Polymer nanotechnology: Nanocomposites

In the large field of nanotechnology, polymer matrix based nanocomposites have become a prominent area of current research and development. Exfoliated clay-based nanocomposites have dominated the polymer literature but there are a large number of other significant areas of current and emerging interest. This review will detail the technology involved with exfoliated clay-based nanocomposites and also include other important areas including barrier properties, flammability resistance, biomedical applications, electrical/electronic/optoelectronic applications and fuel cell interests. The important question of the “nano-effect” of nanoparticle or fiber inclusion relative to their larger scale counterparts is addressed relative to crystallization and glass transition behavior. Of course, other polymer (and composite)-based properties derive benefits from nanoscale filler or fiber addition and these are addressed.     

Trends in Conducting Polymer and Hybrids of Conducting Polymer/Carbon Nanotube: A Review

Several conducting polymers, including polyaniline, polypyrrole, polythiophene, polyvinylpyrrolidone, poly(3,4-ethylenedioxythiophene), poly(m-phenylenediamine), polynaphthylamine, poly(p-phenylene sulfide), and their carbon nanotube reinforced nanocomposites are discussed in this review. The physical, electrical, structural and thermal properties of polymers along with synthesis methods are discussed. A concise note on carbon nanotubes regarding their purification, functionalization, properties and production are reported. Moreover, the article focuses upon synthesis methods, properties and applications of conducting polymer/carbon nanotube nanocomposites are focused. Nanotube dispersion, loading concentration and alignment within conducting polymer/carbon nanotube nanocomposite affect their performance and morphology. The conducting polymer/carbon nanotube nanocomposites are substantially used in sensors, energy storage devices, supercapacitors, solar cells, EMI materials, diodes, and coatings.     

Polymeric ionic liquids: Broadening the properties and applications of polyelectrolytes

The introduction of new ionic moieties, cations and anions, is extending the properties and classical applications of polyelectrolytes. These new polyelectrolytes are being named polymeric ionic liquids (PILs) in analogy to their monomeric constituents (i.e. cations such as imidazolium, pyridinium, pyrrolidonium and anions such as hexafluorophosphate, triflates, amidotriflates). This is giving rise to a new family of functional polymers with particular properties and new applications. The first part of this review will focus on the synthetic aspects of PILs and the main aspects related to their physico-chemical properties. In the second part we will review the new technological applications of these polymers such as polymer electrolytes in electrochemical devices, building blocks in materials science, nanocomposites, gas membranes, innovative anion sensitive materials, smart surfaces, and a countless set of applications in different fields such as energy, environment, optoelectronics, analytical chemistry, biotechnology or catalysis.     

Review on Nanocellulose Polymer Nanocomposites

Recently, nanocellulosic materials have been received significant research interest as potential nanofiller for the reinforcements in the polymer matrices due to its renewable in nature, readily availability, biocompatibility, inexpensive, excellent physical properties, tailorable surface properties, etc. In this review, author attempted to provide an overview of various methods for nanocellulose reinforced polymer nanocomposites fabrications, properties of nanocellulose-based nanocomposites, and their applications. The review has been emphasized for the reinforcement of nanocellulose in various polymer matrices viz. hydrophilic, hydrophobic matrices. Nanocellulose reinforced polymer nanocomposites have huge potential in diverse applications which ranges from biomedical, packaging, electronic to environmental, water treatment fields etc.     

Carbon nanotube induced polymer crystallization: The formation of nanohybrid shish-kebabs

Carbon nanotubes (CNTs) have attracted tremendous attention in recent years because of their superb optical, electronic and mechanical properties. In this article, we aim to discuss CNT-induced polymer crystallization with the focus on the newly discovered nanohybrid shish-kebab (NHSK) structure, wherein the CNT serves as the shish and polymer crystals are the kebabs. Polyethylene (PE) and Nylon 6,6 were successfully decorated on single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs), and vapor grown carbon nanofibers (CNFs). The formation mechanism was attributed to “size-dependent soft epitaxy”. Polymer CNT nanocomposites (PCNs) containing PE, Nylon 6,6 were prepared using a solution blending technique. Both pristine CNTs and NHSKs were used as the precursors for the PCN preparation. The impact of CNTs on the polymer crystallization behavior will be discussed. Furthermore, four different polymers were decorated on CNTs using the physical vapor deposition method, forming a two-dimensional NHSK structure. These NHSKs represent a new type of nanoscale architecture. A variety of possible applications will be discussed.     

