Preparation Of Foams Research Articles

Influence of Reactive Amine-Based Catalysts on Cryogenic Properties of Rigid Polyurethane Foams for Space and On-Ground Applications.

Rigid polyurethane (PUR) foams have outstanding properties, and some of them are successfully used even today as cryogenic insulation. The fourth-generation blowing agent Solstice® LBA and commercial polyols were used for the production of a low-density cryogenic PUR foam composition. A lab-scale pouring method for PUR foam preparation and up-scaling of the processes using an industrial spraying machine are described in this article. For the determination of the foam properties at cryogenic temperature, original methods, devices, and appliances were used. The properties at room and cryogenic temperatures of the developed PUR foams using a low-toxicity, bismuth-based, and low-emission amine catalyst were compared with a reference foam with a conventional tin-based additive amine catalyst. It was found that the values of important cryogenic characteristics such as adhesion strength after cryoshock and the safety coefficient of the PUR foams formed with new reactive-type amine-based catalysts and with the blowing agent Solstice® LBA were higher than those of the foam with conventional catalysts.

Preparation and optimization of conductive PDMS composite foams with absorption-dominated electromagnetic interference shielding performance via silvered aramid microfibers

Electromagnetic interference (EMI) shielding materials with absorption-dominated EMI shielding mechanism can effectively annihilate electromagnetic waves (EMW) and avoid their repeated EMW pollution. However, it is difficult to achieve this goal for conductive polymer-based composites (CPC), because the interface impedance mismatch between air and CPC leads to massive reflection of EMW at the interface. Pores are beneficial to EMW penetrating into the interior of CPC and causing their multiple reflection, scattering and absorption in pores, thus endowing CPC with absorption-dominated EMI shielding characteristic. Herein, highly conductive silvered aramid microfibers (CAMF) were first synthesized via dopamine-assisted electroless deposition of silver coating on aramid microfibers (AMF), and then the conductive porous PDMS composite foams (PDMSF) with absorption-dominated EMI shielding characteristic were prepared and optimized via salt template method. As a result, PDMSF with 1.7 vol% silver content, the conductivity of PDMSF can reach 10-1 S/m, the EMI shielding efficiency (EMI SE) can reach 36.7 dB in X-band, and the average absorption ratio in EMI SE is 87%, while the density of PDMSF is only 0.28 g/cm3. The combination of lightweight, high EMI SE and absorption-dominated EMI shielding characteristic makes the porous PDMSF the latent EMI shielding materials in special constructions (e.g. military, confidential and nuclear facilities, etc.), aerospace, military equipments and transportation, etc.

Preparation and characterization of light weight aluminum matrix syntactic foams with high energy absorbing capacity

Aluminum matrix syntactic foams (AMSFs) with low density are widely utilized in the field of impact resistance owing to their high energy absorbing properties. In present study, to further lower the density and improve the energy absorption of AMSFs, a low-temperature micro-pressure infiltration was utilized to avoid destroying the hollow structure and a bi-continuous structure was designed to increase the energy absorbing interface and improve the deformation behavior. Results show that the hollow sphere content was up to 65% and a breakage rate was below 4% in the composites. Meanwhile, the composites displayed a rather low density of 1.23–1.41 g cm−3, a high compressive strength of 83.96–243.31 MPa, and an excellent energy absorbing capacity of 38.07–99.51 MJ m−3 under quasi-static loading, which outperforms the most advanced AMSFs as reported in the literatures. With the increase of strain rate, the composites showed higher plateau stress and energy absorbing capacity under dynamic loading. The energy was absorbed by shear deformation of cenospheres and interfacial tearing between cenospheres and aluminum matrix. A unique “fracture ring” was observed in bi-continuous structure preventing crack growth.

Enhanced hydrophobicity of shell-ligand-exchanged ZIF-8/melamine foam for excellent oil-water separation

Oil and organic solvent spills have caused serious environmental issues. To address these issues, several novel materials have been developed for the efficient separation of oil/organic solvents from water. In this study, ZIF-8 was loaded onto a melamine foam (MF) skeleton a simple in situ growth method. ZIF-8/MF was modified via a shell-ligand-exchange reaction (SLER) to improve its hydrophobicity. The prepared D-ZIF-8/MF exhibited strong hydrophobicity, with a WCA of 145.1° and an OCA of 0°. D-ZIF-8/MF can absorb up to 68–165 times its weight in oil/organic solvents. D-ZIF-8/MF also exhibited excellent stability, corrosion resistance, recovery, and recyclability. Furthermore, D-ZIF-8/MF has a high oil-water separation efficiency for absorbing organic solvents through a continuous oil-water separation device. This study provides a novel strategy for the preparation of strong hydrophobic foams via surface modification and SLER for oil-water separation. It has immense potential for the scale-up practical treatment of oily wastewater.

