Dioctadecyldimethylammonium Chloride Research Articles

Stretchable and Flexible Painted Thermoelectric Generators on Japanese Paper Using Inks Dispersed with P- and N-Type Single-Walled Carbon Nanotubes.

As power sources for Internet-of-Things sensors, thermoelectric generators must exhibit compactness, flexibility, and low manufacturing costs. Stretchable and flexible painted thermoelectric generators were fabricated on Japanese paper using inks with dispersed p- and n-type single-walled carbon nanotubes (SWCNTs). The p- and n-type SWCNT inks were dispersed using the anionic surfactant of sodium dodecylbenzene sulfonate and the cationic surfactant of dimethyldioctadecylammonium chloride, respectively. The bundle diameters of the p- and n-type SWCNT layers painted on Japanese paper differed significantly; however, the crystallinities of both types of layers were almost the same. The thermoelectric properties of both types of layers exhibited mostly the same values at 30 °C; however, the properties, particularly the electrical conductivity, of the n-type layer increased linearly, and of the p-type layer decreased as the temperature increased. The p- and n-type SWCNT inks were used to paint striped patterns on Japanese paper. By folding at the boundaries of the patterns, painted generators can shrink and expand, even on curved surfaces. The painted generator (length: 145 mm, height: 13 mm) exhibited an output voltage of 10.4 mV and a maximum power of 0.21 μW with a temperature difference of 64 K at 120 °C on the hot side.

Processing effects on bilayer structures formation and rheological behavior of softeners using cationic di(hydrogenated tallow)dimethylammonium chloride aqueous dispersions

AbstractThe use of softeners is essential for enhancing laundered fabrics and hair textures after washing. For these, products based on double‐tailed cationic surfactants are used to reduce friction and static electricity, resulting in softer and smoother fibers. These surfactants form lamellar phases in water, which can be turned into vesicles and other bilayer aggregates upon shearing, greatly impacting on the rheological properties of these formulations. This study aims at elucidating how some parameters of the formulation process impact bilayer structures formation and the product rheology, using di(hydrogenated tallow)dimethylammonium chloride (DHTDMAC) aqueous dispersions as model system. Small angle X‐ray scattering (SAXS) analyses revealed lamellar phases starting from 3% DHTDMAC, with a bilayer thickness of 1.90 ± 0.03 nm, indicating significant carbon chain interdigitation. At this concentration (3%), bilayers exhibited a repetition distance of 69 nm, unveiling a behavior close to the one predicted for infinite swelling, in which lamellar structures persisted even at high dilution. Temperature plays a significant role in the rheological behavior, with elevated temperatures favoring vesicle formation, resulting in reduced apparent viscosity due to lower resistance of vesicles to flow. Upon heating, differential scanning calorimetry (DSC) analyses revealed a transition from Lβ (gel) to Lα (fluid) structures between 28 and 41°C, which was further confirmed by X‐ray diffraction (XRD). Both structural and thermotropic features observed were discussed and compared to information reported for a high‐purity grade homologue of DHTDMAC, dioctadecyldimethylammonium chloride (DODAC) mixed with water. These findings deepen the understanding of fabric softener formulation and the impact of bilayer structures formation on their properties, and should be used to optimize new formulations, enhancing their overall performance and sensorial quality.

Porous hemispherical Au@PdAg catalysts for enhancing ethanol electrooxidation

Direct ethanol fuel cell can convert chemical energy into electric energy directly, and has the advantages of being free from Carnot cycle and being friendly to environment, so it has a broad application prospect. However, the insufficient activity and toxicity resistance of anodic catalysts limit their commercial application, mainly due to the limited adsorption sites and the toxic inactivation of catalysts resulting from the production of toxic intermediates (COads) during the ethanol oxidation reaction (EOR) process. In this study, the Au@PdAg porous hemispherical catalyst assembled by nanotubes was successfully prepared by soft template method and co-reduction method using dioctadecyl dimethyl ammonium chloride (DODAC) as surfactant, and its EOR performance was tested. Au@Pd1.0Ag1.0 has the highest mass current density with a peak value of 4048.8 mAmgPd−1, which is 7.8 times of Pd/C (JM). After 5000 s stability test, the residual current density value is still 863.4 mAmgPd−1. The results showed that the introduction of the oxygenophilic metal Ag was conducive to the formation of OHads and the oxidation of COads. The porous structure of the nanotube assembly facilitates electron transfer and provides more adsorption sites, which makes the catalyst show good electrocatalytic activity and anti-CO poisoning ability.

