Optical properties of azo (EO) chromophore (DR1) doped in poly amic acid (PAM)
In this work, we studied the effects of annealing on the structural and optical properties of an azo electro optic (EO) polymer, Disperse Red1 (DR1), doped in Poly Amic Acid (PAM). Thin films were deposited on glass substrates by spin coating technique. The films were annealed at 195°C. The Structural and optical properties of the doped films were investigated by using UV-VIS spectra, Atomic Force Microscopy (AFM) and Prism Coupling technique. The number of modes, angles of coupling, thickness and refractive index were compared before and after annealing. The experimental results, showed 24nm blue shift in the photon absorption peak and number of modes and surface roughness of thin films decreased after annealing. Thickness was reduced about 1um and refractive index was increased by 0.03.
Degradation study on structural and optical properties of annealed Rhodamine B doped poly(vinyl) alcohol films
Abstract We report the observations on optical and structural properties of thermally treated undoped and doped poly(vinyl) alcohol (PVA) films as a function of doping and annealing temperature. The crystalline peaks of both PVA and Rhodamine B are seen in the X-ray diffraction (XRD) of the as prepared samples where the crystallinity of Rhodamine B increases with doping. At 2 wt% doping, Rhodamine B crystals segregate and are seen at the surface. However, after annealing only PVA peaks remain and Rhodamine B becomes amorphous as seen from XRD and micro-Raman measurements. It is shown how the thermal energy imparted to host PVA and dopant Rhodamine B molecules results in the movement of molecules, breaking the bonds inside the material. The intensity and frequency of Raman active modes is observed to be modified with increasing temperature due to structural changes in polymer bonds. It is also observed that thermal annealing leads to a shift in the optical absorption edge towards lower energies. This is attributed to the modified electronic states. The overall results are interpreted in terms of modifications in structural and optical properties.
Vinyl Acetate Emulsion Polymerization and Copolymerization with Acrylic Monomers
INTRODUCTION EMULSION POLYMERIZATION Emulsion Polymerization of Hydrophobic Monomers Inverse and Emulsifier Free Emulsion Polymerizations Vinyl Acetate Emulsion Polymerization Radiation Induced Vinyl Acetate Emulsion Polymerization THE ROLE OF INGREDIENTS IN VINYL ACETATE EMULSION Monomer Quality and Inhibitors Initiators Emulsifiers Protective Colloids PH and Ionic Strength Controllers Others THEORY AND KINETICS OF VINYL ACETATE HOMOPOLYMERIZATION Effect of Monomer Concentration Effect of Initiator Concentration and Type Effect of Emulsifier Concentration and Type Particle Nucleation Mechanisms Thermodynamics and Kinetics of Particle Morphology Control VINYL ACETATE COPOLYMERIZATION WITH ACRYLIC MONOMERS Reactivity Ratios Propagation Rate in Copolymerization Controlled Monomer Addition The Effect of the Type of the Acrylic Monomer The Effect of the Vinyl Acetate/Acrylic Monomer Feed Ratio COLLOIDAL STABILITY OF VINYL ACETATE HOMO AND COPOLYMERS Basic Phenomena Steric Stabilization Coagulation Ionic Effects EXPERIMENTAL DETERMINATION OF LATTICE PROPERTIES Viscosity Solids Content Free Monomer Content Mean Molecular Weight and Molecular Weight Distribution Graft and Cross-Linked Polymer Content Monomer Sequence Distribution Mean Particle Size and Particle Size Distribution Chemical Composition of Copolymers Scattering of Colloids Surfactant Adsorption on Latex/Water Interface Colloidal Stability Drying and Film Forming Properties of Latices Surface Tension of Dried Latex Films Dynamic Mechanical Properties of Latex Films Aging Properties FACTORS AFFECTING THE FINAL P ROPERTIES OF THE POLYVINYL ACETATE-BASED LATICES The Role of the Type and the Quality of the {Polyvinyl Alcohol Protective Colloids on PVAc Homopolymers The Role of Emulsifiers on the Mean Particle Size and Colloidal Stability The Stabilization of PVAc Latices by Monomeric Carboxylic Groups The Role of the Duration of Polymerization Reaction The Role of Acrylic Comonomers The Role of Monomer Addition Methods and Propagation Rates on Copolymer Composition in Semi-Batch Reactor Operations The Role of the Shapes of Reactor Stirrers and Baffles and Stirring Rate The Role of Antifoaming Agents Seed Latex Preparation and Use Emulsion Polymerization in Continuous Reactors Scale-Up Problems OVERVIEW OF THE USES OF POLYVINYL ACETATE-BASED LATICES SOME NEW APPLICATIONS IN INDUSTRY Ultrasound Sensor Monitoring of Emulsion Polymerization Loop Reactor Continuous Emulsion Polymerization