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| 1 | Biocompatible microcapsules with a water core templated from single emulsions显示文摘Biocompatible microcapsules with a water core are widely used to encapsulate hydrophilic actives.Here,a facile method to fabricate monodisperse biocompatible microcapsules with a water core in large quantity is reported.Microfluidic technology is utilized to emulsify the inner aqueous phase containing the shell polymer into monodisperse drops in the outer oil phase.As the cosolvent in the inner aqueous phase diffuses into the outer oil phase,the solubility of the shell polymer decreases,which eventually precipitates.Since the shell polymer,shellac,contains both hydrophilic and hydrophobic groups,it tends to wet both the inner aqueous phase and the outer oil phase,thus forming a solid shell at the periphery of the drop.We show that the diffusion rate of hydrophilic molecules encapsulated in the water core decreases as their molecular weight increases and the property of the microcapsules could further be modified by polyelectrolyte multilayer coating.These microcapsules are fabricated using FDA-approved polymer and non-toxic solvents and are of great use in drugs,cosmetics and foods. | Linlin Kong Esther Amstad Mingtan Hai Xinyou Ke Dong Chen Chun-Xia Zhao David A.Weitz | 2017 | Chinese Chemical Letters2017，28，9： | 2 |
| 2 | Local high-density distributions of phospholipids induced by the nucleation and growth of smectic liquid crystals at the interface显示文摘Amphiphilic molecules adsorbed at the interface could control the orientation of liquid crystals(LCs)while LCs in turn could influence the distributions of amphiphilic molecules.The studies on the interactions between liquid crystals and amphiphilic molecules at the interface are important for the development of molecular sensors.In this paper,we demonstrate that the development of smectic LC ordering from isotropic at the LC/water interface could induce local high-density distributions of amphiphilic phospholipids.Mixtures of liquid crystals and phospholipids in chloroform are first emulsified in water.By fluorescently labeling the phospholipids adsorbed at the interface,their distributions are visualized under fluorescent confocal microscope.Interestingly,local high-density distributions of phospholipids showing a high fluorescent intensity are observed on the surface of LC droplets.Investigations on the correlation between phospholipid density,surface tension and smectic LC ordering suggest that when domains of smectic LC layers nucleate and grow from isotropic at the LC/water interface as chloroform slowly evaporates at room temperature,phospholipids transition from liquid-expanded to liquid-condensed phases in response to the smectic ordering,which induces a higher surface tension at the interface.The results will provide an important insight into the interactions between liquid crystals and amphiphilic molecules at the interface. | Chenjing Yang Li Chen Rui Zhang Dong Chen Laura R.Arriaga David A.Weitz | 2022 | Chinese Chemical Letters2022，33，8： | 1 |
| 3 | Editorial for the Special Issue on Soft Matter for Green Chemical Engineering显示文摘Soft matter refers to a class of materials that can be easily deformed,either by small forces or by thermal energy.These materials generally have both solid-like and liquid-like behaviors.They are typically characterized by some elastic coefficient whose value is many orders of magnitude less than most solids.The unit of an elastic constant is pressure or energy density.The energies that characterize materials can vary by a few orders of magnitude,from thermal energies to several electron volts,the latter of which characterize a strong covalent bond.However,the elastic coefficients of soft materials can be as much as ten orders of magnitude less than those of solids.This range must reflect a change in the length scale or the density term.Thus,the fundamental physics of soft matter always occurs at larger length scales,and it is the study of these larger length scales that gives the field its great fascination. | David A.Weitz Jian-Feng Chen | 2021 | Engineering2021，7，5： | 0 |
| 4 | Visualization of adaptive polymer flow and displacement in medium-permeable 3D core-on-a-chip显示文摘Polymer flooding has been witnessed an effective technology for enhancing oil recovery from medium-to low-permeability reservoirs;however, direct visualization of polymer solution flow in such reservoir condition is still lacking. In this work, a three-dimensional (3D) core-on-a-chip device with a permeability of around 200 mD was prepared and employed to visualize the pore-scale flow and displacement of a self-adaptive polymer (SAP, 8.7 × 106 g·mol−1)−whose microscopic association structure and macroscopic viscosity can reversibly change in response to shear action−versus partially hydrolyzed polyacrylamide (HPAM), by recording their flow curves, monitoring dynamic transportation process via particle imaging velocimetry, and building 3D structure of remaining oil. The results show that, in single-phase flow, all polymer solutions exhibit flow thinning and then thickening regions as flow rate increases, but the transition between two regimes occurs at a small Weissenberg number (10−3−10−1) in this medium-permeable condition. In contrast to HPAM-1 with close weight-average molecular weight (Mw), the adaptive character not only extends SAP's shear-govern region, allowing SAP to propagate piece by piece and achieve higher accessible pore volume, but it also enhances the elastic resistibility of polymer in the extension-dominated regime, increasing the microscopic displacement efficiency. These two effects result in 1.5–3 times more oil recovery factor for SAP than for HPAM-1. Regarding ultra-high-Mw HPAM-2 (25 × 106 g·mol−1), plugging and chain degradation do occur, thus producing lower oil recovery than SAP. This work provides a direct approach for in-situ assessment of polymer-based displacing system under a more authentic condition of practical reservoirs. | Yan Zhang Xue-Zhi Zhao Pei-Hui Han Li-Yuan Zhang David A.Weitz Yu-Jun Feng | 2023 | Petroleum Science2023，20，2： | 0 |
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