Download or read book The Effect of Assembly Technique on Weak Polyelectrolyte Multilayer Film Morphology and Humidity Swelling deswelling Behavior written by Ziyang Yin and published by . This book was released on 2016 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research is to investigate the film morphology and humidity swelling/deswelling behavior of polyelectrolyte multilayers (PEMs) that are constructed from poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) by two assembly techniques: automated dipping layer-by-layer (LbL) and spin-assisted (SA) LbL. Two sets of pH polyelectrolyte solution conditions were tested: (PAH7.5/PAA3.5) and (PAH7.0/PAA7.0). It was found that when the films were constructed with the same number of bilayers (=20 bilayers), SA-LbL (PAH7.5/PAA3.5) has a greater thickness than (PAH7.0/PAA7.0). (PAH7.5/PAA3.5) thin films constructed by automated dipping LbL did not result in a uniform film morphology, making thickness comparisons between techniques for those assembly conditions difficult. On the other hand, the thickness of (PAH7.0/PAA7.0)20 thin films constructed by automated dipping LbL was a tenth of the thickness of (PAH7.0/PAA7.0)20 thin films constructed by SA-LbL. In addition, film morphology was studied for the uneven automated dipping LbL (PAH7.5/PAA3.5)20 thin film using contact mode AFM. Silane treatment and an adsorbed polyethylenimine (PEI) underlayer were attempted to produce a smooth film surface. However, neither surface treatments gave a smooth film surface for the uneven automated dip-coated LbL (PAH7.5/PAA3.5)20. Therefore, the assembly technique is an important factor on the thin film thickness and film morphology. Humidity swelling/deswelling tests were carried out on SA-LbL (PAH7.5/PAA3.5)20, SA-LbL (PAH7.0/PAA7.0)20, and automated dip-coated LbL (PAH7.0/PAA7.0)20. SALbL (PAH7.5/PAA3.5)20 and SA-LbL (PAH7.0/PAA7.0)20 demonstrated a maximum swelling of approximately 40% under a humid air environment. However, the humidity hysteresis effect for the automated dipping LbL (PAH7.0/PAA7.0)20 was hard to tell due to the high uncertainty in the film thickness.
Download or read book The Influence of Assembly PH and Clay Inclusion on the Actuation of Polyelectrolyte Multilayers written by Xiang Ji and published by . This book was released on 2016 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: The layer-by-layer (LbL) assembly is a useful technique to fabricate multifunctional thin films by exposing substrates alternatively to cationic and anionic solutions. In this work, branched poly(ethyleneimine) (BPEI) and poly (acrylic acid) (PAA) are two weak polyelectrolytes for multilayer films assembly. The BPEI/PAA multilayer films have been proved to have a large-scale reversible swelling/shrinking property when exposed to organic solvents. To further study this actuating behavior, we focus on the effect of the anionic solution on multilayer assembly by adjustment of assembly pH or addition of clay nanoparticles.Thin films of polymer and sodium montmorillonite (Na+-MMT) were grown on silicon wafers or polystyrene substrates. Viscoelasticity properties were measured by a shear rheometer, indicating the clay-containing films were fluid-like when exposure to water and solid-like when exposure to organic solvents. Furthermore, it was proved that clay particles inside the multilayers have enhanced the film stiffness.The influence on film growth was studied by ellipsometer and microscope. FTIR and TGA tests were used to characterize the clay presence in polymer films. By using a balance with a load cell, the stress of films was measured.Swelling/contraction behavior of films soaked in water or ethanol was tested using an in-situ ellipsometer. To quantify the actuation behavior of films, curl degree measurement was carried out. Furthermore, these clay-contained films were proved to have self-folding properties, which have potential application as actuators.