Surfactant‐Templated Synthesis of High‐Performance Noble Metal Electrocatalysts: A Case of Dioctadecyldimethylammonium Chloride

Mesoscopic structures of noble metal (NM) nanomaterials are important parameters that remarkably affect physicochemical properties and electrocatalytic performances. To date, various synthesis strategies have been proposed to prepare NM nanomaterials with well‐defined mesoscopic structures. Specifically, amphiphilic surfactants that chemically composed of hydrophobic tail(s) and hydrophilic head(s) have been utilized as functional templates to precisely engineer mesoscopic structures of NM nanomaterials and further optimize their electrochemical performance. Compared with traditional surfactants, dioctadecyldimethylammonium chloride (DODAC) is a functional amphiphilic surfactant that can assemble into vesical and cylinder micelles and thus template precise synthesis of NM nanomaterials with various advanced structures. In this review, recent developments in DODAC‐templated synthesis of high‐performance NM electrocatalysts with a specific focus on the findings in the group are presented. Three kinds of advanced NM mesoscopic structures, including one‐dimensional (1D) nanowires, three‐dimensional (3D) mesoporous nanospheres (MSs), and sophisticated hollow/asymmetric MSs, are described in detail. Meanwhile, the applications in various electrocatalytic reactions are presented to highlight high activity, selectivity, and stability of NM electrocatalysts. This review provides some insights into both synthesis and application exploration of high‐performance NM electrocatalysts by templated synthesis of amphiphilic surfactants.

A Study on the Removal Characteristics and Mechanism of Phosphorus from Simulated Wastewater Using a Novel Modified Red-Mud-Based Adsorption Material

In this work, a common third-generation environmentally friendly quaternary ammonium salt disinfectant, dimethyl dioctadecyl ammonium chloride (DDAC), was used as the modifier to achieve one-step rapid preparation of the modified red-mud-based adsorption material under the condition of microwave assistance, and applied it to the adsorption phosphorus in solutions. After the process of this modification, the structure of the red mud (RM) was not changed, and the DDAC modification could provide more adsorption active sites. The adsorption experiments indicated that the novel modified red mud (NMRM) exhibited a good adsorption performance for phosphorus. The adsorption capability of NMRM for phosphorus was significantly enhanced, and was about eight times higher than that of the initial RM. The kinetics model of the pseudo-second-order, which implied that phosphorus was chemically adsorbed on the surface of the NMRM, could accurately represent the adsorption procedure of NMRM. The adsorption equilibrium of NMRM could be better depicted using the isotherm model of Freundlich. It was speculated that the ion exchange might be responsible for the adsorption mechanism of NMRM for phosphorus. Thus, the NMRM is a potential material for the treatment of phosphorus-containing wastewater due to its outstanding adsorption capability.

Single and Double Alkyl Chain Quaternary Ammonium Salts as Environment-Friendly Corrosion Inhibitors for a Q235 Steel in 0.5 mol/L H2SO4 Solution

In this work, the corrosion inhibition effects of octadecyl trimethyl ammonium chloride (OTAC) and dioctadecyl dimethyl ammonium chloride (DDAC) on Q235 steel in a 0.5 mol/L H2SO4 solution are studied. The results of the electrochemical experiment, contact angle measurement, and scanning electron microscopy indicate that the two ionic liquids belong to mixed-type corrosion inhibitors with good anti-corrosion performance. Additionally, OTAC has a better anti-corrosion ability than DDAC, implying that the steric hindrance effect of the double alkyl chain is not conducive to the adsorption of DDAC on the electrode surface.

