The synthesis and morphology of semi-interpenetrating polymer networks based on polyurethane–polydimethylsiloxane system

A series of semi-interpenetrating polymer networks (semi-IPNs) based on polyurethane and polydimethylsiloxane were prepared. They are formed by crosslinking the polydimethylsiloxane prepolymer with 3-aminopropyltriethoxysilane in the presence of linear polyurethane. Investigations were carried out by swelling measurement, dynamic mechanical analysis, Fourier transform infrared experiments, and scanning electron microscopy. It is concluded that the crosslinking of the polydimethylsiloxane network is restricted by the presence of the polyurethane, and the grafting level between the two components is low. The system is phase separated, and there is dual phase continuity in the midrange composition.     

Formation and thermal stability of BMI-based interpenetrating polymers for gas separation membranes

Semi-interpenetrating polymer networks (semi-IPNs) were prepared by sol–gel technique through in situ polymerization of bismaleimide (BMI) in thermoplastic polyetherimide (PEI) as well as in polysulfone (PSF). This synthesis route allows arresting thermoset/thermoplastic phase separation at an early stage by solidifying the semi-IPNs through membrane phase inversion. The phase separation could be observed visually in the casting solution or by optical microscope on the surface of the produced membranes. These semi-IPNs with a density lower than their thermoplastic base polymer allowed easier water penetration during membrane phase inversion. This led to improved membrane morphology that was confirmed by scanning electron microscopy. Membranes fabricated from these semi-IPN materials had thinner skin layers and longer straight fingers perpendicular to membrane surface. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that these semi-IPNs membranes have improved glass transition temperatures but a lower thermal stability. However, at ambient conditions, these membranes with their improved structure and morphology showed superior gas separation characteristics compared to base polymers. For example, the permeance was increased by 12–15 times without a significant decrease in the selectivity of oxygen over nitrogen in air separation experiments.     

Effect of spatial constraints on phase separation during polymerization in sequential semi-interpenetrating polymer networks

The viscoelastic properties of sequential semi-interpenetrating polymer networks prepared via the swelling of network polyurethane in different monomers (butyl methacrylate, styrene) followed by their polymerization in the polyurethane matrix have been studied by means of dynamic mechanical analysis. It is found that the relaxation behavior of the test systems and the degree of segregation of the components depends on M _c of the polyurethane matrix because of a change in the molecular mass of the polymer block. The compatibility of the components in sequential semi-interpenetrating polymer networks substantially increases when the network inner space in the polyurethane matrix decreases.     

Effects of Confinement on the Kinetics of Formation of Sequential Semi-Interpenetrating Polymer Networks

Summary: Peculiarities of formation kinetics of sequential semi-interpenetrating polymer networks (semi-IPNs) based on crosslinked polyurethane (PU) with different cross-linking density and linear polystyrene (PS), polybutylmethacrylate (PBMA) and polymethacrylate acid (PMAA) have been studied. The experimental data show the dependence of the kinetic parameters of polymerization on M_c, this dependence being different for various monomers. Sharp discrepancy in molecular mass distribution of polymers formed in various matrices has been observed. The differences in dependencies of reaction kinetics and molecular mass distribution are supposed to be connected to various dependence of the chain growth and termination of various monomers on the density of network, i.e. on the confinements imposed by the intranetwork space.     

Synthesis, characterization and thermoreversible behaviours of poly(dimethyl siloxane)/poly(N-isopropyl acrylamide) semi-interpenetrating networks

Simultaneous and sequential poly(N-isopropyl acrylamide) (PNIPAAm)/poly(dimethyl siloxane) (PDMS) semi-interpenetrating polymer networks (IPNs) with different linear PDMS contents were prepared by free radical polymerization method. Their phase morphologies have been characterized by FTIR, DSC and SEM. The simultaneous semi-IPNs exhibited phase transition temperatures (T_pt) shifted higher temperature from glass transition temperatures (T_g) of their respective homopolymers, suggesting a heterophase morphology and only physical entanglement between the PNIPAAm network and linear PDMS with high molecular weight (Mn≈9000 g/mol). For sequential semi-IPNs, the shift of T_pts towards lower temperature suggested that the chemical interaction between the constituents of the IPNs increased with increasing PDMS content in the network. In addition, these semi-IPNs were characterized for their thermo-sensitive behaviour by equilibrium swelling studies. The results showed that incorporation of hydrophobic PDMS polymer into the thermo- and pH-sensitive PNIPAAm and P(NIPAAm-co-IA) (itaconic acid) hydrogels by semi-IPN formation decreased swelling degrees of IPNs without affecting their LCSTs whereas addition of acrylated PDMS (Tegomer V-Si 2250) as crosslinker instead of N,N^′-methylenebisacrylamide (BIS) into the structures of these hydrogels changed their LCSTs along with their swelling degrees.     

