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Soft Matter

Steven W Cranford, Lin Han, Christine Ortiz, Markus J Buehler
In this study, the pH-dependent friction of layer-by-layer assemblies of poly(allylamine hydrochloride) and poly(acrylic acid) (PAH/PAA) are quantified for microtube array structures via experimental and simulated lateral force microscopy (LFM). A novel coarse-grain tube model is developed, utilizing a molecular dynamics (MD) framework with a Hertzian soft contact potential (such that F ∼ δ(3/2)) to allow the efficient dynamic simulation of 3D arrays consisting of hundreds of tubes at micrometer length scales...
July 21, 2017: Soft Matter
Michelle Gervasio, Kathy Lu
Imprint lithography has been explored as a method to transfer arrays of patterned features onto pure polymers and polymer/metallic nanoparticle composites. Despite the success of this method for those materials, it has never been achieved on the sub-micron scale with polymer-oxide particle hybrids. This study patterns ZnO-PMMA (poly(methyl methacrylate)) hybrids via imprint lithography from co-suspensions of PMMA and ZnO nanoparticles in anisole from 1 vol% to 20 vol% ZnO solids loading. ZnO nanoparticles are functionalized with nonanoic acid to disperse the nanoparticles in anisole with dissolved PMMA...
July 21, 2017: Soft Matter
Nestor Lopez Mora, Yue Gao, M Gertrude Gutierrez, Justin Peruzzi, Ivan Bakker, Ruud J R W Peters, Bianka Siewert, Sylvestre Bonnet, Roxanne E Kieltyka, Jan C M van Hest, Noah Malmstadt, Alexander Kros
Giant Unilamellar Vesicles (GUVs) prepared from phospholipids are becoming popular membrane model systems for use in biophysical studies. The quality, size and yield of GUVs depend on the preparation method used to obtain them. In this study, hydrogels consisting of dextran polymers crosslinked by poly(ethylene glycol) (DexPEG) were used as hydrophilic frameworks for the preparation of vesicle suspensions under physiological ionic strength conditions. A comparative study was conducted using hydrogels with varied physicochemical properties to evaluate their performance for GUV production...
July 21, 2017: Soft Matter
S L M Alexander, S Ahmadmehrabi, L T J Korley
Natural systems utilize nanofiber architectures to guide water transport, tune mechanical properties, and actuate in response to their environment. In order to harness these properties, a hygromorphic bilayer composite comprised of a self-assembled fiber network and an aligned electrospun fiber network was fabricated. Molecular gel self-assembly was utilized to increase hydrophobicity and strength in one layer, while aligned electrospun poly(vinyl alcohol) (PVA) nanofibers increased the rate of hydration and facilitated tunable actuation in the other...
July 21, 2017: Soft Matter
Daniel E Martínez-Tong, Luis A Miccio, Angel Alegria
We present a detailed study on the ionic transport properties of polyethylene oxide (PEO) thin films prepared under different conditions. Using a state-of-the-art Atomic Force Microscopy (AFM) methodology, we simultaneously acquired the nanostructured topography of these semicrystalline polymer films as well as the corresponding dielectric function; in the latter case by probing the frequency-dependent tip-sample electrical interactions. By means of this AFM protocol, we studied the ionic conductivity in the PEO amorphous phase and its dependence on film preparation conditions...
July 21, 2017: Soft Matter
Kenneth P Mineart, Elizabeth G Kelley, Michihiro Nagao, Vivek M Prabhu
Liposomes with PEG-modified surfaces are amenable to nanocarrier applications and can be prepared via two PEGylated lipid incorporation routes: before and after extrusion (i.e., co-extrusion and post-insertion, respectively). The current study quantifies the processing influence on PEG chain partitioning between the interior and exterior liposome surfaces for the first time using small angle neutron scattering.