Successive exposure to traditional disinfectants and quaternary ammonium compounds enhances resistance genes expression and co-selection in biofilm-based partial nitrification-anammox systems

Quaternary ammonium compounds (QACs) are recommended disinfectants with surfactant properties, surpassing triclosan (TCS) and chloroxylenol (PCMX). Given the transition from traditional disinfectants, it is essential to investigate their impacts on biological nitrogen removal systems and the fate of resistance genes (RGs). In this study, three biofilm-based partial nitrification-anammox (PN/A) systems were established. A reactor named PD was successively exposed to 1 mg/L PCMX and 3 mg/L dioctadecyldimethylammonium chloride (DODMAC, a common QACs). A reactor named TD was successively exposed to 1 mg/L TCS and 3 mg/L DODMAC. A reactor named CD served as a control with only 3 mg/L DODMAC exposure. Results indicated that the total nitrogen removal performance of CD deteriorated markedly with DODMAC exposure compared to that of PD and TD. This phenomenon correlated closely with variations in RGs and their co-selection patterns. Pre-exposure to PCMX or TCS increased the abundance of RGs in the extracellular DNA of the PN/A biofilm, but reduced RGs abundances in the extracellular DNA of water. The tolerance of the PN/A system to successive exposure to the two disinfectants may be strengthened through co-selection of QACs RGs (qacEdelta1–01, qacEdelta1–02, qacH-01 and qacH-02) and mobile genetic elements (intI1 and tnpA-04). Furthermore, potential hosts of RGs are crucial for maintaining PN/A performance. Accumulation of extracellular polymeric substances, reactive oxygen species, and lactate dehydrogenase plays vital roles in the accumulation and transmission of RGs within the PN/A system.

Starch/poly (butylene adipate-co-terephthalate) blown films contained the quaternary ammonium salts with different N-alkyl chain lengths as antimicrobials

Antimicrobial biodegradable packaging is in high demand as a one-two punch against microbiological and plastic hazards. Two quaternary ammonium salts (QAS) with different N-alkyl chain lengths were used for starch/poly (butylene adipate-co-terephthalate) (PBAT) blown antimicrobial films. Dioctadecyl dimethyl ammonium chloride (D1821) contributed to a homogeneous film morphology at 5% w/w level, while micro-pores occurred with didodecyl dimethyl ammonium chloride (D1221). Increasing QAS content weakened hydrogen bonding interactions. D1821 promoted the formation of intercalated structure of nano-clays, and improved the strength, thermal stability, barrier, and surface hydrophobicity of the films. Conversely, adding D1221 decreased the mechanical properties, and significantly enhanced the surface hydrophilicity. The films with 3% and 5% w/w D1221 obviously inhibited the growth of both Staphylococcus aureus and Escherichia coli, while those with D1821 cannot show clear zone against the Gram-negative. 5% w/w D1221-loaded film delayed the growth of microorganisms in beef, of which the total viable count was 5.75 lg CFU/g after 21-day chilling storage. Findings supported that QAS had the potential for manufacturing starch/PBAT antimicrobial packaging, but the release kinetics and cytotoxicity still need to be systematically explored before application.

Enhancement of hydrotreating activity of oil-soluble CoMo6 heteropolyacid for 4,6-dimethyldibenzothiophene and vacuum residue by controlling sulfurization degree

An oil-soluble CoMo6 heteropolyacid was synthesized by modifying the heteropolyacid with a surfactant dioctadecyl dimethyl ammonium chloride, and then was used to prepare highly active sulfided catalyst. The effect of sulfurization degree on the hydrotreating activity of the catalyst was investigated, and the results show that the incompletely sulfurized catalyst exhibited high reactivity for 4,6-dimethylbenzothiophene (4,6-DMDBT) and vacuum residue (VR). The unusual finding was attributed to more CoMoS species and surface oxysulfides, and the latter were probably generated in the partial replacement of O atoms with S atoms during the sulfurization. The acidic oxysulfides (SO42- groups) not only improved the activation of 4,6-DMDBT but also facilitated the cleavage of C-C bonds of the intermediate product 3,3′-dimethylcyclohexylbenzene according to the reaction data and DFT calculation. Besides, the catalysts with incomplete sulfide state exhibited outstanding catalytic performance on the upgrading of VR. The proposed incomplete sulfurization strategy provided a new way to prepare bifunctional hydrogenation catalysts with both desulfurization and cracking activities.

