Superhydrophobic surfaces have been fabricated in large quantities via designing suitable micro/nano structures and introducing low surface energies. However, the thermodynamic mechanisms between superhydrophobicity and microstructures still need to be further investigated to better provide a guidance for achieving superhydrophobicity. In this work, a theoretical model based on an actual coating with the microstructures consisting of fibers and nano hemispheres was constructed to analyze the effects of structural parameters on contact angles and free energies, where three wetting phases were defined according to different wetting heights of droplets on the surface. By calculations, the wetting equilibrium states and their corresponding contact angles and structural optimization strategies in the three wetting phases were obtained. Besides, the superhydrophobic coating prepared using magnesium oxysulfate whiskers and SiO2 nano hemispheres was used as an example for the model application. The results of the model analysis showed that there should be two equilibrium states of water droplets on the coating surface. This study is expected to be utilized to guide the design of superhydrophobic surfaces.

Poor mechanical robustness is a major handicap to the practical application of superhydrophobic coatings. It is imperative to design an effective strategy to improve the durability of superhydrophobic coatings. In this work, we prepared a robust superhydrophobic coating using all-in one suspension that contained magnesium oxysulfate whiskers, SiO2 nanoparticles and amino drying varnish via a drop coating method. The suspension was formed through that a mixture of magnesium oxysulfate whiskers and SiO2 nanoparticles modified by tetraethylortho-silicate and octadecyltrichlorosilane was mixed into amino drying varnish diluted with thinner. The results showed that such inorganic-organic composite modification method could effectively improve the modified effect. The prepared coating displayed excellent water repellency not only on the top surface but also at any exposed internal section throughout the coating, and maintained its superior superhydrophobicity even after the top area was scraped off a layer. Notably, the coating exhibited outstanding self-cleaning capability with a contact angle of 168.81 degrees and a very low sliding angle. Further, amino drying varnish as binders replaced by other common commercial paints could also prepare superhydrophobic coatings. This study can not only facilitate the large-scale fabrication and application of superhydrophobic coatings, but also expand the application filed of magnesium oxysulfate whiskers.

超疏水材料因性能独特,应用前景广阔而被广泛关注.本文采用碱式硫酸镁晶须(MOSWs)与二氧化硅纳米粒子制备超疏水涂层,首先对MOSWs及50nmi1、500nmSiO2进行表面改性以降低表面能,然后基于混料实验将三者按比例混合以构造表面粗糙度,以接触角、滚动角及平均粗糙度Ra为响应变量建立回归模型,分析了混合分量的形貌、尺寸与混合比例对响应变量的影响,并探讨了超疏水涂层微观结构对水滴黏附性的影响以及粗糙度与超疏水性能之间的关系.结果表明:MOSWs复合SiO2纳米粒子可制备具有不同黏附性的超疏水涂层,单独使用MOSWs可制备高黏附性超疏水涂层,其接触角达152.59°,涂层水平倒置水滴不滴落;而MOSWs与50 nmSiO2以相同质量分数混合,可制备低黏附性超疏水涂层,其接触角达163.25°,滚动角可趋近0°.所制备涂层的平均粗糙度Ra值位于5-10μm之间时,接触角较大,滚动角较小,超疏水性能较佳.

Developing an effective and sustainable method for the separation of oil and brine mixture is highly necessary for the restoration of environmental pollution caused by the loss of organic solvents during the lithium extraction process from brine. Herein, we report a facile and cost-efficient method to fabricate an underbrine superoleophobic mesh by one-step hydrothermal method. The synthesized CrOx(OH)(3-2x)/nickel mesh possesses flower-like nanostructure, exhibiting superior superhydrophilicity/underbrine superoleophobicity for different ratios of tributyl phosphate and sulfonated kerosene mixtures. Simultaneously, the CrOx(OH)(3-2x)/nickel mesh manifests high efficiency for oil and brine separation with an ultrahigh permeation flux (78136 L.m(-2).h(-1)) and excellent oil rejection efficiency (>99.17%). Furthermore, the as-prepared mesh exhibits high chemical stability, outstanding salt tolerance, and excellent mechanical properties. Importantly, the surface wettability can be changed from superhydrophilicity to superoleophobicity for several times only by ignition of the CrOx(OH)(3-2x)/NM on an alcohol burner for 10 s or modified by OTS. Altogether, the CrOx(OH)(3-2x)/nickel mesh has tremendous potential in practical oil-brine applications.

