Electroactive Copolymer Research Articles

Methyl Methacrylate Copolymer with Pendant Thioxanthenone Groups as Active Layer for Resistive Memory Devices.

An electro-active copolymer of methyl methacrylate and 2-((4-acroylpiperazine-1-yl)methyl)-9H-thioxanthene-9-one (poly(MMA-co-ThS)) was synthesized by radical polymerization. The copolymer has good solubility in most organic solvents, thermal stability up to 282 °C and excellent ability to form thin films on silicon wafers. Poly(MMA-co-ThS) films exhibited an electrochemical and electrochromic activity resulting in the formation of long-lived radical anion states of pendant thioxanthone groups inside the film. These states exhibit optical transitions in the visible region as a broad optical absorption band, 500<λ<900 nm (1.38<Wopt(ThS)<2.48 eV) with a maximum at λmax=675 nm (1.84 eV). Using temperature measurements of the current-voltage characteristics of p-Si(100)/poly(MMA-co-ThS)/Al devices, it was shown that the charge transport in the film occurs by a multiphonon mechanism, which is quantitatively described by the Nasyrov-Gritsenko model of phonon-assisted tunneling between traps. The value of the optical transition energy of the trap, determined by the Nasyrov-Gritsenko model, Wopt=1.8 eV, is in a good agreement with Wopt(ThS), confirming the nature of the traps as 9H-thioxanthen-9-one structures. The n++Si(100)/poly(MMA-co-ThS)/Al memory device exhibited a memristive effect (reversible ON/OFF switching of the device) with an initial "forming" cycle followed by repetitive memory cycles characterized by bipolar switching.

Electroelasticity of copolymer networks

We introduce a novel statistical mechanics-based analysis of electroactive copolymer networks. This enables to express the coupled response of a multi-species polymer network in terms of a Gibbs-like energy-density function. Following the common affine deformation assumption we derive the expressions for the network response in terms of the species’ properties and molar fraction. Next, we specialize the results to the class of monomers with spontaneous electric dipoles and determine the monomers’ orientational distribution in terms of a generalized Langevin function. We reveal that the coupled response of the copolymer depends on the contrast between the intensities of the dipolar moments of the species and their fraction of the chain end-to-end length. In the long chains limit we obtain closed-form expressions for the electrical and mechanical fields. Next, we consider two-species copolymers and find that the long chains approximation is valid for actuation stretch ratios up to 40% of the locking stretch. We also demonstrate that the maximal susceptibility is attained when the contour lengths of the two species are equal. Moreover, the overall electroelastic response is enhanced if the monomers with the weaker dipole are longer than those with the stronger one. Finally, we show that an appropriate choice of actual monomers may lead to copolymers with relative dielectric constants of more than 30.

The Use of Collagen Methacrylate in Actuating Polyethylene Glycol Diacrylate-Acrylic Acid Scaffolds for Muscle Regeneration.

After muscle loss or injury, skeletal muscle tissue has the ability to regenerate and return its function. However, large volume defects in skeletal muscle tissue pose a challenge to regenerate due to the absence of regenerative elements such as biophysical and biochemical cues, making the development of new treatments necessary. One potential solution is to utilize electroactive polymers that can change size or shape in response to an external electric field. Poly(ethylene glycol) diacrylate (PEGDA) is one such polymer, which holds great potential as a scaffold for muscle tissue regeneration due to its mechanical properties. In addition, the versatile chemistry of this polymer allows for the conjugation of new functional groups to enhance its electroactive properties and biocompatibility. Herein, we have developed an electroactive copolymer of PEGDA and acrylic acid (AA) in combination with collagen methacrylate (CMA) to promote cell adhesion and proliferation. The electroactive properties of the CMA + PEGDA:AA constructs were investigated through actuation studies. Furthermore, the biological properties of the hydrogel were investigated in a 14-day in vitro study to evaluate myosin light chain (MLC) expression and metabolic activity of C2C12 mouse myoblast cells. The addition of CMA improved some aspects of material bioactivity, such as MLC expression in C2C12 mouse myoblast cells. However, the incorporation of CMA in the PEGDA:AA hydrogels reduced the sample movement when placed under an electric field, possibly due to steric hindrance from the CMA. Further research is needed to optimize the use of CMA in combination with PEGDA:AA as a potential scaffold for skeletal muscle tissue engineering.