Low-dimensional carbonaceous nanofiller induced polymer crystallization

Low-dimensional carbonaceous nanofillers (LDCNs), i.e., fullerene, carbon nanofiber, carbon nanotube, and graphene, have emerged as a new class of functional nanomaterials world-wide due to their exceptional electrical, thermal, optical, and mechanical properties. One of the most promising applications of LDCNs is in polymer nanocomposites; these materials endow the polymer matrix with significant physical reinforcement and/or multi-functional capabilities. The relations between properties, structure and morphology of polymers in the nanocomposites offer an effective pathway to obtain novel and desired properties via structure manipulation, wherein the interfacial crystallization and the crystalline structure with the matrix are critical factors. By now, extensive studies have reported that LDCNs are highly effective nucleating agents that can significantly accelerate their crystallization kinetics and/or induce unique crystalline morphologies in nanocomposites. This review presents a thorough survey of the current literature on the issues relevant to LDCN-induced polymer crystallization. After a brief introduction to each type of LDCN and its derivatives, LDCN-induced crystallization kinetics with or without flow fields, crystalline modification, and interfacial crystalline morphologies are thoroughly reviewed. Then, the origins of LDCN-induced polymer crystallization are discussed in depth based on molecular simulation and experimental studies. Finally, an overview of the challenges in probing LDCN-induced polymer crystallization and the outlook for future developments in polymer/LDCN nanocomposites conclude this paper. Understanding LDCN-induced polymer crystallization offers a helpful guidance to purposefully regulate the structure and morphology, then achieving high-performance polymer/LDCN nanocomposites.     

Preparation of polyaniline/vermiculite clay nanocomposites by in situ chemical oxidative grafting polymerization

BACKGROUND: Recently, conducting polymers have attracted much attention, since they have interesting physical properties and many potential applications, such as in conductive coating charge storage. Hence the synthesis of conducting polymer nanocomposites is also an area of increasing research activity. RESULTS: Vermiculites (VMTs) were successfully delaminated using an acid treatment. Polyaniline (PANI)/VMT nanocomposites were prepared by in situ chemical oxidative grafting polymerization. CONCLUSION: The chemical grafting of PANI/VMTs was confirmed by Fourier transform infrared and UV‐visible spectroscopy. The percentage of grafted PANI was 142.7 wt% as a mass ratio of the grafting PANI and charged nano‐VMTs, investigated using thermogravimetric analysis. In addition, characteristic agglomerate morphology of PANI was observed in the composites using scanning electron microscopy. Thermal analyses indicated that the introduction of VMT nanosheets had a beneficial effect on the thermal stability of PANI. The electrical conductivity of the nanocomposites was 3.9 × 10^?3 S cm^?1, a value typical for semiconductors. Copyright © 2009 Society of Chemical Industry     

Electrical properties of polymer nanocomposites containing rod-like nanofillers

We present an in-depth critical review of major experimental, simulation, and theoretical work in the field of conducting polymer nanocomposites containing rod-like particles such as carbon nanotubes and metal nanowires. These are a versatile class of materials that are of interest for a wide range of applications. Commercialization of various classes of conducting polymer nanocomposites is growing, yet achieving their full technological potential will hinge on the ability to engineer composites with controllable and well-defined properties, as well as aggressive exploration of new application areas. Thus, the focus of this review is to clarify key structure–property relationships, and to discuss the major gaps and greatest opportunities in the field.     