A novel strategy inspired by steaming Chinese steamed bread for preparation of tannin-furanic rigid bio-foam

Tannin-furanic rigid foam material has been receiving extensive attention due to its renewable, easy-preparation, lightweight, thermal insulation, and flame retardancy, that been considering a potential flame-retardants and thermally-insulating materials in construction field. The most fashionable approaches for tannin-furanic foam manufacturing, currently, are the self-blowing expansion with the aid of blowing agent with/without extra heating, and foaming via mechanical stirring in presence of non-environmentally friendly crosslinker. Herein, a novel and green strategy was proposed for tannin-furanic rigid foam preparation without blowing agent and additional crosslinker by steam-driven foaming. The performance of steam-driven tannin-furanic based foam (SDTF) was evaluated systematically and a possible foaming mechanism was suggested. The results indicated that a totally different surface but similar microstructure morphology of SDTF was developed, which displayed a larger cell size and thicker cell wall than standard tannin-furanic-formaldehyde foam (STF). A much lower pulverization ratio (approximately 4.6%) was reached for SDTF with respect to STF even though its compression strength was only less than half. An excellent thermal insulation performance was verified by the thermal conductivity of SDTF, only approximately 0.0286 W/m·K, which is considered ultra-low value that the STF cannot reach or seldom reach after STF modification or/and special structure design. The flame retardancy of SDTF was investigated by LOI and ignition experiment, which demonstrated a strong flame resistance and self-extinguishing nature, rendering it superior to STF. This preparation strategy provides a promising sustainable and environmentally friendly method for fabrication of green tannin-furanic foam for industry applications.

Preparation of Macroscopic Low-Density Gold Foams with Good Machinability

Uniform, macroscopic monoliths (ranging from a few millimeters to a centimeter) of low-density gold foams with ~95% porosity and ~10-μm-diameter pores were prepared by the casting of gold-coated polystyrene core-shell particles followed by the thermal removal of the polymer core. The Au foams were composed of unique hollow gold spheres and showed superior mechanical integrity and resilience compared to the foams we previously reported. Highly efficient seeding and electroless gold-plating methods in this study caused a significant morphological transition in the gold coatings from coarse particles to fine particles, and finally, to a continuous layer. A modified, scalable casting approach to form large uniform monoliths (up to ~1-cm diameter) and a gentle baking condition to minimize undesirable densification of the final foams enabled us to develop a simple, efficient synthetic route to nanostructured macroscopic low-density gold foams. To demonstrate the improved mechanical stability and machinability, a representative monolithic Au foam (~0.9 g/cm3) was carefully cut into the hollow cylinder of gold foams by a series of machining and processing steps. Finally, we tried to understand the unique mechanical behaviors and properties of this gold foam by nanoindentation measurement.

Rapidly synthesized, self-blowing, non-isocyanate polyurethane network foams with reprocessing to bulk networks via hydroxyurethane dynamic chemistry

Polyurethanes are produced from reactions of isocyanates with alcohols and are most commonly made as cross-linked networks to produce foams. Polyhydroxyurethanes (PHUs) are non-isocyanate polyurethane (NIPU) materials with promising potential as benign alternatives to isocyanate-based polyurethanes. We have developed a rheology-guided, rapid preparation of reprocessable self-blowing PHU foams by decoupling the aminolysis and thiol-decarboxylation of cyclic carbonates, allowing for dramatic reduction of reaction times from 20 h to 30 min to achieve foams without sacrificing morphological and physical properties. We studied the structure–property relationships in network PHU foams by systematically varying the thiol concentrations and demonstrated highly tunable morphological properties, including cell density, cell diameter, and open-cell ratio, and mechanical properties associated with semi-rigid and flexible foams. To address the sustainability challenges of network foams, the dynamic covalent PHU foams were melt-reprocessed into bulk films with full recovery of cross-link density. We further found that the relative modulus–relative density relationship of our foams obeys the cubic cell model proposed by Gibson and Ashby, which was applied to predict and tailor properties of new PHU foams. This study highlights the design and rapid synthesis of highly tunable and dynamic PHU foams with promising sustainability aspects.