Synthetic Control over the Surface Chemistry of Blue-Emitting Perovskite Nanocrystals for Photocatalysis

Lead halide perovskite nanocrystals (NCs) are particularly suitable for light-emitting and photocatalysis applications, where their potential can be maximized by controlling the surface composition of their organic shell. In this study, the preparation of CsPbClxBr3–x NCs at room temperature in toluene is described. Three differently structured surfactants are utilized for the synthesis, each with a specific function, namely, the solubilization of the lead precursor (n-Hept4NBr), the surface passivation with halide modification (dimethyldioctadecylammonium chloride), and the protection of the surface-active sites (octanoic acid) for photocatalysis. Under these conditions, nearly monodispersed blue-emitting nanocubes are selectively obtained in a one-pot synthesis by combining specific amounts of the perovskite precursors. As supported by thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy investigations, the organic shell of the obtained NCs is composed of electrostatically bound dimethyldioctadecylammonium ions, granting robustness to the corresponding NCs, and octanoic acid molecules, interacting with the nanoparticle surface through weaker secondary bonds. The obtained NCs exhibit a high photoluminescence quantum yield (PLQY = 72 ± 3%) notwithstanding multiexponential recombination dynamics of the excited state, resulting from the different passivation modes at the NC surface. Moreover, the NCs show a remarkable optical stability after exposure to high temperatures and to water contact due to the high surface density of the multifunctional organic ligands. The introduction of 4-tert-butylphenyl thiol promotes a charge transfer process at the NC/thiol interface formed upon removal of the labile ligands (octanoic acid) at the NC surface. In these conditions, the NCs are prone to the photoinduced conversion of the aromatic thiol into the corresponding disulfide without varying the optical properties of the perovskite photocatalyst upon the substrate conversion. Therefore, the obtained results cast light on the versatility of the surface engineering of lead halide perovskite NCs for efficient blue emission and photocatalysis with improved stability.

Vesicle‐to‐micelle transition in aqueous mixtures of cationic lipids with Pluronic F127

AbstractAqueous solutions of vesicle‐forming lipids mixed with micelle‐forming copolymers may result in stabilized and biocompatible aggregates. Differential scanning calorimetry (DSC) and dynamic light scattering (DLS) techniques were used here to investigate the effects of the nonionic triblock copolymer Pluronic F127 (F127) on the thermal behavior, structural changes, and hydrodynamic size of cationic vesicles from dioctadecyldimethylammonium chloride (DODAC), dioctadecyldimethylammonium bromide (DODAB), and didodecyldimethylammonium bromide (DDAB) in aqueous dispersion. The DSC thermograms indicate that upon the addition of up to 5.0 mM F127, a vesicle‐to‐micelle transition occurs in three stages. First, there is a predominance of lipid‐F127 mixed vesicles, followed by the co‐existence of mixed vesicles and micelles, and finally, the system is dominated by mixed micelles. DLS results reveal that with the addition of F127 to the lipid dispersions, the size of the assembled structures tends to decrease, also indicating structural changes of vesicles to micelles. These results indicate that the borders between these stages depend on the lipid chain length and counterion type.

Cationic Liposomes with Different Lipid Ratios: Antibacterial Activity, Antibacterial Mechanism, and Cytotoxicity Evaluations.

Due to their strong bacterial binding and bacterial toxicity, cationic liposomes have been utilized as effective antibacterial materials in many studies. However, few researchers have systematically compared their antibacterial activity with their mammalian cell cytotoxicity or have deeply explored their antibacterial and cytotoxicity mechanisms. Here, we prepared a series of cationic liposomes (termed CLs) using dimethyldioctadecylammonium chloride (DODAC) and lecithin at different molar ratios. CLs have the ability to effectively bind with Gram-positive and Gram-negative bacteria through electrostatic and hydrophobic interactions. Further, the CLs with high molar ratios of DODAC (30 and 40 mol%) can disrupt the bacterial wall/membrane, efficiently inducing the production of reactive oxygen species (ROS). More importantly, we carefully compared the antibacterial activity and the mammalian cell cytotoxicity of various CLs differing in DODAC contents and liposomal concentrations and revealed that, whether they are bacterial or mammalian cells, an increasing DODAC content in CLs can lead to an elevated cytotoxicity level. Further, there exists a critical DODAC contents (>20 mol%) in CLs to endow them with effective antibacterial ability. However, the variation in the DODAC content and liposomal concentration of CLs has different degrees of influence on the antibacterial activity or cytotoxicity. For example, CLs at high DODAC content (i.e., CL0.3 and CL0.4) could effectively kill both types of bacterial cells but only cause negligible toxicity to mammalian cells. We believe that a systematic comparison between the antibacterial activity and the cytotoxicity of CLs with different DODAC contents will provide an important reference for the potential clinical applications of cationic liposomes.