July 21, 2017: Soft Matter
Si-Jia Ge, Ti-Peng Zhao, Meng Wang, Lin-Lin Deng, Bao-Ping Lin, Xue-Qin Zhang, Ying Sun, Hong Yang, Er-Qiang Chen
The development of pure polymeric films with anisotropic thermal conductivities for electronic device packaging applications has attracted intense scientific attention. In order to enhance the polymeric film's normal-direction thermal conductivity, homeotropic alignment of macromolecular chains is the primary concern. One of the promising preparation strategies is to perform in situ photopolymerization of homeotropic-oriented liquid crystal monomers. In this work, we design and synthesize a novel tolane-core thiol-ene-tailed liquid crystal monomer...
July 20, 2017: Soft Matter
Chao Yuan, Devin J Roach, Conner K Dunn, Quanyi Mu, Xiao Kuang, Christopher M Yakacki, T J Wang, Kai Yu, H Jerry Qi
In this work, we advance printed active composites by combining 3D printing, printed electronics, and liquid crystal elastomers (LCEs) to achieve soft actuators with free-standing two-way shape changing behaviors. Incorporated LCE strips are activated by Joule heating produced by printed conductive wires, while uniaxial deformation of the LCE strip is utilized as a driving force to achieve bending in the printed composite. The bending behavior of laminated hinges is first characterized in order to obtain a precise control of actuation, which is then exploited to actuate four demonstrative designs: a morphing airplane, a miura-ori structure, a cubic box, and a soft crawler...
July 19, 2017: Soft Matter
Nayoung Park, Jacinta C Conrad
Correction for 'Phase behavior of colloid-polymer depletion mixtures with unary or binary depletants' by Nayoung Park et al., Soft Matter, 2017, 13, 2781-2792.
July 18, 2017: Soft Matter
Lihua Jia, Jianxin Yin, Xiangfeng Guo, Guangzhou Cao, Xuhua Tian, Bo Zhu, Lin Pu
A novel axially chiral cationic Gemini amphiphile gelator (S1) derived from (S)-BINOL has been synthesized and characterized by (1)H NMR, (13)C NMR, ESI-MS and FT-IR analyses. The critical micelle concentration (CMC) of S1 was determined to be 0.21 mM in water at room temperature. A transparent hydrogel with S1 at 43 mM was obtained at room temperature and characterized using various methods including SEM, CD, fluorescence, (1)H NMR, FT-IR, and XRD. The results indicate that the hydrophobic effect of long alkyl chains, π-π stacking of naphthalene rings, and intermolecular hydrogen-bonding of the amide groups of S1 should be responsible for the hydrogel formation...
July 17, 2017: Soft Matter
Hisay Lama, Madivala G Basavaraj, Dillip K Satapathy
The drying of a sessile drop consisting of colloidal particles and the formation of particulate deposits with spatially periodic cracks were ubiquitous. The drying induced stress, which is generated during the evaporation of a colloidal drop, is released by the formation of cracks. We find that the morphology of cracks formed in particulate films dried at substrate temperature, Tsub = 25 °C is markedly different from that of cracks formed at Tsub > 45 °C. The cracks are disordered in the former case, but ordered and periodic in the latter...
July 17, 2017: Soft Matter
Biporjoy Sarkar, Dillip K Satapathy, Manu Jaiswal
We investigate charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) films on functionalized polydimethylsiloxane (PDMS) substrates under varying uniaxial strain up to 16%. Strong anisotropy in transport is observed at a large applied strain (ε > 4%), which is understood in terms of an extrinsic process, involving a change in density of cracks from a few cracks per mm at ε = 4% to >100 cracks per mm at ε = 16%. The quasi-periodic cracks are aligned perpendicular to the stretching direction...
July 14, 2017: Soft Matter
Shi-Qing Wang
Correction for 'Nonlinear rheology of entangled polymers at turning point' by Shi-Qing Wang et al., Soft Matter, 2015, 11, 1454-1458.
July 13, 2017: Soft Matter
Shiwang Cheng, Yuyuan Lu, Gengxin Liu, Shi-Qing Wang
Correction for 'Finite cohesion due to chain entanglement in polymer melts' by Shiwang Cheng et al., Soft Matter, 2016, 12, 3340-3351.
