Photodegradation of Polymers

1 Absorption of Radiation.- 1.1 Radiation and Its Energy.- 1.2 SI Units Used in Photochemistry.- 1.3 Absorption Cross Section.- 1.4 Practical Aspects of the Lambert-Beer Equation.- 2 Electronically Excited States in Polymers.- 2.1 Formation of Excited States.- 2.2 Radiative Processes.- 2.3 Radiationless Transitions.- 2.4 Excitation of Chromophores.- 2.5 Luminescence Emission from Chromophores.- 2.6 Kinetics of Photophysical Processes.- 2.7 Quenching Processes of Excited States.- 2.8 Quenching Processes in Solution.- 2.9 Quenching Processes in Polymer Matrices.- 3 Electronic Energy Transfer Processes in Polymers.- 3.1 Energy Transfer in Photodegradation Processes.- 3.2 Physical Aspects of Electronic Energy Transfer.- 3.3 Radiative Energy Transfer.- 3.4 Electron Exchange Energy Transfer.- 3.5 Resonance Excitation Energy Transfer.- 3.6 Efficiency of Energy Transfer.- 3.7 Spectroscopic Overlap Integral.- 3.8 Energy Transfer Processes in Solution.- 3.9 Diffusion-Controlled Reactions.- 3.10 Solvent Effects.- 3.11 Viscosity Effects.- 3.12 Energy Transfer in Rigid Polymer Matrix.- 3.13 Spectroscopic Methods for the Determination of Electronic Energy Transfer Processes.- 3.14 Singlet—Singlet Energy Transfer in Polymers.- 3.15 Triplet—Triplet Energy Transfer in Polymers.- 3.16 Energy Transfer from Carbonyl Groups to Hydroperoxides..- 3.17 Energy Transfer from Phenyl Group to Hydroperoxides.- 3.18 Excited State Annihilation Processes.- 3.19 Energy Migration in Polymers.- 3.20 Energy Migration in Excimer-Forming Polymers.- 4 Photo-Oxidative Degradation.- 4.1 Introduction to Photochemical Reactions in Polymers.- 4.2 Photochemical Laws.- 4.3 Photochemical Activation.- 4.4 Photodissociation of a Molecule.- 4.5 Quantum Yields of Photodegradation.- 4.6 Absorption of Radiation by Polymers.- 4.7 Formation of UV/Light Absorbing Impurities.- 4.8 Photoinitiation of Polymer Degradation.- 4.9 General Mechanism of Polymer Photo-Oxidative Degradation.- 4.10 Chain Propagation.- 4.11 Photochain-Oxidation Reaction.- 4.12 Main Chain Scission.- 4.13 Chain Branching.- 4.14 Termination Reaction.- 4.15 Dark Processes in Photodegradation of Polymers.- 4.16 Hydrogen Atom Abstraction.- 4.17 Formation of Hydroxy and/or Hydroperoxy Groups.- 4.18 Homolytic Decomposition of Hydroperoxides.- 4.19 Photodecomposition of Hydroperoxide Groups.- 4.20 Reactions of Hydroxy (HO·) and Hydroperoxy (HO2·) Radicals with Polymers.- 4.21 Formation of Carbonyl Groups.- 4.22 Formation of Carboxylic and Per-Carboxylic Groups.- 4.23 Norrish Type I and Type II Reactions.- 4.24 Formation of ?, ?-Unsaturated Carbonyl Groups.- 4.25 Conversion of Polymeric Free Radicals Under UV/Visible Radiation and Warming.- 4.26 Photodegradation of Chlorinated Polymers.- 4.27 Phenyl Ring-Opening Photo-Reactions.- 4.28 PhotoFries Rearrangement in Polymers.- 4.29 Photo-Oxygenation of Polymers by Singlet Oxygen.- 4.30 Photoinitiated Degradation of Polymers.- 4.31 Photoinitiated Degradation of Polymers by Dyes.- 4.32 Photoinduced Electron Transfer.- 5 Physical Factors Which Influence Photodegradation.- 5.1 Effect of Free Volume.- 5.2 Effect of the Glass Transition Temperature.- 5.3 Effect of Crystallinity.- 5.4 Localization of the Oxidation Processes in Semicrystalline Polymers.- 5.5 Chemicrystallization Process.- 5.6 Effect of Polymer Molecular Weight.- 5.7 Effect of the Formation of Hydrogen Bonds.- 5.8 Cage Recombination.- 6 Kinetic Treatments of Degradation.- 6.1 Photodegradation in Isothermal and Non-Isothermal Conditions.- 6.2 Decay of Free Radicals in a Polymer Matrix.- 6.3 Spin Trapping of Polymeric Radicals.- 6.4 Photodepolymerization.- 6.5 Kinetics of Photodegradation.- 6.6 Number of Main Chain Scissions.- 6.7 Quantum Yield of Chain Scission.- 6.8 Quantum Yield of Crosslinking.- 6.9 Principles Governing the Changes in Molecular Weight and Molecular Weight Distribution During Polymer Photodegradation.- 6.10 Reaction Kinetics of Polymer Photo-Oxidation.- 6.11 Diffusion Controlled Oxidation of Polymers.- 6.12 Oxidation Profiles.- 7 Photodegradation of Solid Polymers.- 7.1 Differences Between Photodegradation of Polymers in Solid and Liquid Phases.- 7.2 Polymer Mechanical Properties Affected by Degradation.- 7.3 Role of Water in the Degradation Processes.- 7.4 Effect of Orientation on Degradation.- 7.5 Degradation of Polymers Under Deformation Forces.- 7.6 Feedback in Polymer Degradation.- 7.7 Stress-Accelerated Photo-Oxidation of Polymers.- 7.8 Photodegradation of Polymers for Solar Energy Devices.- 8 Photodecomposition of Polymers by Laser Radiation.- 8.1 Ablative Photodecomposition of Polymers.- 8.2 Photokinetic Etching.- 8.3 Thermal Processing of Polymers by Visible and Infrared Laser Radiation.- 9 Practical Aspects of Polymer Photodegradation.- 9.1 Photodegradation of Polymers Under Weathering Conditions.- 9.2 Photodegradation of Polymers in Natural Waters.- 9.3 Photodegradation of Polymers Under Marine Exposure Conditions.- 9.4 Hydrolysis Processes During Ageing of Polymers.- 9.5 Plastic Ecological Problems.- 9.6 Photodegradable Polymers with Controlled Lifetimes.- 9.7 Ecolyte Plastics.- 9.8 Plastic Protective Films.- 9.9 Recovery of Photodegraded Polymers.- 9.10 Photodegradation of Polymers in the Polluted Atmosphere.- 9.11 Photodegradation of Polymers in the Stratosphere.- 9.12 Photodegradation of Polymers in Space.- 9.13 Atomic Oxygen Reactions with Polymers.- 9.14 Polymeric Photoinitiators Operating with a Fragmentation Mechanism.- 9.15 Positive-Working Photo resists.- 10 References.