Hydrophobicity Enhances the Formation of Protein-Stabilized Foams

Screening proteins for their potential use in foam applications is very laborious and time consuming. It would be beneficial if the foam properties could be predicted based on their molecular properties, but this is currently not possible. For protein-stabilized emulsions, a model was recently introduced to predict the emulsion properties from the protein molecular properties. Since the fundamental mechanisms for foam and emulsion formation are very similar, it is of interest to determine whether the link to molecular properties defined in that model is also applicable to foams. This study aims to link the exposed hydrophobicity with the foam ability and foam stability, using lysozyme variants with altered hydrophobicity, obtained from controlled heat treatment (77 °C for 0–120 min). To establish this link, the molecular characteristics, interfacial properties, and foam ability and stability (at different concentrations) were analysed. The increasing hydrophobicity resulted in an increased adsorption rate constant, and for concentrations in the protein-poor regime, the increasing hydrophobicity enhanced foam ability (i.e., interfacial area created). At higher relative exposed hydrophobicity (i.e., ~2–5 times higher than native lysozyme), the adsorption rate constant and foam ability became independent of hydrophobicity. The foam stability (i.e., foam collapse) was affected by the initial foam structure. In the protein-rich regime—with nearly identical foam structure—the hydrophobicity did not affect the foam stability. The link between exposed hydrophobicity and foam ability confirms the similarity between protein-stabilized foams and emulsions, and thereby indicates that the model proposed for emulsions can be used to predict foam properties in the future.     

pH-Responsive Aqueous Foams of Oleic Acid/Oleate Solution

Aqueous foams of oleic acid/oleate solution were found to be pH-responsive with pH changes. Detailed characterization of the aqueous foams of oleic acid/oleate solution was conducted with respect to their stability, structure, and pH response. The pH values required for foam circulation were studied through pH adjustment. The foaming and defoaming activities of oleic acid/oleate solution were explained by microscopic analysis and oil defoaming mechanisms. Because of the reversibility of oleic acid losing or receiving protons, the foaming and defoaming cycles could be readily repeated many times.      

Influence of Temperature,Concentration, and Gas/Liquid Ratios on the Gas-Mobility Reduction of Foams in Porous Media

The gas-mobility reduction capability of sodium dodecylbenzene sulfonate foams was studied in sandpacks as a function of temperature at different surfactant concentrations and gas/liquid ratios. Increasing the temperature decreased the gas mobility at a given surfactant concentration and gas/liquid ratio. At any given temperature, the gas-mobility reduction was not increased beyond a certain limit with increasing surfactant concentration. While increasing the gas/liquid ratio improved the gas-mobility reduction at 20°C, at higher temperatures the reduction capability decreased after reaching a maximum at a gas/liquid ratio of 9. All the foams became weak at temperatures of 150°C and higher.     

智能水基泡沫研究进展

作为典型的软物质,水基泡沫因具有较小的粒径、较大的比表面积和良好的流动性而广泛应用于洗涤剂、化妆品、食品工程、油气开采等领域。在实际应用中,泡沫的稳定性起着制约性作用。近年来,在环境因素刺激下,能在稳定和非稳定状态之间转变的可控智能泡沫引起了极大关注。针对近年来智能水基泡沫的研究进展,本文综述了基于温度、磁场、光、pH和CO₂响应等智能水基泡沫体系,讨论了不同类型的智能水基泡沫的形成机理及相应性能,展望了智能水基泡沫的应用前景和发展方向。     

Spectral Properties of Foams and Emulsions

The optical and spectral properties of foams and emulsions provide information about their micro-/nanostructures, chemical and time stability and molecular data of their components. Foams and emulsions are collections of different kinds of bubbles or drops with particular properties. A summary of various surfactant and emulsifier types is performed here, as well as an overview of methods for producing foams and emulsions. Absorption, reflectance, and vibrational spectroscopy (Fourier Transform Infrared spectroscopy-FTIR, Raman spectroscopy) studies are detailed in connection with the spectral characterization techniques of colloidal systems. Diffusing Wave Spectroscopy (DWS) data for foams and emulsions are likewise introduced. The utility of spectroscopic approaches has grown as processing power and analysis capabilities have improved. In addition, lasers offer advantages due to the specific properties of the emitted beams which allow focusing on very small volumes and enable accurate, fast, and high spatial resolution sample characterization. Emulsions and foams provide exceptional sensitive bases for measuring low concentrations of molecules down to the level of traces using spectroscopy techniques, thus opening new horizons in microfluidics.     

