Search

DE-102023123638-B4 - Polyoxovanadate as a photoinitiator in the polymerization of monomers or oligomers

DE102023123638B4DE 102023123638 B4DE102023123638 B4DE 102023123638B4DE-102023123638-B4

Abstract

Use of a polyoxovanadate as a photoinitiator in the polymerization of monomers, wherein the polyoxovanadate carries at least two organic ligands with the structure -(CH 2 ) x -R, with x = 0 to 7 and R = OH, N3 , NH2 , Br or COOH, and wherein the monomer is an acrylate-functionalized oligomer selected from acrylate-difunctionalized siloxanes and acrylate-difunctionalized ethylene glycols.

Inventors

  • Eric Vogelsberg
  • Kirill Monakhov

Assignees

  • Leibniz-Institut für Oberflächenmodifizierung e.V.

Dates

Publication Date
20260513
Application Date
20230901

Claims (12)

  1. Use of a polyoxovanadate as a photoinitiator in the polymerization of monomers, wherein the polyoxovanadate carries at least two organic ligands with the structure -(CH 2 ) x -R, with x = 0 to 7 and R = OH, N 3 , NH 2 , Br or COOH, and wherein the monomer is an acrylate-functionalized oligomer selected from acrylate-difunctionalized siloxanes and acrylate-difunctionalized ethylene glycols.
  2. Use according Claim 1 , where x = 1 to 7.
  3. Use according Claim 2 , where R=OH or R=N 3 .
  4. Use according Claim 1 , where x = 0 and R = NH 2 .
  5. Use according to one of the Claims 1 or 2 or 3 , in the polymerization in aqueous medium, wherein the polyoxovanadate comprises countercations selected from alkali metals, and R=OH for all ligands.
  6. Use according Claim 5 , where x=1 to 3 for all ligands.
  7. Use according to one of the Claims 1 until 6 where the polyoxovanadate carries exactly two of the organic ligands and these are in the trans position.
  8. Use according to one of the Claims 1 until 7 , in 3D printing.
  9. Use according to one of the Claims 1 until 8 , in the production of biological and/or medical tissues by means of the polymerization of monomers.
  10. Use according to one of the Claims 1 until 9 , wherein the polyoxovanadate has the structural formula M 2 [V V 6 O 13 {(OCH 2 ) 3 C-CH 2 -R} 2 ] where M is the countercation and -CH 2 -R is the ligand.
  11. A method for the photopolymerization of monomers, comprising the steps of: a) providing the monomer, wherein the monomer is an acrylate-functionalized oligomer selected from acrylate-difunctionalized siloxanes and acrylate-difunctionalized ethylene glycols; b) adding a polyoxovanadate as a photoinitiator, wherein the polyoxovanadate carries at least two organic ligands having the structure -( CH2 ) x -R, with x = 0 to 7 and R = OH, N3 , NH2 , Br or COOH; c) irradiation with light.
  12. Procedure according to Claim 11 , where in step c) the wavelength is 365nm ±40nm and the distance between the light source and the polyoxovanadate from step b) is 30mm ±20mm.

Description

The invention relates to the use of polyoxovanadates as a photoinitiator for polymerization. Currently, a large number of photoinitiators exist for the photopolymerization of monomers, each focusing on use in specific environments. For example, α-hydroxyketone derivatives are used for application in aqueous environments and in biological and medical contexts, one particularly relevant example being 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (structure according to formula I). Another relevant group in this field is that of the phosphine derivatives, the most prominent of which is LAP (lithium phenyl-2,4,6-trimethylbenzoylphosphinate, structure according to formula II). This molecule is characterized by high water solubility (47 g/L) and absorption up to 380 nm with low cytotoxicity. These photoinitiators are referred to as type I photoinitiators. While type I photoinitiators undergo direct homolytic cleavage upon irradiation with light, thus generating a radical, type II photoinitiators typically abstract a proton from a neighboring donor species (often amines). Water-soluble examples include eosin-γ and riboflavin. A disadvantage of type II photoinitiators is the need to add donor molecules. Polyoxometalates have also been discussed as potential photoinitiators. In Liang, Zhije et al. (2022) The polymerization is described using catechol-modified polyoxovanadates. Yin, Panchao et al. (2011 ) reveal a fluorescent surfactant with a hexavanadate cluster as the head group. Chen, Qin et al. (1992) describe Polyoxovanadate coordination compounds with a hexametalate core Furthermore, a Keggin-type polyoxomolybdate H 3 PMo 12 O 40 has already been described as a photoinitiator for the radical polymerization of trimethylolpropane triacrylate ( Xiao, Pu et al. (2013 )). Various other additives or monomers were used there, such as the following: It is described there that in a mixture of molybdophosphoric acid (Phosphomolybdic acid, H₃PMo₁₂O₄₀) with an iodine species and ( TMS) ₃Si -H, as well as the monomer EPOX, which polymerizes cationically, the resulting silylium cation ( R₃Si⁺ ) initiates the cationic polymerization. The molybdophosphoric acid generates the silylium cations. This mixture can also initiate the radical polymerization of acrylates. Currently, the selection of known water-soluble photoinitiators is also severely limited in its applications due to a number of properties of the molecules used. The known photoinitiator according to formula I is cytotoxic at higher concentrations and has an extinction coefficient of 4 M⁻¹cm⁻¹ at 365 nm. Simultaneously, it has relatively low water solubility and therefore must be used in organic solvents or mixtures, which restricts its application. The photoinitiator according to formula III cannot absorb light above 350 nm, and although LAP (according to formula II) is characterized by high water solubility and low cytotoxicity, it is unable to absorb at higher wavelengths of the visible light range. This limitation makes its use in a medical/biological context impossible, as UV light is damaging to cells. Purely inorganic polyoxometalates are not suitable for use in a biological context due to the high cytotoxicity of this class of substances. In general, many type II photoinitiators are limited in their applications by the type of donor molecules that must be added to the mixture (such as triethylamine and ethyl 4-(dimethylamino)benzoate, two toxic or mutagenic substances) to ensure successful polymerization. There is still a great need for new photoinitiators. The object of the invention is to provide suitable photoinitiators for the polymerization of monomers. The initiation should occur as quickly as possible to enable application in 3D printing. The photoinitiators should be so well-suited (e.g., due to favorable extinction coefficients) that they do not require additives such as iodine or silyl compounds, triethylamine, or benzoates. They should be able to effectively initiate the polymerization with as few additives as possible (except for the solvent containing the monomer). The problem is solved by the features of the independent claims. Preferred embodiments are described in the dependent claims. The invention relates to the use of a polyoxovanadate as a photoinitiator in the polymerization of monomers or oligomers (here photopolymerization), for example in the polymerization of acrylates or epoxides, in particular also of acrylate-functionalized oligomers (these oligomers are also referred to in the context of the invention as the monomers to be polymerized). According to the invention, the polyoxovanadate carries at least two organic ligands with the structure -(CH 2 ) x -R, with x = 0 to 7 and R=OH, N 3 , NH 2 , Br or COOH, and the monomer is an acrylate-functionalized oligomer selected from acrylate-difunctionalized siloxanes and acrylate-difunctionalized ethylene glycols. “Polyoxovanadates” within the meaning of the invention are anio