EO Units Research Articles

C–S–H–PCE nanocomposites as hydration accelerator in calcined clay-limestone-blended low carbon cement

Abstract Recently, providing admixtures to improve the performance of the novel low-carbon-blended cement is needed to meet the requirement for environmentally friendly cements. In this study, calcium-silicate-hydrate (C–S–H) nanocomposites which are known as hydration accelerator for Portland cement were employed in such low-carbon cements. The investigation focused on the effect of polycarboxylate ether (PCE) possessing different side-chain lengths on the morphology of C–S–H nanocomposites synthesized from sodium silicate and calcium nitrate via chemical co-precipitation and on their performance (especially early strength enhancement) when applied in a calcined clay-blended cement (OPC substitution rate of 46 wt%). As observed by TEM, addition of PCE effectively controls the size of the C–S–H nanoparticles and delays the transition from C–S–H globules to foils. PCEs with short side-chain (23 EO units) exhibited the highest inhibition effect on the growth of the C–S–H nuclei, which was confirmed by particle size measurements. Additionally, incorporating such C–S–H–PCE nanocomposites into the calcined clay-blended cement (dosage 2.0 % by weight of cement) significantly improved fluidity of the cement pastes. Regarding compressive strength, pristine C–S–H produced only a minor improvement, whereas C–S–H–PCE nanocomposites yielded substantial enhancement, especially after 16 h and 1 day of curing. Remarkably, C–S–H–23PCE pronounced the strongest seeding and strength enhancing effect, owed to its particularly small particle size (d = 21.8 ± 0.3 nm). It also significantly accelerated the hydration of the silicate phases (C3S and C2S) in this blended cement, as was evidenced by isothermal heat flow calorimetry and XRD measurements.

In Situ Efficient End Functionalization of Polyisoprene by Epoxide Compounds via Neodymium-Mediated Coordinative Chain Transfer Polymerization.

The Nd-mediated coordinative chain transfer polymerization (CCTP) of dienes represents one of the state-of-the-art techniques in the current synthetic rubber field. Besides having well-controlled polymerization behaviors as well as high atom economies, it also allows for the generation of highly reactive Al-capped polydienyl chain-ends, which hold great potential, yet much less explored up to date, in achieving end functionalization to mimic the structure of natural rubber. In this study, we demonstrate an efficient in situ method to realize end-functionalizing polyisoprene by introducing epoxide compounds into a CCTP system. The end functionalization efficiency was 92.7%, and the obtained polymers were systematically characterized by 1H NMR, 1H,1H-COSY NMR, DOSY NMR, and MALDI TOF. NMR studies revealed that a maximum of two EO units were introduced to the chain ends, and based on density functional theory (DFT) studies, an energy barrier of 33.3 kcal/mol was required to be overcome to open the ring of the EO monomer. Increasing the ratio of [Ip]/[Nd] resulted in gradually increased viscosities for the reaction medium and therefore gave rise to an end functionalization efficiency that decreased from 92.7% to 74.2%. The end hydroxyl group can also be readily converted to other functionalities, as confirmed by NMR spectroscopy.

POSS based poly (zwitterionic liquids) electrolytes with 3D crosslinked networks for lithium metal batteries

Polymer electrolyte is a potential candidate for the next-generation lithium metal batteries. However, its low room temperature ionic conductivity limited its practical application. Here, a novel POSS-based poly (zwitterionic liquids) organic–inorganic hybrid electrolyte with 3D crosslinked networks was proposed for enabling lithium-ion fast transport by photoinitiated radical polymerization of vinyl zwitterionic monomers and acrylate monomers containing rich EO units and POSS. The synergistic effect of unique structures of 3D organic–inorganic hybrids gel electrolytes such as zwitterionic, rich EO segments and POSS cages facilitate Li+ conduction, resulting in high room temperature ionic conductivity (1.03 × 10-3 S cm-1) and a satisfactory Li+ transference number (0.45). The lithium-symmetric batteries assembled with the novel POSS-based poly (zwitterionic liquids) gel hybrid electrolytes can operate continuously at 0.1 mA cm-2 for 2300 h without any obvious short circuit, indicating good interfacial compatibility between the electrolytes and lithium electrodes. The Li/LiFePO4 batteries assembled with the novel POSS-based poly (zwitterionic liquids) gel hybrid electrolytes exhibit long-term stability.

