Saiful Izwan Abd Razak

A Review of Electrospun Conductive Polyaniline Based Nanofiber Composites and Blends: Processing Features, Applications, and Future Directions

Electrospun polymer nanofibers with high surface area to volume ratio and tunable characteristic are formed through the application of strong electrostatic field. Electrospinning has been identified as a straight forward and viable technique to produce nanofibers from polymer solution as their initial precursor. These nanofiber materials have attracted attention of researchers due to their enhanced and exceptional nanostructural characteristics. Electrospun polyaniline (PANI) based nanofiber is one of the important new materials for the rapidly growing technology development such as nanofiber based sensor devices, conductive tissue engineering scaffold materials, supercapacitors, and flexible solar cells applications. PANI however is relatively hard to process compared to that of other conventional polymers and plastics. The processing of PANI is daunting, mainly due to its rigid backbone which is related to its high level of conjugation. The challenges faced in the electrospinning processing of neat PANI have alternatively led to the development of the electrospun PANI based composites and blends. A review on the research activities of the electrospinning processing of the PANI based nanofibers, the potential prospect in various fields, and their future direction are presented.

In situ surface modification of natural fiber by conducting polyaniline

Newly modified biofibers made up of kenaf fibers (KF) and conducting polyaniline (PANI) were successfully prepared via in situ polymerization. Several characterization methods were done to elucidate the interaction between the KF surfaces and the in situ polymerized PANI. The PANI coated KF (KF/PANI) achieved new electronic properties, without sacrificing its mechanical properties and natural fiber characteristic. Initial mercerization on the KF yielded better PANI coated fibers compared to the untreated KF. Fiber bundle tensile test on the untreated KF/PANI revealed a drop in the unit break of about 48% compared to the untreated neat KF. Meanwhile, the mercerized KF/PANI showed reduction of about 17% compared to the uncoated mercerized KF. The mercerized KF/PANI exhibits polaronic transitions, existence of favorable IR peaks and Raman scattering, enhanced DC conductivity, and better morphological characteristic as a result of the in situ PANI coating. Such electronically modified natural fibers could be suitable as green conducting fillers in composites to replace other synthetic fibers.

Reinforcement of poly(vinyl alcohol) hydrogel with halloysite nanotubes as potential biomedical materials

ABSTRACT This work reports the reinforcement of poly(vinyl alcohol) (PVA) hydrogel with halloysite nanotubes (HNT) as potential biomedical materials. The nanocomposite hydrogel was prepared using the facile and harmless process of freeze–thawing. Mechanical properties of the hydrogels were optimum at 2 wt% of HNT loading. Morphological and topographic analysis of the PVA/HNT hydrogel revealed excellent filler dispersion and smoothing of surface due to good compatibility between the components. Immersion of the PVA/HNT hydrogel in simulated body fluid for 7 days resulted in the formation of fully covered apatite layers on the surface. This is a good indication of bioactivity for artificial cartilage material.

Enhanced Interfacial Interaction and Electronic Properties of Novel Conducting Kenaf/Polyaniline Biofibers

Conducting kenaf/polyaniline (KF/PANI) biofibers were successfully prepared via in situ oxidative polymerization. It was demonstrated, for the first time, the possibility of imparting new electronic properties on KF by coating with acid-doped PANI. The morphological analysis revealed three different PANI morphologies on the KF, depending on the type of acid doping. Enhanced interaction was achieved between the fiber-PANI surfaces, mainly from the π − π interactions. The newly developed conducting biofibers achieved enhancement in DC conductivity up to fivefold compared to the unmodified KF. Mechanical test on the conducting biofibers revealed no significant loss in the tensile properties.

A Conductive polylactic acid/polyaniline porous scaffold via freeze extraction for potential biomedical applications

ABSTRACT This paper reports for the first time a simple yet effective method for fabricating a conductive and highly porous scaffold material made up of polylactic acid (PLA) and conducting polyaniline (PANI). The electrical percolation state was successfully obtained at 3 wt% of PANI inclusions and reached a conductivity level of useable tissue engineering applications at 4 wt%. In addition, preliminary bioactivity test results indicated that the protonating agent could form a chelate at the scaffold surface leading to good in-vitro apatite forming ability during biomimetic immersion. This new conductive scaffold has potential as a suitable biomedical material that requires electrical conductivity.

