Characteristics and performance of electroactive paper actuator made with cellulose/polyurethane semi‐interpenetrating polymer networks

This article introduces a cellulose/polyurethane (PU) semi‐IPN‐based electroactive paper (EAPap) actuator. The fabrication process, bending actuation test, and its characteristics are explained. For the fabrication of cellulose/PU semi‐IPN EAPap actuator, cotton cellulose was dissolved into N,N‐dimethylacetamide (DMAc) and lithium chloride (LiCl) solvent system. PU prepolymer prepared by poly[di(ethylene glycol) adipate] and hexamethylene diisocyanate (HDI) was mixed with DMAc cellulose solution by stirring. The mixed solution was spin‐coated on a wafer and cured to form cellulose/PU semi‐IPN films using 1,1,1‐tris(hudroxymethyl)propane as the crosslinker. The characteristics of the cellulose/PU semi‐IPN film were investigated by FTIR, scanning electron microscopy (SEM), X‐ray diffraction pattern (XRD), and tensile test. The bending actuation performance of the actuator was evaluated in terms of free bending displacement with respect to the actuation frequencies, voltages, and humidity levels. It shows a good bending actuation at room humidity condition. The actuation principle of the actuator is also discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of polyethylene oxide–polyethylene glycol content and humidity on performance of electro‐active paper actuators based on cellulose/polyethylene oxide–polyethylene glycol microcomposite

The effect of humidity and polyethylene oxide (PEO)–polyethylene glycol (PEG) content on the actuator performance of cellulose/PEO–PEG microcomposites was studied. Upon blending 5% PEO–PEG, the maximum bending displacement of the actuator increased nearly twice compared to that of cellulose EAPap actuator. However, further increase of PEO–PEG content resulted in decreased actuator performance. This might be due to the increased intermolecular interaction by hydrogen bonding that reduces the mobility of the molecules. The actuator performance test showed that the increase in humidity level rather reduced the maximum displacement of the actuators. X‐ray diffractogram and Fourier transform infrared spectrum analysis suggested a structural change of the microcomposites as well as disruption of cellulose/PEO–PEG association attributed to the actuator performance degradation at high humidity level. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Dry and durable electro‐active paper actuator based on natural biodegradable polymer

This article describes a dry and durable electro‐active paper (EAPap) actuator based on natural biodegradable polymer: cellulose and chitosan. To fabricate this actuator, cellulose and chitosan were dissolved in trifluoroacetic acid. The solution was cast to form a film followed by depositing thin gold electrode on both sides of the film. The actuator was actuated under AC voltage at an ambient condition by changing the actuation voltage, frequency, and time. The actuator revealed a large bending displacement under low voltage, electrical power consumption at low humidity condition. This cellulose–chitosan blended EAPap actuator is suitable for dry and durable actuator. Details about the fabrication, durability, electrical power consumption, and characteristics as well as morphology of the actuator are explained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characteristics of the interpenetrating polymer network hydrogel composed of chitosan and polyallylamine

A temperature‐ and pH‐dependent hydrogel was studied with interpenetrating polymer network (IPN) hydrogels constructed with water‐insoluble chitosan and polyallylamine. Various IPNs were prepared from different weight ratios of chitosan–polyallylamine. Crosslinked‐IPN hydrogels exhibited relatively high equilibrium water content (EWC) in the range 80–83%. The EWC of IPN hydrogels depended on pH and the amount of complex, which is the content of chitosan and polyallylamine. The differential scanning calorimeter (DSC) thermogram of fully swollen IPN hydrogels appeared between 3 to 4 °C. The IPNs exhibited two glass‐transition temperatures (T_gs), indicating the presence of phase separation in the IPNs as exhibited by dielectric analysis (DEA). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 498–503, 2002     

Electroactive Paper Actuator Made with Chitosan‐Cellulose Films: Effect of Acetic Acid

This paper introduces an electroactive paper (EAPap) prepared with cellulose and chitosan films. The fabrication process, performance test, and the effect of acetic acid dosage of the EAPap were investigated. For the fabrication of cellulose EAPap, cellulose fibers were dissolved into a solution using N,N‐dimethylacetamide and lithium chloride. The solution was cast and immersed in water to form a cellulose film, followed by casting chitosan/acetic acid and glycerol aqueous solutions on the cellulose film. A bending EAPap actuator was made by depositing thin gold electrodes on both sides of the cellulose film. The bending displacement of the EAPap actuators was evaluated with respect to voltage, frequency, humidity, and acetic acid dosage. An optimum mole ratio of the acetic acid and chitosan structure unit was found. Also, the effects of chitosan and acetic acid on the actuation behavior of the cellulose‐chitosan laminated films were investigated.

