Complex Colloidal Particles Research Articles

Self-Assembled Ring-Based Complex Colloidal Particles by Lock-And-Key Interaction and Their Self-Assembly into Unusual Colloidal Crystals.

Creating hierarchical crystalline materials using simple colloids or nanoparticles is very challenging, as it is usually impossible to achieve hierarchical structures without nonhierarchical colloidal interactions. Here, we present a hierarchical self-assembly (SA) route that employs colloidal rings and anisotropic colloidal particles to form complex colloids and uses them as building blocks to form unusual colloidal columnar liquid crystals or crystals. This route is realized by designing hierarchical SA driving forces that is controlled by the colloidal shape and shape-dependent depletion attraction. Depletion-induced lock-and-key interaction is the first driving force, which ensures a high efficiency (>90%) to load colloidal particles of other shapes such as spheres, spherocylinders, and oblate ellipsoids into rings, providing high-quality building blocks. Their SA into ordered superstructures has to require a second driving force such as higher volume fraction and/or stronger depletion attraction. As a result, unusual hierarchical colloidal (liquid) crystals, which have previously been difficult to fabricate by simple binary assembly, can be achieved. This work presents a significant advancement in the field of hierarchical SA, demonstrating a promising strategy for constructing many unprecedented crystalline materials by the SA route.

Self-assembly and aggregation behavior of temperature-controlled modified glycinin and d-galactose colloidal particles

The molecular structure and morphologies of complex colloidal particles with modified glycine (S-11S) and d-galactose were studied by multispectral, microscopic imaging and chromatographic techniques at different temperatures, and the self-assembly and aggregation mechanisms were determined. Overall, high-temperature-treated S-11S and d-galactose associate at cysteine and phenylalanine sites and self-assemble into colloidal particles of greater stability than glycinin and S-11S via ionic and disulfide bonds. The structure and subunit content of composite colloidal particles were changed. Assessing the sub-microstructure reveals that temperature can regulate the directional aggregation of complex colloidal particles. The elasticity of the complex colloidal particles is maximum enhanced at 95 ℃ as confirmed by the rheological. Thus, the heat-treated aggregation of the soy protein and its complex was evaluated to provide a new theoretical basis for the application of soy protein in gels and other areas and contribute to the design of new soy protein products.

Low oil Pickering emulsion gels stabilized by bacterial cellulose nanofiber/soybean protein isolate: An excellent fat replacer for ice cream

Food-grade Pickering emulsion gels with different oil phase fractions stabilized by Bacterial cellulose nanofibers/Soy protein isolate complex colloidal particles were prepared by one-step method. The properties of Pickering emulsion gels with different oil phase fractions (5 %, 10 %, 20 %, 40 %, 60 %, 75 %, v/v) and their applications in ice cream were investigated in the present study. The microstructural results showed that Pickering emulsion gels with the low oil phase fractions (5 %–20 %) were an emulsion droplet-filled gel, where the oil droplets were embedded in the network structure of cross-linked polymer, while Pickering emulsion gels with higher oil phase fractions (40 %–75 %) were an emulsion droplet-aggregated gel, which formed a network structure by flocculated oil droplets. The rheology result showed that the low oil Pickering emulsion gels had the same excellent performance as the high oil Pickering emulsion gels. Furthermore, the low oil Pickering emulsion gels showed good environmental stability under harsh conditions. Consequently, Pickering emulsion gels with 5 % oil phase fraction were used as fat replacers in ice cream and ice cream with different fat replacement rates (30 %, 60 % and 90 %, w/w) was prepared in this work. The results showed the appearance and texture of the ice cream with low oil Pickering emulsion gels as fat replacers was similar to that of the ice cream with no fat replacers, and the melting rate of the ice cream with low oil Pickering emulsion gels as fat replacers showed the lowest value of 21.08 % during the 45 min of melting experiment, as the fat replacer rate in the ice cream reached to 90 %. Therefore, this study demonstrated that low oil Pickering emulsion gels were excellent fat replacers and had great potential application in low calorie food production.

