Bhimrao D. Sarwade

Synthesis and Biodegradability of Polyaspartic Acid: A Critical Review

Poly(aspartic acid) (PAA) being biodegradable is suitable for various industrial medical and agricultural applications to replace many non‐biodegradable polymers in use. Poly(aspartic acid) can be synthesized by different methods with and without catalyst in different forms such as polysuccinimide, either hydrolyzed to acid or salt. The polymer of (aspartic acid) is present in different forms such as α,β and L, D isomers. The conformational analysis of poly(aspartic acid) was done by various analytical methods. Different combinations of these two isomer present in different percentage can be detected by various methods such as Hoffman degradation, IR, and NMR spectroscopic analysis. From the standard test for biodegradability, it was shown that the polymer is fully biodegradable. In this review, synthesis and characterization of homo and copolymer derivatives of PAA, along with the application and biodegradability in comparison with the other polymer in use, is discussed briefly.

Electrochemical Fluorescence Switching from a Patternable Poly(1,3,4‐oxadiazole) Thin Film

A highly soluble poly(1,3,4-oxadiazole) (POD) substituted with long alkyl chains was examined for electrochemical fluorescence switching. The high solubility of the polymers enabled a simple fabrication of an electrochemical cell, which showed reversible fluorescence switching between dark (n-doping) and bright (neutral) states with a maximum on/off ratio of 2.5 and a cyclability longer than 1000 cycles. Photochemical cleavage of the oxadiazole in POD allowed photo-patterning of the POD film upon exposure to UV source. The patterned POD films displayed patterned image reversibly under a step potential of +1.8/-1.8 V.

Multistate fluorescence switching of s-triazine-bridged p-phenylene vinylene polymers

A polymer switch was explored utilizing the redox reaction of iodide ions with highly fluorescent s-triazine (ST)-bridged p-phenylene vinylene (PPV) polymers. The fluorescent polymers were synthesized through the Wittig polycondensation to yield ST-bridged PPV polymers. Utilizing different quenching properties of the polymer with iodine derivatives, the fluorescence of the polymers was modulated electrochemically in a two-electrode device consisting of the fluorescent polymer-doped gel layer containing an iodide and iodine couple and a solid polymer electrolyte layer. The cell showed reversible multistate fluorescence switching in the working potential range of +2V.

NIR electrochemical fluorescence switching from polymethine dyes

A polymethine dye was used as a fluorophore and an electroactive modulator in order to achieve reversible electrochemical fluorescence switching in the near infrared (NIR) region. An NIR emissive polymethine dye, 3H-indolium, 2-[2-[2-chloro-3-[2-[1,3-dihydro-3,3-dimethyl-1-(phenylmethyl)-2H-indol-2-ylidene]ethylidene]-5-(1,1-dimethylethyl)-1-cyclohexen-1-yl]ethenyl]-3,3-dimethyl-1-(phenylmethyl)-bromide (PM1), displayed high absorption and emission in the NIR region. In addition, it showed a relatively reversible electrochemical reaction between −0.5 and 1.1 V vs. Ag wire. In contrast, a keto group (CO) bridged polymethine analogue, 2,6-bis[2-(1,3-dihydro-1-hexyl-3,3-dimethyl-2H-indol-2-ylidene)ethylidene]-4-(1,1-dimethylethyl)cyclohexanone (PM2), showed an irreversible electrochemical reaction, possibly due to the keto group interrupting the full conjugation of the entire molecule in PM2. The reversible redox reaction of PM1 allowed electrochemical fluorescence switching in the NIR region for the first time. The NIR fluorescence switching was visually observable through a visible light cut-off filter with a cyclability of over 100.