Determination of Halogenated Hydrocarbons in Insulating Polymeric Foams

A simultaneous thermal analysis/mass spectroscopy system was used for the determination of halogenated hydrocarbons in polymeric foam insulation materials. The investigation of ten different polymeric foams show that this equipment is a sensitive and reliable tool for the identification and determination of the bubbling agent. The results are compared with the Purge and Trap method. This revised version was published online in July 2006 with corrections to the Cover Date.     

水发泡淀粉挤出泡沫的结构与性能

以水为发泡剂,普通玉米淀粉为原料,采用双螺杆挤出机制备淀粉泡沫材料,研究了发泡剂用量及聚乙烯醇的加入量对泡沫材料结构与性能的影响。 用扫描电子显微镜观察了泡沫材料截面的形态,用万能材料试验机测试了泡沫材料的力学性能。 结果表明,水的质量分数为8%时淀粉泡沫径向膨胀率和发泡倍率最高,分别为22倍和17.6倍,压缩模量最高（4.07 MPa）。 加入质量分数10%的聚乙烯醇(PVA)使淀粉泡沫的孔径变大至1.29 mm,壁厚增加至82.43 μm,同时压缩模量增加至9.70 MPa。     

Environmentally Compatible Hybrid-Type Polyurethane Foams Containing Saccharide and Lignin Components

Semi-rigid polyurethane (PU) foams were prepared using lignin-molasses- poly(ethylene glycol) polyols. Two kinds of lignin, kraft lignin (KL) and sodium lignosulfonate (LS), were used. Both lignin and molasses polyols were mixed with various ratios and were reacted with poly(phenylene methylene) polyisocyanate (MDI) in the presence of silicone surfactant and di-n-butyltin dilaurate. A small amount of water was used as a foaming agent. The apparent density of PU foams increased with increasing lignin content. The compression strength and elastic modulus linearly increase with increasing apparent density, suggesting that mechanical properties are controllable by changing reaction conditions. The PU foams were amorphous and glass transition was detected by differential scanning calorimetry. The glass transition temperature (T_g ) maintained an almost constant value, regardless of the mixing ratio. This indicates that both the phenolic group of lignin and the glucopyranose ring of molasses act as rigid components in PU crosslinking network structures, and both groups contribute to the main chain motion to the same extent. By thermogravimetry (TG), it was confirmed that PU foams are thermally stable up to around 300 °C. By differential scanning calorimetry, T_g was observed at temperatures from 80 to 120 °C.     

PHMG化学键合改性抗菌聚氨酯软质泡沫的制备及性能

通过一步法模塑发泡工艺,将聚六亚甲基胍盐酸盐(PHMG)键合到聚氨酯(PU)分子链上,制备了抗菌聚氨酯软质泡沫。通过红外光谱表征抗菌聚氨酯的化学结构,并用紫外光谱测试聚氨酯中PHMG的键合率,同时测试了聚氨酯的泡孔结构、力学性能、抗菌性能和防霉性能。结果表明,当PHMG的质量分数为0.5%时,聚氨酯中PHMG的键合率达到76.0%,对大肠杆菌和金黄色葡萄球菌的抑菌率均超过99.5%,其防霉等级为0级。     

强度增强泡沫炭的制备、结构与性能

本文采用石油系中间相沥青为原料,通过发泡、炭化和石墨化制备了沥青基泡沫炭,用聚碳硅烷（PCS）浸渍-裂解（PIP）工艺增强泡沫炭的机械强度。采用扫描电子显微镜（SEM）分析其微观结构, X射线衍射（XRD）分析确认PCS的裂解产物为β-SiC。经过三次PIP工艺,压缩强度测试表明泡沫炭的压缩强度随PIP次数的增加而显著提高。     

Stabilization of Liquid Foams through the Synergistic Action of Particles and an Immiscible Liquid