Kinetics of formation of a linear polymer-polymer network system in the presence of 3d metal chelates

For semi-interpenetrating polymer networks (semi-IPNs) based on an incompatible polyurethane network/linear polymethylmethacrylate pair formed in situ in the presence of 3d metal chelates, we have studied the effect of the system composition on the kinetics of formation of the components and the nature of complex formation between the metal compound and the polymer matrix. The ratio of the system components has been shown to have an effect on the selection of the macroligand in formation of complexes of the metal chelate with the polar groups of the semi-IPN, where the general character of the kinetic behavior for the formation of the network and the linear polymer is preserved. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 6, pp. 351–356, November–December, 2006.     

The transparency of polyurethane-poly(methyl methacrylate) interpenetrating and semi-interpenetrating polymer networks

Various combinations of polyurethane (PUR) and poly(methyl methacrylate) (PMMA) were prepared as interpenetrating polymer networks (IPN) or semi-IPNs. In the latter, either the PUR or the PMMA component was crosslinked. The optical transmissions of these materials were measured as a function of the crosslink degrees of both phases. The role of the PUR chain extender, poly(oxypropylene) glycol, is discussed. It is concluded that any means which increases the degree of phase dispersion favours the transparency of PUR/PMMA based IPNs and semi-IPNs.     

Porous molecularly imprinted polymer membranes and polymeric particles

Porous free-standing molecularly imprinted polymer membranes were synthesised by the method of in situ polymerisation using the principle of synthesis of interpenetrating polymer networks and tested in solid-phase extraction of triazine herbicides from aqueous solutions. Atrazine-specific MIP membranes were obtained by the UV-initiated co-polymerisation of methacrylic acid, tri(ethylene glycol) dimethacrylate, and oligourethane acrylate in the presence of a template (atrazine). Addition of oligourethane acrylate provided formation of the highly cross-linked MIP in a form of a free-standing 60 μm thick flexible membrane. High water fluxes through the MIP membranes were achieved due to addition of linear polymers (polyethylene glycol M_w 20,000 and polyurethane M_w 40,000) to the initial mixture of monomers before the polymerization. As a result, typical semi-interpenetrating polymer networks (semi-IPNs) have been formed, where the cross-linked polymer was represented by the atrazine-specific molecularly imprinted polymer, while the linear one was represented by polyethylene glycol/polyurethane. Extraction of the linear polymers from the fully formed semi-IPNs resulted in formation of large pores in the membrane structure. At the same time, extraction of the template molecules lead to formation of the sites in the polymeric network, which in shape and arrangement of functional groups are complementary to atrazine. Reference polymeric membranes were prepared from the same mixture of monomers but in the absence of the template. Recognition properties of the MIP membranes were estimated in solid-phase extraction by their ability to selective re-adsorbtion of atrazine from 10⁻⁸ to 10⁻⁴ M aqueous solutions. The imprinting effect was demonstrated for both types of the MIP membranes and the influence of the type of the linear compound on their recognition properties was estimated. The recognition properties of the MIP membranes were compared to those of the MIP particles of the same composition. Morphology of the MIP membranes was investigated using the SEM microscopy. High fluxes of the developed membranes together with high affinity and adsorption capability make them an attractive alternative to MIP particles in separation processes.     

Sequential semi-interpenetrating polymer networks based on polyurethane and polystyrene

The formation of microheterogeneous sequential semi-interpenetrating polymer networks based on network polyurethanes with different molecular masses of chain segments between crosslinks and a linear polystyrene has been studied by DSC and small-angle X-ray scattering. It has been shown that variation in the molecular mass of polymer segments between polyurethane network junctions affects the formation of the linear component of semi-interpenetrating polymer networks. As a result, the material structure may change in a wide range from a nearly single-phase system to a two-phase one. SAXS measurements indicate that there is a cymbate dependence between the degree of segregation of components of sequential semi-interpenetrating polymer networks and their microheterogeneous structure on the internetwork space. Two hierarchical heterogeneity levels are found to exist in polymer networks, and the features of each of these levels are analyzed.     