July 13, 2017: Soft Matter
Johannes Loehr, Daniel de Las Heras, Michael Loenne, Jonas Bugase, Adam Jarosz, Maciej Urbaniak, Feliks Stobiecki, Andreea Tomita, Rico Huhnstock, Iris Koch, Arno Ehresmann, Dennis Holzinger, Thomas M Fischer
The topologically protected transport of colloidal particles on top of periodic magnetic patterns is studied experimentally, theoretically, and with computer simulations. To uncover the interplay between topology and symmetry we use patterns of all possible two dimensional magnetic point group symmetries with equal lengths lattice vectors. Transport of colloids is achieved by modulating the potential with external, homogeneous but time dependent magnetic fields. The modulation loops can be classified into topologically distinct classes...
July 13, 2017: Soft Matter
Fei Chen, Koshu Takatsuji, Dan Zhao, Xuanji Yu, Sanat K Kumar, Ophelia K C Tsui
The effects of thermal annealing, 12-50 K above the glass transition temperature, on the zero-shear viscosity, η, of polymer nanocomposites (PNCs) and the corresponding host polymers were studied. For all specimens, including neat and 4 wt% dioctyl phthalate (DOP)-plasticized polystyrene (PS), neat poly(methyl methacrylate) (PMMA), and PNCs containing bare and grafted silica nanoparticles in neat and DOP-plasticized PS, the η increased with time initially, and only asymptotically approached a steady-state value after thermal annealing for ∼100 to ∼200 h...
July 12, 2017: Soft Matter
Kazusa Beppu, Ziane Izri, Jun Gohya, Kanta Eto, Masatoshi Ichikawa, Yusuke T Maeda
Controlling the phases of matter is a challenge that spans from condensed materials to biological systems. Here, by imposing a geometric boundary condition, we study the controlled collective motion of Escherichia coli bacteria. A circular microwell isolates a rectified vortex from disordered vortices masked in the bulk. For a doublet of microwells, two vortices emerge but their spinning directions show transition from parallel to anti-parallel. A Vicsek-like model for confined self-propelled particles gives the point where the two spinning patterns occur in equal probability and one geometric quantity governs the transition as seen in experiments...
July 12, 2017: Soft Matter
Dan T Nguyen, Omar A Saleh
The programmable, sequence-dependent hybridization of DNA has spurred the development of DNA hydrogels, polymer networks that swell in water and are comprised either entirely or partially of DNA. Specific applications require hydrogels of particular structure for optimal functionality. Here, we use self-assembling, multi-valent DNA nanostars to examine how hydrogel structure is influenced by the non-equilibrium dynamics of its interacting components. We show that hydrogel aging kinetics - from an arrested, solid-like percolated network to an equilibrium, phase-separated liquid analogous to coacervates - are modulated by DNA hybridization strength and ion-specific nanostar internal flexibility...
July 12, 2017: Soft Matter
Andreas S Poulos, Christopher S Jones, João T Cabral
Linear and circular solvent penetration experiments are used to study the dissolution of anionic SLE3S surfactant mesophases in water. We show that a lamellar (Lα) phase in contact with water will transit through a series of cubic, hexagonal, and micellar phase bands with sharp interfaces identified from their optical textures. In both linear and circular geometries, the kinetics of front propagation and eventual dissolution are well described by diffusive penetration of water, and a simple model applies to both geometries, with a different effective diffusion coefficient for water Df as the only fitting parameter...
July 12, 2017: Soft Matter
Huina Cui, Xiubao Yang, Juan Peng, Feng Qiu
We report the crystallization and microphase separation behavior of an all-conjugated poly(3-hexylthiophene)-b-poly[3-(6-hydroxy)hexylthiophene] (P3HT-b-P3HHT) block copolymer in mixed solvents and demonstrate how the conformations of P3HT and P3HHT chains influence the photophysical properties of the copolymer. It is shown that the balance among π-π stacking of P3HT, P3HHT and microphase separation of the copolymer can be dynamically shifted by controlling the rod-rod interactions of the copolymer via changing the block ratio and solvent blending...
July 12, 2017: Soft Matter
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