Flexible electroactive membranes for the electrochemical detection of dopamine

In addition of a key catecholamine neurotransmitter, dopamine is is the metabolite predominantly produced by specific types of tumors (e.g. paragangliomas and neuroblastomas), which cannot be diagnosed using conventional sensitive tests. Within this context, development of flexible electrochemical sensors to monitor dopamine levels in physiological fluids for the early diagnosis and control of diseases related to abnormal levels of such compound, is necessary. In this work, a flexible self-supported membrane, which acts directly as electrode, has been developed to detect dopamine. The membrane consists of three nanoperforated polylactic acid (PLA) layers, which provide flexibility and mechanical integrity, separated by two layers of an electroactive copolymer, which are obtained by electrochemical copolymerization of 3,4-ethylenedioxythiophene and aniline. The sensitivity and detection limit provided by the electroactive copolymer, which is accessible to dopamine molecules through the nanoperforations of the PLA outer layers, is 1.846 µA/(cm2·µM) and 1.7 µM, respectively, in a urea-rich environments that mimics urine. These values allow us to propose the self-standing flexible electrodes developed in this study for the detection of dopamine in patients affected by paragangliomas and neuroblastomas tumors, which typically present dopamine concentrations between 2 and 7 μM.

Functionalized Thiophene-Based Aptasensors for the Electrochemical Detection of Mucin-1

Mucin-1 (MUC1) is a glycoprotein found in epithelial tissues; its function is to protect the body by blocking pathogens from reaching the cells. Overexpression and elevated serum levels of this protein are observed in breast cancer, lung cancer, stomach cancer, ovarian cancer, and many other types of malignancies. Current methods used to detect cancer are expensive and therefore not readily accessible; some methods are also invasive. The ability to detect MUC1 could allow for early detection of cancer, leading to more successful outcomes. This research focuses on the development of a robust biosensor platform based on aptamer-functionalized electroactive polymers (EAPs) that can be used for the detection of cancer. To achieve this, indium tin oxide slide surfaces were modified to enable the electrochemical growth of an electroactive copolymer of 3,4-ethylenedioxythiophene (EDOT) and 2,2-(3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine-3,3-diyl)diacetic acid (ProDOT(COOH)2), with the carboxylic acid functionalities added to introduce bonding sites for a MUC1-specific aptamer. Three copolymer ratios were investigated to maximize the performance. The aptamer was then attached to the EAPs to create aptasensors that could be used for the electrochemical detection of a MUC1 polypeptide. The limits of detection of the biosensors and their stabilities were evaluated. The MUC1 aptasensor showed stability for at least 6 days, depending on the ratio of the copolymer, when stored in 0.1 M phosphate-buffered saline. The 1:2 EDOT/ProDOT(COOH)2 copolymer was found to be the most stable over time and to offer one of the smallest limits of detection, making it the most favorable ratio for aptasensor optimization. Specifically, the 1:2 EDOT/ProDOT(COOH)2 biosensor provided a limit of detection of 369 fg/mL (418 fM) and a linear range of 625 fg/mL to 6.25 ng/mL (709 fM to 7.09 nM) with the MUC1 peptide APDTRPAPG. The sensor also showed selectivity when tested with competing agents including IgG and cell media. The performance of the aptasensor demonstrated its potential as a highly sensitive and selective biosensor for MUC1 detection.