Download or read book Swelling and Contraction Properties for Polyelectrolyte Multilayers and Polymer Thin Films Measured by In situ Ellipsometry written by Yubing Ma and published by . This book was released on 2016 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Weak polyelectrolyte multilayers (PEMs) fabricated by the Layer by Layer (LBL) assembling technique showed special swollen and contraction behaviors when they came in contact with water and organic liquids. The contraction responses of PEM were found to be dependent on the solvent selection. The correlation between the degrees of the films contraction and the solvent type needed be explored. Therefore, in this study, we utilized solubility parameters to discuss the responses for branched poly (ethylene imine)/poly (acrylic acid) (BPEI/PAA) multilayers when soaked in a variety of solvent liquids. When immersed in organic solvents, film dehydrated and contraction also caused mechanical property changes for BPEI/PAA films. The film's thickness was the best predictor for determining how a film swelled in water or contracted in organic liquid. The hydrogen bonding ability of the solvents played an important role in determining the degree of film contraction in most cases, for these solvents, it did so when increasing the temperature of the measurement corresponding to reducing the strength of the hydrogen bonding, and decreasing the ability to dehydrate the films as well. However, some solvents did not follow the linear trend with the strength of hydrogen bonding; in these, a stronger correlation was observed between contraction degrees and dielectric constants, showing that traditional solvent quality discussions and electrostatics were significant to understanding the contraction behavior of PEMs in organic solvents. Besides the PEM system, the swelling behavior of poly(n-propyl methacrylate), PPMA, films in water were also measured in-situ using spectroscopic ellipsometry. Two different end groups grafted poly (n-propyl methacrylate)s with similar high molecular weight were successfully synthesized by the reversible addition-fragmentation chain-transfer polymerization (RAFT) synthesis method. The end group of the two PPMAs impacted the swelling behavior over the temperature range of 25 to 50 0C At 25 0C, the dithiobenzoate terminated PPMA (PPMA-DB) leading to significantly less swelling (4.2 vol%) than the dodecylsulfanylthiocarbonyl terminated PPMA (PPMA-DD, 6.4 vol%). These PPMA films swelled significantly more than one would expect since their hydrophobicity, which was attributed to the other end group from RAFT being a carboxylic acid in both polymers. As the temperature was increased, the swelling for the PPMA-DB increased; the swelling decreased for the PPMA-DD with a crossover at approximately 350C Both the swelling processes had two stages: an initial rapid swelling within the first minute and then a slow increase in thickness over several hours. The different swelling trends of the PPMA-DB and PPMA-DD described the end group effect on the polymers especially the chain conformations. Additionally, for the mechanical properties of these two kinds of PPMA, the elastic modulus was similar; however, the fracture modulus showed some difference, in that the larger swelling PPMA-DD films have a somewhat smaller fracture strength also influenced by the different end groups.
Download or read book Layer by Layer Directly Assembly of Polyelectrolyte Multilayers with Foaming Structures written by Lihua Xu and published by . This book was released on 2015 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent decades, dynamic Layer-by-Layer (LbL) assembly of multilayer thin films has been widely recognized for many reasons, especially for its versatile functionality and ease of fabrication. Films can be fabricated towards huge amounts of materials, such as polyelectrolytes, organic components, polymeric microgels, etc. Through the long history of LbL assembly research, few papers proposed ideas of making porous films or foamed films directly or indirectly, as foamed material contained plenty of pores, which could be used in insulation materials and fast food-packages. In several papers, the step of acid treatment aimed for irreversible structure transformation applied into films fabricated by the LbL assembly method. This indirect method makes procedures more complex, so direct fabrication with LbL is necessary. However, time-consuming problems and challenges from external environmental factors still limits the development of this technique. In this thesis, a facile fabrication of porous films through the LbL assembly method was introduced. Strong polyelectrolyte, polycation poly(diallyldimethylammonium-chloride) (PolyDADMAC) and polyanion poly(styrene sulfonate acid) (PSSA) are utilized as the original material. And PolyDADMAC was slightly modified by sodium hydroxide (NaOH) and carbon dioxide (CO2) in order to get the bicarbonate structure at the side groups along the chain of the polyelectrolyte. In order to deeply study the films, some other particles, such as the surfactant brij-76 and RDS laponite were added into certain solutions for comparison. Films were achieved by alternately putting clean glass slides into the polycation and polyanion solutions with the rinsing step in between. 20-bilayer film can be achieved after repeating the procedures above 20 times. The principle is that the bicarbonate functional group will react with the hydrogen ions for the sake of letting the gas carbon dioxide out and then make the porous structure throughout the film. The morphology of the films measured by an atomic force microscope (AFM) and a scanning electron microscope (SEM) shows that porous structures are obvious through the whole film when no sodium bicarbonate (NaHCO3) is added into the anion solution. The results help to solve the problem of directly making the foaming films as well as simplifying the procedures.