Liquid foams are familiar from beer, frothed milk, or bubble baths; foams in general also play important roles in oil recovery, lightweight packaging, and insulation. Here a new class of foams is reported, obtained by frothing a suspension of colloidal particles in the presence of a small amount of an immiscible secondary liquid. A unique aspect of these foams, termed capillary foams, is the particle‐mediated spreading of the minority liquid around the gas bubbles. The resulting mixed particle/liquid coating can stabilize bubbles against coalescence even when the particles alone cannot. The coated bubbles are further immobilized by entrapment in a network of excess particles connected by bridges of the minority liquid. Capillary foams were prepared with a diverse set of particle/liquid combinations to demonstrate the generality of the phenomenon. The observed foam stability correlates with the particle affinity for the liquid interface formed by spreading the minority liquid at the bubble surface.     

Effect of Lipid Phase State and Foam Film Type on the Properties of DMPG Stabilized Foams

The drainage and stability of DMPG (l-α-phosphatidyl-dl-glycerol dimyristoyl) foams were studied by a microconductivity method under conditions where three different foam film types could be formed—thin foam films (TFF), common black foam films (CBF), and Newton black foam films (NBF). Foaming properties were investigated at 20 and 28°C where DMPG is in the gel and liquid-crystalline states. Higher conductivity signals were observed at the higher temperature where DMPG was in the liquid-crystalline state, which is indicative of wetter or more stable foams under these conditions. This effect was observed independent of foam film type. However, for a given phase state, the type of foam films formed significantly influenced the stability and rate of drainage of the foam. Indeed, the water content of the foams, obtained under conditions for formation of different foam films, is ranked in the order TFF > CBF > NBF. When the temperature was increased to 28°C (i.e., in the liquid-crystalline state), CBF and NBF showed a slight decrease in film thickness and an increase in film lifetime and surface molecular diffusion coefficient in the adsorbed layer. It is likely that the fluidity of the interfacial layer is an important factor contributing to DMPG foam stabilization.     

超低密度琼脂-明胶复合泡沫的研制

在探讨体系凝胶温度、冷冻速率、干燥温度及真空度等影响泡沫微观结构诸因素的基础上，确定出了琼脂－明胶复合泡沫制备工艺参数。以水作溶剂，成功地制得了密度≤1.0mg/cm^3,孔径≤100μm的琼脂－明胶泡沫；以水／1，4－二氧环己烷作混合溶剂，成功地制得了密度≤2mg/cm^3,孔径≤30μm的琼脂－明胶泡沫。热重－差热（TG－DSC）分析发现，琼脂－明胶复合泡沫的热稳定性可达－200℃。     

有机泡沫浸渍法制备多孔磷灰石-硅灰石(AW)生物活性玻璃陶瓷研究

0引言多孔磷灰石-硅灰石(apatite-wollastonite glass ceramic,AW-GC)生物活性玻璃陶瓷,具有良好的生物活性、骨透导性和一定的可降解性,近年在骨组织工程研究中倍受重视[1￣4]。理想的骨组织修复和支架材料应具备三维立体多孔结构,这种结构有利于细胞粘附增殖、细胞外基质沉积、营养和氧气进入及代谢产物排出,也有利于血管和神经长入[5]。     

以乙烯基酯树脂为多元醇制备聚氨酯硬质泡沫塑料的研究

研究了用乙烯基酯树脂（ＶＥＲ）直接代替通常的聚醚或聚酯型多元醇制备聚氨酯（ＰＵ）硬质泡沫塑料的可能性。实验结果表明,发泡配方中促进氨酯化反应的催化剂Ｎ,Ｎ－二甲基环己胺能与ＢＰＯ复合形成室温引发体系,加速ＶＢＲ的共聚合反应,影响了ＰＵ硬质泡沫塑料形成过程中的发泡与凝胶反应,导致泡了孔骨架基材的交联密度较低,泡孔结构不规整,并显示出较差的物理性能。以ＡＩＢＮ为引发剂时,反应初期主要进行氨酯化反应;仅     

反相乳液法氘代聚苯乙烯微孔泡沫的研制

采用反相乳液技术，以自制全氘代苯乙烯为聚合单体，二乙烯苯为交联剂，在探讨反相乳液法聚合反应机理，表面活性剂的作用机理及其用量对乳液稳定性的影响，有机相（O相）芳烃稀释剂及单体的聚集行为与作用机理等的基础上，成功地制得了密度为25－100mg/cm^3，蜂窝直径2－6um，微孔直径0．5－1．2um的氘代聚苯乙烯特种泡沫材料。     

