Two-component interpenetrating polymer networks (IPNs) from polyurethanes and epoxies. I. Studies on full IPN,pseudo-IPN,and graft polymer alloys of polyurethanes and epoxies

In this article we review the synthesis and morphology and the physical and mechanical properties of two-component interpenetrating polymer networks (IPNs) from polyurethane and epoxy polymers; the corresponding pseudo-IPNs and grafted IPNs are also discussed. A comparison was made of full IPNs, pseudo-IPNs, grafted IPNs, and related homopolymers by examining their mechanical properties, mechanical spectra, and electron microscopy on an investigation of the effects of interpenetration or permanent entanglement in the IPN and related systems. This interpenetration has resulted in improved compatibility between the two polymer systems and has caused a decrease in the degree of phase separation. An observed shift in the dynamic glass transition temperatures (T_gs) of the two components which yielded a single IPN T_g further substantiates our results.     

室温固化蓖麻油聚氨酯/乙烯基聚合物互穿网络材料的一些规律及其性能

研究了蓖麻油与甲苯二异氰酸酯及丙烯酸酯或苯乙烯等乙烯基单体在室温下生成的互穿网络聚合物(IPN)的一些规律及其性能.用红外光谱追踪表明,聚氨酯的生成快于甲基丙烯酸甲酯的聚合.研究IPN凝胶点指出.凝胶点时间随聚氨酯含量增加及聚苯乙烯含量减少而缩短.丙烯酸甲酯在生成IPN过程中凝胶的生成速度要比苯乙烯的场合快.丙烯酸丁酯、丙烯腈或丙烯酸甲酯与蓖麻油聚氨酯生成的IPN的抗张强度在聚氨酯占一半时呈现最大值.透射电镜观察表明,生成速率较快的聚氨酯的微区存在于聚丙烯酸甲酯中.聚丙烯酸甲酯与蓖麻油聚氨酯形成的IPN在tanδ-T,曲线上呈现一个宽的玻璃化转变温度.     

POLYIMIDE/INORGANIC INTERPENETRATING POLYMER NETWORKS FOR STABLE SECOND-ORDER NONLINEAR OPTICS

Thermally stable NLO interpenetrating polymer networks (IPNs) based on an organosoluble polyimides functionalized with methacryloyl groups (PIB), and an alkoxysilane dye (ASD) have been developed. IPNs were formed through the free radical polymerization of methacryloyl group containing PIB, and sol-gel process of ASD. Optically clear samples exhibit large second-order optical nonlinearity (d₃₃ = 6.9-39.6 pm/V at 1064 nm) after poling and curing at 180°C for 2 hours. The temporal stability of the PIB/ASD IPN samples was much better than the inter-chain crosslinking polyimide/inorganic samples. The high rigidity of the polymer backbone and the interpenetrating structure of the polymer networks prevent the randomization of the aligned NLO chromophores     

Room temperature synthesis and mechanical properties of two kinds of elastomeric interpenetrating polymer networks based on castor oil

Two kinds of interpenetrating polymer networks (IPNs) composed of two-component polyurethane (PU) and vinyl or methacrylic polymer (PV), namely, (polyether-castor oil)PU/PV IPN(I) and (polybutadiene-castor oil)PU/PV IPN(II), were synthesized at room temperature using benzoyl peroxide and N,N-dimethylaniline as redox initiator and dibutyltin dilaurate as catalyst. The former IPN was prepared by polymerization of castor oil, NCO-terminated polyether and vinyl or methacrylic monomer together and the latter IPN was obtained by polymerization of castor oil, NCO-terminated polybutadiene, NCO-terminated castor oil and vinyl or methacrylic monomer together. Various synthesis conditions affecting mechanical properties of the two kinds of IPNs were studied. Acrylonitrile (AN) is a good monomer for synthesizing IPN(I), but is a poor monomer for preparing IPN(II). At optimum conditions for the synthesis, both the (polyether-castor oil)PU/PAN IPNs and the (polybutadiene-castor oil)PU/polystyrene (PSt) IPNs possess permanent set about 10%, tensile strength over 13 and 11 MPa and ultimate elongation over 240% and 270%, respectively, thus behaving as elastomers. TEM micrograph of a (polybutadiene-castor oil)PU/PSt IPN showed a microphase separation in the IPN.     

聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿网络聚合物的相容性与力学性能

用同步法合成了聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿网络聚合物［ＰＵ（ＰＥＣＨ）／ＰＭＭＡＩＰＮ］，调节ＩＰＮ中两组分组成比制备出由完全弹性体、增强弹性体、增韧塑料到脆性塑料多种高聚物合金材料．用ＤＳＣ、动态力学谱、ＴＥＭ对ＩＰＮ的研究结果表明，ＰＵ（ＰＥＣＨ）／ＰＭＭＡＩＰＮ的两组分是完全相容的；同时对各种组成比的ＩＰＮ材料进行力学性能测试，用相容性ＩＰＮ中互穿、缠结结构解释其力学行为，并用ＳＥＭ对断面形貌进行了观察解释．     

聚苯乙烯/聚丙烯酸丁酯乳胶互穿聚合物网络的动态力学性能研究

<正> 互穿聚合物网络(IPN)是一种新型聚合物共混物.自Sperling在1969年合成聚丙烯酸乙酯/聚苯乙烯异步IPN(Sequential IPN)后,该领域进展很快.乳胶IPN(latex IPN)是用改进的乳液聚合法合成的一种微观互穿IPN.在前文中,我们报道了聚苯乙烯/聚丙烯酸丁酯(PS/PBA)乳胶IPN的合成,本文研究一些因素对PS/PBA乳胶IPN动态力学性能的影响.     

Interpenetrating polymer network (IPN) nanogels based on gelatin and poly(acrylic acid) by inverse miniemulsion technique: synthesis and characterization

Novel interpenetrating polymer network (IPN) nanogels composed of poly(acrylic acid) and gelatin were synthesised by one pot inverse miniemulsion (IME) technique. This is based on the concept of nanoreactor and cross-checked from template polymerization technique. Acrylic acid (AA) monomer stabilized around the gelatin macromolecules in each droplet was polymerized using ammonium persulfate (APS) and tetramethyl ethylene diamine (TEMED) in 1:5 molar ratio and cross-linked with N,N-methylene bisacrylamide (BIS) to form semi-IPN (sIPN) nanogels, which were sequentially cross-linked using glutaraldehyde (Glu) to form IPNs. Span 20, an FDA approved surfactant was employed for the formation of homopolymer, sIPN and IPN nanogels. Formation of stable gelatin-AA droplets were observed at 2% surfactant concentration. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies of purified nanogels showed small, spherical IPN nanogels with an average diameter of 255 nm. In contrast, sIPN prepared using the same method gave nanogels of larger size. Fourier-transform infrared (FT-IR) spectroscopy, SEM, DLS, X-ray photoelectron spectroscopy (XPS) and zeta potential studies confirm the interpenetration of the two networks. Leaching of free PAA chains in sIPN upon dialysis against distilled water leads to porous nanogels. The non-uniform surface of IPN nanogels seen in transmission electron microscopy (TEM) images suggests the phase separation of two polymer networks. An increase of N/C ratio from 0.07 to 0.17 (from PAA gel to IPN) and O/C ratio from 0.22 to 0.37 (from gelatin gel to IPN) of the nanogels by XPS measurements showed that both polymer components at the nanogel surface are interpenetrated. These nanogels have tailoring properties in order to use them as high potential drug delivery vehicles for cancer targeting.     

