聚氨酯/环氧树脂互穿网络硬质泡沫塑料反应过程和微观结构

聚氨酯／环氧树脂互穿网络(PU／EPIPN)硬泡中异氰酸根的消耗速度较纯PU硬泡高，是由于环氧树脂的固化荆同时也是异氰酸根反应的催化荆。而PU／EP IPN硬泡中环氧基的反应速度和反应程度均较纯EP网络低，归因于互穿网络对基团扩散的阻碍。在互穿网络硬泡形成过程中，存在环氧开环中所新产生的羟基与异氰酸根的反应、大分子多元醇中羟基与环氧基的反应以及异氰酸根与环氧基形成嗯唑烷酮的反应三种形成网络间的化学键的途径。同时由于PU／EPIPN硬泡高度的交联，使得IPN硬泡中两个网络具有良好的相容性。动态力学性能表明所有IPN样品都只有一个玻璃化温度。透射电镜表明IPN样品无明显的相界面。     

二维互穿配位聚合物[Co3(2,6-nda)3(4,4''''-bpy)1.5]n的合成和晶体结构

在中温水热反应条件下,以CoCl2·6H2O、2,6-萘二羧酸(2,6-pda)和4,4'-bpy为原料,合成了一种二维互穿配位聚合物[Co3(2,6-nda)3(4,4'-bpy)1.5]n晶体,对其进行了元素分析、红外光谱表征、TGA-GTA分析和X射线单晶衍射测定.该配位聚合物属单斜晶系,C2/m空间群,晶胞参数为a=1.7285(11)nm,b=1.9965(13)nm,c=1.3994(9)nm,α=90°,β=95.822(11)°,γ=90°,V=4.804(5)nmm3,Z=4,dc=1.457g/cm3,μ=1.089mm-1,F(000)=2136,R1=0.0594,wR2=0.1605.结果显示形成一个二维互穿的网络结构.     

Poly(methyl acrylate)/poly(hydroxyethyl acrylate) sequential interpenetrating polymer networks. Miscibility and water sorption behavior

Sequential poly(methyl acrylate)/poly(hydroxyethyl acrylate) interpenetrating polymer networks with different poly(hydroxyethyl acrylate) contents were prepared by free radical polymerization of hydroxyethyl acrylate inside the previously polymerized poly(methyl acrylate) network. Differential scanning calorimetry on dry samples shows that the interpenetrating polymer networks exhibit phase separation, and no differences are found between the glass transition temperatures of the two phases present in the interpenetrating polymer network and those of the pure components. Thermally stimulated depolarization current experiments were used to study the influence of water sorption on the mobility of the different molecular groups in the poly(hydroxyethyl acrylate) phase of the interpenetrating polymer network. Isothermal water sorption of the interpenetrating polymer networks and pure poly(methyl acrylate) and poly(hydroxyethyl acrylate) networks is analyzed with different theories to compare the behavior of the poly(hydroxyethyl acrylate) phase in the interpenetrating polymer networks with that of the pure poly(hydroxyethyl acrylate) network. Diffusion coefficients of water in the interpenetrating polymer networks are obtained by means of dynamic sorption experiments. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1587–1599, 1999     

Multicomponent latex IPN materials. I. Morphology control

A series of novel structured latex particles with interpenetrating polymer network (IPN) cores and glassy SAN shells were developed in an attempt to investigate the feasibility of these polymers as both toughening and damping agents in thermoplastics. The IPN cores were composed of one impact part (polybutadiene based) and one damping part (acrylic based, with T_g around +10°C). The particle morphologies of these polymers were determined by TEM. The glass transitions and mechanical behavior of the polymers were characterized from DMS. The effect of different components on the final core/shell particle morphologies and mechanical properties was studied. The mechanical behavior of core/shell particles with IPN cores was also compared with that of separate core/shell and multilayered core/shell particles. In addition, normal core/shell synthesis (rubbery part first then the glassy part) and inverted core/shell synthesis (glassy part first then the rubbery part) were performed to provide another access for morphology control. It was found that the core/shell latex particles with poly(butyl acrylate) based copolymers are more miscible than poly(ethylhexyl methacrylate)-based copolymers. The high grafting efficiency of poly(butyl acrylate) plays an important role in governing phase miscibility. The latex particles synthesized by the inverted core/shell mode showed higher miscibility than the normal synthesized ones. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2193–2206, 1997     

Influence of the bulk and surface morphology on adhesion of polystyrene-inter-poly-cross-2-ethylhexyl-methacrylate films and particles

The adhesion behavior of semi-interpenetrating polymer networks (semi-IPNs) of linear polystyrene (PS) in crosslinked poly-2-ethylhexylmethacrylate (EHMA) was studied by variation of the bulk and surface morphology, i.e., domain size, continuity, and concentration in the domains. Semi-IPNs were prepared by liquid-liquid demixing upon cooling of a homogeneous solution of PS in methacrylate monomer, followed by gelation of the PS-rich phase and UV polymerization of the methacrylate resin. Welding of films allowed the preparation of larger objects provided that (1) the samples were phase separated to a high degree and contained domains with a high PS concentration (>90%) and (2) polystyrene was present at the interface. For semi-IPN films, a linear dependence of the adhesion strength on the (crack healing time)^1/4 was obtained. Based on these considerations, a process was developed to obtain melt-processable semi-IPN particles, by quenching droplets of the polymer solution into a cold liquid. These particles obtained a PS-rich skin layer and showed good adhesion after blending with a thermoplast. © 1996 John Wiley & Sons, Inc.     