Download or read book Mechanical Properties and Swelling Behavior of BPEI metal Ion PAA Polyelectrolyte Multilayer Films written by Mingzhe Li and published by . This book was released on 2014 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The layer-by-layer (LbL) technique is a well-established approach of making a wide range of functional thin films known as polyelectrolyte multilayers (PEMs) with nanoscale controllable thickness. LbL assemblies are formed with reversible types of "bonds" (e.g., electrostatic force, hydrogen bonding), and further introduction of metal ions can alter the underlying molecular architecture and create linkages of different strengths, potentially leading to new properties.This study incorporated various metal ions (e.g., Ag+, Cu2+, and Fe3+) into the PEMs assembly from branched poly(ethyleneimine) (BPEI) and poly(acrylic acid) (PAA) by using the BPEI-metal ion complexes as the polycation. In the PEMs the metal ions not only bind with the amine groups in BPEI but also interact with the carboxyl groups in PAA. A combined surface wrinkling-cracking technique was applied as a tool for assessing the mechanical properties of the multilayer films. This technique enables the direct determination of a comprehensive set of key mechanical properties, including Young's modulus, fracture strength, and fracture strain. The incorporation of Ag+ and Cu2+ into the PEMs does not result in change of elastic modulus while Fe3+ decreases the modulus. The introduction of three metal ions lead to an increase in the fracture strength to different extent, respectively. The swelling behavior of metal ion containing PEMs was also investigated by in situ ellipsometry in order to clarify the internal structure.
Download or read book Investigating the Adhesive Strength and Morphology of Polyelectrolyte Multilayers by Atomic Force Microscopy written by Sena Ada and published by . This book was released on 2008 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Polyelectrolyte multilayer (PEM) thin films prepared via the Layer-by-Layer (LbL) deposition technique are of special interest in this research. The purpose of this study is to replace current mechanical closure systems, based on hook-and-loop type fasteners (i.e. Velcro), with PEM thin film systems. The technique is simple, cheap, versatile and environmental friendly; as a consequence a variety of thin films can be easily fabricated. By proposing PEMs as non-mechanical and nanoscopic molecular closures, we aim to obtain hermetic sealing, good adhesive strength, and peel off ease. Atomic force microscopy (AFM) and colloidal probe techniques were used to characterize the morphology, roughness and adhesive properties of PEMs. AFM measurements were conducted in air, necessarily requiring careful control of ambient humidity. PEMs were formed by consecutive deposition of polyanions and polycations on a charged polyethylene terephthalate (PET) solid surface, the result of which was stable nanostructured films. By systemically varying the parameters of PEM build-up process: different combinations of polyelectrolytes, different numbers of bilayers (polyanion/polycation pairs), and miscellaneous types and concentrations of salts (NaCl, NaBr and NaF salts at 0.5 M and 1.0 M concentrations), the adhesion and morphology of PEMs were thoroughly investigated. The PEM thin films specifically investigated include poly(ethyleneimine) (PEI), poly(styrene sulfonate) (PSS), poly(allylamine hydrochloride) (PAH), poly(acrylic acid) (PAA), and poly(diallydimethylammonium chloride) (PDADMAC). Silica colloidal probes were utilized in the investigation, some of which were functionalized with COOH and/or coated with PEI-PSS. Silica colloidal probes were used in order to quantify interaction forces on the PEMs. A functionalized silica colloidal probe (a probe with COOH surface chemistry) and a silica colloidal probe coated with PEI-PSS were used to simulate PEM-PEM interactions. The results suggest that adhesion in the PEMs depend on the number of layers, the salt concentration and the salt type used during the build-up process, the environmental conditions where the adhesion force measurements were made, and the choice of probe.