Characterization of bacterial cellulose nanofibers/soy protein isolate complex particles for Pickering emulsion gels: The effect of protein structure changes induced by pH

In this work, the influence of soy protein isolated at different pH values (1–9) on the self-assembly behaviors of bacterial cellulose nanofibers/soy protein isolate (BCNs/SPI) colloidal particles via anti-solvent precipitation were investigated. The results showed that the formation of BCNs/SPI at pH values of 1–5 was mainly driven by electrostatic interaction, while the formation of those at pH values of 5–9 was driven by weak molecular interactions including hydrogen bonding and steric-hindrance effect. The FTIR demonstrated that the conformation of protein involved a transition from order to disorder at the level of secondary structure as pH values were away from the isoelectric point. The fluorescence spectroscopy and UV–vis adsorption spectroscopy indicated that hydrophobic region of SPI at pH value of 5 displayed more exposed as compared with that at pH values away from the isoelectric point. The changes in structure conformation of SPI induced by pH values led to the changes in properties of the BCNs/SPI colloidal particles including particle size, microstructure, crystallinity, hydrophily, thermal stability, and rheological properties. Furthermore, the structures of BCNs/SPI colloidal particles at different pH values significantly affected the stability of Pickering emulsion gels stabilized by the corresponding complex colloidal particles. This study provided a theoretical basis for the design of food-grade Pickering emulsion gels stabilized by BCNs/SPI complex colloidal particles.

Fabrication of zein and κ-carrageenan colloidal particles for encapsulation of quercetin: In-vitro digestibility and bio-potential activities

The present work aims to prepare and stabilize quercetin (Q) loaded zein colloidal nanoparticles using κ-carrageenan (KC) as a stabilizer. Antisolvent precipitation method was used to fabricate the zein-KC colloidal nanoparticles at pH 5.0. The findings revealed that the newly prepared Q-loaded zein-KC complex colloidal particles had spherical shapes, a particle size below ∼300.0 nm, a high magnitude of negative zeta potential (∼−45.0 mV) and encapsulation efficiency of 62.0%. The molecular interactions among zein, Q and KC in colloidal particles were confirmed by FT-IR analysis, and the combined mixture showed an amorphous diffraction pattern during the XRD analysis without revealing the crystalline peaks of Q or KC, indicating that Q was effectively encapsulated in complex colloidal particles. In aqueous environments, the anionic KC coating on the surface of zein colloidal particles modified the particulate and physicochemical properties of the encapsulated Q and enhanced its water dispersibility, thermal stability, and in-vitro release. The observed improvements were ascribed to hydrogen bonding, hydrophobic and electrostatic interactions among Q, zein, and KC. In addition, Q-loaded zein-KC complex colloidal particles demonstrated strong antioxidant activity. The results of this study revealed that, the KC coated zein colloidal particles, therefore, have great potential for use in hydrophobic nutraceutical encapsulation.

Poly(acrylic acid) Enabling the Synthesis of Highly Uniform Silica Nanoparticles of sub‐100 nm

AbstractRobust synthesis of small colloidal silica (SiO2) nanoparticles with narrow size distributions (<5%) is challenging because the possible involvement of continuous nucleation and growth of SiO2 in the widely used Stöber process usually results in silica nanoparticles with large sizes and broad size distributions. Promoting heterogeneous nucleation and growth of silica is promising to tackle the challenges by in‐situ forming transient colloidal seeds that provide nucleation surfaces for silica condensate. In this work, poly(acrylic acid) (PAA) is introduced to the Stöber synthesis solutions, which are usually composed of ethanol (containing a trace amount of water), tetraethyl orthosilicate (TEOS), and ammonia, to mediate the nucleation of TEOS hydrolysates and growth of SiO2 nanoparticles. PAA reacts with ammonia to form soft PAA‐NH3 complex colloids that serve as transient seeds to facilitate heterogeneous nucleation and growth of SiO2 nanoparticles after adding TEOS to the synthesis solution. The number of PAA‐NH3 complex colloidal particles, which strongly depends on the molar ratio of PAA and ammonia, determines the number of the resulting SiO2 nanoparticles and thus the size of the SiO2 nanoparticles correspondingly according to the supply of TEOS. Highly uniform SiO2 nanoparticles with finely tuned diameters in the sub‐100 region have been successfully synthesized, and the synthesis protocol is feasible to be scaled up while maintaining the high quality of SiO2 nanoparticles.

Zein/pullulan complex colloidal particle-stabilized Pickering emulsions for oral delivery of polymethoxylated flavones: protection effect and in vitro digestion.