A p-Phenylene Vinylene Polymer Bridged by a Triazine for Electro-Fluorescence Switching

A highly fluorescent s-triazine (ST) bridged p-phenylene vinylene (PPV) polymer was synthesized by the Wittig polycondensation reaction of 4, 6-bis (4-formylphenoxy)-2-diphenylamino-s-triazine and 2, 5-bis (triphenylphosphonionmethyl)-1, 4-bis (trimethylsilyl) benzene dibromide, to afford ST bridged PPV polymer (DTTPV). The fluorescence of the polymer was dramatically changed by the application of the external potential from − 2 V to 2 V in a two electrode cell containing a solid polymer electrolyte layer. The fluorescence switching was reversible with a switching time of 4s.

Synthesis and characterization of aromatic-alipathic polyamides containing tetraphenylthiophene units into the backbone

SummaryAromatic-aliphatic polyamides were prepared from 2, 5-bis(4-carboxyethylcarbonylphenyl)-3,4-diphenylthiophene (BCDT) with few commercial diamines by using Yamazakis phosphorylation reaction. The polymers were obtained in good yields and were characterized by solubility tests, viscosity measurements, IR spectroscopy, thermal analysis and X-ray diffraction studies. These polyamides had inherent viscosities in the range of 0.35 to 0.70 dl/g and were amorphous in nature. All the polyamides were readily soluble in solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, N,N-dimethylformamide, nitrobenzene, hexamethylphosphoramide, m-cresol, sulphuric acid and did not lose weight below 300°C in air.

Chemical modification of poly(2,6-dimethyl- 1,4-phenylene oxide) by electrophitic substitution reaction with isocyanates

SummaryThe chemical modification of poly(2,6-dimethyl- 1,4-phenylene oxide) (PPO) has been carried out by incorporating amide groups on PPO backbone by electrophilic substitution reaction with isocyanates. The modified polymers obtained have been characterized by IR and IH-NMR spectroscopy, nitrogen analysis, solubility tests and X-ray diffraction studies.

Photopolymers containing epoxy monomers for holographic recording

Photopolymer films containing epoxy monomers were explored for holographic recording. A photopolymer film composition was optimized by using a s-triazine epoxy monomer and coated on a glass substrate. The film showed high sensitivity to visible light, to lead polymerization as determined by a photo DSC. The diffraction efficiency of the photopolymer film was determined as 61%, which was stable for longer than 1 week. A holographic screw image could be recorded onto the photopolymer film. The image was stable when read by a visible light.

Photopolymers containing triazine monomers for holographic recording

Photopolymer films containing s-triazine (ST) methacrylic monomers were explored for holographic recording. Photofunctional s-triazine derivative having polymerizable group was synthesized starting from the reaction of a ST di-thiol derivative with methacryloyl chloride to give ST methacrylic monomer substituted with methylthio group (TRSM). ST methacrylic monomer substituted with ethylene oxy unit (TREGM) was synthesized from the reaction of a diamine substituted ST dichloride derivative with hydroxyl-ethyleneoxy methacarylate (HEMA). Photopolymer films prepared by mixing the s-triazine monomer with binder, additives, and photoinitiator were sensitive to a visible light and polymerized upon excitation with a visible laser. The optimization of holographic recording media was achieved by controlling the concentration and chemical structure of monomer composition in photopolymer films to control the diffusion and polymerization of monomer. The new photopolymer films containing ST methacrylic monomer substituted with ethylene oxy unit (TREGM) showed diffraction efficiency reaching ~ 90%. High diffraction efficiency and fast response for the photopolymer prepared from TREGM monomer were ascribed to the effective monomer compatibility with the binder to result in high optical clarity of the film.

Copolyesters Containing Oxyethylene Linkages: Synthesis and Characterization

Abstract Oxyethylene-containing copolyesters were synthesized from bisphenol-A (BPA) and diacyl chlorides containing oxyethylene linkages, isophthaloyl chloride (IPC), and terephthaloyl chloride (TPC) by interfacial polycondensation. All the copolyesters were obtained in almost quantitative yields and showed film forming properties. The copolyesters were amorphous/semicrystalline and were soluble in common organic solvents. Copolyesters showed similar pattern of decomposition with no weight loss below 380°C in nitrogen.