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