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Photorheologically reversible micelle composed of polymerizable cationic surfactant and 4-phenylazo benzoic acid

Chinese Journal of Chemical Engineering 2016年第2期24卷 289-292页

作者： Jie Chen Bo Fang Hao Jin Licheng Yu Meng Tian Kejing Li Leiping Jin Mo Yang Shanghai Key laboratory of Multiphase Materials Chemical Engineering Lab of Chemical Engineering RheologyResearch Center of Chemical EngineeringEast China University of Science and Technology

A photorheologically reversible micelle composed of polymerizable cationic surfactant n-cetyl dimethylallyl am- monium chloride （CDAAC） and trans-4-phenylazo benzoic acid （trans-ACA） was prepared. The effects of molar ratio of CDAAC/trans-ACA, time of UV and visible light irradiation and temperature on the rheological properties of micellar system were investigated. The results show that before UV irradiation the system with an optimum CDAAC/trans-ACA molar ratio of 1.4 forms viscoelastic micelles at 45 ℃. After 365 nm UV irradiation, the viscos- ities of micelle systems with different concentrations at fixed molar ratio of 1.4 are decreased by 85%-95%. The CDAAC/trans-ACA （14 mmol. L- 1/10 mmol. L- 1 ） micelle system exhibits shear thinning property and its viscos- ity is decreased obviously with the increases of UV irradiation time less than I h. The rheological process during LIV irradiation for CDAAC/trans-ACA （14 mmol- L- 1/10 mmol. L 1） micelle proves that viscosity, elastic modulus G＇ and viscous modulus G＂ will reduce quickly with the UV light. Furthermore, the micelle system after 1 h UV- irradiation is able to revert to its initial high viscosity with 460 nm visible light irradiation for 4 h, and the micelle can be cycled between low and high viscosity states by repetitive UV and visible light irradiations. The LIV-Vis spectra of CDAAC/trans-ACA micelle indicate that its photosensitive theological properties are related closely to photoisomerization of trans-ACA to c/s-ACA.

关键词： Photorheological micelle Polymerizable cationic surfactant4-Phenylazo benzoic acid Rheological properties

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Gradient Wetting Transition from the Wenzel to Robust Cassie-Baxter States along Nanopillared Cicada Wing and Underlying Mechanism

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Journal of Bionic Engineering 2020年第5期17卷 1009-1018页

作者： Heng Xie Hanxiong Huang Lab for Micro Molding and Polymer rheology Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing and Key Laboratory of Polymer Processing Engineering(Ministry of Education)South China University of TechnologyGuangzhou 510640China

Gradient wettability is important for some living ***,the dynamic responses of water droplets impacting on the surfaces of four regions along the wing vein of cicada Cryptotympana atratafabricius are *** is revealed that a gradient wetting behavior from hydrophilicity(the Wenzel state)to hydrophobicity and further to superhydrophobicity(the Cassie-Baxter state)appears from the foot to apex of the *** droplets impacting on the hydrophilic region of the wing cannot rebound,whereas those impacting on the hydrophobic region can retract and completely *** hydrophobic region exhibits robust water-repelling performance during the dynamic droplet ***,a droplet sitting on the hydrophobic region can recover its spherical shape after squeezed to a water film as thin as 0.45 mm,and lossless droplet transportation can be achieved at the *** on the geometric parameters of the nanopillars at the hydrophilic and hydrophobic regions on the cicada wing,two wetting models are developed for elucidating the mechanism for the gradient wetting *** work directs the design and fabrication of surfaces with gradient wetting behavior by mimicking the nanopillars on cicada wing surface.

关键词： cicada wing nanopillared surface biomimetic gradient wetting transition dynamic wetting behavior

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On-demand Direct Design of Polymeric Thermal Actuator by Machine Learning Algorithm

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Chinese Journal of Polymer Science 2020年第8期38卷 908-914,I0009页

作者： Bo-En Liu Wei Yu Advanced rheology Institute Department of Polymer Science and EngineeringState Key Laboratory for Metal Matrix Composite MaterialsShanghai Key Laboratory of Electrical Insulation and Thermal AgeingShanghai Jiao Tong UniversityShanghai 200240China

The design optimization of thermal-driven actuators is a challenging task because the performance depends on multiple materials parameters,structural parameters,and working *** this work,we adopted large scale finite element simulation together with machine learning algorithm to fulfill the on-demand design of thermal *** element analysis was used to simulate the performance of thermal actuator with two-layer structure,which generated large amount of dataset by considering the variation of parameters including the moduli,thermal expansion coefficient,sample thickness and length,and *** vector regression(SVR)was adopted to establish the relationship between multiple input parameters and the resulting contact ***,a simple interior point algorithm was used to achieve the on-demand design based on the SVR *** contact pressures of thermal actuator constructed from the optimized parameters deviated less than 15%of the target values.