Effect of UV radiation on some polymeric networks based on vinyl ester resin and modified lignin

Some semi-interpenetrating polymer networks (semi-IPNs) based on vinyl ester resin (VER) and ammonium lignosulfonate (ALS) modified lignin were synthesized and characterized using Fourier transform-infrared (FT-IR) spectroscopy, optical microscopy (OM) and differential scanning calorimetry (DSC) techniques. VER was synthesized starting from an epoxy resin in reaction with acrylic acid. The cross-linking reaction was initiated by UV radiation. The synthesized networks showed good compatibility, due to some possible interactions between the functional groups from VER and ALS components (OH, especially). A slight effect of photostabilization of the VER was noticed, due to the ALS structures which were incorporated into the resin matrix.     

Polyurethane-polyacrylamide IPNs. I. Synthesis and characterization

Hydrophobic-hydrophilic interpenetrating polymer networks (IPNs) of polyurethane and polyacrylamide have been synthesized. The IPNs have been characterized by IR, thermal, and mechanical studies. SEM studies indicate phase mixing of some IPNs. Solvent resistance and surface hydrophilicity as evidenced by contact angle measurements suggest that these IPNs could be used for biomedical applications.     

Phase-mixed poly(ethylene glycol)/poly(trimethylolpropane triacrylate) semi-interpenetrating polymer networks obtained by rapid network formation

Semi-interpenetrating polymer networks (semi-IPNs) of poly(ethylene glycol) (PEG) in poly(trimethylolpropane triacrylate) (TMPTA) were synthesized from PEG melts in neat TMPTA monomer, using PEG of molecular weights from 4000 to 100,000 g/mol. Differential scanning calorimetry and transmission electron microscopy were used to examine phase separation occurring during network formation. The degree of phase separation was observed to depend upon the rate of PEG aggregation relative to the rate of network formation during TMPTA polymerization. Higher molecular weight PEG and acrylate-functionalized PEG formed more phase-mixed networks compared to lower molecular weight PEG; acetatefunctionalized PEG showed no difference from unmodified PEG in the extent of phase mixing. For networks that demonstrated phase separation, the PEG was observed to be in two states: some being phase mixed and solvent inextractable, and some being phase separated and solvent extractable. Phase-mixed networks could be obtained from this thermodynamically incompatible polymer pair utilizing rapid photopolymerization systems to overcome PEG phase aggregation and kinetically entrap the PEG in a nonequilibrium phase-mixed state. These mixed-phase semi-IPNs of PEG and TMPTA may be useful in biological applications where the presence of PEG is desired throughout the bulk matrix rather than as a surface graft to reduce biological interactions. © 1994 John Wiley & Sons, Inc.     

聚醋酸乙烯酯/聚丙烯酸甲酯互穿网络聚合物的研究 Ⅴ.互穿缠结对相区结构的稳定作用

用定量的甲苯溶胀聚醋酸乙烯酯/聚丙烯酸甲酯互穿网络聚合物(PVAc/PMA IPN),使体系处于分相的热力学条件;或醇解其中的PVAc 网络,即增加两组份的化学不相容性.动态力学谱和透射电镜等结果表明,IPN 和网络Ⅰ的交联密度较高的半 IPN 试样,没有发生进一步的相分离,证明网络互穿缠结是永久性的物理缠结,并且有强迫互容作用的存在.     

聚氨酯/丙烯酸酯类树脂互穿网络的结构形态与力学性能研究——网络间化学键的影响

通过示差扫描量热计、扫描电镜与广角Ｘ 光衍射仪研究了由碳化二亚胺改性二苯基甲烷二异氰酸酯合成的聚氨酯（ＰＵ）与丙烯酸酯类树脂（ＶＥＲ）形成的同步互穿网络（ＳＩＮ）的结构、形态与力学性能,发现网络间的化学键对其影响极大．网络间没有化学键连接的ＰＵ／ＶＥＲＳＩＮｓ是一个热力学不相容体系,存在显著的相分离形态,后者同时与两个网络的形成速率与工程因素有关;对于网络间有化学键连接的ＰＵ／ＶＥＲＳＩＮｓ,两个网络间存在一定的相容性与互穿程度,故较显著地提高ＳＩＮ的力学性能．     

Preparation and characterization of pavement materials with phase-change temperature modulation

A kind of pavement crack repairing material with temperature regulation property was successfully prepared through one-step method, in which the paraffin was incorporated into the polyurethane/epoxy resin-interpenetrating polymer networks. Differential scanning calorimeter results indicated that the phase-change latent heat of sample A was 14.4 kJ kg^?1, and the phase transition temperature was ??0.3 °C. FTIR and thermogravimetry measurements verified that the paraffin was successfully incorporated into the interpenetrating polymer network without leakage and reacted with the carrier, which exhibited high thermal stability above 300 °C. After 1 year of road test, there was no breakage for the repairing pavement with paraffin–polyurethane/epoxy resin-interpenetrating polymer networks, and there was almost no change for the accumulated attenuation of phase-change latent heat. Therefore, the materials of paraffin–polyurethane/epoxy resin-interpenetrating polymer networks have good chemical stability and thermal stability.