     

Sorption characterization of poly(vinyl alcohol)/chitosan interpenetrating polymer network hydrogels

Poly(vinyl alcohol) (PVA)/chitosan interpenetrating polymer networks (IPN) were prepared by UV irradiation. The water sorption behavior of the IPNs was measured at various temperatures and humidity levels. The water uptake of IPN13 is greater than that of other IPNs. Vapor sorption behavior is more affected by the density of water vapor than by hydrophilic properties with increasing temperature. Equilibrium water uptake increases as humidity increases, and the increase is more noticeable at high humidity. The sorption system of all IPNs is a relaxation‐controlled mechanism at a relative humidity (RH) of 90%, but it is a Fickian diffusion‐controlled mechanism when the RH is below 50%. With an increase in humidity, the diffusion coefficients were found to increase due to greater penetration of water into the IPNs. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 86–90, 2003     

Synthesis,characterization, and anticorrosive coating properties of waterborne interpenetrating polymer network based on epoxy‐acrylic‐oleic acid with butylated melamine formaldehyde

The present study reports the synthesis and characterization of waterborne interpenetrating network (IPN) of epoxy‐acrylic‐oleic acid (EpAcO) with butylated melamine formaldehyde (BMF). The effect of BMF on the formation of IPN was investigated in terms of physicochemical, spectral, morphological, and thermal analyses. The coating properties of the IPN were investigated for their physicomechanical, corrosion resistance, and antimicrobial activity. The formation of the IPN was confirmed by FTIR and ¹H NMR analyses as well as physicochemical properties. The EpAcO‐BMF IPN coatings were found to exhibit far superior corrosion resistance performance and good thermal stability when compared with the reported waterborne epoxy acrylic‐melamine formaldehyde systems [EpAc‐MF]. The preliminary antimicrobial investigations of the IPNs were carried out by agar diffusion method against some bacteria and fungi. The results revealed that antimicrobial activities were enhanced upon the formation of IPN. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of hydrogels based on chitosan and copolymer of poly(dimethylsiloxane) and poly(vinyl alcohol)

Copolymers composed of poly(vinyl alcohol) (PVA) and poly(dimethylsiloxane) (PDMS) were crosslinked with chitosan to prepare semi‐interpenetrating polymer network (IPN) hydrogels by an ultraviolet (UV) irradiation method for application as potential biomedical materials. PVA/PDMS copolymer and chitosan was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2‐dimethoxy‐2‐phenylacetophenone as a nontoxic photoinitiator by UV irradiation. Various semi‐interpenetrating polymer networks (semi‐IPNs) were prepared from different weight ratios of chitosan and the copolymer of PVA/PDMS. Photocrosslinked hydrogels exhibited an equilibrium water content (EWC) in the range of 65–95%. Swelling behaviors of these hydrogels were studied by immersion of the gels in various buffer solutions. Particularly, the PCN13 as the highest chitosan weight ratio in semi‐IPN hydrogels showed the highest EWC in time‐dependent and pH‐dependent swelling. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2591–2596, 2002     

Water and temperature response of semi‐IPN hydrogels composed of chitosan and polyacrylonitrile

Temperature‐responsive semi‐interpenetrating polymer networks (semi‐IPNs) constructed with chitosan and polyacrylonitrile (PAN) were crosslinked with glutaraldehyde. The semi‐IPN determined the sorption behavior of water at several temperatures and at a relative humidity (RH) of 95% using a dynamic vapor sorption (DVS) system. Water diffusion coefficients of semi‐IPNs were calculated according to the Fickian Law at several temperatures and exhibited a relatively water uptake, 0.1–0.4 at room temperature. The water uptake of hydrogels depended on temperature. The apparent activation energy was dependent of the composition of the semi‐IPN with value of 32.8–34.8 kJmol^?1. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 12: 2721–2724, 2003     

Mechanical, electrical, piezoelectric and electro-active behavior of aligned multi-walled carbon nanotube/cellulose composites

Multi-walled carbon nanotubes (MWCNTs) were covalently grafted to cellulose to make an MWCNT/cellulose (M/C) composite. Aligned M/C composite was obtained by mechanical stretching process. The stretching effect was demonstrated by observing morphology as well as measuring mechanical, electrical and piezoelectric properties of the M/C composite. The influence of aligned MWCNTs on the actuator performance of the M/C composite was evaluated in terms of bending displacement and resonance frequency depending on the stretching ratio and environmental humidity level. The aligned MWCNTs contributed to remarkably enhancing the mechanical and piezoelectric properties, but also improving actuator performance of the M/C composite.     