Retrospective Analysis of Polyethylene Oxide and Polypropylene Oxide Block Copolymers Production and Industrial Applications (Review)

Introduction. Nowadays block copolymers of PEO and PPO (poloxamers, pluronics, proxanols) are among the most popular polymers in the pharmaceutical and biotechnological industries. They can be applied as effective nonionic surfactants, biological membrane stabilizers, elements of targeted delivery systems, solubilizers, as well as excipients in the technology of traditional dosage forms – gelling agents, lubricants, etc. For the past fifty years, the world's largest manufacturer of poloxamers has been the German chemical concern BASF. However, today in the Russian Federation there is a risk of defects, which defines the relevance of import substitution of this excipient.Text. The purpose of this review is to highlight the experience of production and implementation of PEO and PPO block copolymers into novel Russian scientists’ developments, comparing them with the experience of foreign research groups, which is necessary to assess the potential for import substitution. PEO and PPO block copolymers have been known in the Soviet Union since the late 60s as far as they are mentioned in textbooks of 1964 and 1973. Domestic block copolymers of PEO and PPO have been used in the oil refining industry, as well as in some branches of light industry and in the decontamination of radioactive waste. The unique domestic synthesis of PEO and PPO block copolymers was established in 1978 on the basis of the "Orgsintez" factory. Soviet poloxamers were produced under the brand name "proxanol" in a wide range of ratios of EO and PO units and molecular weights. It should be noted that today in the Russian Federation, industrial batches of the solubilizer Emuxol 268, which is close in its properties to the well-known poloxamer 188, are still produced, and block copolymers with other ratios of EO and PO units are synthesized to order.Conclusion. According to the retrospective analysis, the modern Russian industry has enough experience and resources to establish the synthesis of PEO and PPO block copolymers necessary to produce drugs and to develop innovative delivery systems and drugs. Based on the materials of the systematic review, the most complete register of known brands of PEO and PPO block copolymers synthesized over the past 50 years in our country and in the world was compiled for the first time, with a detailed description of their physicochemical properties.

Polymer electrolytes comprising oligomeric lithium borate salts and poly(ethylene oxide)

Polymer electrolytes comprising lithium borate salts and high molecular weight poly(ethylene oxide) PEO are prepared by casting from solution. The branched structure of borate salts, obtained in a two-step synthesis process, includes three oligomeric oxyethylene segments of various lengths n and a butyl group. The weight proportions of polymer and oligomeric salts are chosen so that they represent certain molar proportions of EO units (coming both from anion and from polymer matrix) to lithium: 50:1, 32:1, 16:1, and 10:1. Samples of the electrolytes are investigated by differential scanning calorimetry (DSC) and impedance spectroscopy in a wide range of temperature. For each electrolyte, characteristic parameters such as glass transition temperature Tg are calculated. It is found, that some systems – for example, electrolytes composed of borate salt with average length n = 7.5 and molar ratio EO:Li of 32:1 and 50:1 exhibit values of the glass transition temperature lower than the values obtained for pure PEO and pure borate salt, which is also reflected in characteristic frequency of the dielectric relaxations related to segmental chain motion. The low Tg partially compensates decrease in conductivity caused by crystallization. Interestingly, mixed PEO-borate salt systems also exhibit transference numbers higher than those of pure borate salt.

Enhanced Copolymer Characterization for Polyethers Using Gel Permeation Chromatography Combined with Artificial Neural Networks.

