In recent years, light-induced polymerization processes have gained an accelerative attention due to their environmental advantages over other industrial processes. It proceeds with low or no volatile organic compounds emissions, low energy consumption, and excellent time and spatial control. Consequently, this polymerization technique has been extensively used in numerous applications including adhesives, coatings, dental materials, biomaterials, 3D printing, optics, microelectronics, and nanotechnology etc. Nowadays, light-emitting diodes (LEDs) appeared to be significant alternatives to the traditional UV irradiation sources (e.g., Hg lamps). Notably, LEDs can compete with these traditional light sources due to numerous advantages such as low operating costs, low energy consumption, low heat generation, longer emission wavelengths, portability, simplicity, easy availability and safety in handling. The initiation step for free radical polymerization (FRP) or cationic polymerization (CP) depends on the photoinitiator (PI) used and this latter compound constitutes the key-component of the resin in charge to generate active species under light irradiation. Therefore, one of the most highly challenging purposes is the development of new PIs for both FRP and CP having absorption properties in line with the emission wavelength of the LED.
Background
A photoinitiator (PI; or a photoinitiating system, PIS, where a PI is introduced) allows the initiation of a polymerization reaction under exposure to a light source. These reactions are largely encountered in many industrial day life applications or in promising laboratory developments both in traditional and high-tech areas: UV curing, laser imaging, microlithography, stereolithography, 3D printing, microelectronics, optics, holography, medicine, dentistry, nanotechnology, and so on. Fantastic developments have appeared all along the past four decades. Significant achievements have been done since the early works on photopolymerization in the 60’s and the traditional developments of the UV Curing area. Today, high-tech applications are continuously emerging. A tailor-made photochemistry and chemistry have appeared in this area and knows today a remarkable success. The search for a safe and green technology has been launched and is growing.
In the last forty years, many aspects of light-induced polymerization reactions have been discussed in books, book chapters and review papers. As far as books are concerned, each of them usually covers more deeply selected aspects depending first on the origin (university, industry) and the activity sector of the author (photochemistry, polymer chemistry, applications, and so on) and second on the goals of the book (e.g., general presentation of the technology, guide for end-users, academic scope). Our previous general book published more than twenty years ago (Photoinitiation, Photopolymerization and Photocuring, Hanser, 1995) already provided a first account on the photosensitive systems. Unfortunately, for obvious reasons, all these three fascinating and complementary aspects that continuously appeared in the literature could no longer be developed in detail in a single monograph because of the rapid growth of the research. This was the reason why our second book (Photoinitiators for Polymer Synthesis, Wiley, 2012) that showed the huge progress made between 1995 and 2011 was only focused on the photosensitive systems.
The Collection
Why a new Article Collection? Indeed, in 2011, one could have had the feeling that almost everything has been foreseen and checked in the design of photoinitiators and photoinitiating systems. But science is ever going on! Thanks to novel methods of investigation (both experimental and theoretical) and novel ideas, huge progress has been made in the last eight years! A lot of new structures and new combinations previously unimaginable and now usable in novel and promising applications have been published and have opened new unsuspected horizons.
The above considerations prompted us to propose today a new Article Collection on photoinitiator applications and photopolymerization processes which is intended to be the most complete monograph existing on the subject with the following ideas as guidelines:
- to give the best up-to-date situation of the subject and the most recent developments;
- to provide a concise presentation of the backgrounds in photopolymerization and photochemistry;
- to deliver a complete presentation of the PIs and PISs with an emphasis on the excited state properties, the involved mechanisms and the structure/reactivity/efficiency relationships;
- to outline the latest developments and trends in the design of novel tailor-made PI and PIS systems;
- to develop the role of current or new PIs and PISs in the corresponding existing, emerging, promising or challenging applications for e.g. photopolymerization under LEDs, laser diodes, visible, Near Infra Red lights or under soft irradiation conditions, photopolymerization of thick samples, the access to composites, photocuring in shadow areas, two-photon polymerization, light induced thermal polymerization, controlled reactions, thiol-ene processes, IPN synthesis, in-situ incorporation of nanoparticles, grafting reactions for complex architectures, CuAAC additions, photoredox polymerization, polymerization of self-assembled systems, photohydrosilylation reactions, sol-gel photopolymerization, elaboration of nano-objects in optics or nano-patterns in microelectronics, photocuring in the coating area, dentistry, biosciences, 3D printing technologies, and more.
Designed Monomers and Polymers accepts original research articles and data notes. When submitting your article, please select the Article Collection "Developments in Photopolymerization" from the drop-down menu in the submission system.