以硫酸镁和氢氧化钠为原料,邻苯二甲酸氢钾为络合剂,采用络合-水热法制备了碱式硫酸镁纳米线;采用宏观动力学方法结合微观结构分析,进行碱式硫酸镁结晶机理研究.通过分析Mg浓度与时间的变化关系曲线,建立结晶动力学方程;然后根据晶体缺陷分析碱式硫酸镁纳米线表面成核机制.实验结果表明:碱式硫酸镁纳米线在140和160℃结晶机理为多核控制表面生长;在180和200℃时结晶机理发生了变化,转变为线性控制表面生长;碱式硫酸镁纳米线的晶格中存在着较多的刃型位错与螺型位错,可以促进其表面成核、快速生长.

Basic magnesium chloride (BMC) whiskers were prepared by hydrothermal method using magnesium chloride and calcium hydroxide as raw materials. Subsequently, nano-MgO was obtained by pyrolysis of the resulting whisker. Transmission electron microscopy (TEM) images showed that the diameter of nano-MgO was between 20 and 40 nm. The corresponding selected-area electron diffraction (SAED) pattern demonstrated the single-crystalline nature with the exposed plane of {111} and {110}. TG-DTG, SEM, XRD, and FT-IR analysis confirmed the four-step pyrolysis processes of BMC whisker. Results showed two molecules of crystal water lost during the first and second steps, respectively. Subsequently, two hydrogen chloride molecules were released in the third step. Finally, hydroxy water was dehydrated. The thermal decomposition kinetics of BMC whisker was studied by means of Satava and differential method. It indicates that the first step of the thermal decomposition of BMC whiskers is random nucleation and subsequent growth mechanism. The second step is two-dimensional diffusion. The third and the final steps are phase boundary reaction and one-dimensional phase boundary reaction mechanism, respectively.

采用沉淀法以六水氯化镁(MgCl2·6 H 2 O)和氨水(NH 3·H 2 O)为原料制备出氢氧化镁,热解得到了片状镂空纳米氧化镁.利用Kissinger法计算出氢氧化镁的热解表观活化能E和指前因子A,并用Ozawa-Fly-nm-Wall方程法进行了验证;采用Satava法分析得出氢氧化镁热解机理为随机成核及生长;通过TEM和SAED分析,该氧化镁纳米级平均粒径在20 nm左右,微米级尺寸在200～500 nm之间,暴露晶面族为{110};经XRD分析,氧化镁微纳结构的形成机理与前驱体热解过程中分解产物逸出方式以及晶体结构变化有关.

Magnesium hydroxide sulfate hydrate (MOS) nanowires were prepared with hydrothermal method by using potassium acid phthalate (KHpht) as the complexant. Complexation formed by pht(2-) and Mg2+ in this preparation system was analyzed by potentiometric titration. The effect of pht(2-) adsorption on MOS nanowires was investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR) and transmission electron microscopy (TEM). These results show that pht(2-) complexes with Mg2+ in the reaction system substantially decreases free Mg2+ concentration and solution supersaturation. Chemical bonding between Mg2+ and pht(2-) exists on the surface of MOS crystal. Owing to the different configuration of the crystal lattice, pht(2-) adsorption on the lateral growth plane is more preferential than that on the axial growth plane, resulting in the formation with ratio of MOS nanowires.

Polypropylene (PP) composites containing magnesium oxysulfate particle (MOSp), magnesium oxysulfate whisker (MOSw), or magnesium oxysulfate sector (MOSs) were prepared via melt blending method. Scanning electron microscopy results showed that three magnesium oxysulfate (MOS) fillers all dispersed homogeneously in PP matrix and displayed vague and fuzzy interfaces. Wide-angle X-ray diffraction (WXRD) patterns showed that MOSp induced the most amount of β-PP, which was supported by polarized light microscopy (PLM) photographs. Moreover, PLM photographs also showed that the presence of MOSp, MOSw, or MOSw decreased the PP spherulites, especially for MOSp. As such, mechanical tests showed that incorporation of MOSp into PP matrix greatly improved the impact strength and least lowered the nominal strain at break. The yield strength and Young’s modulus of composites were greatly enhanced with MOSw. Two possible reasons for this phenomenon are rigidity of MOSw and microstructure of composites. Rheological properties were measured via small amplitude oscillatory shear. The results showed that PP melts containing MOSw exhibited significant yield stress and “shear-thinning” behaviors, which indicated the formation of MOSw network and the transition from “liquid-like” PP matrix to “solid-like” composites. The rheological results greatly proved the enhancement in tensile properties of MOSw-incorporated composites.