Gel permeation chromatography (GPC) is a generally applied method for the mass analysis of various polymers and copolymers, but it inherently fails to provide additional important information such as the composition of copolymers. However, we will show that GPC measurements using different solvents can yield not just the correct molecular weight but the composition of the copolymer. Accordingly, artificial neural networks (ANNs) have been developed to process the data of GPC measurements and determine the molecular weight and the chemical composition of the copolymers. The target values of the ANNs were obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and nuclear magnetic resonance (NMR) spectroscopy. Our GPC-ANN method is demonstrated by the analysis of various poloxamers, i.e., poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO) block copolymers. Two ANNs were constructed. The first one (ANN_1) works in a wider mass range (from 900 to 12,500 dalton), while the second one (ANN_2) produces more output values. ANN_2 can thus predict seven characteristic copolymer parameters, namely, two average molecular weights, the average weight fraction of the EO unit, and four average numbers of the repeat units. The correlation between the experimentally obtained outputs and the predicted ones is high (r > 0.98). The accuracy of the ANNs is very convincing, and both ANNs predict the number-average molecular weight (Mn) with an accuracy below 5%. Furthermore, this work is the first step for creating an open database and applications extending the use of the GPC-ANN method for the analysis of copolymers.

Effect of oxyethylene and oxypropylene groups on the interfacial structure and property of extended surfactants: Molecular simulation and experimental study

Extended surfactants including oxyethylene (EO) and oxypropylene (PO) groups have great potential applications in the fields of oil recovery, separation and extraction, fabric washing, medicine and cosmetics vehicles. In this work, the interfacial structure and dynamic property of six alkyl polyoxypropylene polyoxyethylene ether carboxylates (C12POmEOnC, m = 5 and 15, n = 5, 10 and 15) at the water/oil interface were investigated with interfacial tension (IFT) experiments and molecular dynamics (MD) simulations. C12PO15EO5C was found to reduce the experimental IFT value to the order of 10-3 mN/m. Further, the interfacial thickness, stretch degree, hydrogen bond number and radial distribution function were calculated and analyzed in detailed simulations. The simulation results demonstrated that long PO chain curled in a helical shape to wrap hydrophilic oxygen atoms in the oil phase and reached a compact arrangement on the interface but short PO chain could not; long EO chain partially laid flat on the interface (about 5 EO units) and partially extended into the aqueous phase bringing the hydrophilic oxygen atoms close to water molecules while forming vacancies on the water side. Therefore, C12PO15EO5C had the tightest interfacial arrangement. Theoretical and experimental results are in fairly good agreement and they will provide enlightening insights into the design and synthesis of more effective extended surfactants.

General adsorption isotherm for polyoxyethylene alkyl ethers CnEOm adsorbed at the water/air surface

An empirical adsorption isotherm model is presented based on fundamental thermodynamic equations of adsorption for the homologous series of the nonionic surfactants polyoxyethylene alkyl ethers (CnEOm) at the aqueous solution surface to determine the surface tension and surface pressure isotherms, surface equation of state, and molar characteristics for the adsorbed surfactant molecules. The new model describes the surface properties of CnEOm much better than the original Langmuir adsorption model used as thermodynamic basis. The analysis of the results shows that the increase of the alkyl chain length n (hydrophobic part) leads to an increase in the adsorption activity, while the increase of hydrophilic head group given by the number of EO units m, leads to a better solubility in water, and hence, to a smaller adsorbed amount. The results also show that the ethylene oxide group mainly influences the molar surface area.

Relaxation Dynamics and Ion Conduction of Poly(Ethylene Carbonate/Ethylene Oxide) Copolymer-Based Electrolytes