Prospects of conducting polymer and graphene as counter electrodes in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) garner considerable research interest because of high photo-to-electric conversion efficiencies at low production cost. Platinum has been reported as an efficient metal as a counter electrode (CE) in DSSCs for its outstanding electro catalytic performance. However, the high cost and susceptibility to corrosion of Pt are paving the way for exploring new materials to replace Pt as a counter electrode in DSSCs. Various conducting polymers, graphene and conducting polymer-graphene nanocomposites have been found as counter electrodes in DSSCs with remarkable photovoltaic performances. The urge to produce composites or hybrids with nanomaterials is derived from the improvement of photovoltaic performances. This review will focus on the unique physical and chemical properties of conducting polymers and graphene, their individual photovoltaic performances as counter electrodes in DSSCs, followed by the synergistic effect of conducting polymers and graphene in conducting polymer-graphene nanocomposites as counter electrodes in DSSCs. Finally a brief outlook is provided to improve the photovoltaic performance of DSSCs using conducting polymers and graphene-based counter electrodes.     

Nanocomposite polymer electrolytes by in situ polymerization of methyl methacrylate: For electrochemical applications

Hybrid materials, which combine properties of organic–inorganic materials, are of profound interest owing to their unexpected synergistically derived properties and are considered as innovative advanced materials promising new applications in many fields such as optics, electronics, ionics and mechanics. Inorganic fillers are added to polymers in order to increase some of the properties of the compounds. These hybrid polymeric materials are replacing the pristine polymers due to their higher strength and stiffness. In the present work, studies concerning the preparation of poly (methylmethacrylate) [PMMA] and the nanocomposites PMMA/SiO₂, PMMA/TiO₂ are reported. These nanocomposite polymers were synthesized by means of free radical polymerization of methylmethacrylate, further “sol–gel” transformation‐based hydrolysis and condensation of corresponding alkoxide was used to prepare the inorganic phase during the polymerization process of MMA. Electrolytes were synthesized based on these nanocomposite polymers and have shown superior properties as compared to conventional polymer electrolytes. The nanocomposites and the nanocomposite polymer electrolytes (NPEs) with different lithium salts were investigated through an array of techniques including FTIR and calorimetry along with the electrochemical and rheological techniques. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of polyaniline derivative and silver nanoparticle composites

BACKGROUND: There has been a recent surge of interest in the synthesis and applications of electroactive polymers with incorporated metal nanoparticles. These hybrid systems are expected to display synergistic properties between the conjugated polymers and the metal nanoparticles, making them potential candidates for applications in sensors and electronic devices. RESULTS: Composites of polyaniline derivatives—polyaniline, poly(2,5‐dimethoxyaniline) and poly(aniline‐2,5‐dimethoxyaniline)—and silver nanoparticles were prepared through simultaneous polymerization of aniline derivative and reduction of AgNO₃ in the presence of poly(styrene sulfonic acid) (PSS). We used AgNO₃ as one of the initial components (1) to form the silver nanoparticles and (2) as an oxidizing agent for initiation of the polymerization reaction. UV‐visible spectra of the synthesized nanocomposites reveal the synchronized formation of silver nanoparticles and polymer matrix. The morphology of the silver nanoparticles and degree of their dispersion in the nanocomposites were characterized by transmission electron microscopy. Thermogravimetric analysis and differential scanning calorimetry results indicate an enhancement of the thermal stability of the nanocomposites compared to the pure polymers. The electrical conductivity of the nanocomposites is in the range 10^?4 to 10^?2 S cm^?1. CONCLUSION: A single‐step process for the synthesis of silver nanoparticle–polyaniline derivative nanocomposites doped with PSS has been demonstrated. The approach in which silver nanoparticles are formed simultaneously during the polymerization process results in a good dispersion of the nanoparticles in the conductive polymer matrix. Copyright © 2008 Society of Chemical Industry     

Electrochemical sensors based on conducting polymer—polypyrrole

Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole (Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention is paid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties of this polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical target DNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinity agents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered.     

