Photoinitiators for switchable controlled polymerization activated by visible light
Technology Status: TRL 3 (tested in laboratory) PATENT APPL
Sectors of Application: Coating (wood, metal, plastics), dental resins, adhesives insdustries, 3D pronting.
Introduction
Photopolymerization is currently used in industry in a broad range of applications such as coating of materials (for example, wood, metal, plastics), decorative paints for outdoor and indoor, binding with adhesives, advanced manufacturing (for example, 3D printing) and medical applications (for example, light-curable dental resins).
Description of solution
Living free-radical polymerization is widely used in industry for the preparation of polymers and polyolefins with a certain control on the degree of polymerization, the molecular weight of the polymer and the polydispersity index. In particular, reversible addition fragmentation chain transfer (hereinafter, RAFT) polymerization is a useful method to control the length of the polymer while providing a certain degree of homogeneity in polymer chain lengths. is a mechanism where the propagation step involves a chain transfer agent that can reversibly and rapidly add to a certain polymer chain, which means that, when carried out under the control of a RAFT agent, the reaction mixture contains polymer chains with similar lengths, which allows for the formation of polymers with a narrow index of polydispersity and allows for carrying out block polymerization reactions in a reliable way.
Having all this in mind, ICIQ researchers have designed proprietary ditihiocarbamate compounds useful as photoinitiators of free radical living polymerization. As seen below, the developed initiator exhibits a good balance between speed of curing under low intensity blue light irradiation and a narrow polysdispersity.
The specific carboxylic group in the compound of formula (I) advantageously facilitates that the compounds absorb light in the visible range of the spectrum, in particular in the 400-500 nm region (blue light).
The growth of the polymer can further be controlled by switching on and off of the light source.
Advantages and unique selling points
- Safety: Without using UV all the problems related to operating with UV light are avoided, as exposure of individuals to UV radiation causes health concerns.
- Non-colored product: most photoinitiators operating under visible light are colored systems, which typically results in poor control over the aspect of the cured or dried product and does not allow for the production of non-colored products.
- Light from the visible spectrum: It absorbs light in the visible range of the spectrum, in particular in the 400-500 nm region (blue light). This advantageously allows for avoiding the use of UV light in polymerization applications.
- Control of the growth of the polymer: The growth of the polymer can be controlled by switching on and off.
- Accessible and cost-effective: The synthesis of initiators is Accessible and cost-effective
Status of Technology
A proof of concept has been achieved in a laboratory scale.
Type of partnership sought
ICIQ is seeking industrial partners for the joint development of applications of these photoinitiating systems through R&D collaborations and license agreements. To this end, and as first step, ICIQ is offering to interested companies small amounts of the materials for the company to assess the suitability of the compounds to the needs of the partner.
IP Situation
Two patent applications have been filed:
1-Title of the patent: Photoinitiator compounds
-Application numbers: WO 2020/011922 A1
-Applicant: Fundació Institut Català d’Investigació Química (ICIQ)
-Inventors: Paolo Melchiorre, Bertrand Schweitzer-Chaput and Frank Arroyave
-Application date: 11 July 2019
2-Title of the patent: Carboxylic dithiocarbamic acid anhydride compounds and compositions thereof
-Application numbers: EP20382017.0
-Applicant: Fundació Institut Català d’Investigació Química (ICIQ)
-Inventors: Paolo Melchiorre, Bertrand Schweitzer-Chaput, Frank Arroyave and Fernando Bravo Lara
-Application date: 15 January 2020
References