Poly(ethylene carbonate/ethylene oxide) P(EC/EO) copolymer was synthesized from EC monomer as a new matrix component of solid polymer electrolytes (SPEs), and the correlation between polymer dynamics and ionic conductivity in the P(EC/EO)-based SPEs at various lithium salt weight fractions (wLi) was investigated by dielectric spectroscopy, rheology, and molecular dynamics (MD) simulations. With the addition of lithium salt, the molecular motions at various scales (i.e., from local to segmental and global motion scales) were found to change as follows: (i) the local motion of P(EC/EO) was slightly accelerated, and at wLi ≥ 0.22, it was separated into two relaxation modes, one faster and the other slower than that of P(EC/EO), (ii) the segmental motion of P(EC/EO) became significantly slower with the addition of lithium salt, and (iii) the global terminal relaxation became slightly slower with the increase of wLi. Thus, the motion of P(EC/EO) at various scales in SPEs changed with different trends with increasing lithium salt. It was also found that the temperature dependence of the ionic conductivity was described by a Vogel–Fulcher–Tammann-type function, which was correlated with the segmental motion, as is known in other SPE systems. Furthermore, from MD simulations, lithium ions are coordinated with the EC units more likely and with a closer distance than EO units in P(EC/EO), and the coordination number of oxygens around one lithium ion was estimated as 6–7 at the distance of 0.30 nm. These results suggest that the coordination structure of the oxygens around the lithium ion is slightly disrupted due to the presence of EC units compared to the chelating structure of pure PEO electrolytes.

Build up ‘highway’ in membrane via solvothermal annealing for high-efficient CO2 capture

Poly (ethylene oxide) (PEO) membranes are attractive for CO2 capture due to the particular dipolar–quadrupolar interaction between EO units and CO2 molecules, which offer high CO2/N2 selectivity. However, the low CO2 permeability of PEO membranes hampers their practical applications. Herein, a simple solvothermal annealing approach was proposed to enhance the flexibility of PEO chains via ‘activating’ the disengagement and rearrangement of side chains, which is essential for boosting the gas permeability. The effects of solvothermal annealing temperature, time, and solvent on the CO2/N2 separation performance were comprehensively investigated. The mechanism for the performance enhancement was proposed: a “highway” for gas transportation was built up by the released flexible side chains, which were confirmed by the mechanical and Li ion conductivity characterizations. The optimized PEO membrane offers a superior CO2 permeability of 1294 Barrer, a high CO2/N2 selectivity of 50, and 110-h long-term running stability, being beyond the 2008 Robeson’s upper bound line and promoting the practical application of PEO membranes in CO2 capture by reducing the cost.

Enhanced interfacial stability with a novel boron-centered crosslinked hybrid polymer gel electrolytes for lithium metal batteries

Low coulombic efficiency and serious safety issues due to uncontrollable lithium dendrite growth has severely impeded the practical application of lithium-ion batteries (LIBs) with lithium metal as the anode. In this work, we design and fabricate a novel single ion conducting crosslinked polymer gel electrolytes containing negatively charged delocalized state borate structures and rich EO units via one-step photoinitiated in-situ radical polymerization in presence of PVDF-HFP as reinforcing materials. Herein, we synthesize a novel lithium bis(macid acid) borate to give anion covalently bonded to the polymer main chain and vinyl monomers containing rich EO units are chosen to build polymer framework to ensure fast ion transport. As expected, the tailored boron-centered single-ion-conducting polymer gel electrolytes exhibit high ionic conductivity up to 1.03×10−3 S cm−1 at 32 °C, excellent oxidation potential up to 5.05 V vs Li+/Li at 1 mV/s, and a near-single ion conducting behavior (lithium ion transference number of 0.65). The Lithium (Li) metal symmetric cells assembled with the novel boron-centered single-ion-conducting polymer gel electrolytes show long-term stable cycling over >700 h at room temperature without short circuit, which implies the excellent stability of blend membranes during lithium metal deposition and stripping processes. Moreover, the Li/LiFePO4 cells assembled with the boron-centered single-ion-conducting polymer gel electrolytes exhibit excellent rate performance and cycling performance. The initial discharge capacity is 161.3 mAh g−1 at 0.1 C and a capacity of 127.7 mAh g−1 maintains with nearly 100% coulombic efficiency after 100 cycles. Moreover, the Li/LiFePO4 cells deliver stable coulombic efficiency close to 100% at 0.5 C after 300 cycles.