Polymethoxylated flavones (PMFs) show multiple biological functions, while their high hydrophobicity leads to a low bioaccessibility and limits their wide applications. The design of a reasonable food-grade drug delivery system is an effective strategy to improve the low bioaccessibility of PMFs. In this study, sinensetin, tangeretin and nobiletin were encapsulated in Pickering emulsions stabilized by zein/pullulan complex colloidal particles (ZPPs), and the protection effect and in vitro digestion were characterized. Rheological analysis revealed that ZPP-Pickering emulsion loading with PMFs maintained a strong gel-like network structure. Moreover, the ability to scavenge free radicals of PMFs was improved by the emulsion delivery system. The antioxidant activity of PMFs encapsulated in Pickering emulsion was positively correlated with the oil volume fraction (φ). ZPP-Pickering emulsion loading with PMFs can effectively delay lipid oxidation, and the φ (70%) of Pickering emulsion showed the most pronounced effects, in which the lipid hydroperoxide content and malondialdehyde content decreased by 64.3% and 38.3% after 15 days of storage, compared with the bulk oil group, respectively. The bioaccessibility of the three PMFs has been increased by ZPP-Pickering emulsion simultaneously and it presented the highest values as its φ was 50%, in which the bioaccessibility of sinensetin, tangeretin and nobiletin increased by 2.5, 3.2 and 3.9 times, compared with the bulk oil group, respectively. Pickering emulsion stabilized by ZPPs is an excellent nutrient delivery system for delivering three PMFs simultaneously and imparting functional properties to bioactive delivery systems. © 2022 Society of Chemical Industry.

Cellulose nanocrystals concentration and oil-water ratio for solid-liquid controllable emulsion polymerization

Stabilities of cellulose Pickering emulsions are of great importance to utilize them effectively, but influenced by their complex compositions, such as, colloidal particles, oil phases and water phases. In this work, solid-liquid controllable polymerization products could obtain by adjusting cellulose nanocrystals (CNCs) concentration and vinyl acetate (VAc)-water ratio. The emulsions in zone Ӏ (w/o) and II (o/w) of the three-phase diagram were selected for researching. The polymerization emulsions in zone II illustrated the o/w ratio played a more important role than CNCs concentration in the storage stability and practicality of the polymerized emulsion; The polymer in zone Ӏ showed a large number of porous structures. This is an innovative method that different forms of target products are obtained through the guidance of three-phase diagram, which not only broadens the application field, but also applies to other Pickering emulsion systems.

Preparation of pickering emulsion stabilised by Zein/Grape seed proanthocyanidins binary composite

SummaryThis paper introduced a kind of binary composite particle constructed by zein particles and grape seed proanthocyanidins (PAs). The physicochemical performance of the zein/PAs complex colloidal particles (ZPAPs) was systematically evaluated. Fourier transform infrared spectroscopy (FTIR) showed that the interactions between zein and PAs were mainly hydrogen bonds and hydrophobic interactions. The three‐phase contact angle (θo/w) of zein particles was around 120.7 ± 0.7°, and it was decreased to 100.8 ± 0.6° after the addition of PAs, indicating that ZPAPs were more suitable for stabilising Pickering emulsion. ZPAPs stabilised peanut oil Pickering emulsion (ZPAPEs) at 0.5–0.7 (v/v) oil fractions had no obvious phase separation during a 30‐day storage, indicating its good storage stability. Rheological results showed that ZPAPEs had excellent plasticity and viscoelasticity. Confocal laser scanning microscopy (CLSM) showed that particles had stably anchored on the surface of oil droplets which could effectively prevent from Ostwald ripening. The incorporation of PAs to zein endowed zein with stronger affinity, thus enhancing the stability of Pickering emulsion. This research constructed a new novel food‐grade emulsifier to prepare Pickering emulsion with potential applications, and further broaden the bioavailability of PAs.

Fabrication and characterization of Pickering emulsion gels stabilized by zein/pullulan complex colloidal particles.

