The influence of UHMWPE with varying morphologies on the non-isothermal crystallization kinetics of HDPE.

The current study aims to examine how the morphology of ultra-high molecular weight polyethylene (UHMWPE) particles impacts the kinetics of non-isothermal crystallization in high-density polyethylene (HDPE). To prepare blends of HDPE and UHMWPE, melt blending is utilized. High-temperature melting and subsequent shearing are used to cause the morphological changes in UHMWPE particles. The morphological evolution of UHMWPE particles is observed utilizing scanning electron microscopy (SEM). The non-isothermal crystallization kinetics of HDPE with varying UHMWPE morphologies are investigated using the Jeziony and Mo methods. The nucleation activity of UHMWPE particles in HDPE crystallization is assessed using the Dobreva and Gutzow model. Furthermore, the crystallization activation energy of HDPE blends is evaluated using the Friedman model. The results exhibit that after undergoing high-temperature melting, the UHMWPE particles underwent significant morphological changes, leading to enhanced interaction with the two phases and reduced nucleation activity. Additionally, it can increase the crystallization activation energy, which causes a decrease in the HDPE crystallization rate. However, subsequent shearing has crushed the UHMWPE particles into smaller pieces, enhancing their nucleation activity, decreasing the activation energy required for crystallization and increasing the HDPE crystallization rate.

Research on Properties of PBAT/CaCO3 Composite Films Modified with Titanate Coupling Agent.

High cost, low crystallinity, and low-melt strength limit the market application of the biodegradable material poly (butylene adipate-co-terephthalate) (PBAT), which has become a major obstacle to the promotion of PBAT products. Herein, with PBAT as resin matrix and calcium carbonate (CaCO3) as filler, PBAT/CaCO3 composite films were designed and prepared with a twin-screw extruder and single-screw extrusion blow-molding machine designed, and the effects of particle size (1250 mesh, 2000 mesh), particle content (0-36%) and titanate coupling agent (TC) surface modification of CaCO3 on the properties of PBAT/CaCO3 composite film were investigated. The results showed that the size and content of CaCO3 particles had a significant effect on the tensile properties of the composites. The addition of unmodified CaCO3 decreased the tensile properties of the composites by more than 30%. TC-modified CaCO3 improved the overall performance of PBAT/CaCO3 composite films. The thermal analysis showed that the addition of titanate coupling agent 201 (TC-2) increased the decomposition temperature of CaCO3 from 533.9 °C to 566.1 °C, thereby enhancing the thermal stability of the material. Due to the heterogeneous nucleation of CaCO3, the addition of modified CaCO3 raised the crystallization temperature of the film from 97.51 °C to 99.67 °C and increased the degree of crystallization from 7.09% to 14.83%. The tensile property test results showed that the film reached the maximum tensile strength of 20.55 MPa with the addition of TC-2 at 1%. The results of contact angle, water absorption, and water vapor transmission performance tests showed that TC-2 modified CaCO3 increased the water contact angle of the composite film from 85.7° to 94.6° and decreased the water absorption from 13% to 1%. When the additional amount of TC-2 was 1%, the water vapor transmission rate of the composites was reduced by 27.99%, and the water vapor permeability coefficient was reduced by 43.19%.

Mechanical Properties, Crystallization Behaviors and Phase Morphologies of PLA/GTR Blends by Reactive Compatibilization.

Different ratios of Polylactic acid/Ground tire rubber (PLA/GTR) were prepared by melt blending and adding dicumyl peroxide (DCP) as a reactive compatibilizer. The compatibilizer could initiate a reaction between PLA and GTR to increase the compatibility and interfacial adhesion of the two phases, as indicated by Fourier transform infrared (FTIR) spectrometry and scanning electron microscopy (SEM). Adding the compatibilizer significantly improved the impact strength of the PLA/GTR blends without compromising the tensile strength. The elongation at the break and notched Izod impact strength of the blend increased by 61.8% and 150%, respectively, but there was only a 4.1% decline in tensile strength compared with the neat PLA. The plastic deformation on the impact fractured surface showed that the improvement of toughness could be attributed to the compatibilization initiated by DCP. Therefore, the improvement of the interfacial adhesion and compatibility of the two phases induced a brittle-ductile transition that occurred in the failure of blends. Moreover, the crystallinity of blends reached 40.5% without a further annealing treatment, which was nearly 24 times of the neat PLA, and the crystallization rate was enhanced simultaneously. These exciting findings suggest that compatibilization can provide a promising avenue for fabricating GTR-toughened PLA blends with balanced stiffness-toughness.

The Research on Anti-Nickel Contamination Mechanism and Performance for Boron-Modified FCC Catalyst.