МОДЕЛІ ФОРМ ПРЕДСТАВЛЕННЯ НАВЧАЮЧИХ СУКУПНОСТЕЙ ДЛЯ БАГАТОРІВНЕВИХ СИСТЕМ ДІАГНОСТУВАННЯ ВУЗЛІВ ЕЛЕКТРОТЕХНІЧНОГО ОБЛАДНАННЯ

The results of consideration of advanced mathematical models of vibration diagnostic signals are given, which take into account both the properties of diagnostic objects and the modes (speed, electric temperature, etc.) in which the object under study operates. Models of representation of training sets corresponding to certain technical states of EO units and which can work in different modes are considered. The method of representation of training sets in the form of a matrix which elements represent scattering ellipses corresponding both to certain kinds of defects of separate knots of EO, and modes of its work is offered. The structure of construction of training sets on a flat (2D) and volume (3D) matrix is ​​substantiated, the elements of which contain sets corresponding to separate units of EA, and their combination forms a separate electrotechnical unit. References 18, figures 5.

Molecular Level Differences in Ionic Solvation and Transport Behavior in Ethylene Oxide-Based Homopolymer and Block Copolymer Electrolytes.

Block copolymer electrolytes (BCE) such as polystyrene-block-poly(ethylene oxide) (SEO) blended with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and composed of mechanically robust insulating and rubbery conducting nanodomains are promising solid-state electrolytes for Li batteries. Here, we compare ionic solvation, association, distribution, and conductivity in SEO-LiTFSI BCEs and their homopolymer PEO-LiTFSI analogs toward a fundamental understanding of the maximum in conductivity and transport mechanisms as a function of salt concentration. Ionic conductivity measurements reveal that SEO-LiTFSI and PEO-LiTFSI exhibit similar behaviors up to a Li/EO ratio of 1/12, where roughly half of the available solvation sites in the system are filled, and conductivity is maximized. As the Li/EO ratios increase to 1/5 the conductivity, of the PEO-LiTFSI drops nearly 3-fold, while the conductivity of SEO-LiTFSI remains constant. FTIR spectroscopy reveals that additional Li cations in the homopolymer electrolyte are complexed by additional EO units when the Li/EO ratio exceeds 1/12, while in the BCE, the proportion of complexed and uncomplexed EO units remains constant; Raman spectroscopy data at the same concentrations show that Li cations in the SEO-LiTFSI samples tend to coordinate more to their counteranions. Atomistic-scale molecular dynamics simulations corroborate these results and further show that associated ions tend to segregate to the SEO-LiTFSI domain interfaces. The opportunity for "excess" salt to be sequestered at BCE interfaces results in the retention of an optimum ratio of uncompleted and complexed PEO solvation sites in the middle of the conductive nanodomains of the BCE and maximized conductivity over a broad range of salt concentrations.

Fine tuning the structural colours of photonic nanosheet suspensions by polymer doping.

Aqueous suspensions of nanosheets are readily obtained by exfoliating low-dimensional mineral compounds like H3Sb3P2O14. The nanosheets self-organize, at low concentration, into a periodic stack of membranes, i.e. a lamellar liquid-crystalline phase. Due to the dilution, this stack has a large period of a few hundred nanometres, it behaves as a 1-dimensional photonic material and displays structural colours. We experimentally investigated the dependence of the period on the nanosheet concentration. We theoretically showed that it cannot be explained by the usual DLVO interaction between uniform lamellae but that the particulate nature of nanosheet-laden membranes must be considered. Moreover, we observed that adding small amounts of 100 kDa poly(ethylene oxide) (PEO) decreases the period and allows tuning the colour throughout the visible range. PEO adsorbs on the nanosheets, inducing a strong reduction of the nanosheet charge. This is probably due to the Lewis-base character of the EO units of PEO that become protonated at the low pH of the system, an interpretation supported by theoretical modeling. Oddly enough, adding small amounts of 1 MDa PEO has the opposite effect of increasing the period, suggesting the presence of an additional intermembrane repulsion not yet identified. From an applied perspective, our work shows how the colours of these 1-dimensional photonic materials can easily be tuned not only by varying the nanosheet concentration (which might entail a phase transition) but also by adding PEO. From a theoretical perspective, our approach represents a necessary step towards establishing the phase diagram of aqueous suspensions of charged nanosheets.