关键词： Polymer composites Thermal actuator Finite element analysis Support vector regression

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Sliding Dynamics of Slide-Ring Polymers Based on the Bead-Spring Model

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Chinese Journal of Polymer Science 2023年第9期41卷 1410-1424,I0007页

作者： Zhong-Qiang Xiong Wei Yu Advanced rheology Institute Department of Polymer Science and EngineeringState Key Laboratory for Metal Matrix Composite MaterialsShanghai Jiao Tong UniversityShanghai200240China

Understanding the sliding dynamics is critical for developing rotaxane-based mechanically interlocked *** this work,we studied the sliding behavior of a sliding ring and its influence on the dynamics of attached polymer chains based on the heterogeneous beadspring *** sliding constraint was treated as direction-related confinement with the heterogeneous friction coefficient and constraint *** relaxation spectrum,the diffusion dynamics,and the sliding dynamics under/after drag were studied for typical sliding chain topologies,namely,the sliding dangling chain,the constraint sliding chain,and the sliding *** with the non-sliding chains(such as the free chain,the dangling chain,and the network strand),the slide of one or two chain ends induces an additional slow process in the transition from the Rouse-type behavior to the long-time terminal *** effect of the sliding-related process on the diffusion of specific chain segments relies on the chain *** slow sliding relaxation process is also observed in the sliding process during and after chain deformation,whose characteristic time is at least three times the terminal relaxation time of the free chain with the same length,and will increase with the friction coefficient(i.e.,the interaction)between the ring and the polymer *** results of this work will benefit the understanding of the sliding dynamics in experiments.

关键词： Sliding chain Bead-spring model Heterogeneity Diffusion Mean conformation

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OVERSHOOTS IN STRESS AND FREE ENERGY CHANGE DURING THE FLOWINDUCED CRYSTALLIZATION OF POLYMERIC MELT IN SHEAR FLOW

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Chinese Journal of Polymer Science 2010年第4期28卷 657-666页

作者：张洪斌 Advanced rheology Institute School of Chemistry and Chemical TechnologyShanghai Jiao Tong University

The effect of pre-shear flow on the subsequent crystallization process of polymeric melt was investigated and a flow-induced crystallization （FIC） model based on the conformation tensor incorporating the pre-shear effect was proposed. The model is capable of predicting the overshoot phenomena of the stress and the flow-induced free energy change of the polymeric system at high pre-shear rates. Under the condition of flow, the increase in the activated nuclei number was contributed by the flow-induced free energy change, which showed an overwhelming effect on the nuclei formation during the pre-shear process at high shear rates. The half crystallization time （t1/2） of polypropylene （PP） as functions of pre-shear rate and pre-shear time at different crystallization temperatures was predicted and compared with the experiment data. Both numerical and experimental results showed that t1/2 of PP decreased dramatically when the flow started but leveled off at long times. It was found that two transformation stages in t1/2 existed within a wide range of shear rates. For the first stage where the melting polymer experienced a relatively weak shear flow, the acceleration of crystallization kinetics was mainly contributed by the steady value of free energy change while in the second stage for high shear rates, strong overshoot in flow-induced free energy change occurred and the crystallization kinetics was thus significantly enhanced. The overshoots in stress and flow-induced free energy change reflected an important role of flow on the primary nucleation especially when the flow was strong enough.