Download or read book Adhesive Properties of Wet Polyelectrolyte Multilayer Films and Electrophoretic Deposition of Polyelectrolyte Complexes written by Chao Li and published by . This book was released on 2016 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Weak polyelectrolyte multilayers prepared by using layer-by-layer (LbL) technique are known to become sticky upon contact with water and behave as a viscoelastic fluid, but the full extent of this wet adhesive property is not fully understood. In this study, the wet adhesive performance of polyelectrolyte multilayers consisting of branched poly(ethylene imine) and poly(acrylic acid) under controlled conditions was investigated by using a 90° peel test. The peel force is highest under neutral condition, and it decreases in acidic/basic environment. The addition of metal ions changes the peel force, either increasing it or decreasing it based on the nature of the metal ion. Addition of Cu2+ stiffens multilayers, preventing multilayers from acting as an effective wet adhesive. The films are also characterized with zeta potential and shear rheometry, and the adhesiveness can be recovered by rewetting for at least 5 times. This polyelectrolyte based wet adhesive can be adhered to soft, wet surfaces like biological tissues such as liver. These multilayer films in this work show wet adhesive properties, however, the layer by layer technique used to fabricate these films requires several steps and take a long time. Therefore, new methods are needed to make these thin films. Spin-assisted LbL assembly, spray-assisted LbL assembly and electric field-assisted LbL assembly are widely studied because they are simple and time-saving. Electric field-assisted LbL assembly has been gaining an increasing interest. One option for realizing this may be the electrophoretic deposition of weak polyelectrolyte complexes, made by mixing polyelectrolytes of opposite charge together, has not been studied yet. Therefore, electrodeposition of polyelectrolyte complexes under different conditions (i.e. pH, ratio of polycation and polyanion, concentration of polyelectrolyte complexes, concentration of salt and type of electric field) was investigated in this work. Polyelectrolyte complexes at moderate pH values and at the ratio of polycation and polyanion at 20 shows highest electrophoretic mobility. The thickness of polyelectrolyte complex film decreases with decreasing the concentration of polyelectrolyte complexes while the thickness increases when a proper amount of salt is added during preparing polyelectrolyte complexes. Under controlling pulse current at 10mA, a thicker film can be achieved but the surface is rougher compared with one prepared by using pulse potential at 10V. This work provides insight into both the wet adhesive properties of polyelectrolyte multilayers and electrophoretic deposition of polyelectrolyte complexes.
Download or read book Polyelectrolytes written by Visakh P. M. and published by Springer. This book was released on 2014-09-03 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a valuable reference source to graduate and post graduate students, engineering students, research scholars polymer engineers from industry. The book provides the reader with current developments of theoretical models describing the thermodynamics polyelectrolytes as well as experimental findings. A particular emphasis is put on the rheological description of polyelectrolyte solutions and hydrogels.
Download or read book Handbook of Polyelectrolytes and Their Applications Applications of polyelectrolytes and theoretical models written by Sukant K. Tripathy and published by . This book was released on 2002 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Porous Polymers written by Michael S. Silverstein and published by John Wiley & Sons. This book was released on 2011-02-14 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the various aspects of the porous polymer field into one volume. It not only presents a fundamental description of the field, but also describes the state of the art for such materials and provides a glimpse into the future. Emphasizing a different aspect of the ongoing research and development in porous polymers, the book is divided into three sections: Synthesis, Characterization, and Applications. The first part of each chapter presents the basic scientific and engineering principles underlying the topic, while the second part presents the state of the art results based on those principles. In this fashion, the book connects and integrates topics from seemingly disparate fields, each of which embodies different aspects inherent in the diverse field of porous polymeric materials.
Download or read book Holographic Sensors written by Ali Kemal Yetisen and published by Springer. This book was released on 2014-12-03 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a theoretical and experimental approach for the rapid fabrication, optimization and testing of holographic sensors for the quantification of pH, organic solvents, metal cations, and glucose in solutions. Developing non-invasive and reusable diagnostics sensors that can be easily manufactured will support the monitoring of high-risk individuals in any clinical or point-of-care setting. Sensor fabrication approaches outlined include silver-halide chemistry, laser ablation and photopolymerization. The sensors employ off-axis Bragg diffraction gratings of ordered silver nanoparticles and localized refractive index changes in poly (2-hydroxyethyl methacrylate) and polyacrylamide films. The sensors exhibited reversible Bragg peak shifts, and diffracted the spectrum of narrow-band light over the wavelength range λpeak ≈ 495-1100 nm. Clinical trials of glucose sensors in the urine samples of diabetic patients demonstrated that they offer superior performance compared to commercial high-throughput urinalysis devices. Lastly, a generic smartphone application to quantify colorimetric tests was developed and tested for both Android and iOS operating systems. The sensing platform and smartphone application may have implications for the development of low-cost, reusable and equipment-free point-of-care diagnostic devices.
Download or read book Bio inspired Polymers written by Nico Bruns and published by Royal Society of Chemistry. This book was released on 2016-10-14 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many key aspects of life are based on naturally occurring polymers, such as polysaccharides, proteins and DNA. Unsurprisingly, their molecular functionalities, macromolecular structures and material properties are providing inspiration for designing new polymeric materials with specific functions, for example, responsive, adaptive and self-healing materials. Bio-inspired Polymers covers all aspects of the subject, ranging from the synthesis of novel polymers, to structure-property relationships, materials with advanced properties and applications of bio-inspired polymers in such diverse fields as drug delivery, tissue engineering, optical materials and lightweight structural materials. Written and edited by leading experts on the topic, the book provides a comprehensive review and essential graduate level text on bio-inspired polymers for biochemists, materials scientists and chemists working in both industry and academia.