Thermal characteristics of IPNs composed of polyallylamine and chitosan

Interpenetrating polymer network (IPN) hydrogels composed of polyallylamine and chitosan were synthesized by radical polymerization using 2,2‐dimethyl‐2‐ phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The IPNs thus obtained were characterized by using Fourier transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). The melting temperatures of IPNs were observed with increasing chitosan content by DSC. DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated by TGA and appeared at near 270 °C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1956–1960, 2002     

Electrical behavior of chitosan and poly(hydroxyethyl methacrylate) hydrogel in the contact system

Semi‐interpenetrating polymer networks (semi‐IPNs), as polymer hydrogels composed of chitosan and poly(hydroxyethyl methacrylate) (PHEMA), exhibiting electrical‐sensitive behavior, were prepared. The swelling behavior of the chitosan/PHEMA hydrogels was studied by immersing the gels in various concentrations of aqueous NaCl solution. The electrical responses of the semi‐IPN hydrogel, in applied electric fields, were also investigated. When the semi‐IPN hydrogels were swollen, where one electrode was placed in contact with the gel and the other fixed 30 mm apart from one, they exhibited bending behavior on the application of an electric field on a contact system. The electroresponsive behavior of the present semi‐IPN was also affected by the electrolyte concentration of the external solution. The semi‐IPN also showed various degrees of increased bending behavior depending on the electric stimulus. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 915–919, 2004     

Synthesis,characterization and actuation behavior of polyaniline‐coated electroactive paper actuators

This investigation deals with the synthesis, characterization and actuation behavior of conductive polyaniline‐coated electroactive paper actuators. The actuator is made by electrochemical deposition of conductive polyaniline on a cellulose paper. The aim of the investigation was to improve the bending displacement of electroactive paper actuators. The displacement outputs of the actuators show that a trilayer is better than a bilayer configuration. The nature of the dopant ion used in the electro‐generation affects the performance. A change in humidity plays a vital role in actuation performance of the actuators. Comparing the performance of electroactive paper actuators with and without a conductive polyaniline coating, the coating improves the displacement output threefold. Finally, the actuation principle mechanism is addressed. Copyright © 2007 Society of Chemical Industry     

Electrically conductive semi‐IPNs based on polyaniline and crosslinked polyvinylacetate

Electrically conductive semi‐IPNs based on polyaniline and crosslinked polyvinylacetate were prepared. Polyaniline successfully percolated through the crosslinked PVAc networks and the resulting semi‐IPNs show a continuous network morphology. The conductivity of the semi‐IPN increases with increasing content of polyaniline and increasing acidity used during the polymerization of the polyaniline. The conductivity of the semi‐IPN is 0.13 S/cm, with the highest polyaniline content of 19.3 wt %. The depression of polyaniline with temperature change is smallest followed by the depression of semi‐IPN of the polyaniline/crosslinked polyvinylacetate, which is considerably smaller than the depression of crosslinked polyvinylacetate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2287–2293, 2002     

Effect of poly(ethylene oxide)‐ poly(ethylene glycol) addition on actuation behavior of cellulose electroactive paper

This article reports the influence of poly(ethylene oxide)‐ poly(ethylene glycol) (PEO‐PEG) addition on its actuation behavior of cellulose electroactive paper. The actuator showed its maximum bending displacement of 5.0 mm with very low electrical power consumption (7 mW/mm) at an ambient condition. Increased displacement output and decreased electrical power consumption of the actuator might be due to the improved polymer chain flexibility and ion mobility. The ion migration effect might play a more important role in actuation principle. Present investigation reveals that cellulose/PEO‐PEG‐based EAPap actuators are suitable to construct an actuator working at normal ambient condition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Cure kinetics and physical properties of dicyanate/polyetherimide semi‐IPNs

The curing behavior and physical properties of dicyanate/polyetherimide (PEI) semi‐interpenetrating polymer network (IPN) systems were investigated. Differential scanning calorimetry (DSC) was used to study the curing behavior of the dicyanate/PEI semi‐IPN systems. The curing rate of the semi‐IPN system decreased as the PEI content increased. An autocatalytic reaction mechanism can describe well the curing kinetics of the semi‐IPN systems. The reaction kinetic parameters were determined by fitting DSC conversion data to the kinetic equation. The glass transition temperature of the semi‐IPNs decreased with increasing PEI content. Two glass transitions due to phase‐separated morphology were observed for the semi‐IPN containing over 15 phr (parts per hundred parts of dicyanate resin) PEI. The thermal stability and dynamic mechanical properties of the semi‐IPNs were measured by thermal analysis.     