关键词： Crystallization kinetics Half crystallization time Flow Model Conformation tensor

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Interfacial Chain Entanglements Induced Melt Memory Effect in Poly(ε-caprolactone)/Silica Nanocomposites

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Chinese Journal of Polymer Science 2022年第11期40卷 1451-1465页

作者： Xiang Liu Wen-Zhi Cui Wei Yu Advanced rheology Institute Department of Polymer Science and EngineeringShanghai Key Laboratory of Electrical Insulation and Thermal AgeingState Key Laboratory for Metal Matrix Composite MaterialsShanghai Jiao Tong UniversityShanghai200240China

It is known that the enhanced melt memory effect is strongly correlated with the retarded chain ***,previous studies using differential scanning calorimetry(DSC)showed a weakened or even vanished melt memory in polymer nanocomposites,although adding nanoparticles in polymers often reduces chain *** this work,we added two kinds of silica nanoparticles,O15 and W22 nanoparticles(with low and high surface silanol density,respectively),to poly(ε-caprolactone)(PCL),where the degree of chain entanglements near nanoparticles increases,and chain dynamics is gradually retarded with increasing silica *** strongly aggregated W22 nanoparticles show significant heterogeneous nucleation,while well-dispersed O15 nanoparticles exhibit very weak heterogeneous *** contrast to the restrained self-nucleation effects during the rapid non-isothermal crystallization of two nanocomposites,we found evident melt memory effects during the slow isothermal crystallization in PCL/O15 nanocomposites as indicated by DSC and polarized light microscopy(PLM)*** melt memory becomes stronger with more O15 nanoparticles,but depends non-monotonically on the loadings of W22 *** lifetime of the melt memory effects matches the chain re-entanglement time of the SN melts of nanocomposites,which is consistent with our previous work on PCL miscible *** complicated influence of silica on nucleation and crystal growth is induced by the spatial inhomogeneity of chain entanglements in the silica-filled PCL *** decrease in the entanglement density of the interfacial chains in the SN melts of nanocomposites is conducive to nucleate under slow isothermal crystallization,but the chain mobility is still greatly restrained by the nanoparticles,causing the slow growth rate of spherulites and the difficulty to form nuclei under fast non-isothermal crystallization.

关键词： PCL Silica nanocomposite Self-nucleation crystallization

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Universal Concentration Scaling on Rheometric Properties of Polydisperse and High Molecular Weight Polyacrylamide Aqueous Solutions

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Chinese Journal of Polymer Science 2022年第11期40卷 1432-1440页

作者： Yuan-Qi Fan Alfredo Lanzaro Xue-Feng Yuan Institute for Systems rheology Guangzhou UniversityHigher Education Mega-CenterGuangzhou510006China

A great progress has been made over the last decades in studying concentration scaling on rheometric properties of monodisperse polymer ***,the effects of polydisperse polymer solutions on such a concentration scaling remain *** this work,rheometric properties of industrially relevant polydisperse and high molecular weight polyacrylamide(PAAm)aqueous solution have been *** results show a concentration scaling of the characteristic relaxation time,the plateau modulus and the zero-shear viscosity across a concentration range from 10c^(*)to 250c^(*).The time-concentration superposition principle is validated and extended in the data analysis of the terminal dynamic *** concentration scaling exponent of their shifting factors is significantly smaller than the results of monodisperse polymer solutions in good andθsolvents reported in the *** steady shear viscosity and shear stress of 18M PAAm aqueous solutions with relatively lower concentration(≤35c^(*))could also be superimposed into a master curve with the shear-thinning exponent of 0.73±0.03 and0.27±0.03,respectively,over a wide range of shear rates in about six orders of ***,for 18M PAAm aqueous solutions with higher concentration(≥48c^(*))in an intermediate shear thinning regime,the scaling exponent shows a pronounced concentration *** shear thinning exponent of steady shear viscosity varies from 0.73 to 0.57 as concentration is increased,and then increases from 0.57 to 0.90from sufficiently high shear *** increasing shear rate,the shear-thinning exponent of 18M PAAm aqueous solutions at all concentrations converges to the lower bounded value observed in the relatively less concentrated(≤35c^(*))18M PAAm aqueous solutions,i.e.,0.73±0.02 for shear viscosity and 0.27±0.02 for steady shear stress,*** reveals that the concentration effects of polydisperse polymer solutions could be greatly reduced by the dynamic"molecular indi

关键词： Polymer solution Polydispersity Rheometric properties Time-concentration superposition principle

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Modeling of unidirectional blood flow in microvessels with effects of shear-induced dispersion and particle migration

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Applied Mathematics and Mechanics(English Edition) 2022年第10期43卷 1585-1600页

作者： G.ROURE F.R.CUNHA laboratory of Microhydrodynamics and rheology Department of Mechanical EngineeringUniversity of BrasíliaBrasília70910900Brazil Department of Chemical and Biological Engineering University of Colorado BoulderBoulder803090596USA