Sandwich-type electrochemical immunosensor based on nitrogen-doped porous carbon and nanoporous trimetallic nanozyme (PdAgCu) for determination of prostate specific antigen.

Asandwich-type electrochemical immunosensor was designed for the ultrasensitive detection of prostate-specific antigen (PSA), using Au nanoparticles (Au NPs) modified nitrogen-doped porous carbon (NPC) as sensor platform and trimetallic PdAgCu mesoporous nanospheres (PdAgCu MNSs) as enzyme-mimicking labels. NPC was prepared by a facile one-step pyrolysis strategy of biomimetic phylloid zeolite imidazole framework (ZIF-L) nanosheets. Through this strategy, the graphitization of the microcrystalline structure enhanced the electrical conductivity, while its enlarged specific surface area and abundant pore volume can enrich H2O2 to improve the catalytic efficiency. Moreover, Au NPs were used to modify NPC without cross-linking agents to further optimize electron transport while capturing primary antibodies, improving stability and sensitivity of theimmunosensor. PdAgCu MNSs with uniform size, cylindrical open mesoporous channels, and continuous crystal frame structure were self-assembling synthesized by electrostatic adsorption and ascorbic acid (AA) co-reduction with amphiphilic dioctadecyldimethylammonium chloride (DODAC) as surfactant-cum-micelle, whose unique structure maximizes the use of polyatoms to expose catalytic sites, exhibiting good biocompatibility and electrocatalytic ability. Under the optimal conditions, the immunosensor showed superior sensitivity, a wide dynamic detection range (10fgmL-1 ~ 100ngmL-1) and a low limit of detection (LOD, 3.29fgmL-1). This work provides a convenient strategy for the clinical detection of PSA.

Defect-Rich and Single-Crystalline PdCu Ultrathin Nanowires Promoting Ethanol Oxidation Electrocatalysis

Developing high-performance electrocatalysts for the ethanol oxidation reaction (EOR) is greatly significant for the practical application of direct ethanol fuel cells, but it is still unsatisfactory. In this manuscript, we reported a facile aqueous synthesis of PdCu ultrathin nanowires (UNWs) as a highly active and stable electrocatalyst for EOR electrocatalysis. The synthesis relied on the columnar nucleation of PdCu alloys via co-reduction of Pd and Cu precursors in an aqueous solution with a highly hydrophobic dioctadecyldimethylammonium chloride as the structure-directing surfactant. PdCu UNWs featured ultrathin diameter (∼3.2 nm), defect-rich surface (high-index site), single-crystalline structure, and well-alloyed composition. They disclosed the remarkable mass activity of 3.02 A mgPd–1 and the good chronoamperometric and cycling stability for EOR electrocatalysis, both of which are better than its counterpart catalysts and commercial Pd/C. Mechanism studies further confirmed that PdCu UNWs had much better diffusion ability and lower activation energy based on their structural and compositional add-in synergies.

Interface and Charge Induced Molecular Self-Assembly Strategy for the Synthesis of Reduced Graphene Oxide Coated with Mesoporous Platinum Sheets.

