复配胶体对长保质期面包用耐烘焙果味酱品质的影响

研究了可用于长保质期面包夹心耐烘焙果味酱的胶体,通过正交试验探讨了复配胶体对耐烘焙果味酱感官、质构、保水性及含耐烘焙果味酱面包品质的影响。结果表明,以低甲氧基果胶0.5%、褐藻酸钠0.3%、羧甲基纤维素钠0.3%或褐藻酸钠0.3%、羧甲基纤维素钠0.3%,可生产出酱体均匀细腻、流散性适宜、耐烘烤,与长保质期面包配合可保存3个月的耐烘焙果味酱。     

清洁压裂液性能与破胶研究

采用阳离子季铵盐与水杨酸钠复配制备粘弹性体系——清洁压裂液,考察其性能及破胶情况。研究了水、原油、液化石油气及煤气对清洁压裂液粘弹体系的影响。结果表明,水对其稀释作用有限,原油可以使其破胶。制备了3种不同使用温度的清洁压裂液,破胶后体系黏度小于3 mPa·s,破胶时间0.5～6 h。清洁压裂液自身对粘土有抑制膨胀作用,抑制率73.6%,与 KCl 复配后抑制率达86.6%。研究表明,清洁压裂液对煤芯伤害率为41.13%,明显小于对照组线性瓜胶的伤害率78.64%。在阜新煤田压裂现场应用表明,清洁压裂液携砂性能良好,使用破胶剂返排效果理想。     

Dispersible SnO2:Sb and TiO2 Nanocrystals After Calcination at High Temperature

High-temperature treatment of functional nanomaterials, through postsynthesis calcination, often represents an important step to unlock their full potential. However, such calcination steps usually severely limit the preparation of colloidal solutions of the nanoparticles due to the formation of sintered agglomerates. Herein, a simple route is reported to obtain colloidal solutions of calcined n-conductive antimony doped tin oxide (ATO) as well as titanium dioxide (TiO₂) nanoparticles without the need for additional sacrificial materials. This is achieved by making use of the reduced contact between individual nanoparticles when they are assembled into aerogels. Following the calcination of the aerogels at 500 °C, redispersion of the nanoparticles into stable colloidal solutions with various solvents can be achieved. Although a slight degree of sintering is inevitable, the size of the resulting aggregates in solution is still remarkably small with values below 30 nm.     

Super-Macroporous Lightweight Materials Templated from Bicontinuous Intra-Phase Jammed Emulsion Gels Based on Nanochitin (Small 39/2023)

Non-equilibrium multiphase systems are formed by mixing two immiscible nanoparticle dispersions, leading to bicontinuous emulsions that template cryogels with interconnected, tortuous channels. Herein, a renewable, rod-like biocolloid (chitin nanocrystals, ChNC) is used to kinetically arrest bicontinuous morphologies. Specifically, it is found that ChNC stabilizes intra-phase jammed bicontinuous systems at an ultra-low particle concentration (as low as 0.6 wt.%), leading to tailorable morphologies. The synergistic effects of ChNC high aspect ratio, intrinsic stiffness, and interparticle interactions produce hydrogelation and, upon drying, lead to open channels bearing dual characteristic sizes, suitably integrated into robust bicontinuous ultra-lightweight solids. Overall, it demonstrates the successful formation of ChNC-jammed bicontinuous emulsions and a facile emulsion templating route to synthesize chitin cryogels that form unique super-macroporous networks.     

Photomechanical Laser Fragmentation of IrO2 Microparticles for the Synthesis of Active and Redox-Sensitive Colloidal Nanoclusters

Pulsed laser fragmentation of microparticles (MPs) in liquid is a synthesis method for producing high-purity nanoparticles (NPs) from virtually any material. Compared with laser ablation in liquids (LAL), the use of MPs enables a fully continuous, single-step synthesis of colloidal NPs. Although having been employed in several studies, neither the fragmentation mechanism nor the efficiency or scalability have been described. Starting from time-resolved investigations of the single-pulse fragmentation of single IrO₂ MPs in water, the contribution of stress-mediated processes to the fragmentation mechanism is highlighted. Single-pulse, multiparticle fragmentation is then performed in a continuously operated liquid jet. Here, 2 nm-sized nanoclusters (NCs) accompanied by larger fragments with sizes ranging between several ten nm and several µm are generated. For the nanosized product, an unprecedented efficiency of up to 18 µg J⁻¹ is reached, which exceeds comparable values reported for high-power LAL by one order of magnitude. The generated NCs exhibit high catalytic activity and stability in oxygen evolution reactions while simultaneously expressing a redox-sensitive fluorescence, thus rendering them promising candidates in electrocatalytic sensing. The provided insights will pave the way for laser fragmentation of MPs to become a versatile, scalable yet simple technique for nanomaterial design and development.     