Inorganic-organic gel electrolytes with 3D cross-linking star-shaped structured networks for lithium ion batteries

Abstract Inorganic–organic electrolytes with 3D cross-linking star-shaped structured networks (3D-GPEs), consisting of multifunctional epoxy POSS and rich EO unites, are proposed for lithium ion batteries. Here, multifunctional epoxy POSS, epoxy and amino monomers containing rich EO units are chosen to build tough and compact 3D network membranes as host polymer to guarantee fast ion transport through epoxy ring-open polymerization with no initiator or no small molecule by-products generating. The electrochemical properties of 3D-GPEs and the performances of Li/LiFePO4 cells assembled with 3D-GPEs were investigated. As a result, the ionic conductivity of 3D-GPEs containing POSS is up to 2.35 × 10−3 S cm−1 at room temperature, which is almost two times than that of the GPEs without POSS. The electrochemical windows of the 3D-GPEs containing POSS are wide up to 5.25 V, indicating excellent electrochemical stability. The Li/3D-GPEs/LiFePO4 batteries exhibit good cycling performance and high rate capability. Moreover, Li/LiFePO4 cells assembled with 3D-GPEs containing POSS deliver higher discharge capacity. The discharge capability of LiFePO4/ 3D-GPE/Li is 148 mAh g−1 with excellent capacity retention after 80th cycle at 0.1C at room temperature.

Tailored pore gradient in phenolic membranes for adjustable permselectivity by leveraging different poloxamers

Cost-affordable phenolic membranes having gradient nanostructures can be facilely synthesized from resol oligomers in the presence of ZnCl2 and poloxamers. The gradient nanostructures are formed by stacking phenolic nanoparticles with gradually enlarged diameters as the distance from the upper surface increases. The use of poloxamers for creating gelation surroundings is of great significance for controlling the nucleation and growth of phenolic nanoparticles, which in turn dictates the performance of the phenolic membranes thus-produced. Hence, a study of the effects of poloxamers species on the preparation of the phenolic membranes is highly demanded since such robust membranes have much potential to be scale up for mass production. Herein, the poloxamer Pluronic F127 (EO106-PO70-EO106; EO = ethyleneoxide, PO = propyleneoxide) was introduced in the membrane-forming formulations. As opposed to P123 (EO20-PO70-EO20) that we used previously, F127 possessing extended PEO chains can delay the gelation during membrane formation. Hence, the phenolic nucleates are able to grow for longer durations, leading to the generation of more distinct gradient nanostructures in the phenolic membranes. Enhanced permeance can then be realized with F127-derived phenolic membranes. We also demonstrate that L31 (EO1-PO22-EO1) with merely single terminal EO units at the ends of the PPO block could be used to prepare gradient phenolic membranes. This work is not only much helpful to deeply understand the design of the structural gradient in phenolic membranes, but capable of sheding light on the development of such intriguing structures for water purification.

A reverse micellar system with Triton X-100: effect of surfactant polydispersity and preparation of monodisperse silica nanoparticles.

Reverse micellar systems possess a characteristic nanoscale water-in-oil (w/o) structure and can offer mild conditions as a unique and versatile reaction medium. Reverse microemulsions containing water/TX-100 + hexanol/hexane are studied in this work through experimental techniques and simulation methods. Surfactant dosages and water amount affect the micellar structure profoundly, and the polydispersity of the surfactant molecules affects the micellar structure remarkably. TX-100 with 9-10 EO units can form micelles in a simply piling way, while TX-100 with 5-10 EO units endows the micelles with a hierarchical micellar interface and a more compact structure, leading to monodisperse micelles with a smaller diameter. Water in the polar cores has three states. In the reverse micellar system using TX-100 with 9-10 EO units, hydrolysis of tetraethoxysilane happens rapidly and the formed silica gels are apt to aggregate, resulting in polydisperse silica nanoparticles. For the micellar system using TX-100 with 5-10 EO units, the micellar hierarchical distributed interface facilitates the material exchange of tetraethoxysilane and limits the hydrolysis of tetraethoxysilane inside the micelles, providing monodisperse silica nanoparticles.