Experimental Investigation on Flow Characteristics of Aqueous Foams through the Jet Device and Horizontal Pipe

Aqueous foam is regarded as a versatile medium in numerous scientific and engineering applications due to its high viscosity and low density. The objective of this study is to investigate the flow characteristics of aqueous foams through the jet device and horizontal pipe. The pressure distribution and foam production capacity are measured at different operating conditions. Experimental results show that the pressure fluctuations reduce significantly by increasing the foam liquid concentration, especially in the downstream of jet device. The bubble flow turns into homogeneous foams gradually when the concentration increases from 0.025% to 0.35%, while the foam behaviors take little change at a higher concentration, and the foamability reaches a limit. Subjected to the large pressure difference produced between the top and bottom of horizontal pipe, aqueous foams undergo a gas–liquid separation at a high terminal pressure, resulting in bubbles at the top and liquid at the bottom. Therefore, the terminal pressure should be kept less than a critical value to hold a good foam pattern. Based on the above contributions, it is believed that the study laid an important foundation for the widespread application of foam technology.     

Stability of Polymer and Surfactant Mixture Enhanced Foams in the Presence of Oil Under Static and Dynamic Conditions

Three different types of foaming agents including hydrocarbon surfactant TQ01, partial fluorinated surfactant BF01, and per-fluorinated surfactant QF01 exhibited good foaming ability and foam stability under 95°C high temperature and 32,325 ppm salinity conditions. The oil-tolerance ability order with respect to Malaysia Off-shore (MOS) crude oil for surfactant TQ01, BF01, and QF01 is TQ01 < BF01 < QF01. Introduction of polymer into the foam formula could significantly increase foam stability. Different polymers show different abilities of increasing foam stability. Spreading coefficient and entering coefficient are close to zero for surfactant BF01 foaming system and much less than zero for surfactant QF01 foaming system, so the oil-resistance ability of foam generated by surfactant QF01 is the strongest. For surfactant TQ01 foaming system, the calculated spreading coefficient and entering coefficient are greater than zero; therefore, the TQ01 foam system is more sensitive to MOS crude oil and its oil-resistance ability is the poorest. Core flooding test indicated that using the 0.4% BF01 and 0.2% YH1096 combined foaming formula could increase the pressure drop across the porous media significantly, indicating that strong foam was generated in the presence of MOS crude oil.     

Highly Stretchable Composite Foams via Sustainable Utilization of Waste Tire Rubbers for Temperature-Dependent Electromagnetic Wave Absorption

Recently, the sustainable utilization of waste resources has become a low-cost and effective strategy to design high-performance functional materials to solve the increasingly serious environmental pollution problem. Herein, the flexible and highly stretchable polyurethane (PU) composite foams assisted by one-dimensional carbon nanotubes (CNTs) and zero-dimensional Fe₃O₄ were fabricated using waste tire rubbers (WTRs) as reinforcements during a simple self-foaming process. The collaborative introduction of conductive CNTs, magnetic Fe₃O₄, and WTRs with three-dimensional cross-linked structures enabled the construction of an efficient electronic transmission path and heterointerfaces inside the composite foam. The resulting composite foam possessed a desired minimum reflection loss (RL_min) of −47.43 dB, and also exhibited superior mechanical properties with a tensile strength of >3 MPa and multiple tensile deformation recovery abilities. In addition, increasing the temperature could significantly improve the electromagnetic wave absorption performance of the composite foam. This comprehensive composite foam derived from WTRs has shown a promising development potential for using waste materials to relieve electromagnetic pollution.     

A Film Model of Sound Propagation in Gas–Liquid Foams: 2. The Sound Absorption

The concepts of the sound energy dissipation in gas–liquid foams are described within the framework of the film model of sound propagation. The high absorption of sound in foams is explained by hydrodynamic losses in foam films. The experimental dependence of the absorption coefficient on the foam expansion is explained. The calculated expansion corresponding to the absorption maximum is close to the experimental value.