Propulsion efficiency of achiral microswimmers in viscoelastic polymer fluids

We report the effects of polymer size, concentration, and polymer fluid viscoelasticity on the propulsion kinematics of achiral microswimmers. Magnetically driven swimmer's step-out frequency, orientation angle, and propulsion efficiency are shown to be dependent on fluid microstructure, viscosity, and viscoelasticity. Additionally, by exploring the swimming dynamics of two geometrically distinct achiral structures, we observe differences in propulsion efficiencies of swimmers. Results indicate that larger four-bead swimmers are more efficiently propelled in fluids with significant elasticity in contrast to smaller 3-bead swimmers, which are able to use shear thinning behavior for efficient propulsion. Insights gained from these investigations will assist the development of future microswimmer designs and control strategies targeting applications in complex fluids.     

Scalable,Versatile Synthesis of Ultrathin Polyetherimide Films and Coatings via Interfacial Polymerization

Polyetherimides (PEI) are high-performance thermoplastic polymers featuring a high dielectric constant and excellent thermal stability. In particular, PEI thin films are of increasing interest for use in solid-state capacitors and membranes, yet the cost and thickness are limited by conventional synthesis and thermal drawing techniques. Here, a method of synthesizing ultrathin PEI films and coatings is introduced based on interfacial polymerization (IP) of poly(amic acid), followed by thermal imidization. Control of transport, reaction, and precipitation kinetics enables tailoring of PEI film morphology from a nanometer-scale smooth film to a porous micrometer-scale layer of polymer microparticles. At short reaction times (≈1 min) freestanding films are formed with ≈1 µm thickness, which to our knowledge surpass commercial state-of-the-art films (3–5 µm minimum thickness) made by thermal drawing. PEI films synthesized via the IP route have thermal and optical properties on par with conventional PEI. The use of the final PEI is demonstrated in structurally colored films, dielectric layers in capacitors, and show that the IP route can form nanometer-scale coatings on carbon nanotubes. The rapid film formation rate and fine property control are attractive for scale-up, and established methods for roll-to-roll processing can be applied in future work.     

Template-Directed Polymerization of Binary Acrylate Monomers on Surface-Activated Lignin Nanoparticles in Toughening of Bio-Latex Films

Fabricating bio-latex colloids with core–shell nanostructure is an effective method for obtaining films with enhanced mechanical characteristics. Nano-sized lignin is rising as a class of sustainable nanomaterials that can be incorporated into latex colloids. Fundamental knowledge of the correlation between surface chemistry of lignin nanoparticles (LNPs) and integration efficiency in latex colloids and from it thermally processed latex films are scarce. Here, an approach to integrate self-assembled nanospheres of allylated lignin as the surface-activated cores in a seeded free-radical emulsion copolymerization of butyl acrylate and methyl methacrylate is proposed. The interfacial-modulating function on allylated LNPs regulates the emulsion polymerization and it successfully produces a multi-energy dissipative latex film structure containing a lignin-dominated core (16% dry weight basis). At an optimized allyl-terminated surface functionality of 1.04 mmol g⁻¹, the LNPs-integrated latex film exhibits extremely high toughness value above 57.7 MJ m⁻³. With multiple morphological and microstructural characterizations, the well-ordered packing of latex colloids under the nanoconfinement of LNPs in the latex films is revealed. It is concluded that the surface chemistry metrics of colloidal cores in terms of the abundance of polymerization-modulating anchors and their accessibility have a delicate control over the structural evolution of core–shell latex colloids.     

Bitumen–solids attachment induced by cation activation

Interactions between negatively charged bitumen and fine solids under oil sands extraction conditions were simulated using mature fine tailings (MFT) and hydrocarbon oil with dissolved carboxylic acids. Their attachment induced by cation activation was evaluated with different types of cations by simple dynamic attachment tests. The results revealed that solid hydrophobization by adsorbing surfactants was key for oil–solid attachment. Activation by multivalent metal cations was due to surface precipitation of metal hydroxides, followed by chemisorbing anionic surfactants on metal-activated solids to form metal carboxylate complexes/precipitates, thereby hydrophobizing the solids. Activation by cationic surfactants depended on their hydrocarbon chain lengths. For short hydrocarbon chains, where hydrophobic interaction is weaker than electrostatic interaction between the added cationic and anionic surfactants, the added cations promote the adsorption of anionic surfactants by electrostatic interaction to render the solids hydrophobic. For long hydrocarbon chains where hydrophobic interaction is stronger than electrostatic interaction between the added cationic and anionic surfactants, the adsorption of anionic surfactants occurs through the hydrophobic association of the hydrocarbon chains, posing the head group towards water, thereby making the solids less hydrophobic. Activation by cationic flocculants was purely physical (hydrogen bonding and electrostatic): when the solids were turned positive by the added cationic flocculants, the added anionic surfactants then adsorbed onto the solids to render them hydrophobic. It appeared that soluble multivalent metal species (e.g., Ca²⁺ and Mg²⁺) were much less harmful to bitumen extraction than those heavy metals coated on the solids, either in the form of surface precipitates or hydrolyzed ionic species.