Electro-Active Copolymer of Methyl Methacrylate and 2((4-Acryloylpiperazin-1-yl)methyl)-9H-thioxanthen-9-one for Memristor Memory Technologies: Electrochemical and Electrochromic Properties

Electro-Active Copolymer of Methyl Methacrylate and 2((4-Acryloylpiperazin-1-yl)methyl)-9H-thioxanthen-9-one for Memristor Memory Technologies: Electrochemical and Electrochromic Properties

On the magnetoelectric performance of multiferroic particulate composite materials

In the current work, quantitative analysis of magnetoelectric particulate composite material system explicated the main mechanisms responsible for the below-optimal performance of this class of materials. We considered compliant particulate composite materials, with constituents relevant to technological and scientific interest, leading to 0–3 Terfenol-D/PVDF–TrFE composite samples. To this objective, thick Terfenol-D/PVDF–TrFE films (10–15 µm) were fabricated and analyzed for chemical, mechanical, and magnetic properties to demonstrate their suitability for energy applications in harsh environmental conditions. The vigorous experimental characterization of the composite exemplified the multifunctional properties, quantifying the interrelationship between the composition and performance. We observed that the addition of magnetic particles to the electroactive copolymer matrix resulted in improvement in the mechanical and electrical properties since the particles acted as pinning sites, hindering the deformation of the chains and enhancing polarization. The effective modulus model was amended to account for the crystallization-induced change in material stiffness. We also measured and computed the magnetic particles motion to explicate the detrimental effect of mobility and migration on the overall magnetoelectric coupling performance of the composite. Thereby, we derived an analytical model based on the magnetic force due to the co-presence of alternating and constant magnetic fields, and the viscous drag force due to the viscoelastic properties of the electroactive copolymer matrix. We demonstrated that the mobility of the particles plays a crucial role in the short and long term performance of magnetoelectric coupling in multiferroic particulate composites, uncovering the underpinnings of the dichotomy in performance between experimentally measured and analytically predicted coupling coefficients, thus allowing for the proposal of new approaches to realize the scientific potential of magnetoelectric particulate composites in energy applications.

DOPA-derived electroactive copolymer and IGF-1 immobilized poly(lactic-co-glycolic acid)/hydroxyapatite biodegradable microspheres for synergistic bone repair

Abstract Owing to defect features (irregular shape and size) and local environments (e.g., pulsation of dura matter and proximity of the brain), the skull is one of the most difficult to repair. Electroactive microsphere systems with good injectability, adjustable size, high surface-to-volume ratio and surface modifiability, exhibit excellent bone regeneration potential. Herein, the electroactive microspheres were prepared by immobilizing aniline tetramer (AT) on poly(lactic-co-glycolic acid)/hydroxyapatite (PLGA/HA) microspheres. Subsequently, the 3,4-hydroxyphenalyalanine-containing recombinant insulin-like growth-factor-1 (DOPA-IGF-1) inspired by bioorthogonal chemistry was designed by combining the recombinant DNA technology and tyrosinase treatment, and modified on electroactive scaffolds surface. The as-prepared microspheres exhibited excellent sphericity and homogeneity with an average diameter of 329.2 ± 16.5 μm. Interestingly, the electroactive microsphere exhibits significant cell proliferation and enhanced osteogenic differentiation, and combining with DOPA-IGF-1 can further synergistically induce mineralization and osteogenic differentiation. Rat calvarial defect repair experiments showed excellent repairability in forming mineralized collagen deposition within the transplanted composite microspheres scaffold in the bone defect site. Thus, biomimetic composite microsphere with electroactivity and bioactivity exhibits considerable potential for calvarial defect repair.

