Nanocrystalline TiO 2 and conjugated polyimide are good composite materials for solar energy harvesting applications. Vat dyes have a specific high color fastness property with high wavelength absorption. By applying this property of vat dyes, we synthesized Safranin O and a perylene 3,4,9,10-tetracarboxylic dianhydride (PTCDA) based conjugated polyimide through the condensation polymerization technique. Synthesized polyimide was used to construct a TiO 2 −polymer composite material for dye-sensitized solar cells (DSSCs). The synthesized polyimide has good absorption properties, and a small bandgap of 2.23 eV, contains alternating electronaccepting−electrondonating units, and revealed high thermal stability. It shows good electrical properties, i.e., conductivity of the order of ∼10 −4 S cm −1 and an activation energy of 0.1 eV before transition and 0.6 eV after transition, follows an Arrheniustype behavior, and has thermal transitions. Fabrication of electrodes and DSSC was performed for determining the photovoltaic properties of the synthesized polyimide. The obtained photovoltaic parameters, i.e., J sc = 65 μAcm −2 , V oc = 0.128 V, and FF = 0.36, demonstrated their successful use in dye-sensitized solar cells.

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A straightforward and novel methodology has been developed for the synthesis of ultra-high-molecular weight polyacrylamide (PAM) by vertical solution polymerization technique. By varying the concentrations of acrylamide monomer, three different grades of polymers (PAM-V 1 , PAM-V 2 , and PAM-V 3 ) have been synthesized and compared with the series of different grades of PAM (PAM-C 1 , PAM-C 2 , and PAM-C 3 ) synthesized through conventional solution polymerization technique. The synthesized grades PAM-V 1 , PAM-V 2 , PAM-V 3 , PAM-C 1 , PAM-C 2 , and PAM-C 3 have been characterized by 1 H NMR, infrared spectroscopy, intrinsic viscosity measurement, molecular weight determination by gel permeation chromatography, and thermal analysis. Rheological analysis has been carried out on the aqueous solutions of various grades of PAMs. Swelling behavior of ultra-high-molecular weight PAMs has also been investigated. The flocculation performances of all grades have been investigated in kaolin suspension by settling and jar test methods. were characterized by 1 H NMR spectroscopic study and the spectra of PAM-V 3 and PAM-C 3 are shown in Fig. 1. A broad peak observed at 2.07 ppm was attributed to the CH protons Sch 1. Schematic representation of (a) vVSP technique and (b) CSP technique respectively. [Color figure can be viewed at wileyonlinelibrary.com]

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