Visualizing phase separation in polystyrene/polystyrene homo‐IPNs via sulfonation

BACKGROUND: Polystyrene/polystyrene (PS/PS) interpenetrating polymer networks (IPNs) represent ideal homo‐IPNs. Whether phase separation occurs in this system has been a long‐standing problem, which is closely related to the self‐organization mechanism in IPN formation and is important to the exploration of new polymer morphologies and properties by topological isomerism. RESULTS: A series of bead samples of PS/PS sequential IPNs with the same nominal divinylbenzene contents were synthesized by suspension polymerization, followed by sulfonation. Scanning electron micrographs and energy‐dispersive X‐ray mapping show unique distinctive topography on both surfaces and fractured surfaces and large heterogeneity in sulfonation of the PS/PS IPN beads, which for the first time provide visual evidence for dual‐phase continuity in PS/PS IPNs. CONCLUSION: The phase separation behavior is proposed to be due to hydrodynamic screening, architectural asymmetry and excluded volume interactions between network I and the precursor chains of network II. This is considered to represent pure IPN effects in sequential formation and may shed light on the general constitution mechanism and molecular design of IPN materials. Copyright © 2009 Society of Chemical Industry     

Synthesis and characteristics of interpenetrating polymer network hydrogel composed of chitosan and poly(acrylic acid)

Interpenetrating polymer network (IPN) hydrogels composed of chitosan and poly(acrylic acid) (PAAc) were synthesized by UV irradiation method, and their structure, crystallinity, swelling behavior, thermal property, and mechanical property were investigated. Chitosan/PAAc IPNs exhibited relatively high equilibrium water content and also showed reasonable sensitivity to pH. From the swelling behaviors at various pH's, Fourier transform infrared spectra at high temperature and thermal analysis confirmed the formation of polyelectrolyte complex due to the reaction between amino groups in chitosan and carboxyl groups in PAAc. For this reason, even at a swollen state, the present chitosan/PAAc IPNs possess good mechanical properties. Particularly, the CA‐2 sample (with a weight ratio of chitosan/PAAc = 50/50, molar ratio [NH₂]/[COOH] = 25/75) showed the lowest equilibrium water content and free water content, attributed to the more compact structure of the polyelectrolyte than CA‐1 or CA‐3 due to the high amount of interchain bond within the IPN. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 113–120, 1999     

Damping Properties of Polyorganosiloxane/Poly(methyl methacrylate) Interpenetrating Networks

Interpenetrating polymer networks (IPNs) based on polyorganosiloxane/poly(methyl methacrylate) were prepared via sequential polymerization and the damping and mechanical properties of these materials were studied. The effects of crosslinking in both the first‐ and second‐formed networks were investigated. The experimental results show that the extent of damping of the IPNs was decreased and shifted to higher temperature as the content of poly(methyl methacrylate) was increased; the mechanical properties such as tensile strength and hardness (Shore A) were increased with increasing poly(methyl methacrylate) (PMMA) content. The loss factor peak becomes narrower with increasing crosslinker level in the first‐formed network (polysiloxane network), while increasing crosslinker content in the second‐formed network (PMMA network) results in a broadening of the IPN transition peak and moves the IPN transition to higher temperatures as well.     

Curing and mechanical properties of dicyanate/poly(ether sulfone) semi‐interpenetrating polymer networks

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of a dicyanate resin and a poly(ether sulfone) (PES) were prepared, and their curing behavior and mechanical properties were investigated. The curing behavior of the dicyanate/PES semi‐IPN systems catalyzed by an organic metal salt was analyzed. Differential scanning calorimetry was used to study the curing behavior of the semi‐IPN systems. The curing rate of the semi‐IPN systems decreased as the PES content increased. An autocatalytic reaction mechanism was used to analyze the curing reaction of the semi‐IPN systems. The glass‐transition temperature of the semi‐IPNs decreased with increasing PES content. The thermal decomposition behavior of the semi‐IPNs was investigated. The morphology of the semi‐IPNs was investigated with scanning electron microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1079–1084, 2003