The design of porous noble metal catalysts holds great promise in various electrocatalytic applications. However, it is still a challenge to improve the durability performance through constructing stable framework. Here, an interface and charge induced strategy is developed to synthesize large-sized continuous reduced graphene oxide@mesoporous platinum (denoted as rGO@mPt) sheets under kinetic control by molecular self-assembly design. Graphene oxide (GO) is a promising large-sized growth interface for platinum. Cationic surfactant dioctadecyldimethylammonium chloride bridges the negatively charged GO and platinum precursors, while creating interconnected mesopores. The successful synthesis of rGO@mPt sheets relies on proper kinetic control, which is achieved by controlling pH, temperature, and the complexation of bromide ions. rGO@mPt sheets present strong crystallinity with a pure face-centered cubic Pt phase. Worm-like mesostructures with an average pore size of 2.2nm exist throughout the sheets. rGO@mPt sheets possess both stable framework and abundant active sites, which markedly improve the durability on methanol oxidation reaction while maintaining relatively good catalytic activity. Long-term stability test shows a slight loss of 1.2% activity after 250 cycles. Amperometric i-t curves reveal the mass current three times higher compared to commercial Pt/C at 3000s.

An integrated strategy for the extraction and solidification of Th(IV) ions from aqueous HNO3 solution based on self-assembly triggered by [DODMA]+[DGA]- ionic liquids

Based on the dioctadecyldimethylammonium chloride surfactant, three novel ionic liquids (ILs) involving dioctadecyldimethylammonium ([DODMA]+ cations and N,N-dialkyl-diglycolamide acid (DGA) anions was firstly designed and synthesized for extraction of thorium ions in nitric acid solution. The integrated extraction and solidification of Th(IV) was developed by formation of self-assembly (SA) solid in two-phase interface. The SA solid was identified by spectroscopic methods including SEM with mapping EDS, XPS, FT-IR and ESI-HRMS. The excellent extraction efficiency was observed for extraction of thorium using [DODMA]+[DGA]- ionic liquids, more than 99% of Th(IV) were extracted and enriched as SA solid in one-step process. The outstanding selectivity of Th(IV) to Ln(III) and U(VI) was observed, and separation factors were up to 3470 for Th/Eu and more than of 1980 for Th/U, respectively. The proposed strategy not only provides an alternate method for the separation of thorium ions with uranyl ions and lanthanides(III) ions in the nuclear fuel cycle, but also pioneers to develop the self-assembly extraction based on [DODMA]+ ionic liquids. In view of the similarity of Pu(IV) and Th(IV), the simple integrated strategy may be further expanded for extraction and enrichment of Pu(IV) in nuclear industry.

Nicotinic-Acid-Ornamented Tetrameric Rare-Earth-Substituted Phospho(III)tungstates with the Coexistence of Mixed Keggin/Dawson Building Blocks and Its Honeycomb Nanofilm for Detecting Toxins.

A fascinating class of nicotinic-acid-ornamented tetrameric rare-earth (RE)-substituted phospho(III)tungstates [NH2(CH3)2]10Na4H8[RE2(NA)(HNA)(H2O)6(W2O4)(β-H2P2IIIW13O49)(α-HPIIIW9O33)]2·22 H2O [RE = Nd3+ (1-Nd), Tb3+ (2-Tb), Dy3+ (3-Dy), Ho3+ (4-Ho), HNA = nicotinic acid] were isolated through a one-step reaction method of Na2WO4·2H2O, H3PO3, HNA, NH2(CH3)2·HCl, and RE(NO3)·6H2O. Of meticulous concern is that HPO32- was used as a template to construct tetrameric RE-substituted phospho(III)tungstates including mixed heteropolyoxotungstate building blocks. Their hybrid polyoxoanions are composed of two symmetrical [RE2(NA)(HNA)(H2O)6(W2O4)(β-H2P2IIIW13O49)(α-HPW9O33)]11- units linked by RE-O-W bonds. The symmetrical unit consists of one peculiar heterometal nicotinic-acid-ornamented [RE2(NA)(HNA)(W2O4)]9+ cluster connecting a pentavacant Dawson-like [β-H2P2W13O49]12- and a trivacant Keggin [α-HPW9O33]8- subunits. Furthermore, dimethyldioctadecylammonium chloride (DMDODA·Cl) was used to combine with 1-Nd in the CHCl3-H2O system through electrostatic interactions, leading to the 1-Nd@DMDODA composite material. The honeycomb-patterned film of the 1-Nd @DMDODA composite material was successfully constructed by using the breath figure method on a glassy carbon electrode, which can offer abundant binding sites to Au nanoparticles (nano-Au). Ulteriorly, Au-functionalized 1-Nd@DMDODA-modified electrode was utilized as an electrochemical sensor to detect ochratoxin A, showing a good detection limit of 1.19 pM.

