# US 9,753,431 B2 · Visible light photoinitiating system for preparing high diffraction efficiency hologram optical polymer material

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- Number: US 9,753,431 B2
- Document ID: US9753431B2
- Status: Granted
- Kind: B2
- Application number: 14/131,676
- Filed: 2012-05-25
- Published: 2014-07-10
- Granted: 2017-09-05
- Earliest claimed: 2011-07-29
- Assignees: Huazhong University of Science and Technology
- Applicants: Xiaolin Xie; Haiyan Peng; Xingping Zhou; Chengfu Zheng; Hongwei Ge
- Inventors: Xiaolin Xie; Haiyan Peng; Xingping Zhou; Chengfu Zheng; Hongwei Ge
- Web page: https://patentgrep.com/patent/US9753431B2

## CPC

- G03H 1/04: Processes or apparatus for producing holograms (G03H1/26 takes precedence)
- C08F 2/50: with sensitising agents
- G03F 7/001: {Phase modulating patterns, e.g. refractive index patterns}
- G03F 7/029: Inorganic compounds; Onium compounds; Organic compounds having hetero atoms other than oxygen, nitrogen or sulfur
- G03F 7/031: Organic compounds not covered by group G03F7/029
- G03H 1/181: {Pre-exposure processing, e.g. hypersensitisation}
- G11B 7/24044: for storing optical interference patterns, e.g. holograms; for storing data in three dimensions [3D], e.g. volume storage (G11B7/24038 takes precedence)
- G11B 7/245: containing a polymeric component
- G03H 2260/12: Photopolymer
- G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00})
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

The present invention provides a visible light photoinitiating system for preparing a holographic photopolymer material with high-diffraction efficiency. The photoinitiating system comprises a photosensitizer and a co-initiator, and its mechanism is that the photosensitizer transforms from ground state to excited state after absorbing photons, and then interacts with the co-initiator through transfer of electrons and protons, which produces an alkyl (or aryl) free radical R and a ketyl radical K; wherein the free radical R initiates the addition polymerization of monomers that are capable of free radical polymerization, whereas the radical K inhibits the chain propagation of the macromolecular free radicals to a certain degree due to the steric hindrance effect, and thus delays the gelation time of the photopolymerization, which helps to increase the phase separation between the polymer and the functional components. A holographic photopolymer material with high-diffraction efficiency can be obtained by employing this visible light photoinitiating system.

## Claims

### Claim 1

A visible light photoinitiating system, comprising a photosensitizer and a co-initiator, within which system an alkyl or aryl free radical for initiating photopolymerization and a ketyl radical for inhibiting photopolymerization are generated upon exposure to a single laser beam, wherein said photosensitizer comprises one or more selected from the group consisting of C1, C2, C3, C4, and C5, said C1, C2, C3, C4, and C5 having the following structures, respectively:
wherein substitutes R1, R2, R3, R4, R5, and R6 may be same or different, and may be jointly, respectively or independent, and of —SH, —CN, —NO2, —CnH2n+1 (n≦0 to 8), —CnH2n+1O (n=0 to 8), N(CnH2n+1)2 (n=0 to 8), phenyl, thienyl, and thiazolyl.

### Claim 2 (depends on 1)

The photoinitiating system according to claim 1, wherein a ratio by mass of the photosensitizer to the co-initiator is between 20:1 and 1:20.

### Claim 3 (depends on 1)

The visible light photoinitiating system according to claim 1, wherein said co-initiator comprises one or more selected from the group consisting of N,N,N-triethylamine, N-Methyl maleimide, N-ethyl maleimide, triethanolamine N-phenyl glycine, acetyl phenyl glycine, p-chlorophenyl glycine, 3-bromine phenyl glycine, 3-nitrile phenyl glycine, N-phenyl glycine ethyl ester, 2,4,6-tri(trichloromethyl)-1,3,5-triazine, and 2-(4′-methoxy phenyl)-4,6-bi(trichloromethyl)-1,3,5-triazine.

### Claim 4 (depends on 1)

The visible light photoinitiating system according to claim 1, wherein C2 is other than 3-acetylcoumarin.

### Claim 5 (depends on 1)

The visible light photoinitiating system according to claim 1, wherein said photosensitizer comprises at least one photosensitizer or photosensitizer combination selected from the group consisting of:
C1 and C2 in the proportion of 1:2, wherein R1═R4═N(C2H5)2 and R2═R3═H);
C2 and C4 in the proportion of 2:3, wherein R1═C8H17, R2=thiazolyl, and R3═OH;
C3, wherein R1═C8H17O, R2═NH2, and R3=thienyl;
C4, wherein R1═N(C8H17)2, R2═NO2, and R3═H; and
C1 and C5 in the proportion of 1:1, wherein R1=phenyl, R2═R3═R5═H, R4═CN, and R6═SH.

### Claim 6 (depends on 1)

The visible light photoinitiating system according to claim 1, in combination with a non-epoxy polymerizable material.

### Claim 7 (depends on 5)

The visible light photoinitiating system according to claim 5, wherein the non-epoxy polymerizable material comprises one or more selected from the group consisting of methyl methacrylate, methyl acrylamide, N-vinyl pyrrolidone, butyl acrylate, 2-ethylhexyl acrylate, N-isopropyl acrylamide, ethylene dimethacrylate, trimethylolpropane trimethacrylate, N-vinyl carbazole, pentaerythritol tetraacrylate, and methylene diacrylamide.

### Claim 8 (depends on 1)

The visible light photoinitiating system according to claim 1, wherein the laser beam has a wavelength of 441.6 nm.