A fabrication strategy for protein sensors based on an electroactive molecularly imprinted polymer: Cases of bovine serum albumin and trypsin sensing

A high-performance molecularly imprinted sensing platform inspired by natural recognition mechanisms was fabricated to detect protein by employing a linear electro-polymerizable molecularly imprinted polymer as macromonomer. This was achieved via the combination of a biosensor fabrication with a self-assembly imprinting technique without the use of chemical labels. An amphipathic electroactive copolymer was designed as macro-monomer to maintain structural integrity of the protein template via self-assembly, resulting in generation of a 3D construction around the protein molecule to form imprinted sites. Electro-polymerization was utilized not only to anchor imprinted sites but also to enhance electron transfer. The adaptable sensing platform was based on a strengthened recognition reaction between the MIP layer and template protein after the generation of an electroactive network. Bovine serum albumin (BSA) and trypsin were used as model proteins to investigate the method’s generality, which gave broad detection ranges of 10−14–10−5 mg mL−1 for BSA and 10−13–10−8 mg mL−1 for trypsin. These results indicate that the proposed fabrication offers an effective and versatile strategy for protein recognition.

“Olive-Structured” Nanocomposite Based on Multiwalled Carbon Nanotubes Decorated with an Electroactive Copolymer for Environmental Nitrite Detection

A high-performance nitrite sensor based on a unique “olive-structured” electroactive copolymer/multiwalled carbon nanotube (MWCNT) nanocomposite is demonstrated for nitrite monitoring in the enviro...

Spectral, thermal and morphological characteristics of ultrasonically synthesized poly(anisidine-co-phenylenediamine)/bentonite nanocomposites: A potential anti-diabetic drug carrier

With the aim to explore the drug delivery efficacy of an electroactive copolymer based clay nanocomposite, the present work reports for the first time, ultrasound-assisted copolymerization of o-anisidine and o-phenylenediamine/bentonite nanocomposites. The nanocomposites were characterized for their spectral, thermal and morphological characteristics. IR studies revealed the existence of electrostatic interactions between the NH functional groups of the copolymers with the SiO of Bentonite, while XRD analysis confirmed the formation of a partially exfoliated nanocomposite. The polaronic state of the copolymers was shown by UV–visible studies, while TGA confirmed the amount of loading of the copolymer in the clay. The nanocomposites were loaded with metformin hydrochloride (100mg) — an anti-diabetic drug to investigate the release profiles in intestinal fluid (pH7.4). Release kinetics followed the zero order model in intestinal fluid (pH7.4) and showed sustained release. The release behaviour was observed to be influenced by the composition of the copolymers and this property could be utilized to control as well as optimize the release of metformin hydrochloride as per loading and dosage.

Injectable electroactive hydrogels based on Pluronic® F127 and tetraaniline copolymer

Nowadays, injectable electroactive hydrogels have received much attention in biomedical field. In this article, an electroactive copolymer was successfully synthesized by chemical coupling of tetraaniline (TA) onto the chain end of Pluronic® F127. The structure of the resultant copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), and 1H NMR. Cyclic voltammetry (CV) measurements of the copolymer solution indicated good electroactivity. Moreover, the electroactive copolymer showed temperature-responsive sol-gel transitions in aqueous media. Gelation properties of the hydrogels were also studied by rheometer and the results showed that the introduction of TA segment could enhance the mechanical properties of hydrogel. Based on the analyses of 13C NMR spectra and dynamic light scattering (DLS), the sol-gel transition mechanism was attributed to the dehydration of PEG chains in F127. The MTT assay revealed that the TA conjugated F127 copolymer showed excellent biocompatibility. And the copolymer could form gel in vivo at 15min post injection. Therefore, this biocompatible copolymer acted as injectable electroactive hydrogels may have great potential in biomedical uses.

Synthesis of Water-Dispersible Molecularly Imprinted Electroactive Nanoparticles for the Sensitive and Selective Paracetamol Detection.