Fluid catalytic cracking (FCC) is still a key process in the modern refining area, in which nickel-contamination for an FCC catalyst could obviously increase the dry gas and coke yields and thus seriously affect the stability of the FCC unit. From the points of surface acidity modification and Ni-passivation, in this paper, a boron-modified FCC catalyst (BM-Cat) was prepared using the in situ addition method with B2O3 as a boron source and emphatically investigated its mechanism and performance of anti-nickel contamination. The mechanism research results suggested that, in calcination, boron could destroy the structure of the Y zeolite and thus decrease the total acid sites and strong acid sites of the Y zeolite from 291.5 and 44.6 µmol·g-1 to 244.2 and 32.1 µmol·g-1, respectively, which could obviously improve the dry gas and coke selectivity of the catalyst and thus enhance the nickel capacity for BM-Cat; on the other hand, under hydrothermal conditions, boron could react with NiO and form into NiB2O4, which could obviously raise the range of the reduction temperature for NiO from 350-600 °C to 650-800 °C and thus promote the nickel-passivation ability for BM-Cat. Therefore, evaluation results of heavy oil catalytic cracking indicated that, under the same nickel-contamination condition, in contrast to the compared catalyst (C-Cat), the dry gas yield, coke yield, and H2/CH4 of BM-Cat obviously decreased by 0.77 percentage points, 2.09 percentage points, and 13.53%, respectively, with light yield and total liquid yield increasing by 3.25 and 2.08 percentage points, respectively, which fully demonstrates the excellent anti-nickel contamination performance of BM-Cat.

Mechanical Properties, Melting and Crystallization Behaviors, and Morphology of Carbon Nanotubes/Continuous Carbon Fiber Reinforced Polyethylene Terephthalate Composites.

Carbon nanotube/continuous carbon fiber reinforced poly(ethylene terephthalate) (CNT/CCF/PET) composites are prepared by melt impregnating. The effects of CF and CNT content on the mechanical properties, melt and crystallization behaviors, and submicroscopic morphology of CNT/CCF/PET composites are studied. The tensile test results show that the increase of CF and the addition of appropriate amount of CNT improved the tensile strength and tensile modulus of the composites. When the content of CNT is 1.0 wt% and the content of CF is 56 wt%, the properties of the composites are the best, with tensile strength of 1728.7 MPa and tensile modulus of 25.1 GPa, which is much higher than that of traditional resin matrix composites. The results of dynamic mechanical analysis (DMA) show that the storage modulus of the composites increased with the increase of CF and CNT content. In particular, the addition of CNT greatly reduced the loss modulus of the composites. Morphological analysis show that the addition of CNT improved the fiber-matrix interface of the composite, which changes from fiber pull-out and fracture failure to fiber matrix fracture failure, and the fiber matrix interface is firmly bonded. In addition, there are polymer coated CNT protrusions on the surface of the fiber was observed. The results of differential scanning calorimetry (DSC) show that the melting temperature and crystallization temperature of the composites increased with the increase of CF content. The addition of CNT had little effect on the melting temperature of the composites, but it further improved the crystallization temperature of the composites. The effect of CNT content on the crystallization kinetics of the composites is studied. The non-isothermal crystallization kinetics of the composites is described by Jeziorny's improved Avrami equation. The results show that CNT has a great influence on the crystallization type of the composites. As a nucleating agent, CNT has obvious heterogeneous nucleation effect in the composites, which improves the crystallization rate of PET.

Synthesis of Si-Modified Pseudo-Boehmite@kaolin Composite and Its Application as a Novel Matrix Material for FCC Catalyst.

Fluid catalytic cracking (FCC) has been the primary processing technology for heavy oil. Due to the inferior properties of heavy oil, an excellent performance is demanded of FCC catalysts. In this work, based on the acid extracting method, Si-modified pseudo-boehmite units (Si-PB) are constructed in situ and introduced into the structure of kaolin to synthesize a Si-PB@kaolin composite. The synthesized Si-PB@kaolin is further characterized and used as a matrix material for the FCC catalyst. The results indicate that, compared with a conventional kaolin matrix, a Si-PB@kaolin composite could significantly improve the heavy oil catalytic cracking performance of the prepared FCC catalyst because of its excellent properties, such as a larger surface area, a higher pore volume, and a good surface acidity. For the fresh FCC catalysts, compared with the FCC catalysts using conventional kaolin (Cat-1), the gasoline yield and total liquid yield of the catalyst containing Si-PB@kaolin (Cat-2) could obviously increase by 2.06% and 1.55%, respectively, with the bottom yield decreasing by 2.64%. After vanadium and nickel contamination, compared with Cat-1, the gasoline yield and total liquid yield of Cat-2 could increase by 1.97% and 1.24%, respectively, with the bottom yield decreasing by 1.80 percentage points.