Polyaniline-coated kenaf core and its effect on the mechanical and electrical properties of epoxy resin

Novel conducting kenaf core/polyaniline (KC-PANI) biofibers were successfully prepared via in situ oxidative polymerization. The newly developed conducting KC achieved enhancement in DC conductivity up to seven fold compared to the raw KC. Enhanced interaction was obtained between the acetylated KC-PANI surfaces compared to untreated KC-PANI, without significant loss in the cellulose crystallinity. The morphological analysis revealed uniform layers of PANI deposited on the surface of acetylated KC. Epoxy resin (EP) containing KC-PANI (EP/KC-PANI composites) showed that the electrical percolation of KC-PANI occurred at 20 wt.%. The tensile strength of the EP/KC-PANI composites was slightly reduced compared to that of EP/KC composites at the same loading fraction. However, the flexural test revealed that the presence of KC-PANI increased the flexural strength of the EP composites by up to 15 wt.% loading. Electron micrograph of the EP/KC-PANI composite indicated favourable adhesion between components.

Hybrid composites of short acetylated kenaf bast fiber and conducting polyaniline nanowires in epoxy resin

This article reports the preparation and characterization of newly developed hybrid composites consisting of epoxy resin (EP) matrix, acetylated kenaf bast fiber (AKF) and conducting polyaniline (PANI) nanowires. Initially, the EP/AKF composites were prepared by varying the AKF loading (5–30 wt%). The EP/AKF displayed an optimum tensile strength at 20 wt% AKF loading which was higher than that of untreated kenaf fiber EP composites (EP/UKF). The hybrid composites of EP/AKF/PANI were then prepared by using 20 wt% AKF loading with PANI inclusions from 2 to 14 wt%. The addition of PANI into EP/AKF induced positive electrical properties without considerably sacrificing its mechanical integrity. It was found that the electrical percolation threshold of these hybrid composites was at 11 wt% of PANI loading. PANI inclusions at above the percolation loading resulted in reduction of tensile and flexural strength. Meanwhile, no significant mechanical loss was observed below the threshold. The fracture morphological analysis revealed the occurrences of PANI nanowires pull out from the matrix. The Fourier transform infrared spectroscopy showed that the PANI component still maintained its doped condition inside the EP/20AKF. Water absorption and thermal analysis indicate that the PANI incorporation induced lower water uptakes and greater thermal stability to the EP/20AKF, respectively.

Para-Hydroxybenzene Sulfonic Acid as a Suitable Dopant for the Preparation of Conductive Epoxy/Polyaniline Nanowires Nanocomposites Blend: Electrical vs Mechanical Properties

This article reports improved mechanical properties of epoxy/polyaniline nanowires nanocomposite (EP/PANI) by using para-hydroxybenzene sulfonic acid as the dopant. The PANI nanowires show no chain dedoping in the EP. Mechanical properties of the nanocomposites were maintained while achieving its conductive state and revealed pull-out of bundles rather than individual nanowire.

Polyaniline-coated halloysite nanotubes: effect of para-hydroxybenzene sulfonic acid doping

This paper reports new method of preparing electrically conducting polyaniline-coated halloysite nanotube (HNT-PANI) by using para-hydroxybenzene sulfonic acid as the doping agent. The achieved DC electrical conductivity of the HNT-PANI was 9.83 × 10−2 Scm−1. The HNT revealed no damages by the acid doping while achieving its conductive state. The HNT-PANI exhibits polaronic transitions, existence of favorable IR peaks and Raman scattering, increased thermal stability, and desirable morphological characteristic as a result of the in situ coating. Such electronically modified tube-like clay could be useful in many applications such as conductive fillers in nanocomposites and drug delivery with the advantage of being cost effective.

Simultaneous numerical optimization of the mechanical and electrical properties of polyaniline coated kenaf fiber using response surface methodology: nanostructured polyaniline on natural fiber

Response surface methodology was used to simultaneously optimize the electrical and mechanical properties of newly developed conducting biofibers made up of kenaf fiber/polyaniline (KF/PANI). The effect of process parameters such as PANI amount (1–10 wt.%), dopant concentration (5–25 N), and molar ratio of aniline/oxidant solutions (0.5–1.5) were studied using Design of Experiment. Both of the responses (electrical conductivity and unit break) obtained a quadratic model. The experimental values were in good agreement compared to the optimized process. The scanning electron microscope images of the optimized sample revealed uniform PANI component on the KF with nanofibrillar features.