     

Synthesis,Characterization and Physicomechanical Properties of Novel Water-based Biodegradable Polyurethane Dispersion

Novel water-based biodegradable polyurethane dispersions with an aim to develop environmentally friendly materials, including medicine, various industries, have been prepared in this study. Biodegradable ionic polyurethanes (IPU) were synthesized based on polyols from renewable resources, such as castor oil (CO), in the presence of a polyester polyol and polyethylene glycol (PEG) with hydrophilic property and 1,6-hexamethylene diisocyanate. 1,4-Butanediol and dibutyltin dilaurate, were used as a chain extender and catalyst, respectively. The comprehensive investigations of the structure and properties of five types of synthesized polyurethanes demonstrated biodegradability relationship of these polyurethanes with their structure and composition. In this research effects of different types and content of polyols on biodegradability and physico mechanical properties of prepared PUDs were investigated. The structure, properties and physico mechanical and application behavior of mentioned materials were characterized by ¹H NMR, FTIR spectroscopy, thermogravimetric analysis (TG/DTG) and dynamic mechanical thermal analysis (DMTA). The adhesion properties were measured by pull off test as well. Particle size was measured by dynamic light scattering (DLS) methods. The biodegradability of prepared polyurethane dispersions was confirmed by water uptake, hydrolytic and enzymatic degradation in phosphate buffer saline (PBS) with lipase enzyme in PBS. Results showed that by the incorporation of natural components into the polymer chain, adjusting of hydrophilic and hydrolytic liability properties of soft segments and especial relevant designs, useful polyurethane can be synthesized with desirable property of biodegradability and dispersion stability. Except for one sample, other samples were decomposed totally in enzymatic media.     

Interpenetrating polymer networks based on polyurethane and polysiloxane

A series of interpenetrating polymer networks (IPNs), based on a polyurethane (PU) and polydimethylsiloxane, has been synthesized and characterized by means of DSC, TEM, TGA, 1H-NMR and IR spectroscopies, and other techniques. The homo-networks have been characterized by swelling in n-hexane and chloroform. The IPNs are obtained by combination of a PU based of the castor oil and 2,4-toluene diisocyanate (TDI) with different amounts of polydimethylsiloxane-α,ω-diol (PDMS). These materials have interesting individual physical properties, but some IPNs exhibited superior properties than either of the separate networks. For interesting results, it was used as compatibilizer the polydimethylsiloxane graft polyalkylene oxide. All the IPNs exhibited phase separation and maximum extent at the point of phase inversion.     

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.     

聚氨酯与接枝乙烯基酯树脂互穿网络研究: 自由基共聚 单体的影响

通过分子设计技术合成了两种侧链种类和长度可能控制的接枝乙烯基酯树脂(VER),并用它们与聚氨酯(PU)形成了同步互穿网络(SIN)。通过DSC,SEM,TEM,FTIR等考察了接枝VER的共聚单体对VERSIN的形态结构与力学性能的影响。研究结果表明,用甲基丙烯酸甲酯(MMA)为共聚单体的接枝VER网络中的MMA链段与PU网络中的硬段有较好的相容性,导致这类PU/接枝VERSIN中两个网络间的相容性和互穿程度好于由苯乙烯为共聚单体时合成4SIN。因此,在这两类共聚单体合成的SIN中,由MMA形成的接枝VER网络增强PU网络的效果更为显著。     

SYNTHESIS AND CHARACTERIZATION OF POLYDIMETHYLSILOXANE/POLYSTYRENE SEMIINTERPENETRATING POLYMER NETWORKS

The synthesis of pseudo- and semi-interpenetrating polymer networks (IPNs) based on poly-dimethylsiloxane (PDMS) and polystyrene (PS) is described. IPNs were obtained by simultaneous and in situsequential synthesis procedure. The preliminary studies on IPNs properties such as transition temperature,microphase separation and mechanical behaviors have been carried out by using differential scanningcalorimetry (DSC) and scanning electron microscopy (SEM). The experimental evidence clearly showed thatsemi-IPNs obtained by sequential synthesis procedure have higher interpenetrating extent than pseudo-IPNssynthesized by simultaneous procedure. Over the full composition, the PDMS/PS IPNs are immiscible. Thepseudo-IPNs microphase separation can be greatly subdued through the formation of grafting bonds betweentwo networks as well as the kinetic rate-matching of the individual network crosslinking.