Rajni M. Patel

Indium oxide thin film based ammonia gas and ethanol vapour sensor

A sensor for ammonia gas and ethanol vapour has been fabricated using indium oxide thin film as sensing layer and indium tin oxide thin film encapsulated in poly(methyl methacrylate) (PMMA) as a miniature heater. For the fabrication of miniature heater indium tin oxide thin film was grown on special high temperature corning glass substrate by flash evaporation method. Gold was deposited on the film using thermal evaporation technique under high vacuum. The film was then annealed at 700 K for an hour. The thermocouple attached on sensing surface measures the appropriate operating temperature.The thin film gas sensor for ammonia was operated at different concentrations in the temperature range 323–493 K. At 473 K the sensitivity of the sensor was found to be saturate. The detrimental effect of humidity on ammonia sensing is removed by intermittent periodic heating of the sensor at the two temperatures 323K and 448 K, respectively. The indium oxide ethanol vapour sensor operated at fixed concentration of 400 ppm in the temperature range 293–393 K. Above 373 K, the sensor conductance was found to be saturate. With various thicknesses from 150–300 nm of indium oxide sensor there was no variation in the sensitivity measurements of ethanol vapour. The block diagram of circuits for detecting the ammonia gas and ethanol vapour has been included in this paper.

Exopolymer production by Bacillus species

Abstract An exopolymer producing bacterium Bacillus megaterium was isolated from the infected plant leaf of Aralia species. The isolated organism produced 10–11 g/l of polymer in a synthetic medium consisting of glucose, ammonium nitrate and various salts. Optimum conditions for polymer production were determined. Amongst various carbon and nitrogen sources tested sucrose and ammonium nitrate gave maximum production. C N ratio of the medium, temperature and pH for optimum polymer production were also investigated. Some of the physico-chemical properties, such as relative viscosity, specific viscosity and reduced viscosity of the polymer were studied at various concentrations and temperatures. Intrinsic viscosity of the polymer was also determined.

Friedel-Crafts polyketones : Synthesis, characterization and antimicrobial properties

Low molecular weight Friedel-Crafts polyetherketones (PEK) were prepared from o-chloro anisole, 1,4-phenylenedioxy diacetychloride (1,4-PDC), chloroacetylchloride (CAC), 1,2-dichloroethane (DEC) and dichloromethane (DCM) using anhydrous AlCl3 as catalyst and CS2 as solvent. The polyetherketones were characterized by IR spectra and Gel permeation chromatography (GPC). The kinetic parameters for the thermal behaviour of the resins were obtained from thermo gravimetric analysis (TGA) using the Broido and Doyle method. Differential scanning calorimetry (DSC) traces were employed to obtain heat of fusion. All the polyetherketones were tested for their biological activity against bacteria, fungi and yeast. It was observed that most of the polyetherketones synthesized can be used as antibacterial and antifungal agents.

Acrylic Homo- and Co-polymers Based on 2, 4-dichlorophenyl Methacrylate and 8-quinolinyl Methacrylate

The monomer 2, 4-dichlorophenyl methacrylate (2,4-DMA) was synthesized from 2, 4-dichlorophenol and characterized by conventional methods. The homopolymers of 2,4-dichlorophenyl methacrylate and its copolymers with 8-quinolinyl methacrylate (8-QMA) in different feed ratio were prepared by free radical polymerization using dimethyl formamide (DMF) as a solvent and 2,2′-azobis iso butyronitrile (AIBN) as an initiator. The resulting polymers were characterized by using IR spectroscopy. Reactivity ratios of monomer were evaluated using UV-spectroscopy. Average molecular weights and polydispersity were determined by gel permeation chromatography (GPC). Solution viscosity was also obtained. The thermal analysis was carried out using TGA and DSC. The homo- and co-polymers were also tested for their antimicrobial properties against selected microorganism. The metal ion uptake capacity of synthesized copolymers was estimated by batch equilibration method using different metal ion solution under different experimental conditions. It is observed that due to the presence of pendant ester bound quinoline group, the copolymers are capable of adsorbing cations from their aqueous solution.

Synthesis, Thermal Behaviour and Biological Activity of Chlorine Containing Polyketones

Abstract Chlorine containing compounds are known to possess biological activity. This observation prompted us to synthesis Friedel-Crafts polyketones from o-chlorophenol, chloroacetyl chloride, 1,2-dichloroethane and dichloromethane using anhydrous aluminium chloride as catalyst and nitrobenzene (PhNO2) as a solvent. The IR spectral data of these compounds indicates the presence of carbonyl and chlorine group in the resin backbone. The kinetic parameters for the thermal decomposition of the resins were evaluated from TG and DSC thermograms using methods of Broido and Doyle. Microbial study indicates the ability of the polyketone to inhibit the growth of selected species of bacteria, fungi and yeast.