High-expansion-ratio PLLA/PDLA/HNT composite foams with good thermally insulating property and enhanced compression performance via supercritical CO2

It has been a great challenge to prepare high-expansion-ratio polylactide (PLA) foam with eminent thermal insulation and compression performance in packaging field. Herein, a naturally formed nanofiller halloysite nanotube (HNT) and stereocomplex (SC) crystallites were introduced into PLA with a supercritical CO2 foaming method to improve foaming behavior and physical properties. The compressive performance and thermal insulation properties of the obtained poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA)/HNT composite foams were successfully investigated. At a HNT content of 1 wt%, the PLLA/PDLA/HNT blend foam with an expansion ratio of 36.7 folds showed a thermal conductivity as low as 30.60 mW/(m·K). Meanwhile, the compressive modulus of PLLA/PDLA/HNT foam was 115% higher than that of PLLA/PDLA foam without HNT. Moreover, the crystallinity of PLLA/PDLA/HNT foam was dramatically improved after annealing, thus the results showed that compressive modulus of the annealed foam increased by as high as 72%, while it still maintained good heat insulation with the thermal conductivity of 32.63 mW/(m·K). This work provides a green method for the preparation of biodegradable PLA foams with admirable heat resistance and mechanical performance.

From the perspective of cells as dispersed phase in foam injection molding: Cell deformation of PP/PTFE foams

The objective of the present work was to study deformation of cells of polypropylene/polytetrafluoroethylene (PP/PTFE) composite foams prepared via foam injection molding (FIM) with supercritical nitrogen (N2) as foaming agent. Different contents of N2 and various contents of PTFE were applied as variables to study the cell deformation in the flow direction. Scanning electronic microscope (SEM) was used to study the cell structure. It is found that the increase in both contents of N2 and PTFE were favourable for deformation of the cells. With the increase in both the contents of N2 and PTFE, the cell density increased, the cell size in short axis decreased, and the change in cell size in long axis depended on the cell structure being upon deformation or not. The deformation of the cells was signified by an abrupt increase of cell size in long axis and the ratio of cell size in long axis to short axis being larger than one. It is then found that the cell deformation in this study occurred unexpectedly with the increase in cell density. This is attributed to the fact that the increase in either N2 or PTFE content increases both the cell density and the tendency of cell deformation. This study has brought a new perspective to study the cell deformation in FIM via regarding cells as dispersed phase, and will provide experimental support for preparation of foams with oriented cells in the future.

Fast synthesis of crosslinked self-blowing poly(β-hydroxythioether) foams by decarboxylative-alkylation of thiols at room temperature

A novel strategy was developed to prepare a self-blowing poly(β-hydroxythioether) foam at room temperature by S-alkylation of 5-membered bis-cyclic carbonate using multifunctional thiol monomers. Two different thiol compounds, trimethylolpropane tris(3-mercaptopropionate) and pentaerythritol tetrakis(3-mercaptopropanoic acid) were used for the decarboxylative s-alkylation reaction. The thiol compounds simultaneously act as crosslinking agents and generate carbon dioxide during the decarboxylative s-alkylation reaction. This enables foam preparation without an external blowing agent. The use of tetrathiol monomer improves thermal stability, provides flexibility to the foams, and induces an increase in the glass transition temperature (Tg) due to a higher degree of cross-linking. The apparent density of the foams decreases with the increase of the tetrathiol ratio. This novel solvent-free approach paves the way to design sustainable foams with modular properties using accessible components and additives, as well as provides an alternative to non-isocyanate polyurethane foams.

Preparing low-Density microcellular polystyrene foam by in-Situ fibrillated PTFE and supramolecular nucleator TMC-300 in the presence of sc-CO2

A method using in-situ fibrillated polytetrafluoroethylene (PTFE) and octamethylenedicarboxylicdibenzoylhydrazide (TMC-300) supramolecular nucleator was presented to prepare low density polystyrene foams. This study used a torque rheometer in the molten compound preparation of PS/fibrillated-PTFE/TMC-300 composites. Scanning electron microscopy showed in-situ fibrillated polytetrafluoroethylene in Polystyrene melt and a nanofiber network with high aspect ratio. The formation of nanometer-sized fiber networks improved the melt viscoelasticity of matrices which promoted cell nucleation. As the results demonstrated, low-density foams with 11 μm average cell size were obtained using Polystyrene. The self-assembly nucleating agent TMC-300 was then introduced to the composite materials. TMC-300 and polytetrafluoroethylene as a composite cell nucleating agent were used in Polystyrene foams. Meanwhile, their nucleating efficiency was investigated. TMC-300 completed self-assembly in Polystyrene and served as composite nucleating agent in combination with polytetrafluoroethylene. Compared with the sample PS/PTFE-0.5, the average cell size of the sample PS/PTFE-0.5/TMC-2 had a reduction rate of 28.16% from 12.18 μm to 8.75 μm. The cell density increased by an order of magnitude. The composite nucleating agent was successful in controlling Polystyrene foam cell morphology, thus leading to the preparation of low-density Polystyrene microporous foams.

