Polymerization Method In Presence Research Articles

Preparation and characterization of self-electrical stimuli conductive gellan based nano scaffold for nerve regeneration containing chopped short spun nanofibers of PVDF/MCM41 and polyaniline/graphene nanoparticles: Physical, mechanical and morphological studies

Conductive self -electrical stimuli bioactive scaffolds could be used the potential for peripheral nerve regeneration with the maximum efficiency. To produce such conductive self-electrical stimuli bioactive scaffolds, chopped spun piezoelectric nanofibers of polyvinylidene fluoride/mesoporous silica nanoparticle (PVDF/MCM41) are prepared and incorporated in gellan/polyaniline/graphene (gellan/PAG) nanocomposites which have been previously prepared by incorporation of polyaniline/graphene (PAG) nanoparticles in gellan gel at 80 °C. Highly conductive binary doped polyaniline/graphene nanoparticles are prepared by chemical oxidative polymerization of aniline monomer using in-suite precipitation polymerization method in presence of graphene nanoparticles and sodium dodecyl sulfate. All intermediate and final products including spun PVDF/MCM41 nanofibers, PAG nanoparticles, and gellan-gelatin gel scaffolds containing PVDF/MCM41 nano spun fibers and PAG nanoparticles are characterized using different analysis methods. Chemical and structural analyses of PAG nanoparticles and PVDF/MCM41 nanofibers have been done using FTIR and XRD methods. The morphological structure of different samples is investigated using SEM. Morphological investigation and DLS results confirm fabrication of MCM41 nanoparticle with a completely spherical shape and the average size of 50 nm of which have been dispersed in electrospun PVDF nanofibers very well. Also, the preparation of PAG nanoparticle with high conductivity is verified with morphological and conductivity tests. MTT easy and biocompatibility test results indicate potential applicability of the prepared conductive self -stimuli nano-scaffold for nerve regeneration applications.

Preparation and characterization of ketonic polymer for coating applications

Abstract A systematic study has been performed to develop a synthetic resin from cyclohexanone by self–polymerization method in presence of a base catalyst. In addition, an effort has been made to characterize a product by analyzing its various physico–chemical properties such as hydroxyl content, iodine value, acid value, solubility, viscosity, adhesive strength, and average molecular weight. To investigate the effects of operating parameters on physico–chemical properties, reaction time was varied between 7 and 20 h, catalyst loading was varied between 0.05–0.4, and temperature was varied in the range of 90–160 °C. The extent of polymerization reaction increased with the increase of catalyst loading, reaction temperature and reaction time. A good quality resin was obtained when the reaction was performed in a closed reactor. The study confirmed that KOH offers better quality product than NaOH. The average molecular weight of the products lies in the range of 300–1200. It has been further observed that the adhesive strength of the solid resins is comparable with the commercial fivistick material. The article includes the development of mathematical model to find the product properties.

Preparation of magnetic and conductive graphite nanoflakes/SrFe12O19/polythiophene nanofiber-nanocomposites and its radar absorbing application

This study, we synthesized graphite-nanoflakes (GNFs) by acid treatment and thermal shock and then using the ultrasonic irradiation technique to exfoliate flake-carbon. The SrFe12O19 nanoparticles (NPs) were coated by co-precipitate method on GNFs after by alkaline treatment. Finally nanocomposite (GNF/SrFe12O19/PTh) was prepared by in-situ oxidative polymerization method in presence of thiophene (Th) as monomer. The magnetic and electrical conducting properties of the resulting nanocomposites were measured by using vibrating sample magnetometer and standard four-point-probe method, respectively. The synthesized nanocomposites were characterized by X-ray diffraction (XRD) and fourier transform infrared spectra (FTIR). In addition, morphological analyses were investigated by scanning electron microscopy (SEM). A minimum reflection loss (RL) of GNFs/SrFe12O19/PTh with 50 % wt GNFs/SrFe12O19 as core were observed −28 and −39 dB at 9.7 and 12 GHz for a 1.5 mm thickness. The results indicated that we can perform good microwave shielding in X-band (8–12 GHz) by these nanocomposites.

Preparation of conductive polyaniline/graphene nanocomposites via in situ emulsion polymerization and product characterization

This work, which is a part of our ongoing studies on developing conductive scaffolds for nerve tissue engineering, reports synthesis of highly conductive binary-doped polyaniline nanoparticles and polyaniline/graphene nanocomposites. The samples were synthesized through chemical oxidation of aniline via in situ emulsion polymerization method in presence of hydrochloric acid and sodium dodecyl sulfate. Graphene nanosheets were also prepared via modified Hummer's method followed by chemical reduction using hydrazine monohydrate. Electrical conductivity measurements using a standard four-point probe technique with FTIR and UV–vis studies revealed that conductive binary-doped emeraldine salt polyaniline had been successfully produced. The results also showed that incorporation of less than 1wt.% of graphene nanosheets into polymeric matrix had improved electrical conductivity of polyaniline from 2 to 7Scm−1. The SEM micrographs illustrated that the synthesized polyaniline had spherical morphology with particle size of 10–15nm. The results of the investigated thermal properties showed that binary doping process and also incorporation of graphene into polymeric matrix had improved thermal stability of polyaniline main chains. Finally, this work supported proper morphological, electrical, and thermal properties of prepared PANI/graphene nanocomposites and their potential use in different biomedical applications such as tissue engineering, biosensor, controlled drug delivery systems, and surface coating.

Structural and electrochemical properties of polythiophene

Polythiophenes (PTs) were prepared by chemical oxidative polymerization method in presence and absence of three different (cationic – CTAB, anionic – SDS and non-ionic – Triton X-100) surfactants using FeCl 3 as oxidant. The prepared PTs were characterized by FT-IR, UV–Vis, XRD, SEM and cyclic voltammetry studies. The FT-IR spectra inferred the polymerization of thiophene and elucidate the corresponding functional groups of PTs. Our results on the UV–Vis spectra demonstrate the n− π* electronic transition of the conjugated molecules. Further the red shift in the absorption peak confirms the longer conjugation length of PTs. The amorphous nature of the PTs was inferred from the XRD pattern. The PTs prepared with surfactant exhibited different morphology compared to PT prepared without surfactant. The specific capacitances (SC) of the prepared PTs were calculated using cyclic voltammetry technique, the PT prepared with TRITRON X-100 exhibited higher SC of 117 F/g compared to SC of surfactant free PT (78 F/g). Hence, the PTs prepared with surfactants were found to be suitable electrode materials for redox supercapacitors.

A comparative study on water-based coatings prepared in the presence of oligomeric and conventional protective colloids

Poly(vinyl acetate-co-butyl acrylate) latexes were prepared by using semi-continuous emulsion polymerization method in presence of two different protective colloids which were oligomeric N-methylol acrylamide and conventional poly(vinyl alcohol). The effects of these protective colloids on colloidal, surface and film properties of latexes were examined. Poly(vinyl acetate-co-butyl acrylate) synthesized with oligomeric N-methylol acrylamide, which was characterized by FT-IR, NMR and MALDI-TOF MS, was found to have lower viscosity, finer particle size, better latex stability, lower polydispersity, higher T g and better film forming behavior compared to those synthesized from the poly(vinyl alcohol).