Miscibility and properties of polyurethane/benzyl starch semi‐interpenetrating polymer networks

We successfully prepared a series of transparent materials with semi‐interpenetrating polymer networks (semi‐IPNs) from castor‐oil‐based polyurethane (PU) and benzyl starch (BS). The miscibility, morphology, and properties of the semi‐IPN films were investigated with attenuated total reflection/Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, scanning electron microscopy, wide‐angle X‐ray diffraction, electron spin resonance (ESR), ultraviolet–visible spectroscopy, and tensile testing. The results revealed that the semi‐IPN films had good or certain miscibility with BS concentrations of 5–70 wt % because of the strong intermolecular interactions between PU and BS. With an increase in the concentration of BS, the tensile strength and Young's modulus of the semi‐IPN materials increased. The ESR data confirmed that the segment volume of PU in the semi‐IPNs increased with the addition of BS; that is, the chain stiffness increased as a result of strong interactions between PU and BS macromolecules. It was concluded that starch derivatives containing benzyl groups in the side chains more easily penetrated the PU networks to form semi‐IPNs than those containing aliphatic groups, and this led to improved properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 603–615, 2005     

Studies on the Morphology of Natural Rubber/Polyacrylate Interpenetrating Polymer Networks

The interpenetrating polymer network(IPN) systems have attracted a lot of attention because of their unique two-phase structure and properties. There have been many publications concerning the IPNs in which poly (isoprene) (PIP) or polyacrylates (PAC) is formed as one of the networks.In the present study, Four serles of natural rubber(NR)/PAC IPNs were prepared and their morphologies were investigated with dynamic mechanics analysis(DMA) and transmission electron microscopy (TEM).     

Thermal transitions of benzene in copolymers and interpenetrating polymer networks based on hydrophilic and hydrophobic components: Experimental evidence of hydrophobic interaction

Thermal transitions of benzene in a hydrophobic polymer network have been explained by us in terms of the phase diagram of the polymer‐solvent system. In this work, we executed a similar study on copolymers and interpenetrating polymer networks (IPNs) with controllable hydrophilic/hydrophobic ratios. Copolymers and IPNs were swollen with different amounts of benzene and subjected to cooling and heating scans with differential scanning calorimetry (DSC). Synthesis of the IPNs was carried out in such a way that phase separation appeared, and three qualitatively different types of DSC thermograms were identified depending on the benzene content of IPN. Thermal transitions of benzene in the hydrophilic/hydrophobic copolymers can also be explained as a consequence of the phase diagram of the system, but an increase in the glass‐transition temperature of the system can be correlated with the interactions among the hydrophilic groups of the copolymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1713–1721, 2003     

Investigation of swelling,drug release and diffusion behaviors of poly(N‐isopropylacrylamide)/poly (N‐vinylpyrrolidone) full‐IPN hydrogels

The synthesis of sequential full interpenetrating polymer networks (IPNs) based on poly (N‐isopropylacrylamide) (PNIPAAm) and negatively charged poly(N‐vinyl‐2‐pyrrolidone) (PNVP) was described and their swelling, drug release, and diffusion studies were investigated. PNIPAAm was used as a host network. According to swelling experiments, IPNs gave relatively lower swelling ratios compared to PNIPAAm hydrogel due to the higher cross‐linking density. Lidocaine (LD) was used as a model drug for the investigation of drug release behavior of IPNs. LD uptake of the IPNs were found to increase from 24 to 166 (mg LD / g dry gel) with increasing amount of PNIPAAm and AMPS contents in the IPN structure. It was observed that the specific interaction between drug and AMPS co‐monomer influenced the drug release profile. In the diffusion transport mechanism study in water, the results indicated that the swelling exponents n for all IPNs are in the range from 0.50 to 0.72. This implies that the swelling transport mechanism was transferred from Fickian to non‐Fickian transport, with increasing AMPS content and NIPAAm character in the IPN structure. In addition, diffusion of LD within the IPNs showed similar trend. The incorporation of AMPS leads to an increase in electrostatic interaction between charge sites on carboxylate ions and cationic LD molecules. Therefore, the highest diffusion coefficient (D) of drug was found for IPN2 sample. Copyright © 2007 John Wiley & Sons, Ltd.     

