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.     

Group contribution analysis of the damping behavior of homopolymers,statistical copolymers,and interpenetrating polymer networks based on acrylic,vinyl, and styrenic mers

The integral of loss modulus versus temperature plots in the vicinity of the glass transition temperature (loss area, LA) was characterized for various homopolymers, statistical copolymers, and interpenetrating polymer networks (IPNs), based on acrylics, vinyls, and styrenic mers. The quantity LA was found to be a molecular characteristic, governed by the structure of the individual mers. The LA of both IPNs and statistical copolymers obeys an additive relation of the component polymers. A group contribution analysis for LA was developed in which each moiety contributes a specific value to LA. A table derived via this group-contribution analysis permits the prediction of LA values. The results show that backbone motions and the moieties attached directly to the backbone contribute the most to the damping peak, and that long side chains act as diluents.     

Two-component interpenetrating polymer networks (IPNs) from polyurethanes and epoxies. II. Effect of different charge groups in polyurethanes and epoxies on properties and morphologies of two-component IPNs

Two-component interpenetrating polymer networks (IPNs) that contained charge groups in the backbones of the polyurethane and epoxy networks were studied. IPNs that contained opposite charge groups, similar charge groups, no charge groups, and corresponding pseudo-IPNs were prepared. A comparison of mechanical properties, water-resistance data, mechanical spectra, and electron microscopy showed that improved properties and morphologies resulted in IPNs that contained opposite charge groups. Presumably, interactions between the opposite charge groups in the constituent networks resulted in a forced compatibility between the two polymers which decreased the degree of phase separation.     

Interpenetrating polymer networks from polyurethanes and methacrylate polymers. II. Interpenetrating polymer networks with opposite charge groups

Interpenetrating polymer networks (IPNs) with opposite charge groups (tertiary amine and carboxyl groups) made from polyurethanes and methacrylate polymers have been synthesized and their properties and morphology, studied. With increasing carboxyl group concentration the mechanical properties and compatibility between the component networks were significantly improved, possibly because of the negative (or zero) free energy produced by the interaction contribution between the tertiary amine groups in the polyurethanes and the carboxyl groups in the methacrylate polymers determined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The improved molecular mixing in these IPNs was thought to be due to the influence of the opposite charge groups in these systems.     

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.     

Synthesis and Characterization of Polymeric Acid‐Doped Polyaniline Interpenetrating Polymer Networks

Polyaniline (PANI)/poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS) semi‐interpenetrating network polymers (semi‐IPNs) were prepared using the simultaneous method. The formation and properties of the interpenetrating PANI/PAMPS semi‐IPNs were investigated using Fourier transform infrared spectroscopy, X‐ray diffraction, solid‐state ¹³C‐NMR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The interaction of PAMPS with PANI as a polymeric acid dopant was also investigated. These semi‐IPNs had a different microstructure compared to that of pure PANI. Packing structures and several decomposition steps were ordered for each semi‐IPN, while pure PANI exhibits a single amorphous peak and one decomposition step. The NMR spectra show that these peaks broaden and shifted downfield in the semi‐IPNs. A thermal reaction between PANI and PAMPS was observed using DSC and TGA, and the data from the two techniques are in agreement.     

The Preparation of Ipns of Polystyrene-Polyethylene and Poly(Butyl Methacrylate)-Polyethylene and Their Dynamic Mechanical Behavior

IPNs based on polyethylene and vinyl polymers were prepared according to a new procedure. We studied the dynamic mechanical behavior of two series of IPNs: polystyrene (PS)-polyethylene (PE) and poly(butyl methacrylate) (PBMA)-PE at the frequency ω = 1 Hz and in the temperature region from ?50 to 200°C. Temperature dependences of the components of the dynamic modulus of elasticity G' and G" of the networks PS and PBMA have shapes typical of amorphous networks; the corresponding dependences of pure PE show, however, features typical of a semicrystalline polymer. IPNs of the system PS/PE show two-phase behavior. At T < 110°C, PE functions as a plasticizer. In the system PBMA/PE, better miscibility of components is seen, and PE exerts a reinforcing effect on the mechanical behavior over the whole temperature region. In both systems, network density increases with increasing PE content in IPNs. Better homogeneity and a slight increase in the network density of IPNs with PBMA/PE in comparison to PS/PE networks are probably caused by a greater number of grafted PBMA chains in the PE network compared to the PS network.     