Zein particles are unsuitable as stabilizers of Pickering emulsions because of their high hydrophobicity. However, few studies have reported on the use of a strong hydrophilic neutral polysaccharide to regulate its wettability. In this work, zein/pullulan complex particles (ZPPs) were formulated by an anti-solvent method to fabricate Pickering emulsions. The presence of pullulan increased the size, decreased the zeta, and provided excellent resistance to the gravitational separation of zein. Scanning electron microscopy (SEM) revealed that the shape of zein particles changed from spherical as they became aggregated ZPP nanoparticles. Fourier transform infrared (FTIR) spectroscopy indicated that the flocculation phenomenon of ZPPs was related to the hydrogen bond between zein and pullulan. Moreover, the hydrophobicity of zein was modified by hydrophilic pullulan to endow the ZPPs with nearly neutral wettability when the mass ratio was 15:1, allowing for the preparation of stable Pickering emulsions. In contrast to zein, the ZPPs contributed to building a compact interface layer around the droplets and smaller emulsion droplets. Under a certain ZPP concentration, the size and viscosity of emulsion increased with an increase in the oil volume fraction, indicating that the Pickering emulsions stabilized by ZPPs showed better stability against coalescence. Confocal laser scanning microscopy (CLSM) revealed that the ZPPs constructed a dense filling layer on the surface of oil droplets, thus further emphasizing that ZPPs can potentially be used in fabricating Pickering emulsion gels. Zein/pullulan complex particles are an excellent Pickering emulsion gel stabilizer that can be used in the delivery system of bioactive substances in food formulations. © 2020 Society of Chemical Industry.

Development of pea protein and high methoxyl pectin colloidal particles stabilized high internal phase pickering emulsions for β-carotene protection and delivery

The demand for novel-delivery systems with natural biopolymers to stabilize and deliver biologically active and functional β-carotene (BC) is increasing. Protein-polysaccharide colloidal particles exhibited great potential for the stabilization and delivery of BC-loaded high internal phase Pickering emulsions (HIPPEs). In this study, pea protein isolate (PPI) and high methoxyl pectin (HMP) colloidal particles were fabricated and used for stabilizing and delivering BC-loaded HIPPEs. PPI-HMP complexes exhibited spherical shapes with Z-average diameters of 379 nm at pH 4.0. Turbidity, zeta-potential, and fluorescence spectroscopy results evidenced that the formations of PPI-HMP colloidal particles were primarily driven by electrostatic attraction. pH, and storage stability of HIPPEs was profoundly enhanced with PPI-HMP colloidal particles. HIPPEs with PPI-HMP colloidal particles exhibited the highest BC retention and the chemical stability of BC at pH 6.0 (68.3%) was pronouncedly higher than that at pH 3.0 (49.5%). Confocal laser scanning microscope (CLSM) graphs demonstrated HIPPEs were stabilized by a dense network surrounding the oil droplets. Compared to corn oil (control), both PPI and PPI-HMP complex-stabilized HIPPEs exhibited a higher extent of lipolysis and BC bioaccessibility. Both lipolysis extent and BC bioaccessibility of HIPPEs with PPI-HMP colloidal particles (36.5%, and 25.8%) were lower than those with PPI (42.7%, and 31.4%). This research evidenced that PPI-HMP complex colloidal particles can be synthesized for fabricating stable BC-loaded HIPPEs with enhanced chemical stability and controlled release property.

Self-assembled heteromorphous raspberry-like colloidal particles from Pickering-like emulsion polymerization

Heteromorphous raspberry-like poly(vinylidene fluoride)/polystyrene (PVDF/PS) complex colloidal particles (CCPs) were prepared by a facile and high-efficiency approach with one pot Pickering-like emulsion polymerization following conventional free radical polymerization mechanism. Difference of hydrophobicity between PVDF and PS drove the initial generated snowman-like particles self-assembling into colloidal particle clusters and then a Pickering-like emulsion continued polymerization till formation of the heteromorphous raspberry-like PVDF/PS CCPs. In order to achieve heteromorphous raspberry-like PVDF/PS CCPs with homogeneous size and morphology, influences of St/PVDF feed ratio, polymerization time, and polymerization temperature were systematically investigated. When the feed ratio of St/PVDF was high for synthesis of the CCPs, double crystallization peaks for PVDF were observed with a strong peak at about 132 °C and a weak peak at near 70 °C, indicating that partial PVDF seed particles were covered completely by PS. Furthermore, the static water contact angle of latex nanocoating prepared with the heteromorphous raspberry-like PVDF/PS CCPs reached 153.9°, exhibiting a superhydrophobicity. As a result, an alternative way is provided for fabrication of hierarchical colloidal particles and even superhydrophobic smart coatings.

