1. Morphology and Tg behavior of polyurethane-poly(methyl methacrylate) IPN's

Synthese sous pression allant jusqu'a 20000 kg/cm 2 . Influence de la pression sur la compatibilite

Gradient‐IPN‐modified hydrogel beads: Their synthesis by diffusion–polycondensation and function as controlled drug delivery agents

AbstractInterpenetrating polymer network (IPN) membranes and gradient–IPN polymers were synthesized by immersing crosslinked, 2‐hydroxyethylmethacrylate copolymer beads which were swollen in polyol in solutions of diisocyanates. Diffusion of reactants and polycondensation take place simultaneously, and the polymer beads are modified by a polyurethane–IPN layer whose thickness and compositional gradient are a function of reaction rate and diffusion rate. When the reaction is fast relative to diffusion, the reaction zone is narrow and the IPN boundary layer is sharp, whereas when diffusion dominates, the reaction zone and the IPN‐modified region becomes broader and more diffuse. A water‐soluble drug imbibed into such gradient‐IPN‐modified hydrogel beads is released over a prolonged time period due to the less permeable IPN barrier and because of a drug‐distribution gradient in the polymer, which follows the polyurethane gradient. Diffusion polycondensation can be considered a special case of interfacial polycondensation, one in which the interface area is expanded into and stabilized by a preformed polymer matrix, which serves as reaction medium.

Polyurethane interpenetrating polymer networks. V. Engineering properties of polyurethane–poly(methyl methacrylate) IPN's

AbstractThe engineering properties of polyurethane–poly(methyl methacrylate) simultaneous interpenetrating networks (SIN's) were evaluated. The hardness behavior reflected the observed phase inversion in the electron‐microscopic studies. The maximum ultimate tensile strength was observed at 85% polyurethane–15% poly(methyl methacrylate) IPN and was due to the filler‐reinforcing effect of the rigid poly(methyl methacrylate) phase. The ultimate tensile strenght of the 75/25 polyurethane–poly(methyl methacrylate) IPN was higher than that of the corresponding pseudo‐IPN's (only one network crosslinked) and the linear blend. The leathery and glassy compositions did not show any reinforcement in the ultimate tensile strength. This indicated that the reinforcement in the ultimate tensile strength was not directly related to interpenetration (by increased physical entanglement crosslinks), but indirectly related by reducing the rigid phase domain sizes and increasing the adhesion between the two phases, thus enhancing the filler‐reinforcing effect similar to that observed in a carbon black‐filled rubber. The tear strengths of the polyurethane‐rich IPN's pseudo‐IPN's, and linear blends were found to be higher than that of the pure polyurethane as a combined result of increased modulus and tensile strength. The weight retentions in the thermal decomposition of the IPN's, pseudo‐IPN's, and linear blends were higher than the proportional average of the component networks. The results seemed to indicate that this enhancement was related to the presence of the unzipped methyl methacrylate monomer. It was suggested that the monomers acted as radical scavengers in the polyurethane degradation, thus delaying the further reaction of the polyurethane radicals into volatile amines, isocyanates, alcohols, olefins, and carbon dioxide.