High-Strength Bio-Degradable Polymer Foams with Stable High Volume-Expansion Ratio Using Chain Extension and Green Supercritical Mixed-Gas Foaming.

The preparation of biodegradable polymer foams with a stable high volume-expansion ratio (VER) is challenging. For example, poly (butylene adipate-co-terephthalate) (PBAT) foams have a low melt strength and high shrinkage. In this study, polylactic acid (PLA), which has a high VER and crystallinity, was added to PBAT to reduce shrinkage during the supercritical molded-bead foaming process. The epoxy chain extender ADR4368 was used both as a chain extender and a compatibilizer to mitigate the linear chain structure and incompatibility and improve the foamability of PBAT. The branched-chain structure increased the energy-storage modulus (G') and complex viscosity (η*), which are the key factors for the growth of cells, by 1-2 orders of magnitude. Subsequently, we innovatively used the CO2 and N2 composite gas method. The foam-shrinkage performance was further inhibited; the final foam had a VER of 23.39 and a stable cell was obtained. Finally, after steam forming, the results showed that the mechanical strength of the PBAT/PLA blended composite foam was considerably improved by the addition of PLA. The compressive strength (50%), bending strength, and fracture load by bending reached 270.23 kPa, 0.36 MPa, and 23.32 N, respectively. This study provides a potential strategy for the development of PBAT-based foam packaging materials with stable cell structure, high VER, and excellent mechanical strength.

Green Processing of Neat Poly(lactic acid) Using Carbon Dioxide under Elevated Pressure for Preparation of Advanced Materials: A Review (2012-2022).

This review provides a concise overview of up-to-date developments in the processing of neat poly(lactic acid) (PLA), improvement in its properties, and preparation of advanced materials using a green medium (CO2 under elevated pressure). Pressurized CO2 in the dense and supercritical state is a superior alternative medium to organic solvents, as it is easily available, fully recyclable, has easily tunable properties, and can be completely removed from the final material without post-processing steps. This review summarizes the state of the art on PLA drying, impregnation, foaming, and particle generation by the employment of dense and supercritical CO2 for the development of new materials. An analysis of the effect of processing methods on the final material properties was focused on neat PLA and PLA with an addition of natural bioactive components. It was demonstrated that CO2-assisted processes enable the control of PLA properties, reduce operating times, and require less energy compared to conventional ones. The described environmentally friendly processing techniques and the versatility of PLA were employed for the preparation of foams, aerogels, scaffolds, microparticles, and nanoparticles, as well as bioactive materials. These PLA-based materials can find application in tissue engineering, drug delivery, active food packaging, compostable packaging, wastewater treatment, or thermal insulation, among others.

Flame Retardant Combinations with Expandable Graphite/Phosphorus/CuO/Castor Oil in Flexible Polyurethane Foams

A series of flexible polyurethane foams (FPUFs) were prepared with single and different combinations of flame retardants and additives. Expandable graphite (EG), phosphorous polyol (OP), copper (II) oxide (CuO), and/or castor oil (CAS) were added to FPUF during the foam preparation in a one-step process. The purpose of the study is to evaluate the synergistic effects of the flame retardants, additives, and the presence of bio-based content on the mechanical properties, flame retardancy, and smoke behavior of FPUFs. The combination of 10 wt % EG and 5 wt % OP in FPUF significantly improves the char yield. In the cone calorimeter experiment, the char yield is nearly three times higher than that with 10 wt % EG alone. The smoke behavior is additionally evaluated in a smoke density chamber (SDC). Comparing the samples with a single flame retardant, 10 wt % EG in FPUF considerably reduces the amount of smoke released and the emission of toxic gases. Replacing the amount of 10 wt % polyether polyol in FPUF with CAS maintains the physical and mechanical properties and fire behavior and enhances the bio-based content. The presence of 0.1 wt % CuO in FPUF effectively reduces the emission of hydrogen cyanide. As a result, this study proposes a multicomponent flame retardant strategy for FPUF to enhance the biomass content and address the weaknesses in flame retardancy, smoke, and toxic gas emissions. A starting point is disclosed for future product development.