聚醚聚氨酯/环氧树脂互穿网络聚合物的研究(Ⅱ)

合成了不同类型聚醚聚氨酯/环氧树脂(PU/EP)互穿网络聚合物(IPN),通过改变PU中聚乙二醇分子量、3OH/2OH及NCO/OH比值等,研究IPN组份间分子混合程度,采用电镜、动态力学分析及应力应变等测试方法表征。结果表明:聚乙二醇分子量降低及3OH/2OH、NCO/OH比的提高,可使相容性提高,材料力学性能增强。     

Viscoelastic behavior and phase domain formation in Millar interpenetrating polymer networks of polystyrene

Millar-type interpenetrating polymer networks (IPNs) are composed of two identical networks. In the present case Millar IPNs of polystyrene/polystyrene were prepared where the crosslinker levels of the two networks differed by a factor of 10. Polymer network I contained 0.4% divinylbenzene (DVB) and polymer network II contained 4% DVB, the polymers having the following weight proportions: 75/25, 50/50, and 25/75. A single polystyrene network containing 2.2% DVB was synthesized for comparison with the 50/50 Millar IPN, both containing the same average amount of crosslinker. The creep behavior of the Millar IPNs was found to be dominated by polymer network I, as were the rubbery moduli and swelling behavior in toluene. These results suggested that polymer I domains are more continuous in space and polymer II domains are less continuous. The Donatelli equation predicted polymer II domain sizes of 60 Å to 100 Å for the Millar IPNs. Electron micrographs of specimens containing 1% isoprene in polymer II offered visual evidence for the segregation of polymer II domains from polymer I, and showed that the polymer II domains were, in fact, less continuous. Polymer II domains varied from about 50 to 100 Å in size, as predicted. These results have implications for gelation processes in general.     

Synthesis and characterization of polyaniline filled PU/PMMA interpenetrating polymer networks

A series of conducting interpenetrating polymer networks (IPNs), are prepared by sequential polymerization of castor oil based polyurethane (PU) with poly(methyl methacrylate) (PMMA) and polyaniline doped with camphor sulphonic acid (PAni)_CSA. The effect of different amount of PAni (varies from 2.5-12.5%) on the properties of PU/PMMA (50/50) IPNs such as electrical properties like conductivity, dielectric constant and dissipation factor; mechanical properties like tensile strength and percentage elongation at break have been reported. (PAni)_CSA filled IPNs shows improved tensile strength than the unfilled IPN system. The thermal stability and surface morphology of unfilled and (PAni)_CSA filled PU/PMMA (50/50) IPN sheets were investigated using a thermogravimetric analyzer (TGA) and a scanning electron microscope (SEM). TGA thermograms of (PAni)_CSA filled PU/PMMA (50/50) IPNs show a three-step thermal degradation process. SEM micrograms of filled PU/PMMA IPN system shows spherulitic structure at higher concentration of (PAni)_CSA.     

Hydrogel‐like elastic membrane consisting of semi‐interpenetrating polymer networks based on a phosphorylcholine polymer and a segmented polyurethane

To obtain a hydrogel‐like elastic membrane, we prepared semi‐interpenetrating polymer networks (IPNs) by the radical polymerization of methacrylates such as 2‐methacryloyloxyethyl phosphorylcholine (MPC), 2‐hydroxyethylmethacrylate, and triethyleneglycol dimethacrylate diffused into segmented polyurethane (SPU) membranes swollen with a monomer mixture. The values of Young's modulus for the hydrated semi‐IPN membranes were less than that for an SPU membrane because of higher hydration, but they were much higher than that for a hydrated MPC polymer gel (non‐SPU). According to a thermal analysis, the MPC polymer influenced the segment association of SPU. The diffusion coefficient of 8‐anilino‐1‐naphthalenesulfonic acid sodium salt from the semi‐IPN membrane could be controlled with different MPC unit concentrations in the membrane, and it was about 7 × 10² times higher than that of the SPU membrane. Fibroblast cell adhesion on the semi‐IPN membrane was effectively reduced by the MPC units. We concluded that semi‐IPNs composed of the MPC polymer and SPU may be novel polymer materials possessing attractive mechanical, diffusive‐release, and nonbiofouling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 68–75, 2003     

Analysis of interpenetrating polymer networks via quartz crystal microbalance with dissipation monitoring