Morphology and mechanical properties of styrene–butadiene–styrene/poly(methyl methacrylate–co-n-butyl acrylate) interpenetrating polymer networks

A series of interpenetrating polymer networks (IPNs) based on styrenic triblock copolymer, polystyrene-b-polybutadiene-b-polystyrene (SBS), and random copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA) were prepared. Corresponding semi-IPNs of the same composition without a crosslinking agent were also synthesized for comparison, and toluene was used as a common solvent to investigate the influence of the presence of the common solvent during the IPN synthesis. Throughout the compositions of IPNs tested, SBS appears to form a continuous phase and the domain size decreases gradually with the increase in SBS concentration. IPNs are found to have finer domain sizes than semi-IPNs because of the higher intermixing between polymers. The microstructure of SBS could be observed using highly magnified transmission electron microscopy (TEM). The dynamic mechanical behavior of the IPNs shows the inward shifting of two glass transition peaks, corresponding to polybutadiene phase of SBS and p(MMA–co-nBA) phase respectively, which indicates enhanced intermixing. The increase in loss tangent of styrene blocks of SBS by the addition of common solvent indicates the structural change of the microstructure in SBS, and this structural change can also be confirmed through the observation of the morphology of SBS-rich phase with higher magnification. © 1997 John Wiley & Sons, Ltd.     

各类多组分聚合物中的特殊相互作用

本文以作者实验室的新结果为主,评述了关于向各类多组分聚合物中引入特殊相互作用及其对相客性的影响以及该领域的发展趋势.所讨论的多组分聚合物包括简单共混物、嵌段共混物、互穿网络聚合物、共聚物和均聚物的共混物、离聚物的共混物以及无机粒子和聚合物的复合物等.     

Synthesis and characterization of biodegradable,amorphous, soft IPNs with shape‐memory effect

Star‐shaped oligo[(D ,L ‐lactide)‐co‐ε‐caprolactone]s (PCLA) with various number average molecular weights were synthesized via ring‐opening polymerization of D ,L ‐lactide (DLLA) and ε‐caprolactone (CL) with organic Sn as catalyst and pentaerythritol as an initiator. The elastic amorphous interpenetrating polymer networks (IPNs) of polyesterurethane/poly(ethylene glycol) dimethacrylate (PEGDMA) were synthesized in situ by UV‐photopolymerization of PEGDMA and thermal polymerization of PCLA with isophorone diisocyanate (IPDI). IPNs are transparent soft materials and the gel content of the IPNs is exceeding 87%. They are rubbery when PEGDMA content is above 10% at room temperature. IPNs show good shape‐memory properties. IPNs recover quickly its permanent form in 10 sec when the environment temperature is above its glass transition temperature (T_g). IPNs have only one single T_g between the T_g of PEGDMA and polyesterurethane. The strain recovery rate (R_r) and the strain fixity rate (R_f) are above 90%. No characteristic peaks of PEG crystallites in X‐ray diffraction pattern (XRD) demonstrate that they are amorphous polymer networks. The wettability, degradation rate, mechanical properties, and T_g of the IPNs could be conveniently adjusted by changing PEGDMA content in IPNs. The soft IPNs are promising suitable as potential soft substrates with tailored mechanical properties for potential clinical or medical use. Copyright © 2011 John Wiley & Sons, Ltd.     

A model of polyelectrolyte conductance in moist solvents as a basis of water sensors

The conductance of interpenetrated polymer networks (IPNs) containing quaternary amino groups was studied in cyclohexane, toluene, ethyl ether, ethyl acetate, and tetrahydrofurane as a function of water content by electrochemical impedance spectroscopy. IPNs were then used as sensitive materials to detect water traces in organic solvents with promising results for the construction of a moisture sensor. The detection onset for water concentration increased with the dielectric constant of the solvent. Different IPN-based sensors in the same solvent showed a detection limit at lower water concentration if their characteristic plot [conductance/relative humidity (RH%) in air] was shifted toward lower RH%. This suggests that the composition of this class of polymers can be tuned to achieve the best performance for each solvent.     