Precise control of cyclodextrin-based pseudo-polyrotaxane lamellar structure via axis polymer composition.

Self-assembly of cyclodextrin (CD) with guest polymers has attracted much attention owing to its biocompatibility and accessibility. In this study, we investigate the composition effect of poly(ethylene oxide)m-b-poly(propylene oxide)n-b-poly(ethylene oxide)m (EOmPOnEOm) triblock copolymers on lamellar or plate structures formed by complexation with β-CD. EO5PO29EO5, EO14PO29EO14, and EO75PO29EO75 show periodic lamellar morphology consisting of single-crystalline pseudo-polyrotaxane (PPR) nanosheets with a thickness equal to the central PO length. This is because β-CDs selectively cover the PO component and cause the microphase separation between β-CD and EO layers. The thickness of the EO layers increases linearly with increasing number of EO units, which suggests that the EO chains are constrained into virtual cylinders with the diameter of the β-CD. This means that we can precisely control the thickness of both the crystal (β-CD and PO) and the amorphous (EO) layers in the lamellar structure. In contrast, EO2PO29EO2 forms a thin plate structure, where not only PO but also EO chains are covered with β-CD. Furthermore, the length of the central PO component is necessary to form the lamellar structure with the phase separation between the β-CD and EO layers. These findings provide a more fundamental understanding to enhance the variety and applicability of CD-based self-assembled materials.

The Performance Comparison Of Branched Methyl Stearate Ethoxylate and Linear Methyl Stearate Ethoxylate

Abstract In this paper, the physicochemical properties and application properties of two isomers, one with a branched structure (9,10-dihydroxystearic acid ethoxylate) and the another with a linear structure (stearic acid ethoxylates) were systematically studied. It has been found that: (1) The DHSAE-15 (9,10-dihydroxystearic acid ethoxylated with 15 mean EO units) with a branched structure has better wettability and higher efficiency in reducing surface tension than the corresponding linear product SAE-15 (stearic acid ethoxylated with a 15 mean EO units); (2) SAE-15 has better detergency than DHASE-15; (3) the spatial configuration plays a limiting role on the size of the aggregate.

Worm-like micelles and vesicles formed by alkyl-oligo(ethylene glycol)-glycoside carbohydrate surfactants: The effect of precisely tuned amphiphilicity on aggregate packing

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Recent work has produced a promising molecular candidate for the formation of viscoelastic worm-like micellar solutions: a tri(ethylene glycol)-linked oleyl-β-D-glucoside surfactant (GlcC18:1) exhibited near ideal Maxwell behavior at low concentrations (2.9 wt%) without additives at room temperature. Here, fourteen surfactants have been synthesized with structural variations based around GlcC18:1. Each contain an oligo(ethylene glycol) linker of varying length (2, 3, 4, 6 EO units) between a carbohydrate head-group (glucose, galactose, mannose, maltose, lactose, cellobiose) and a cis-unsaturated alkyl tail-group (oleyl, linoleyl, erucyl). The aqueous adsorption kinetics and self-assembly of these surfactants was explored using tensiometry and small-angle neutron scattering (SANS), respectively. With SANS we observed the formation of worm-like micelles for four surfactants, and vesicles for two surfactants which exhibited behavior similar to insoluble lipids. We also observed temperature-induced micellar elongation due to dehydration of the oligo(ethylene glycol) linker, resulting in a further three surfactants forming worm-like micelles at 50 °C. Worm-like micellar fluids were further characterized using rheology to reveal two surfactants with vastly superior viscoelastic properties compared to GlcC18:1, with >2 orders of magnitude increase in viscosity and >3 orders of magnitude increase in stress relaxation time. These results provide insight into structure-function relationships for non-ionic surfactants and demonstrate a class of designed amphiphiles with a special propensity for forming viscoelastic worm-like micellar solutions at low concentrations.