A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to assess the physical properties of interpenetrating polymer networks (IPNs) through swelling experiments in ambient humidity and in phosphate-buffered saline (PBS), pH 7.4. The IPNs, based on acrylamide (AAm) and poly(ethylene glycol) (pEG), swell from thin, rigid films when dry (16.7 +/- 5.2 nm on Si/SiO(2)) to expanded, viscoelastic films when hydrated (107 +/- 24.2 nm on Si/SiO2). The dry IPNs could be analyzed using the Sauerbrey relationship, but for the hydrated films it was necessary to interpret QCM-D data with a Kelvin-Voigt viscoelastic model. A complex modulus |G| of 116 +/- 38.1 kPa for the swollen IPN surface on Si/SiO2 was defined by the model. The QCM-D was also employed to quantify the adsorption of human fibrinogen, a protein important in thrombus formation, onto the IPNs. Fibrinogen adsorption studies demonstrated the sensitivity of the QCM-D, as well as confirmed the nonfouling nature of the IPN surface, where less than 5 ng/cm2 of fibrinogen was adsorbed.     

Polyurethane–polyacrylate interpenetrating polymer networks. I

Two-component topologically interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) composed of a melamine-cured polyacrylate and five different polyether-based polyurethanes were made. The linear polymers and prepolymers were combined in solution, together with the necessary crosslinking agents and catalysts; films were cast, chain-extended, and crosslinked in situ. Infrared spectroscopy indicated that little or no reaction between the different networks occurred. In all cases, except for one IPN which was made from a very highly crosslinked polyurethane, maxima in tensile strength, significantly higher than the tensile strengths of the components, occurred. This was explained by an increase in crosslink density resulting from interpenetration. Some enhancement in other physical properties (impact strength and thermal resistance) was also noted.     

Thermal,mechanical, and morphological properties of soybean oil-based polyurethane/epoxy resin interpenetrating polymer networks (IPNs)

A series of interpenetrating polymer networks (IPNs) based on epoxy (EP) resin and polyurethane (PU) prepolymer derived from soybean oil-based polyols with different mass ratios were synthesized. The structure, thermal properties, damping properties, tensile properties, and morphology of soybean oil-based PU/EP IPNs were characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), universal test machine, and scanning electron microscopy (SEM). DSC and DMA results show that the glass transition temperature of the soybean oil-based PU/EP IPN decreases with the increase of PU prepolymer contents. Soybean oil-based PU/EP IPNs have better damping properties than that of the pure epoxy resin. The tensile strength and modulus of PU/EP IPNs decrease, while elongation at break increases with the increase of PU prepolymer contents. SEM observations reveal that phase separation appears in PU/EP IPNs with higher PU prepolymer contents.     

The Effect of Synthesis Method on Three-component IPNs Morphology and Property

Three-component IPNs were synthesized from polyurethane/poly (methyl acrylate aminoethyl methacrylate)/epoxy resin [PU/P(MADMA)/EP] by simultaneous synthesis interpenetrating polymer networks method(SINs) and sequential synthesis interpenetrating polymer networks method (STPNs). Comparing the effect of the two synthesis methods on the morphology and mechanical properties of three-component IPNs, it was found that the compatibility of three-component IPNs depends on the component ratios and interpenetrating formation , the different synthesis methods make the entanglement and interpenetrating between networks changed. The tensile strength of SIPNs is bigger than that of SINs, while the elongation at break of SINs is bigger than that of SIPNs. It is feasible to use stepwise staining method to observe the morphology change.     

Swelling Behavior of Semi‐Interpenetrating Polymer Network Hydrogels Based on Chitosan and Poly(acryl amide)

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of chitosan and polyacrylamide (PAAm) hydrogels have been prepared, and the effect of changing pH, temperature, ionic concentration, and applied electric fields on the swelling of the hydrogels was investigated. The swelling kinetics increased rapidly, reaching equilibrium within 60 min. The semi‐IPN hydrogels exhibited a relatively high swelling ratios of 385%–569% at T=25°C. The swelling ratio increased with decreasing pH below pH=7 due to the dissociation of ionic bonds. The swelling ratio of the semi‐IPN hydrogels was pH, ionic concentration, temperature, and electric field dependent. Differential scanning calorimetry (DSC) was used to determine the volume of free water in the semi‐IPN hydrogels, which was found to increase with increasing PAAm content.