Zinc borate mother solution is cycled to prepare 2ZnO3B(2)O(3)7H(2)O, 3ZnO5B(2)O(3)14H(2)O, and 4ZnOB(2)O(3)H(2)O based on the properties of borate depolymerization. The results show uniform quadrilateral-prism-like and octahedron-like 2ZnO3B(2)O(3)7H(2)O are synthesized at different temperatures. Flake-like 3ZnO5B(2)O(3)14H(2)O is fabricated as reaction time prolonging, and 2ZnO3B(2)O(3)7H(2)O changed into 3ZnO5B(2)O(3)14H(2)O spontaneously. Meanwhile, resulting 2ZnO3B(2)O(3)7H(2)O is investigated to fabricate high aspect ratio of 4ZnOB(2)O(3)H(2)O whisker. Impressively, uniform 4ZnOB(2)O(3)H(2)O whisker can be resynthesized by the filtrates of 2ZnO3B(2)O(3)7H(2)O and 3ZnO5B(2)O(3)14H(2)O via the zero-waste technology.

以MgSO4·7H2 O和NaOH为原料,邻苯二甲酸氢钾(KHpht)作为络合剂,采用络合-水热法制备碱式硫酸镁(MOS)纳米线.考察了反应条件对MOS纳米线形貌的影响,并对产物进行了表征和分析.确定了制备MOS纳米线的较优条件:MgSO4浓度为0.3 mol/L,n(NaOH)/n(MgSO4)为2.5,n(KHpht)/n(MgSO4)为1.1,无水乙醇作为分散剂,水热合成温度160℃,反应时间10 h.所得到MOS纳米线形貌均匀,长度在10～20μm,直径在20～100 nm,纳米线沿[010]方向生长.

Isotactic polypropylene (iPP) composites containing magnesium oxysulfate whisker (MOSw) or lauric acid-modified MOSw (LA-MOSw) were prepared via melt mixing in a torque rheometer. Scanning electron microscopy pictures showed that the interface between MOSw and iPP matrix was defined, whereas a vague interface was seen in the iPP–LA-MOSw composites. Mechanical properties of these two groups of composites were investigated in terms of tensile, notched impact, and flexural behavior aspects for the purposes of studying toughening effect of MOSw and LA-MOSw. Tensile results showed that yield strength of composites further reduced with the presence of LA, indicating the decrease in interfacial interaction bewteen iPP matrix and MOSw. As such, LA-MOSw performed better than MOSw in toughening of iPP matrix. Flexural strength and modulus of iPP–MOSw composites increased sharply with the increase in MOSw content, while less dependence on the LA-MOSw content indicated that MOSw was deemed beneficial to increase the stiffness. In addition, flammability properties were investigated by cone calorimetry experiment. The results showed that the peak heat release rate apparently reduced with addition of MOSw or LA-MOSw. Besides, iPP–LA-MOSw composites showed higher specific extinction area values than iPP–MOSw composites, which meant the weaker smoke suppression effect of LA-MOSw. It was chiefly because of the incomplete combustion caused by the continuous and complete charred (MgO) shield. The presence of LA was another possible reason.

Well-dispersed, high-aspect-ratio 4ZnO·B 2 O 3 ·H 2 O whiskers (4ZnO·B 2 O 3 ·H 2 O HARw ) were synthesized by a facile hydrothermal method with the aid of ZnSO 4 ·7H 2 O. The formation mechanism was investigated, and the results showed that Zn 2+ and SO 4 2− ions played a crucial role in the control of 4ZnO·B 2 O 3 ·H 2 O HARw extended along [010] direction. X-ray diffraction (XRD) analysis, high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetry (TG)-differential scanning calorimetry (DSC) results confirmed that the powder was 4ZnO·B 2 O 3 ·H 2 O. Scanning electron microscopy (SEM) and TEM showed that the average aspect ratio of the product was about 100. Nanocomposites of surface-modified 4ZnO·B 2 O 3 ·H 2 O SM-HARw /PP were prepared and their mechanical properties measured. The results suggested that the mechanical properties of 4ZnO·B 2 O 3 ·H 2 O SM-HARw /PP composites were superior to composites made with low-aspect-ratio whiskers (4ZnO·B 2 O 3 ·H 2 O SM-LARw ), which displayed poorer mechanical properties even at low addition.

In this paper a simple method is provided to solve the durability problem of superhydrophobic coatings. Using a traditional approach we give new functions to anhydrite whiskers in the superhydrophobic coating field.

Anhydrous calcium sulfate whisker (ACSw) was modified by dual-surface modification with sodium silicate solution as inorganic modifer and stearic acid as organic modifier. The samples were characterized by water contact angle (WCA), X-ray diffraction (XRD), field emission scanning electron microscope(FESEM), fourier infrared spectrum (FT-IR), and X-ray photoelectron spectroscope (XPS). The results showed that ACSw surface property changed to Hydrophobic after inorganic-organic modification, while its crystal structure remained unchanged. FT-IR and XPS resutls indicated that -Ca-SiO3 structure was generated firstly on the surface of whiskers after reaction with sodium silicate solution. And then a mixing coating layer containing both -Ca-HSiO3 and -Ca-COOR structures were formed through bonding interaction with stearic acid rather than physical absorption after particle hydrolyzation of -Ca-SiO3 structure.