Development and characterization of pickering emulsion stabilized by zein/corn fiber gum (CFG) complex colloidal particles

Pickering emulsions stabilized by food-compatible particles have drawn researchers’ attention in recent years. In this study, we have fabricated Pickering emulsions stabilized by zein/corn fiber gum (CFG) complex particles (ZCPs) via electrostatic interaction. The particle size of zein nanoparticle was 173.4 ± 2.16 nm, and the ζ-potential was +27.4 ± 1.27 mV. The presence of CFG significantly changed the particle size and ζ-potential of zein nanoparticles. The average ζ-potential of ZCPs was about −27 mV. The average particle size of ZCPs was much larger than that of pure zein nanoparticles, varying from 309 nm to 901 nm. When the mass ratio of zein to CFG was 2:1, ZCPs had the smallest particle size of 309.4 ± 2.48 nm and the ζ-potential was −26.7 ± 0.84 mV, which confirmed the adsorption of CFG onto the surface of zein particles. With an increase in CFG concentration, the contact angles (θo/w) of ZCPs tended to decrease. When the mass ratio of zein to CFG was 2:1, the θo/w was close to 90°, which favored for fabricating stable Pickering emulsion. In addition, at a constant particle concentration, with increasing oil volume fraction, the particle size and viscosity of Pickering emulsion stabilized by ZCPs increased. CLSM and Cryo-SEM observations indicated that ZCPs adsorbed homogeneously at the oil-water interface, and the adsorption of the ZCPs favored the formation of a densely packed layer at the interface, contributing to the formation of gel network structure of emulsion droplets. This study provided new insight into the fabrication food-grade Pickering emulsion, which can be used as delivery system for bioactive compound in food formulations.

Zein/tannic acid complex nanoparticles‐stabilised emulsion as a novel delivery system for controlled release of curcumin

SummaryThe present work was aimed to evaluate the potential of the gel‐like Pickering emulsions (50%, v/v, oil) stabilised by zein/tannic acid (TA) complex colloidal particles (ZTPE) as a new encapsulation system of lipophilic ingredients. Compared with sodium caseinate‐stabilised emulsions (SCE) and bulk oil, the better protective effects of ZTPE on the chemical stability of curcumin were observed when they suffered from UV light, and the lipid oxidation rate remarkably reduced in ZTPE. Also, the zein particle layers loaded with TA around the oil droplets can provide protection against harsh gastric environment, facilitating to slow down the release of free fatty acids (FFA) and curcumin during in vitro simulated digestion. These findings show that ZTPE have a good potential to act as an efficient encapsulating agent to protect functional ingredients from degradation and control their release during digestion, which can further improve the bioavailability of bioactive ingredients.

Pickering Emulsion Gels Prepared by Hydrogen-Bonded Zein/Tannic Acid Complex Colloidal Particles.

Food-grade colloidal particles and complexes, which are formed via modulation of the noncovalent interactions between macromolecules and natural small molecules, can be developed as novel functional ingredients in a safe and sustainable way. For this study was prepared a novel zein/tannic acid (TA) complex colloidal particle (ZTP) based on the hydrogen-bonding interaction between zein and TA in aqueous ethanol solution by using a simple antisolvent approach. Pickering emulsion gels with high oil volume fraction (φ(oil) > 50%) were successfully fabricated via one-step homogenization. Circular dichroism (CD) and small-angle X-ray scattering (SAXS) measurements, which were used to characterize the structure of zein/TA complexes in ethanol solution, clearly showed that TA binding generated a conformational change of zein without altering their supramolecular structure at pH 5.0 and intermediate TA concentrations. Consequently, the resultant ZTP had tuned near neutral wettability (θ(ow) ∼ 86°) and enhanced interfacial reactivity, but without significantly decreased surface charge. These allowed the ZTP to stabilize the oil droplets and further triggered cross-linking to form a continuous network among and around the oil droplets and protein particles, leading to the formation of stable Pickering emulsion gels. Layer-by-layer (LbL) interfacial architecture on the oil-water surface of the droplets was observed, which implied a possibility to fabricate hierarchical interface microstructure via modulation of the noncovalent interaction between hydrophobic protein and natural polyphenol.

Stable emulsions prepared by self-assembly of hyaluronic acid and chitosan for papain loading.