A novel kind of water-dispersible molecularly imprinted electroactive nanoparticles was prepared combining macromolecular self-assembly with molecularly imprinting technique employing paracetamol (PCM) as template molecule. An amphiphilic electroactive copolymer (P(NVC-EHA-AA), PNEA) containing carbazole group was first synthesized through a one-pot free radical copolymerization. The coassembly of the electroactive copolymers with the template molecules (PCM) in aqueous solution generated nanoparticles embedded with PCM, leading to the formation of molecularly imprinted electroactive nanoparticles (MIENPs). A robust MIP film was formed on the surface of electrode by electrodeposition of MIENPs and subsequent electropolymerization of the carbazole units in MIENPs. After the extraction of PCM molecules, a MIP sensor was successfully constructed. It should be noted that electropolymerization of the electroactive units in MIENPs creates cross-conjugated polymer network, which not only locks the recognition sites but also significantly accelerates the electron transfer and thus enhances the response signal of the MIP sensor. These advantages endowed the MIP sensor with good selectivity and high sensitivity for PCM detection. The MIP sensor could recognize PCM from its possible interfering substances with good selectivity. Under the optimal conditions, two linear ranges from 1 μM to 0.1 mM and 0.1 to 10 mM with a detection limit of 0.3 μM were obtained for PCM detection. The MIP sensor also showed good stability and repeatability, which has been successfully used to analyze PCM in tablets and human urine samples with satisfactory results.

Electroactive degradable copolymers enhancing osteogenic differentiation from bone marrow derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) have attracted great interest in the field of regenerative medicine, particularly in bone regeneration. Osteogenic differentiation from MSCs is regulated by various environmental factors including hormones, growth factors, chemicals and physical cues from biomaterials. We present the use of electroactive degradable copolymers to guide the osteogenic differentiation from bone marrow derived MSCs (BMSCs). The biodegradable conductive copolymers based on polylactide and tunable contents of the aniline oligomer were synthesized by ring opening polymerization and free radical polymerization, and subsequent functionalization with the aniline tetramer. Electroactive nanofibrous scaffolds were created via a thermally induced phase separation technique. The cell culture of BMSCs and MC3T3-E1 cells on electroactive copolymers showed that these copolymers were cytocompatible and the proliferation for both cells was significantly enhanced. Osteogenic differentiation from BMSCs on the electroactive copolymers was promoted compared to polylactide in terms of gene expression and von Kossa staining. Furthermore, protein adsorption on the electroactive copolymer surface was greatly increased, and this may contribute to the enhanced proliferation and differentiation of BMSCs. This is the first report about degradable electroactive polymers directing osteogenic differentiation from BMSCs and the results indicated that electroactive degradable polymers have great potential for application in bone regeneration.

The influence of supporting electrolyte on the electrochemical properties of copolymer films based on azulene and 3-thiophene acetic acid

New conducting copolymers of azulene and 3-thiophene acetic acid were electrochemically synthesized by multiple scan cyclic voltammetry onto a Pt substrate using three different supporting electrolytes (tetrabutylamonium hexafluorophosphate (TBAPF6), tetrabutylamonium tetrafluoroborate, and tetrabutylamonium perchlorate) in acetonitrile. The effect of the suporting electrolyte on the electrochemical and morphological properties of copolymers films based on azulene and 3-thiophene acetic acid has been investigated. The films exhibited a good p-doping behavior proved by the UV–vis spectral modifications due to transition from neutral to doped state. The electroactive copolymer films obtained on a wide potential range in TBAPF6 have exhibited the best response to hydrogen peroxide over a concentration range of 20–140 nM, with a sensitivity of 0.48 μA/nM.

Functionalization of reduced graphene oxide by electroactive polymer for biosensing applications

A novel biosensing platform was designed by the functionalizing reduced graphene oxide sheets (rGO) with electroactive copolymer juglone. The composite film showed well-defined, stable electroactivity in a biocompatible buffer medium. Square wave voltammetry is used to record the redox signal for DNA hybridization. Current increase upon hybridization (signal-on) evidenced that short DNA target as well as polymerase chain reaction (PCR), so called ‘real sample’ products, related to different lineages of Mycobacterium tuberculosis strain. The signal-on reached ∼40% with 1 nM of short DNA (25 mer) target, while PCR product (Africanum, EAI and Beijing strains) produced a current change of ∼20%.