Download or read book Spectroscopic Ellipsometry and Reflectometry written by Harland G. Tompkins and published by Wiley-Interscience. This book was released on 1999-03-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: While single wave ellipsometry has been around for years, spectroscopic ellipsometry is fast becoming the method of choice for measuring the thickness and optical properties of thin films. This book provides the first practical introduction to spectroscopic ellipsometry and the related techniques of reflectometry. A guide for practitioners and researchers in a variety of disciplines, it addresses a broad range of applications in physics, chemistry, electrical engineering, and materials science.
Download or read book Soft Actuators written by Kinji Asaka and published by Springer Nature. This book was released on 2019-08-28 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the second edition of Soft Actuators, originally published in 2014, with 12 chapters added to the first edition. The subject of this new edition is current comprehensive research and development of soft actuators, covering interdisciplinary study of materials science, mechanics, electronics, robotics, and bioscience. The book includes contemporary research of actuators based on biomaterials for their potential in future artificial muscle technology. Readers will find detailed and useful information about materials, methods of synthesis, fabrication, and measurements to study soft actuators. Additionally, the topics of materials, modeling, and applications not only promote the further research and development of soft actuators, but bring benefits for utilization and industrialization. This volume makes generous use of color figures, diagrams, and photographs that provide easy-to-understand descriptions of the mechanisms, apparatus, and motions of soft actuators. Also, in this second edition the chapters on modeling, materials design, and device design have been given a wider scope and made easier to comprehend, which will be helpful in practical applications of soft actuators. Readers of this work can acquire the newest technology and information about basic science and practical applications of flexible, lightweight, and noiseless soft actuators, which differ from conventional mechanical engines and electric motors. This new edition of Soft Actuators will inspire readers with fresh ideas and encourage their research and development, thus opening up a new field of applications for the utilization and industrialization of soft actuators.
Download or read book Bioactive Surfaces written by Hans G. Börner and published by Springer Science & Business Media. This book was released on 2011-06-01 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Erik Wischerhoff, Nezha Badi, André Laschewsky and Jean-François Lutz Smart Polymer Surfaces: Concepts and Applications in Biosciences; S. Petersen, M. Gattermayer and M. Biesalski Hold on at the Right Spot: Bioactive Surfaces for the Design of Live-Cell Micropatterns; Julien Polleux Interfacing Cell Surface Receptors to Hybrid Nanopatterned Surfaces: A Molecular Approach for Dissecting the Adhesion Machinery; Abigail Pulsipher and Muhammad N. Yousaf Self-Assembled Monolayers as Dynamic Model Substrates for Cell Biology; D. Volodkin, A. Skirtach and H. Möhwald LbL Films as Reservoirs for Bioactive Molecules; R. Gentsch and H. G. Börner Designing Three-Dimensional Materials at the Interface to Biology; Joerg C. Tiller Antimicrobial Surfaces;
Download or read book PEDOT written by Andreas Elschner and published by CRC Press. This book was released on 2010-11-02 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: While there is information available in handbooks on polythiophene chemistry and physics, until now, few if any books have focused exclusively on the most forwardly developed electrically conductive polymer, Poly (3,4-ethylenedioxythiophene)-otherwise known as PEDOT. This resource provides full chemical, physical, and technical information about this important conducting polymer, discussing basic knowledge and exploring its technical applications. Presented information is based on information generated at universities and through academic research, as well as by industrial scientists, providing a complete picture of the experimental and the practical aspects of this important polymer.
Download or read book Handbook of Industrial Water Soluble Polymers written by Peter A. Williams and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural and synthetic water soluble polymers are used in a wide range of familiar industrial and consumer products, including coatings and inks, papers, adhesives, cosmetics and personal care products. They perform a variety of functions without which these products would be significantly more expensive, less effective or both. Written for research, development and formulation chemists, technologists and engineers at graduate level and beyond in the fine and specialty chemicals, polymers, food and pharmaceutical industries, the Handbook of Industrial Water Soluble Polymers deals specifically with the functional properties of both natural and synthetic water soluble polymers. By taking a function based approach, rather than a “polymer specific” approach the book illustrates how polymer structure leads to effect, and shows how different polymer types can be employed to achieve appropriate product properties.