Preparation of Hexagonal Boron Nitride-Containing Foam with Improved Thermal Conductivity of Epoxy Resins

With the continuous development of electrical and electronic devices, the thermal conductivity of dielectric polymer composites within devices is becoming increasingly important. However, improving the thermal conductivity usually requires the incorporation of a large amount of filler in polymer material, which undoubtedly increases the production cost while destroying the processability and the dielectric properties of the material. In this work, an efficient heat transfer network was constructed inside the resin matrix to overcome this drawback. Using the opposite surface potentials of hexagonal boron nitride (h-BN) and polyethyleneimine (PEI) in solvent, h-BN was anchored on the surface of melamine foam (MF) by an electrostatic self-assembly technique to construct a thermal conductive skeleton with a three-dimensional open pore structure, and the corresponding epoxy (EP) composite was prepared by vacuum-assisted impregnation. This EP–MF@BN composite showed a significant increase in the heat arrival rate at an extremely low filler loading. At a h-BN loading of 2.1 wt %, the thermal conductivity of the composite reached 0.433 W/(m·K), which was 147% higher than that of the pure resin matrix. This is mainly attributed to the unique three-dimensional open-hole structure of the MF foam, which formed a three-dimensional frame structure with extremely low thermal resistance after anchoring by h-BN, thus providing a great degree of weakening of the scattering behavior during phonon transport. In addition, the transport behavior of carriers inside the composite under strong electric field conditions was analyzed in the current study. This strategy of constructing an efficient heat transfer network inside the polymer matrix provides an idea and method for the preparation of composites in the field of electrical insulation.

Upcycling of waste epoxy thermosets to robust polyurethane foams via an in situ degradation-foaming process

High-efficiency and energy-saving conversion of epoxy thermosets into "three-high" (high value, high quality and high performance) products is highly desired from the viewpoints of both environmental protection and resource utilization. Here, we demonstrate a new strategy for mild degradation of epoxy thermosets and in situ preparation of polyurethane foam from degradation solutions. The degradation solution contains the unreacted solvent polyethylene glycol and polyol degradation products after alcoholysis, both of which can react with isocyanate to produce polyurethane. The use of an insoluble catalyst makes it possible to achieve in-situ foaming of the degradation solution, which realizes the direct and full utilization of degradation products. Owing to the rigid epoxy skeleton of the degradation products, the obtained rigid polyurethane foam exhibited high mechanical properties (∼170kPa), good thermal insulation performance (33–35 mW•m−1•K−1), low water absorption (3–5%), regular pore structure and good thermal stability, thus can be a good candidate for building insulation materials.

Safety and Effects of a Commercial Ozone Foam Preparation on Endometrial Environment and Fertility of Mares.

Mares' subfertility represents a complex diagnostic and therapeutic challenge and both clinical and subclinical endometritis are considered major causes of impaired fertility. Thanks to its properties, ozone has a big potential as a treatment for equine endometritis. Therefore, the aim of this study is to describe the safety and the effects on endometrium and reproductive parameters of mares of a commercial ozone foam preparation (Riger Spray®). Twenty-four mares were treated during estrus: ozone group with an intrauterine instillation of ozone foam preparation (OG, n=16) and control group with 20 ml of lactated Ringer's solution (CG, n=8). Samples for endometrial cytology were collected before the ozone treatment (T0), after 24 h (T1), after one week (T2), two weeks (T3), and when the subsequent estrous phase was detected (T4). Furthermore, samples for histological examination and uterine swab for bacteriological examination were collected at T0 and T4. At T1, a statistically significant increase of endometrial inflammation in the OG mares compared to T0 (P<.05) and to CG at same time point (P<.05) was observed, but it was already resolved at T2. No differences in endometrial inflammation in CG, biopsy grade before and after the treatment in the two groups, number of mares pregnant at the end of the season and number of mares pregnant at the first cycle were observed. However, the number of inseminations required for pregnancy tended to be lower (P=.0711) in the OG (1.69±0.06) than in CG mares (2.60±0.89).