A simple, green and effective process is developed to fabricate hyaluronic acid (HA)/chitosan (CS) complex colloidal particles through electrostatic interactions. The obtained complexes can be used as biocompatible emulsifiers and novel potential carriers for papain loading. An HA/CS mass ratio of 2 is the optimal condition leading to the smallest Dh (420.9 nm). The complexes with eight different mass ratios are used to stabilize white oil/water emulsions. The structure of the complexes at the oil-water interface varies in response to the mass ratio and can be classified into two typical structures, similar to typical polymeric surfactants and solid particulate emulsifiers. Furthermore, papain is introduced into the complex systems. Formation of the papain/HA/CS complexes in a compact form can protect the enzyme. Here, a novel strategy is introduced to fabricate a biocompatible emulsion from the HA/CS complexes and demonstrate that the stable complex is a suitable enzyme delivery system.

Optically transparent metal-containing polymer materials

The review is focused on some aspects of the synthesis, functionalization, and properties of optically transparent metal-containing polymer materials. A distinctive feature of these materials is a combination of a high transparency in the visible spectral range and a high content of metals that are distributed in a polymer matrix as complex compounds or colloidal particles formed by metal compounds or metals in their element states. Depending on their composition, the materials selectively transform electromagnetic radiation and particles flows hazardous to health, luminesce, are moderately conducting, etc. The properties of the material can be predicted and formed purposively in the stage of the preparation of initial compositions, which introduces various modifiers.

Evidence for SERRS Enhancement in the Spectra of Ruthenium Dye–Metal Nanoparticle Conjugates

Metal–molecule interfaces have a high potential for applications in various fields of chemistry, as the features and functions of metal nanostructures can be modified and, to a certain degree, extended by surface-bound molecules. In this article, the functionalization of complex colloidal particles, namely, Au nanopeanuts and Au/Pt/Au nanoraspberries, with the commercially available Ru complexes N719, N749, and Z907 is reported; these Ru complexes have already been applied as photosensitizers in dye-sensitized solar cells. A detailed investigation of the conjugates by means of Raman spectroscopy showed that the electronic structures of the ruthenium complexes are retained upon binding to the metal nanoparticles. Furthermore, microfluidics as an efficient tool for the systematic investigations of SER(R)S signal-enhancement dispersion in colloidal solutions was applied. The enhancement profiles obtained differed from the extinction spectra of the nanoparticles, indicating that electronically resonant processes are involved in the Raman signal enhancement of the investigated nanoparticle conjugates, in addition to the Raman signal enhancement due to the SERS effect.

Formation of complex colloidal particles: morphologies and mechanisms

Dissipative particle dynamics (DPD) simulation is employed to examine the formation of complex colloidal particles. The dependence of the structure of such colloidal particles on the structure of the polymer, the interactions between the solvent and the segments of the polymer, and interactions between the same and/or different segments of the polymer are investigated. Families of shell–core, multicore, patchy, stacked layered, and cylindrical layered particles are obtained. The pathways for the formation of such complex colloidal particles are identified.

The chemical crosslinking of polyelectrolyte complex colloidal particles and the pervaporation performance of their membranes

Water dispersible polyelectrolyte complexes (PECs) of sodium carboxymethyl cellulose (CMCNa) and poly(diallyldimethylammonium chloride) (PDDA) were crosslinked via glutaraldehyde (GA) to improve the water resistance and stability performance of their pervaporation membranes. Relative crosslinking degrees (RCDs) of PECs with different GA contents were obtained by Fourier Transform Infrared Spectroscopy (FT-IR). Free volume of crosslinked PECs membranes (CPECMs) was examined by Doppler Broadening Energy Spectroscopy (DBES). The surface hydrophilicity and morphology of CPECMs were investigated by dynamic contact angle (DCA) and atomic force microscope (AFM), respectively. CPECMs were subjected to pervaporation dehydration of aqueous isopropanol mixtures. It was found that CPECMs showed very high water resistance, super permeability and good selectivity. Crosslinked PECs membrane with 0.5 wt% GA (CPECM0.5) showed a permeate flux of 21.2 kg/(m 2 h) and water content in permeate of 98.1 wt% in dehydrating 50 wt% aqueous isopropanol mixture at 70 °C. Moreover, good long time stability of CPECMs for dehydration of aqueous isopropanol mixture was also observed. These excellent performance are attributed to the chemical crosslinking of polyelectrolyte complex colloidal particles.