A cell-free layer,adjacent to microvessel walls,is present in the blood flow in the microcirculation *** layer is of vital importance for the transport of oxygen-saturated red cells to unsaturated *** this work,we first discuss the physics of formation of this cell-free layer in terms of a balance between the shear-induced dispersion and particle *** this end,we use high-viscosity drops as prototypes for cells,and discuss our results in terms of physical parameters such as the viscosity ratio and the capillary *** also provide a short-time analysis of the transient drift-dispersion equation,which helps us better explain the formation process of the cell-free ***,we present models for investigating the blood flow in two different scales of *** investigating the blood flow in venules and arterioles,we consider a continuous core-flow model,where the core-flow solution is considered to be a Casson fluid,surrounded by a small annular gap of Newtonian plasma,corresponding to the cell-free *** also propose a simple model for smaller vessels,such as capillaries,whose diameters are of a few *** this lower-bound limit,we consider a periodic configuration of aligned,rigid,and axi-symmetric cells,moving in a Newtonian *** this regime,we approximate the fluid flow using the lubrication *** intrinsic viscosity of the blood is theoretically predicted,for both the lower and upper-bound regimes,as a function of the non-dimensional vessel diameter,in good agreement with the previous experimental *** compare our theoretical predictions with the experimental data,and obtain qualitatively good agreement with the well-known Fåhræus-Lindqvist effect.A possible application of this work could be in illness diagnosis by evaluating changes in the intrinsic viscosity due to blood abnormalities.

关键词： theory flow dispersion

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Catalytic activities of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol

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Journal of Environmental Sciences 2015年第9期27卷 83-90页

作者： Ogheneochuko Oputu Mahabubur Chowdhury Kudzanai Nyamayaro Olalekan Fatoki Veruscha Fester Department of Chemistry Cape Peninsula University of Technology Flow Process and rheology Centre Cape Peninsula University of Technology

We report the catalytic properties of ultra-small β-FeOOH nanorods in ozonation of4-chlorophenol（4-CP）. XRD, TEM, EDS, SAED, FTIR and BET were used to characterize the prepared material. Interaction between O3 and β-FeOOH was evident from the FTIR *** removal efficiency of 4-CP was significantly enhanced in the presence of β-FeOOH compared to ozone alone. Removal efficiency of 99% and 67% was achieved after 40 min in the presence of combined ozone and catalyst and ozone only, respectively. Increasing catalyst load increased COD removal efficiency. Maximum COD removal of 97% was achieved using a catalyst load of 0.1 g/100 m L of 4-CP solution. Initial 4-CP concentration was not found to be rate limiting below 2 × 10^-3mol/L. The catalytic properties of the material during ozonation process were found to be pronounced at lower initial p H of *** stage first order kinetics was applied to describe the kinetic behavior of the nanorods at low p H. The first stage of catalytic ozonation was attributed to the heterogeneous surface breakdown of O3 by β-FeOOH, while the second stage was attributed to homogeneous catalysis initiated by reductive dissolution of β-FeOOH at low p H.

关键词： Ultra-small β-FeOOH Heterogeneous–homogeneous catalysis Catalytic ozonation Waste water treatment

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The viscosity at the glass transition of a liquid lubricant

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Friction 2019年第1期7卷 86-91页

作者： Scott BAIR Center for High-Pressure rheology George W.Woodruff School of Mechanical Engineering Georgia Institute of Technology

In the classical study of elastohydrodynamic lubrication(EHL) which does not employ real, measurable viscosity in analysis, the possibility of a glass transition has not been considered in many years. Indeed, the two rheological assumptions of classical EHL, the Newtonian inlet and the equivalence of a traction curve to a flow curve, would not have persisted so long had the pressure dependence of the viscosity been accurately stated. With the recent appearance of viscosity obtained from viscometers in EHL analysis, the possibility of a glass transition in the contact should be reexamined, especially for the fragile traction fluids. This article employs published data for a synthetic cycloaliphatic hydrocarbon to estimate the glass transition viscosity so that, when using real viscosities in EHL simulations, the state of the liquid may be assessed. Far into the glassy state the liquid should be treated as an elastic solid with a yield stress.

关键词： elastohydrodynamic lubrication glass transition high pressure viscosity EHL friction

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