Interactions between Cationic Ion Pair Amphiphile Vesicles and Hyaluronan-A Physicochemical Study.

High-resolution ultrasound spectroscopy (HR-US), size and ζ-potential titrations, and isothermal titration calorimetry (ITC) were used to characterize the interactions between hyaluronan and catanionic ion pair amphiphile vesicles composed of hexadecyltrimethylammonium-dodecylsulphate (HTMA-DS), dioctadecyldimethylammonium chloride (DODAC), and cholesterol. In addition to these methods, visual observations were performed with the selected molecular weight of hyaluronan. A very good correlation was obtained between data from size titration, HR-US, and visual observation, which indicated in lower charge ratios the formation of hyaluronan-coated vesicles. On the contrary, at higher charge ratios, coated vesicles disintegrated to a size of around 2000 nm. The intensity of these interactions and the disaggregation were dependent on the molecular weight of hyaluronan. All interactions studied by ITC showed strong exothermic behavior, and these interactions between vesicles and hyaluronan were confirmed from the first addition, independently of the molecular weight of hyaluronan.

Double-Chain Cationic Surfactants: Swelling, Structure, Phase Transitions and Additive Effects.

Double-chain amphiphilic compounds, including surfactants and lipids, have broad significance in applications like personal care and biology. A study on the phase structures and their transitions focusing on dioctadecyldimethylammonium chloride (DODAC), used inter alia in hair conditioners, is presented. The phase behaviour is dominated by two bilayer lamellar phases, Lβ and Lα, with “solid” and “melted” alkyl chains, respectively. In particular, the study is focused on the effect of additives of different polarity on the phase transitions and structures. The main techniques used for investigation were differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). From the WAXS reflections, the distance between the alkyl chains in the bilayers was obtained, and from SAXS, the thicknesses of the surfactant and water layers. The Lα phase was found to have a bilayer structure, generally found for most surfactants; a Lβ phase made up of bilayers with considerable chain tilting and interdigitation was also identified. Depending mainly on the polarity of the additives, their effects on the phase stabilities and structure vary. Compounds like urea have no significant effect, while fatty acids and fatty alcohols have significant effects, but which are quite different depending on the nonpolar part. In most cases, Lβ and Lα phases exist over wide composition ranges; certain additives induce transitions to other phases, which include cubic, reversed hexagonal liquid crystals and bicontinuous liquid phases. For a system containing additives, which induce a significant lowering of the Lβ–Lα transition, we identified the possibility of a triggered phase transition via dilution with water.

Effect of functionalized organic saponite on performance, crystallization and rheology of poly (lactic acid)

In the work, organic saponite (OSAP) was modified with dioctadecyl dimethyl ammonium chloride and saponite by intercalation reaction. Moreover, functionalized OSAP (FOSAP) was prepared with OSAP, BASF chain extender Joncryl ® ADR 4468 and p-phenylenediamine. The optimum reaction conditions of FOSAP were optimized by orthogonal experiment. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) results demonstrated that saponite had been successfully modified. Moreover, FOSAP/poly (lactic acid) (PLA) nanocomposites were prepared by melting intercalation with PLA and FOSAP. The mechanical properties, rheological behavior and crystallization properties of FOSAP/PLA nanocomposites were investigated. Mechanical properties showed that the impact strength and elongation at break of FOSAP/PLA nanocomposites reached 13.21 KJ/m2 and 71.47%, respectively, when the amount of FOSAP in PLA was 0.3 wt%. In addition, the Cole-Cole curve showed that FOSAP had strong interfacial compatibility with PLA. Furthermore, the crystallization behaviors of PLA before and after modification during isothermal crystallization at 150 °C were investigated by Rheonaut technology for simultaneous rheology and FTIR, which demonstrated that FOSAP effectively promoted the crystallization of PLA and increased the storage modulus. Avrami equation showed that FOSAP changed the nucleation growing mode and significantly accelerated the crystallization rate of PLA, therefore the comprehensive performance of PLA was improved.