Formulasi Dan Uji Aktivitas Antibakteri Facial Foam Minyak Biji Jintan Hitam (Nigella Sativa Oil)

Acne is a disease that most people suffer especially among adolescent, one of the causes of acne is usually caused by the growth of acne-causing bacteria that is Staphylococcus epidermidis. One of the ingredients that can be used as an antibacterial product is black cumin seed oil (Nigella sativa oil), it is known that black cumin seed oil contains Thymoquinone and α-pinen which are efficacious as antibacterial. This research aims to produce a cosmetic preparation in the form of a face wash that effectively cleans the skin from dust and dirt from makeup, as well as preparations that have antibacterial activity against Staphylococcus epidermidis by using the well diffusion method. Black cumin seed oil is formulated into facial foam in several concentrations, namely 3% (FI), 5% (FII) and 7% (FIII). Evaluation of fa cial foam preparations includes examination of organoleptic, pH, foam power, skin irritation, homogeneity, wetting power, alcohol insoluble portion, freeze and thaw, examination of mineral oil, washability and antibacterial activity. Data analysis using One Way ANOVA statistical test and descriptive. The result showed that the physical stability test, the three facial foam formulas have good physical stability and meet the pH requirements of topical cosmetic preparation. In the antibacterial activity test, it was found that the facial foam preparation of black cumin seed oil give inhibition of 15.37 mm (FI), 16.52 mm (FII) and 17.25 mm (FIII). Based on the one way ANOVA statistical data, the p value &lt;0,05 which means that three is a significant difference in inhibition diameter between FI, FII and FIII which negative control and positive control. It is concluded that the facial foam preparations of black cumin seed oil was physically stable and based on antibacterial activity tests, it is known that FIII has the most bacterial resistance of 17.25 mm with medium resistance category.

Chemical Recycling of Polyurethane Waste via a Microwave-Assisted Glycolysis Process.

In this work, we explored a microwave-assisted glycolysis process to chemically recycle rigid polyurethane (PU) foam waste to obtain a single-phase product with suitable physio-chemical properties as a secondary raw material for the preparation of new rigid PU products. Such an approach was compared to a conventionally heated (ConvH) process, analyzing the performances of different catalysts. The use of microwaves allowed a 94% decrease in the reaction time scale of rigid PU depolymerization, with a concurrent 45% reduction in energy expense. By using a PU/diethylene glycol mass ratio of 1.5, best performances were obtained with a 30 mmol/100gPU potassium acetate concentration, both in terms of the product viscosity and aromatic amine byproduct content. The glycolysis products recovered were employed in substitution to virgin polyol for rigid PU foam preparation, showing improved compressive strength and comparable thermal insulation properties up to a 30% content with respect to the traditional non-recycled counterpart.

PH-responsive, salt-resistant, and highly stable foam based on a silicone-containing dynamic imine surfactant

The preparation of a responsive foam, which can be destroyed on-demand and re-formed in a short time upon the imposition of an external environmental stimulus, using a dynamic imine surfactant (DIS) alone, remains a major challenge due to the presence of unreacted oil-soluble precursor. We report herein the design and synthesis of a novel silicone-containing DIS based on commercial 1,3-bis(3-aminopropyl)tetramethyldisiloxane, BAPTS, as an amino-containing precursor, and 3-(4-formylphenoxy)-N,N,N-trimethylpropan-1-aminium, as an aldehyde-containing precursor. 1H NMR spectrometry and FT-IR spectroscopy have been employed to confirm the formation of dynamic covalent bonds and to calculate the conversion of aldehyde to imine. Surface activity and foam properties have been systematically investigated. The results demonstrated that a traditional one-head-one-tail silicone-containing DIS was firstly formed at pH > 7.0 and then transformed into Bola-type DIS at pH > 9.0. Due to the low surface tension resulting from the introduction of silicone group and complete consumption of BAPTS at pH > 9.0, the as-prepared DIS surfactant showed excellent foam performance. Indeed, the foam could be reversibly switched on and off by alternately changing the pH, irrespective of the electrolyte concentration. The foaming performance was only minimally influenced by different electrolytes (NaCl, CaCl2, and MgSO4), but foam stability was sensitive to these electrolytes. Despite the foam becoming highly unstable at low electrolyte concentration (t1/2 < 0.5 min), its stability was significantly enhanced at high electrolyte concentration (t1/2 = 0.5–20 h) due to a microstructure transition from low viscosity spherical micelles to high viscosity rodlike micelles. Such a system may potentially be applied in mineral floatation or foam flood in oil production.