Specific Interactions in a Variety of Multicomponent Polymers

For a variety of multicomponent polymers including simple blends, block copolymers, IPNs, lonomer blends, homopolymer/block copolymer blends and composites composed of Inorganic particles and polymer matrix, the current situation and trend of introducing specific Interactions and its effect on the misclbility and properties of the systems have been reviewed with emphasis on the recent results obtained in the author' s laboratory.     

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.     

Study of the processes of epoxyallyl polymer formation of IPN type upon curing of oligomer-oligomer mixtures

The process of epoxyallyl polymer formation upon curing of oligomers, proceeding simultaneously in independent directions, was studied. A significant mutual influence of epoxy and allyl groups on the level of transformation was established.     

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.     

Regioselective nucleophilic ring-opening reaction of chiral epoxyallyl alcohols: a ready access to the pyran core of macrolactin 3

Herein we report the synthetic strategy towards the pyran core of macrolactin 3 via Sharpless epoxidation, titanium(IV) mediated regioselective ring-opening reaction of epoxyallyl alcohol/epoxy alcohol and oxa-Michael addition as the key steps.     

Temperature-pH Sensitive IPN Hydrogels Composed of Silk Sericin and Poly （N-isopropylacrylamide）

In recent years IPN hydrogels have been attracted attentions as biomedical materials1-3. Among which poly(N-isopropylacrylamide) (PNIPAAm) was frequently used to impart temperature responsive function4, 5. Many of the second components were introduced for…     

BaTiO3 / (PU/UP-IPNS)复合材料的相容性、力学性能和阻尼性能研究(英)

以水热法合成的BaTiO3纤维和同步法制备的互穿聚合物网络为原料，采用原位分散聚合法获得了一系列BaTiO3/(PU／UP-IPNs)复合材料。采用傅立叶交换红外分光光度计跟踪考察了IPNs的聚合过程，用透射电镜观测了IPNs及其复合物的形貌。结果表明，IPNs中两相相畴尺寸在纳米级范围内，在此基础上，实现了BaTiO3纤维状的复合。动态力学性能的检测结果表明，相较纯IPNs，复合材料的阻尼损耗模量和阻尼损耗因子值均有所提高，且在低温区均出现了肩峰。复合物的最大损耗因子值均大于0．4，在约50℃范围内，E’值提高100MPa。力学性能检测结果表明，IPNs中的连续相是决定材料力学性能的主要因素；有机／无机组分间混溶性的降低，使BaTiO3/IPNs复合材料的抗张强度和断裂伸长率均下降。     

ENHANCED WATER SORPTION OF A SEMI-INTERPENETRATING POLYMER NETWORK (IPN) OF POLY(2-HYDROXYETHYL METHACRYLATE) (PHEMA) AND POLY(ETHYLENE GLYCOL) (PEG)

ABSTRACT

An attempt was made to enhance the water-sorption capacity of polymers of 2-hydroxyethyl methacrylate (HEMA) by preparing its semi-interpenetrating polymer network (IPN) with a hydrophilic polymer such as poly(ethylene glycol) (PEG). The effects of various factors, such as history of the polymer sample, chemical architecture of the IPN, presence of salt ions in the swelling medium, and temperature of the swelling medium, were investigated on the water sorption kinetics of the IPNs. The IPN was characterized by IR spectral analysis and various structural parameters, such as molecular weight between crosslinks (M_c), crosslink density (q) and number of elastically effective chains (V_e), were evaluated. The IPNs were also assessed for their antithrombogenic potential.     

丁腈羟聚氨酯/聚甲基丙烯酸酯互穿网络聚合物的动态力学性能研究

采用同步法合成的丁腈羟聚氨酯/聚甲基丙烯酸酯类IPN样品,以TPA动态力学方法研究它的丙烯酸酯组份中,不同组份比,侧基结构和含量与动态力学性能的关系。结果指出,这些体系是半相容体系和相容体系。包含甲基丙烯酸正丁酯,异丁酯的IPN力学阻尼峰比甲基丙烯酸甲酸所具有的峰明显加宽。IPN中丙烯腈对体系的动态力学影响较大。