3D Printing of Polyvinylidene Fluoride Based Piezoelectric Nanocomposites: An Overview

Recently, polyvinylidene fluoride (PVDF) based nanocomposites have attracted much attention for next-generation wearable applications such as promising piezoelectric energy harvesters (nanogenerators), energy storage devices, sensing devices, and biomedical devices due to their high flexibility, and high dielectric and piezoelectric properties. 3D printing technology, PVDF based piezoelectric nanocomposites, the studies based on 3D printing of PVDF based piezoelectric nanocomposites by inkjet printing and fused deposition modeling, and enhancements of energy harvesting and storage performance of nanocomposites by structural design are comprehensively overviewed here. An insight is provided into 3D printing techniques, structure and properties of PVDF based polymers, various nanofillers and production methods for nanocomposites, solutions to enhance β phase (crystallinity) of PVDF, and improvements of nanocomposites’ breakdown strength, discharged energy density, and piezoelectric power output by mentoring structural design.     

Designing π-conjugated polymers for organic electronics

Conjugated polymers have attracted an increasing amount of attention in recent years for various organic electronic devices because of their potential advantages over inorganic and small-molecule organic semiconductors. Chemists can design and synthesize a variety of conjugated polymers with different architectures and functional moieties to meet the requirements of these organic devices. This review concentrates on five conjugated polymer systems with 1D and 2D topological structures, and on one polymer designing approach. This includes (i) conjugated polyphenylenes (polyfluorenes, polycarbazoles, and various stepladder polymers), (ii) other polycyclic aromatic hydrocarbons (PAHs) as substructures of conjugated polymers, (iii) thiophene and fused thiophene containing conjugated polymers, (iv) conjugated macrocycles, (v) graphene nanoribbons, and finally (vi) a design approach, the alternating donor–acceptor (D–A) copolymers. By summarizing the performances of the different classes of conjugated polymers in devices such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and polymer solar cells (PSCs), the correlation of polymer structure and device property, as well as the remaining challenges, will be highlighted for each class separately. Finally, we summarize the current progress for conjugated polymers and propose future research opportunities to improve their performance in this exciting research field.     

Conducting Polymer Nanostructures: Template Synthesis and Applications in Energy Storage

Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their nanoscaled size: high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity. Template methods are emerging for a sort of facile, efficient, and highly controllable synthesis of conducting polymer nanostructures. This paper reviews template synthesis routes for conducting polymer nanostructures, including soft and hard template methods, as well as its mechanisms. The application of conducting polymer mesostructures in energy storage devices, such as supercapacitors and rechargeable batteries, are discussed.     

Polymer nanocomposites from modified clays: Recent advances and challenges

Since the end of the last century, the discovery of polymer nanocomposites and their ever-expanding use in various applications has been the result of continuous developments in polymer science and nanotechnology. In that regard, progress in developments on the use of modified natural and synthetic clays for designing polymer nanocomposites is presented herein. The modified clays used in composite preparation include natural clays such as montmorrilonite, hectorite, sepiolite, laponite, saponite, rectorite, bentonite, vermiculite, biedellite, kaolinite, and chlorite, as well as synthetic clays including various layered double hydroxides, synthetic montmorrilonite, hectorite, etc. The preparation, structure and properties of polymer nanocomposites using the modified clays are discussed. Even at a low loading, these composites are endowed with remarkably enhanced mechanical, thermal, dynamic mechanical, adhesion and barrier properties, flame retardancy, etc. The properties of the nanocomposites depend significantly on the chemistry of polymer matrices, nature of clays, their modification and the preparation methods. The uniform dispersion of clays in polymer matrices is a general prerequisite for achieving improved mechanical and physical characteristics. Various theories and models used to design polymer/clay nanocomposites have also been highlighted. A synopsis of the applications of these advanced, high-performance polymer nanocomposites is presented, pointing out gaps to motivate potential research in this field.     