SYNTHESIS, CHARACTERIZATION, THERMAL PROPERTIES AND ANTIMICROBIAL ACTIVITY OF ACRYLIC COPOLYMERS DERIVED FROM 2,4-DICHLOROPHENYL ACRYLATE

ABSTRACT Copolymer of monomer 2,4-dichlorophenylacrylate (2,4-DCPA) and methylmethacrylate (MMA) were synthesized with different monomer feed ratio using dimethylformamide (DMF) as a solvent and 2,2’-azobisisobutyronitrile (AIBN) as an initiator at 70 oC. The copolymers were characterized by IR-Spectroscopy and copolymer composition was determined with UV-Spectroscopy. The linearization method of Fineman Ross (F-R) and Kelen Tudos (K-T) were used to obtain the monomer reactivity ratios. Thermal analyses of polymer were carried out in nitrogen atmosphere thermal gravimetric analyses (TGA) and differential thermal analyses (DTA). The molecular weight and intrinsic viscosity were determined by vapor pressure osmometry (VPO). The homo and copolymers were tested for their antimicrobial properties against selected microorganisms. Key words: Copolymer / Thermal Analysis / Reactivity Ratio / Antimicrobial Activity INTRODUCTION Copolymer is the most successful and powerful method for effecting systematic change in polymer [1]. Phenyl acrylate polymers are relatively newly developed materials compared to the commercial polymer such as vinylics. Acrylate is considered as reactive monomers primarily because of the presence of aromatic ring [2]. Choudhary Veena and coworkers [3-5] prepared copolymer of methyl methacrylate (MMA) with a variety of vinyl monomers. Strum [6] reported about thirty eight ester useful as commercial bactericides and fungicides. Plunder and coworkers [7] synthesized acrylics ester, useful as biocides by reacting pentachloro phenol,

Copolymers of 2,4‐Dichlorophenyl Methacrylate with Styrene: Synthesis, Thermal Properties, and Antimicrobial Activity

The methacrylate monomer, 2,4‐dichlorophenyl methacrylate (2,4‐DMA), was synthesized by reacting 2,4‐dichlorophenol (2,4‐D) with methacryloyl chloride. The free‐radical initiated copolymerization of 2,4‐DMA with styrene was carried out in a toluene solution at 70°C using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator with different monomer feed ratios. The monomer 2,4‐DMA and the copolymers were characterized by Fourier transform infrared spectral studies. Copolymer composition was determined by UV‐spectroscopy. The reactivity ratio of the monomers was obtained employing the conventional linearization method of Fineman–Ross. The molecular weights (M¯w, M¯n) and polydispersity index of the polymers were determined using gel permeation chromatography. Thermogravimetric analysis (TGA) of the polymers was carried out in nitrogen atmosphere. Antimicrobial effects of the homo‐ and copolymers were also investigated for various microorganisms.

2,4‐Dichlorophenyl Acrylate/8‐Quinolinyl Methacrylate Copolymers: Ion‐Exchange Study

The chelating ion‐exchange properties of the 2,4‐dichlorophenyl acrylate (2,4‐DCPA)/8‐quinolinyl methacrylate (8‐QMA) copolymers, synthesized using different monomer feed ratios, were investigated by the batch equilibrium method. Five metal ions Cu+2, Ni+2, Co+2, Zn+2, and Fe+3 were used to evaluate the cation‐exchanger capability of 2,4‐DCPA‐co‐8‐QMA copolymers. The ion‐exchange study was carried out for three different experimental variables viz., pH of the aqueous medium, ionic strength of electrolyte and shaking time. It was observed that due to the presence of a pendant ester‐bound quinolinyl group, the copolymers are better suited as cation exchangers.

Synthesis and Biological Activity of Polyketone Resins. Part I: Systems Based on Toluene with Carbon Disulphide as Solvent

Polyketone resins have been synthesized by reacting toluene, chloroacezyl chloride, 1,2-dichloroethane and dichloromethane using anhydrous aluminium chloride as catalyst. The polyketones thus obtained were characterized by IR analyses and number average molecular weight by vapour pressure osmometry. The thermal properties were studied by thermogravimetry and differential scanning calorimetry. All the polyketone resins were tested for their biological activity against bacteria and fungi. The results show that the growth of the tested organisms can be controlled by the polyketones.

ANTIMICROBIAL ACTIVITY OF COPOLYMERS OF 2,4-DICHLOROPHENYL ACRYLATE WITH STYRENE: SYNTHESIS, CHARACTERIZATION AND REACTIVITY RATIOS

Some copolymers of 2,4-dichlorophenyl acrylate (2,4-DCPA) with styrene (St) of different feed compositions were prepared by free radical polymerization technique using 2,2′-azobisisobutyronitrile (AIBN) as an initiator, and the copolymers were characterized by IR spectroscopy. The copolymer composition obtained by UV-spectra led to determination of reactivity ratio by employing Fineman-Ross (F-R) and Kelen-Tudos (K-T) methods. Average molecular weight, as well as intrinsic viscosity, was obtained by vapor pressure osmometry (VPO) and Ubbleholde viscometer. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) of copolymers were carried out under nitrogen atmosphere. Antimicrobial effects of the homo and copolymers were also investigated against various microorganisms such as bacteria, fungi and yeasts.