Epoxy/SiO2 interpenetrating polymer networks

We demonstrate a potentially useful method of generating an SiO₂ morphology, in situ, with interpenetrating polymer networks (IPN) chemistry. Organic/inorganic IPNs were synthesized with an organic phase made of epoxy resin and an SiO₂ phase made by sol—gel chemistry. The two types of polymerization used were sequential and simultaneous with SiO₂ content ranging from 0.02 to 0.43 g SiO₂/g total weight. The resultant morphologies were examined by small angle X-ray scattering and transmission electron microscopy. The sequential IPNs were strongly phase separated into a finely divided SiO₂ phase of ∼10 nm size scale. The simultaneous IPNs were weakly phase separated with considerable mixing in the phases. Thermal studies showed increased thermal stability for the IPNs, compared with unfilled epoxies or physically mixed silica filled epoxies.     

聚丙烯酸酯－环氧树脂IPN乳液的合成

研究摩岩石刻保护材料聚丙烯酸酯-环氧树脂互穿聚合物网络乳液的合成,讨论影响凝聚率,乳液稳定性和乳液胶膜耐水性、吸水率的因素,得到最佳工艺条件。     

聚氨酯/乙烯基酯树脂互穿聚合物网络阻尼性能的研究

采用二步法制备了聚氨酯／乙烯基酯树脂互穿聚合物网络,动态力学分析法研究了ＩＰＮ的阻尼性能。结果表明,聚氨酯／乙烯基酯树脂互穿聚合物网络出现宽温度阻尼范围。当聚氨酯／乙烯基酯树脂＝４０／６０时,材料的宽温度范围的阻尼性能最好。在体系中引入柔性链可改善低温阻尼性能,而引入刚性链则降低阻尼值、提高阻尼温度、阻尼温度范围变窄。在体系中引入大侧基能显著提高聚氨酯／乙烯基酯树脂互穿聚合物网络的阻尼性能,提高交     

3D diamond‐containing nanocomposites based on hybrid polyurethane–poly(2‐hydroxyethyl methacrylate) semi‐IPNs: Composition‐nanostructure‐segmental dynamics‐elastic properties relationships

Nanostructure, glass transition dynamics and elastic properties were studied in the 3D nanodiamond‐containing composites based on polyurethane‐poly(2‐hydroxyethyl methacrylate) semi‐interpenetrating polymer networks (PU‐PHEMA semi‐IPNs), neat PU or PHEMA matrices. Nanodiamond (ND) content in the nanocomposites varied from 0.25 to 3 wt %. Combined differential scanning calorimetry/ laser‐interferometric creep rate spectroscopy/atomic force microscopy approach was utilized. A large impact of small 3D ND additives on PU‐PHEMA networks' dynamics and properties was revealed under conditions when an average inter‐particle distance L exceeds by far gyration radius R_g. The pronounced heterogeneity of glass transitions' dynamics and two opposite effects were observed. The main effect was a strong suppression of PHEMA glass transition dynamics at 90–180 °C, with the enhancement of creep resistance and threefold to sixfold increasing modulus of elasticity. The peculiarly crosslinked structure of nanocomposites, due to double covalent hybridization, resulted in low rheological percolation threshold, and a synergistic effect in dynamics was observed. Less pronounced effect of accelerating dynamics in the temperature region between β‐ and α‐transitions in PHEMA was associated with dynamics in domains with loosened molecular packing. The distinct physical limit for “anomalous” decreasing T_g is predicted in terms of the notion of the common segmental nature of α‐ and β‐relaxations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1696–1712, 2008     

Mechanism of adhesion of polyurethane/polymethacrylate simultaneous interpenetrating networks adhesives to polymer substrates

Polyether-based polyurethane/poly (methyl methacrylate-co-ethyleneglycol dimethacrylate) interpenetrating polymer networks [PU/P (MMA–co–EGDMA)-IPNs] were synthesized and used as adhesives to adhere vulcanized natural rubber (NR) and soft polyvinyl chloride (PVC). The structure and morphology of the IPN adhesives in bulk and near the adhesive/substrate interfaces were investigated. A new mechanism of adhesion called conjugate interpenetration of networks across interfaces, which is suitable for IPN adhesives and polymer substrates, was put forward. According to this mechanism, while forming simultaneous interpenetrating networks in the adhesive, the monomers in the IPN adhesive can permeate polymer substrates and polymerize in situ to form gradient IPNs, thereby producing conjugate three-component IPNs near the adhesive/substrate interfaces. It is the conjugate interpenetration of the networks across the interfaces that strengthens interfacial combination remarkably and results in high bond strength of IPN adhesives. © 1994 John Wiley & Sons, Inc.