Poly(N-isopropylacrylamide-acrylic acid) copolymer microgels for various applications: A review

Smart polymer microgels have been attracting a lot of attention due to their quick response to variation in environmental stimuli like temperature, pH, ionic strength, and presence of some biological molecules. Poly(N-isopropylacrylamide) and its copolymer microgels have been synthesized and characterized for various applications in last 10 years. Synthesis, properties, and applications of poly(N-isopropylacryamide-co-acrylic acid) [P(NIPAM-AA)] copolymer microgels have been extensively reported in literature. This article describes synthesis, fundamental properties, and applications of P(NIPAM-AA) microgels in the field of medical science, environment, nanotechnology, catalysis, and photonics.     

Nanocomposites of PEDOT:PSS with Graphene and its Derivatives for Flexible Electronic Applications: A Review

Rapid technological advancements in flexible nanoelectronics have fueled the need for high-performance materials with advanced structural architectures and superior properties. In this regard, conducting polymer nanocomposites are at the forefront of current innovative research owing to their excellent properties. Among these sets of unique materials, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) nanocomposites continue to pave the way in several applications including those entailing thermoelectricity, transparent electrodes, photovoltaics, technical coatings, lighting, sensing, bioelectronics, hole transport layers, interconnectors, electroactive layers, and motion-sensing conductors. The versatility and intriguing properties of these composites, particularly with 2D nanomaterials, have garnered significant attention from academia as well as industry. Therefore, in this review, the latest developments in PEDOT:PSS nanocomposites with graphene and its derivatives are focused on. First, the synthesis and fabrication of PEDOT:PSS nanocomposites with emphasis on recent techniques developed to overcome the challenges associated with direct production is discussed. Thereafter, the characterization and thermoelectric properties of the materials are explained. This provides detailed insights into the characteristic features of various nanocomposites and the influence of individual nanoparticles in the PEDOT:PSS matrix. Then, a conclusion, including a critical summary of the extensive applications of the PEDOT:PSS/graphene nanocomposites for electrochemical, electrostatic, optoelectronic, and thermoelectric devices, is provided.     

Hybrid magnetic nanocomposites containing polyconjugated polymers

Publications concerning metal–polymer nanocomposites based on polyconjugated polymers and magnetic nanoparticles that have been published mostly over the last decade and a half are analyzed. Methods of preparing nanomaterials and their structures and electric and magnetic properties are discussed. The use of metal–polymer nanocomposites in various fields of engineering is exemplified.     

Synthesis and characterization of polyaniline derivatives and related carbon nanotubes nanocomposites - Study of optical properties and band gap calculation

Poly(o-methylaniline) (POTO), poly(o-methoxyaniline) (POAS), poly(2,5-dimethylaniline) (PDMA), poly(2,5-dimethoxyaniline) (PDOA), and nanocomposite based on multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) embedded in these conducting polymers, were synthesized by oxidative polymerization. We used the Langmuir-Schaefer (LS) technique to fabricate films at the air-water interface and performed the doping process on the undoped films by dipping the substrates in 1 M hydrochloric acid (HCl) aqueous solution. We recorded UV-vis spectra for both the undoped and doped forms and calculated the related band gaps by using the Tauc equation. Experimental data showed the substituents affected the final oxidation ratio of the polymer chains and the presence of carbon nanotubes (CNTs) in the medium of reaction changed the properties in relation of the kind and number of substituents along the aromatic ring. The study of UV-vis spectra of the undoped nanocomposites and the calculated band gaps highlighted that the conducting polymer chains simply wrapped up around CNTs with no strong interaction. Both the kind and number of substituents along the aromatic rings strongly affected the protonation process, since their capability of “tuning” the formation of the polaronic state. The presence of CNTs in the polymer matrix showed no appreciable influence in the chemical properties of the doped nanocomposites with respect to the pure conducting polymers.