Versatile method for synthesis of electrically conductive polypyrrole-polystyrene clay nanocomposites using ATRP and chemical polymerisation methods

A synthetic route for the preparation of a novel solution copolymer derived from styrene (St), pyrrole (Py) and its organoclay nanocomposite with conductive and mechanical properties is demonstrated. The electroactive copolymer of polystyrene-g-polypyrrole (PSt-g-Ppy) nanocomposite was successfully prepared by atom transfer radical polymerisation (ATRP) and chemical polymerisation methods. First, potassium pyrrole was reacted by α-chlorophenyl acetyl chloride to prepare an initiator that can polymerise styrene by ATRP technique. Then, polypyrrole was prepared by chemical polymerisation using FeCl3 as an oxidant in dichloromethane,s solvent. Nanocomposites of the copolymer with modified montmorillonite were prepared with a solution intercalation method. The conductivity of the copolymer was measured by the four-point probe method. The structures of the intermediate, copolymer and nanocomposite were investigated by Fourier transform infrared spectroscopy, 1H-NMR and X-ray diffraction techniques. The molecular weight of the copolymer was determined by gel permeation chromatography. Their thermal behaviour was examined by differential scanning calorimetry and thermogravimetric analyses.

Electrochemical Synthesis and Characterization of Nano Poly(o-anisidine-co-ethyl 4-aminobenzoate)

Electroactive copolymer of o-anisidine and ethyl 4-aminobenzoate were synthesized in 1 M HClO4 using cyclic voltammetry on glassy carbon electrode. The copolymer was characterized by FT-IR spectral data. The surface morphology was studied using SEM analysis. The grain size of the copolymer was measured using XRD studies and was found to be 70 nm. The electrical conductivity of the copolymer was 3.14 ×10−3 S cm−1, as determined using a four-probe conductivity meter.

Synthesis and properties of novel electroactive poly(aryl ether ketone) bearing oligoaniline segments

A novel hyperbranched electroactive azo copolymer with different oligoaniline segments was synthesized by an oxidative coupling polymerization approach, exhibiting an exciting molecular structure. The detailed characteristics of the obtained copolymer were systematically studied by Fourier-transform infrared (FTIR) spectra, nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC) and X-ray powder diffraction (XRD). The thermal resistance of the copolymer was investigated by thermogravimetric analysis (TGA). Through cyclic voltammogram (CV), we explored the electrochemical behavior of the copolymer. Moreover, photoisomerization process and doping process of the copolymer were monitored with UV–vis spectra. Dielectric properties of the as-synthesized copolymer were investigated in detail, and gratifying results have been reported. Firstly, a large enhancement in the dielectric constant was achieved utilizing HCl-doping of the conjugated oligoaniline segments. Secondly, the copolymer in HCl-doped form possessed much higher dielectric constants compared with the similar linear polymer, mainly due to the branched molecular architecture.

Electropolymerization of Dialkoxythiophenes and its Morphologies

Dialkoxysubstitued thiophene monomers were synthesized by the nucleophilic substitution and transetherification reactions. Electrochemical homopolymerization of 3,4-dioctyloxythiophene (DOOT), copolymerization of 3,4-dimethoxythiophene (DMOT) with DOOT were carried out via potentiodynamic and galvanostat methods in the supporting electrolyte. The polymers were characterized via cyclic voltammetry (CV), scanning electron microscopy (SEM), gel permeation chromatography (GPC). In the polymerization process, the electroactive copolymer was formed on the electrode surface with the Eonset(ox) at 970mV, which is 20mV higher than that of DOOT. The Eredox of the copolymer was approximately 15mV higher than that of POOT. The momorphology studies indicated that the electrochemical deposition of P(DMOT-co-DOOT) proceeds via a mechanism of nucleation and two-dimensional (2-D) growth.