A comprehensive text that covers everything from the processes and mechanisms to the reactions and industrial applications of photoinitiators Photoinitiators offers a wide-ranging overview of existing photoinitiators and photoinitiating systems and their uses in ever-growing green technologies. The authors—noted experts on the topic—provide a concise review of the backgrounds in photopolymerization and photochemistry, explain the available structures, and examine excited state properties, involved mechanisms, and structure, reactivity, and efficiency relationships. The text also contains information on the latest developments and trends in the design of novel tailor-made systems. The book explores the role of current systems in existing and emerging processes and applications. Comprehensive in scope, it covers polymerization of thick samples and in-shadow areas, polymerization under LEDs, NIR light induced thermal polymerization, photoinitiators for novel specific and improved properties, and much more. Written by an experienced and internationally renowned team of authors, this important book: Provides detailed information about excited state processes, mechanisms, and design of efficient photoinitiator systems Discusses the performance of photoinitiators of polymerization by numerous examples of reactions and application Includes information on industrial applications Presents a review of current developments and challenges Offers an introduction to the background information necessary to understand the field Discusses the role played by photoinitiators in a variety of different polymerization reactions Written for polymer chemists, photochemists, and materials scientists, Photoinitiators will also earn a place on the bookshelves of photochemists seeking an authoritative, one-stop guide to the processes, mechanisms, and industrial applications of photoinitiators.

The development of photosensitive materials in general and photoreactive polymers in particular is responsible for major advances in the information, imaging, and electronic industries. Computer parts manufacturing, information storage, and book and magazine publishing all depend on photoreactive polymer systems. The photo-and radiation-induced processes in polymers are also active areas of research. New information on the preparation and properties of com mercially available photosensitive systems is constantly being acquired. The recent demand for environmentally safe solvent-free and water-soluble materials also motivated changes in the composition of photopolymers and photoresists. The interest in holographic recording media for head-up displays, light scanners, and data recording stimulated development of reconfigurable and visible light sensitive materials. Photoconductive polymerizable coatings are being tested in electrostatic proofing and color printing. The list of available initiators, poly meric binders, and other coating ingredients is continually evolving to respond to the requirements of low component loss (low diffusivity) and the high rate of photochemical reactions.

The use of photoinitiators in the UV curing process shows remarkable possibilities in myriad applications. Highlighting critical factors such as reactivity, cure speeds, and application details, Industrial Photoinitiators: A Technical Guide is a practical, accessible, industrially oriented text that explains the theory, describes the products, and

Ultra Violet (UV)-curable resins are widely used for coating, adhesives, composite fillers, and 3D printing because of their many advantages, including high curing rate and energy efficiency. If a UV-curable resin is exposed to UV light irradiation for a fixed amount of time, the polymerization rate and the final degree of conversion (DoC) decline with curing depth due to light attenuation. This will lead to an uneven DoC distribution, especially when photo-curing resin within a large volume. Many material properties of a cured resin are directly linked to DoC. Consequently, the spatial gradient in the DoC that is caused by the light attenuation may degrade the performance of a resin for applications involving large curing depths. Therefore, it is crucial to investigate and predict the evolution of the DoC throughout a volume to better control the properties of a cured resin. Current curing kinetic models provide insight into how DoC evolves with depth for a pure resin cured by a collimated light beam. However, they do not accurately describe how DoC evolves within UV-curable composites or systems in which multi-directional ray propagation is in play. Moreover, they do not provide insight into how polymeric networks form or how they influence the polymerization process. Therefore, this dissertation describes three novel simulation frameworks for predicting the evolution of DoC and polymetric network in UV-curable systems. The first framework uses Maxwell's Laws of Electromagnetic Theory and a series of finite difference time domain (FDTD) simulations to predict light intensity distribution at different reaction time steps. It also uses curing kinetic models and optical properties models to predict DoC and optical properties within a volume. The framework is applied to simulate the photo-induced, free-radical polymerization of acrylate-based composites. It is used to study the influence of resin refractive index, filler refractive index, and filler particle size on the spatial and temporal evolution of DoC. The simulation results reveal that: 1) The change of resin refractive index during polymerization has a significant impact on both light propagation and DoC within a UV-curable composite. 2) Smaller fillers scatter more light than larger fillers. 3) Larger refractive index mismatch between the resin and filler leads to more light scattering and greater light attenuation. In turn, this increases the polymerization rate at shallow depths but decreases it at greater depths. Similar to the first framework, the second framework is also designed to predict the spatial and temporal evolution of DoC within a UV-curable system. However, this framework utilizes the Monte Carlo (MC) method for light transportation to predict light intensity distribution. This framework is used to study the influence of filler volume fraction and filler particle on the curing depth and curing width. The simulation results are in agreement with experimental results published in the research literature. The framework is also applied to simulate the formation of adhesive joints in a PAAW fixture application. The influence of the light source, filler, and workpiece surface on the final DoC distribution are investigated. The study shows that: 1) Both the beam spread from a LED light and the usage of filler have big influences on the curing width of an adhesive joint. However, such influences will not be aggregated. 2)The light scattering by the fillers leads to a higher DoC in the secondary curing zone at shallow depth ranges, while the beam spread of the LED light beam results in a higher DoC in the secondary curing zone at deep depth ranges. 3) If the adhesive is not thick, then a highly reflective workpiece surface can promote the polymerization rate near the workpiece surface. 4) Inside the primary curing zone, diffuse reflection caused by the workpiece surface greatly promotes the polymerization rate near the workpiece surface. The third framework is developed to model photo-induced, free radical polymerization through a molecular dynamics approach. The framework is applied to simulate the photo-polymerization of Bisphenol A (EO)10 Diacrylate under varying conditions of curing light intensity and photo-initiator concentration. The simulation results are compared to the curing kinetic data experimentally derived in this investigation as well as from other studies. The results also reveal that: 1) gelation is highly correlated to the formation of giant molecules, 2) differences in the number of free radicals generated at the beginning of polymerization significantly affect polymer network formation at low to intermediate conversion, and thus affect the gelation point, and 3) increasing light intensity or photo-initiator concentration tends to delay the gelation point, but does not affect ultimate polymer network structure near the latter stages of photo-polymerization.

Photoinitiated Polymerization discusses the latest developments in photoinitiated polymerization. This book includes the current state of free radical, cationic, and based catalyzed photopolymerization and their applications.