One-Step Fabrication of a Functionally Integrated Device Based on Polydimethylsiloxane-Coated SiO2 NPs for Efficient and Continuous Oil Absorption.

The construction of superhydrophobic surfaces necessitates the rational design of topographic surface structure and the reduction of surface energy. To date, the reported strategies are usually complex with multi-steps and costly. Thus, the simultaneous achievement of the two indispensable factors is highly desired, yet rather challenging. Herein, we develop a novel structure engineering strategy of realizing the fabrication of a functionally integrated device (FID) with a superhydrophobic surface via a one-step spraying method. Specifically, silica nanoparticles are used to control the surface roughness of the device, while polydimethylsiloxane is employed as the hydrophobic coating. Benefitting from the adopted superhydrophobicity, the as-fabricated FID exhibits a continuous, excellent oil-water separating performance (e.g., 92.5% separating efficiency) when coupled with a peristaltic pump. Notably, a smart design of incorporating a gas switch is adopted in this device, thereby effectively preventing water from entering the FID, realizing thorough oil collection, and avoiding secondary pollution. This work opens up an avenue for the design and development of the FID, accessible for rapid preparation and large-scale practical application.

Mini-Generator Based on Reciprocating Vertical Motions Driven by Intracorporeal Energy.

Most implantable devices rely on a power supply from batteries and require replacement surgeries once the batteries run low. Mini-generators that harvest intracorporeal energy available in the human body are promising replacements of batteries and prolong the lifetime of implantable devices, thus reducing surgery pain, risks, and cost. Although various sources of energy available in the human body are used for electricity generation using piezoelectric and triboelectric materials or intravascular turbines, concerns about material durability or thrombus risks remain, and developing novel strategies to fabricate a mini-generator to harvest the intracorporeal energy is still challenging. Herein, a mini-generator system is designed by exporting the systolic/diastolic blood pressure from the femoral artery of a sheep to trigger the pressure-responsive reciprocating vertical motions of a conductor. By applying a magnetic field, an induced voltage of 0.32 V and a stable output power of 13.86 µW are obtained, which is promising to power a state-of-the-art pacemaker (8-10 µW). The noncontact electricity generation strategy provides a novel avenue to sustainable power supply for implantable devices.

Removal of Oil Spills through a Self-Propelled Smart Device.

Oil/water separation through superhydrophobic/superoleophilic materials has attracted considerable interest over the past decades; however, dealing with oil spills on broad waters through an active way remains a challenge. Herein, we report a self-propelled smart device driven by the decomposition of hydrogen peroxide that can spontaneously move on the water surface and collect floating oil droplets inside with superhydrophobic and superoleophilic properties. Moreover, the self-propelled smart device exhibits excellent stability and high efficiency for oil/water separation. We believe this study may provide a promising strategy for fabricating smart aquatic devices that have potential applications in water remediation.

Macroscopic supramolecular assembly of rigid hydrogels assisted by a flexible spacing coating.

To address the difficult challenge of realizing macroscopic supramolecular assembly (MSA) of high-modulus hydrogels, we propose a strategy of introducing a flexible spacing coating to improve the surface compliance for efficient MSA, which holds promise to develop versatile MSA methods for fabricating hydrogel-based tissue scaffolds, and to provide insight into the MSA mechanism.

Elasticity-Dependent Fast Underwater Adhesion Demonstrated by Macroscopic Supramolecular Assembly.

Macroscopic supramolecular assembly (MSA) is a recent development in supramolecular chemistry to associate visible building blocks through non-covalent interactions in a multivalent manner. Although various substrates (e.g. hydrogels, rigid materials) have been used, a general design rule of building blocks in MSA systems and interpretation of the assembly mechanism are lacking and are required. Herein we design three model systems with varied elastic modulus and correlated the MSA probability with the elasticity. Based on the effects of substrate deformability on multivalency, we have proposed an elastic-modulus-dependent rule that building blocks below a critical modulus of 2.5 MPa can achieve MSA for the used host/guest system. Moreover, this MSA rule applies well to the design of materials for fast underwater adhesion: Soft substrates (0.5 MPa) can achieve underwater adhesion within 10 s with one order of magnitude higher strength than that of rigid substrates (2.5 MPa).

Macroscopic Supramolecular Assembly through Electrostatic Interactions Based on a Flexible Spacing Coating.

Macroscopic supramolecular assembly (MSA) is a recent advance in supramolecular chemistry that involves associating large building blocks with a size larger than 10 µm through noncovalent interactions. However, until now the applicable material system is rather limited to hydrogels, and MSA of rigid materials with supramolecular interactions widely used in molecular assembly has rarely been reported due to the difficulty in achieving multivalency between rigid surfaces. Herein, the concept of flexible spacing coating is applied with highly flowable properties, and the electrostatic-interaction-driven MSA of relatively rigid polydimethylsiloxane building blocks is demonstrated. With the flexible spacing coating of a polyelectrolyte multilayer, the oppositely charged rigid building blocks can realize MSA under shaking in water for 5 min. The major contribution of the electrostatic interaction is confirmed by both qualitative controlled MSA experiments in other solvents, disassembly in ionic solution and quantitative results with an in situ force measurement method.