Polypropylene (PP) composites containing magnesium oxysulfate whisker (MOSw) or lauric acid (LA) modified MOSw (LAMOSw) were prepared via melt mixing in a torque rheometer. The heterogeneous nucleating effect of LAMOSw was clearly observed in polarized light microscopy (PLM) pictures with the presence of an abundance of small spherulites. MOSw exhibited no nucleation effect and formed a few spherulites with large size. Compared with PP/MOSw composites, PP/LAMOSw exhibited better impact strength, tensile strength and nominal strain at break, ascribing to three possible reasons: (i) more β-crystal PP formed, (ii) better dispersity of LAMOSw in PP matrix and (iii) the plasticizing effect of LA. The results of dynamic mechanical thermal analysis (DMTA) indicated that brittleness of the PP matrix at low temperature was improved by the addition of LAMOSw, while the interfacial interactions between MOSw and PP matrix were actually weakened by LA, as evidenced by the higher tanδ values over the entire range of test temperatures. In terms of the rheological properties of the composites, both the η* and G′ at low frequencies increase with the addition of MOSw or LAMOSw, indicating that the PP matrix was transformed from liquid-like to solid-like. However, a network of whiskers did not form because no plateau was found in the G′ at low frequencies. With low filler content, LAMOSw produced a stronger solid-like behavior than MOSw mainly due to the better dispersion of the LAMOSw in PP matrix. However, for highly-filled composites, the η* of PP/LAMOSw at low frequencies was smaller than that of PP/MOSw composite, since the particle-particle contact effect played a major role.

Series of magnesium oxysulfate/polypropylene (MOS/PP) composites magnesium oxysulfate particle (MOSP), magnesium oxysulfate whisker (MOSW), and magnesium oxysulfate sector (MOSS) were prepared via melt blending method using magnesium oxysulfate (magnesium oxysulfate particle (MOSP), magnesium oxysulfate whisker (MOSW), and magnesium oxysulfate sector (MOSS)) as fillers, lauric acid (LA) as modifier and PP resin as the matrix.SEM results indicate that both modified MOSP and MOSW are fine dispersed in the PP matrix, whereas the incompatibility issue still exist.For MOSS/PP composites, MOSS with huge size and complicated morphology and partial dispersed MOSW are coexisted, with more interface defects observed.Wide angle X-ray diffraction (WXRD) results suggest that addition of MOS can induce the formation of β-crystal PP which is irrelevant to LA, especially for the MOSP/PP sample.The incorporation of three kinds of MOS slightly decreases yield strength of the PP matrix.One reason is the incompatibility between MOS and the PP matrix, and the formation of β-crystal is another important reason.In contrast, introducing MOSW can maintain the yield strength and tension fracture toughness and reinforce the modulus of PP matrix obviously, which is mainly due to the high aspect ratios of whisker morphology.In addition, the most obviously toughening effect happens on the MOSP/PP composites for two reasons.On the one hand, MOSP is more efficient for inducing β-crystal PP as compared with MOSW and MOSS.On the other hand, the more fatty acid salt attached to the surface of MOSP results in the stronger plastification effect to the PP matrix.

Single crystalline calcium chloroborate (Ca2B5O9Cl) whiskers with uniform diameter have been fabricated by a two-step process. The precursor was firstly prepared by the sedimentation reaction between CaCl2, H3BO3 and NaOH aqueous solutions, and then sintered at different temperatures for 6 h with KCl as flux. The XRD indicates that the product synthesized at 600 °C is Orthorhombic Ca2B5O9Cl. SEM and TEM results show that the Ca2B5O9Cl is whisker with the diameter about 0.2–0.5 μm and the length up to 15 μm. SAED analysis shows that the whisker is single crystalline and grows along [001] direction. The possible formation process and growth mechanism were proposed.

Abstract The influence of calcium carbonate (CaCO3) with different polymorphs (calcite and aragonite) and morphologies (granular and rod-like) on mechanical and crystallization properties of polypropylene (PP) was investigated. Meanwhile, these CaCO3 fillers coated with oleic acid were added in different contents to PP. The results indicate that the tensile strength, flexural strength, modulus, and crystallization property of the filler-treated samples are improved, but the impact strength decreased. The crystallinity of the composites is higher than that of neat PP. Moreover, in the rod shape filler-treated sample, in both whisker species, the mechanical properties of composites are superior to the particles filled. Differential scanning calorimetry, X-ray diffraction, and mechanical tests display that calcite whisker-reinforced composite has higher crystallization enthalpy, melting enthalpy, degree of crystallinity, and mechanical properties than aragonite whiskers and calcite particles filled composites.