Self-Correction Strategy for Precise, Massive, and Parallel Macroscopic Supramolecular Assembly.

Macroscopic supramolecular assembly (MSA) represents a new advancement in supramolecular chemistry involving building blocks with sizes beyond tens of micrometers associating through noncovalent interactions. MSA is established as a unique method to fabricate supramolecularly assembled materials by shortening the length scale between bulk materials and building blocks. However, improving the precise alignment during assembly to form orderly assembled structures remains a challenge. Although the pretreatment of building blocks can ameliorate order to a certain degree, defects or mismatching still exists, which limits the practical applications of MSA. Therefore, an iterative poststrategy is proposed, where self-correction based on dynamic assembly/disassembly is applied to achieve precise, massive, and parallel assembly. The self-correction process consists of two key steps: the identification of poorly ordered structures and the selective correction of these structures. This study develops a diffusion-kinetics-dependent disassembly to well identify the poorly aligned structures and correct these structures through iterations of disassembly/reassembly in a programmed fashion. Finally, a massive and parallel assembly of 100 precise dimers over eight iteration cycles is achieved, thus providing a powerful solution to the problem of processing insensitivity to errors in self-assembly-related methods.

Chemical and Equipment-Free Strategy To Fabricate Water/Oil Separating Materials for Emergent Oil Spill Accidents.

Oil spill accidents normally have two important features when considering practical cleanup strategies: (1) unexpected occurrence in any situations possibly without specific equipment and chemicals; (2) emergency to be cleaned to minimize the influences on ecosystems. To address these two practical problems regarding removal of spilt oil, we have proposed an in situ, rapid, and facile candle-soot strategy to fabricate water/oil separating materials based on superhydrophobicity/superoleophilicity. The one-step fabrication method is independent of any chemicals or equipment and can be ready for use through short smoking processes within 5 min by using raw materials available in daily life such as textiles. The as-prepared materials perform good durability for repeated separation test and high recovery rate of various oils from water/oil mixtures. This strategy provides possibility of rapid response to sudden oil spill accidents, especially in cases without any equipment or chemicals and in poor countries/areas those could hardly afford transportation and storage of expensive separating materials.

Biomimicking of a Swim Bladder and Its Application as a Mini-Generator.

A model fish with a man-made swim bladder achieves fast vertical motions based on density adjustments in a pressure-responsive way. When exposed to a magnetic field, a mini-generator is achieved by harvesting energy from the environment, working with pressure differences in the blood-pressure range and at the frequency of a beating heart.

Converting chemical energy into electricity through a functionally cooperating device with diving-surfacing cycles.

A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity.

Supramolecular assembly of macroscopic building blocks through self-propelled locomotion by dissipating chemical energy.

Chemical energy supplied by the catalytic decomposition of H2O2 is introduced into macroscopic building blocks, which self-propel, interact with each other, and finally assemble into ordered and advanced structures. The geometry is highly dependent on the way that the catalyst is loaded. The integration of catalyst and building block provides assembling component as well as its energy of motion.

pH-responsive on-off motion of a superhydrophobic boat: towards the design of a minirobot.

Combining chemical reactions and stimuli-responsive surfaces as clutch system, a functional cooperating minirobot with on-off locomotion that is responsive to pH changes is fabricated. Its locomotion can be switched on by changing pH value of the solution from 1 to 13, turned off by adjusting the pH back to acidic, and restarted by transforming the solution to basic.

Bell-shaped superhydrophilic-superhydrophobic-superhydrophilic double transformation on a pH-responsive smart surface.

Superhydrophobic to neutral water droplets, superhydrophilic to acidic or basic. This double transition of surface wettability in response to a single stimulus - pH - is demonstrated for the first time. The smart surface is composed of a rough gold surface modified with a self-assembled monolayer (SAM) containing three thiols, HS(CH2 )11 CH3 , HS(CH2 )10 COOH, and HS(CH2 )11 NH2 . A ternary diagram is generated that describes wettability as a function of the SAM composition and the pH of the surrounding solution.

A facile method to immobilize cucurbituril on surfaces through photocrosslinking with azido groups.

We develop a facile method to immobilize cucurbituril on silicon substrates through photochemical reaction with azido groups. Combining photolithography and the competitive molecular recognition between CB[7] and acridine orange base or 1-adamantanecarboxylic acid, a patterned surface with reversible fluorescence emission can be obtained.