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WO2022008859A1 - Nouveaux substrats améliorés de spectroscopie raman - Google Patents

Nouveaux substrats améliorés de spectroscopie raman Download PDF

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Publication number
WO2022008859A1
WO2022008859A1 PCT/GB2021/000076 GB2021000076W WO2022008859A1 WO 2022008859 A1 WO2022008859 A1 WO 2022008859A1 GB 2021000076 W GB2021000076 W GB 2021000076W WO 2022008859 A1 WO2022008859 A1 WO 2022008859A1
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Prior art keywords
raman
substrate
pfac
fluorocarbon polymer
support material
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Ceased
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PCT/GB2021/000076
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English (en)
Inventor
Clare Michelle NIXON
Corrine Amy Stone
Neil Charles Shand
Terry Clark
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UK Secretary of State for Defence
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UK Secretary of State for Defence
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Priority claimed from GBGB2010387.5A external-priority patent/GB202010387D0/en
Priority claimed from GBGB2102465.8A external-priority patent/GB202102465D0/en
Application filed by UK Secretary of State for Defence filed Critical UK Secretary of State for Defence
Publication of WO2022008859A1 publication Critical patent/WO2022008859A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
    • B05D5/06—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/62—Plasma-deposition of organic layers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65—Raman scattering
    • G01N21/658—Raman scattering enhancement Raman, e.g. surface plasmons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2202/00—Metallic substrate
    • B05D2202/40—Metallic substrate based on other transition elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2252/00—Sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2502/00—Acrylic polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2506/00—Halogenated polymers
    • B05D2506/10—Fluorinated polymers

Definitions

  • the present invention is concerned with new and improved substrates and methods for Raman spectroscopy, and especially substrates capable of enabling detection of materials that are generally difficult to detect/identify through use of surface enhanced Raman spectroscopy (SERS).
  • SERS surface enhanced Raman spectroscopy
  • the substrates and methods are especially suitable for enabling detection/identification of explosives, such as 1, 3, 5-trinitroperhydro-l, 3, 5-triazine (RDX) and pentaerythritol tetranitrate (PETN), with Raman spectroscopy.
  • Raman spectroscopy A known disadvantage of Raman spectroscopy is that the Raman effect is generally inherently very weak, and thus detection and identification of materials using Raman spectroscopy can suffer from low sensitivity, and generation of weak Raman signals.
  • One way to overcome this may be to use highly optimised methodologies or instrumentation.
  • SERS surface enhanced Raman spectroscopy
  • some materials, such as the explosives RDX and PETN, are generally difficult to detect/identify through use of SERS, and an alternative approach to detecting these types of materials with high sensitivity is required.
  • a number of solutions have been proposed to enhance detection of materials using Raman spectroscopy, including to enhance SERS detection, especially though modification of the substrates used for Raman spectroscopy.
  • One solution has been to generate hydrophobic Raman substrate surfaces, in order to concentrate samples of materials on the substrates prior to analysis.
  • a Teflon coated steel substrate (sold as the m-RimTM slide or SpectRimTM slide) is reportedly able to detect RDX and PETN at a concentration of 1 mg/ml in the solvent acetonitrile.
  • these are high concentrations of material, and further it has been shown that the Teflon coated steel substrate is restricted in the solvents that can be used for applying samples to the substrate.
  • Some solvents such as acetone, do not form a droplet on the substance surface but instead wet the surface, and consequently do not produce the desired increased concentration of material on the surface, and thus not the required improvement in sensitivity. It remains difficult, for example, to identify/detect certain explosives, such as RDX and PETN, with sufficient sensitivity, such as at least 10 pg/ml, which is desirable.
  • SERS surface enhanced Raman spectroscopy
  • the present invention provides for a Raman substrate having a surface comprising a fluorocarbon polymer, wherein the fluorocarbon polymer comprises, or is assembled from, perfluoroalkyl acrylate monomer units.
  • the fluorocarbon polymer generally provides for a Raman substrate having a super hydrophobic surface.
  • the surface comprising the fluorocarbon polymer may be generated through plasma polymerisation deposition of a perfluoroalkyl acrylate monomer, by itself, or in combination with a linking chemical moiety, or through deposition with a different second monomer or fluorocarbon (or perfluoroalkyl acrylate) monomer, and in particular may be through pulsed plasma deposition.
  • the Applicant has surprisingly found that a Raman substrate having a surface coated with a fluorocarbon polymer comprising, or assembled from, perfluoroalkyl acrylate monomer units, especially generated by plasma polymerization (or pulsed plasma polymerisation) is capable of improving the sensitivity of detection of certain materials by Raman spectroscopy.
  • plasma polymerisation or pulsed plasma polymerisation
  • monomers containing polymerisable unsaturated acrylate groups and perfluoroalkyl chains is capable of improving the sensitivity of detection of certain materials by Raman spectroscopy.
  • Raman substrates can be used for detecting the explosives RDX and PETN with improved sensitivity.
  • Fluorocarbon polymer surfaces, or coatings, generated by plasma polymerization (or pulsed plasma polymerisation) of monomers (precursor molecules) containing at least one polymerisable unsaturated acrylate group and at least one perfluoroalkyl chain are especially applicable to the first aspect of the invention due to their exceptional properties.
  • the exceptional properties include speed of polymerization, generally mild processing conditions and exceptional hydrophobic, as well as oleophobic, properties.
  • the exceptional properties of these monomers, and subsequent polymers, are believed to be attributed to the peculiar chemical architecture of the perfluoroalkyl polymer chains.
  • Examples of such monomers include lH,lH,2FI,2H-perfluorodecyl acrylate (PFDA, also known as PFAC-8), and lH,lH,2H,2H-perfluorooctylacrylate (PFOA, also known as PFAC-6), which, by themselves, are capable of generating poly(lH,lH,2H,2H-perfluorodecyl acrylate) or poly(lH,lH,2H,2H-perfluorooctylacrylate), respectively.
  • PFDA lH,lH,2FI,2H-perfluorodecyl acrylate
  • PFOA also known as PFAC-6
  • fluorocarbon polymer surfaces could alternatively be generated from PFAC-10 (1H, 1H, 2H, 2H-perfluorododecyl acrylate), or indeed the corresponding methacrylates of PFAC-6, PFAC-8 or PFAC-10.
  • the fluorocarbon polymer could thus comprise the unit, or repeating unit, -[CH 2 CRi(C(0)0(CFl2)x(CF2)yCF3)]-, providing repeating side chains of -C(0)0(CH 2 ) x (CF2)yCF 3 , which unit, or repeating unit, could be separated by spacer molecules, or alternatively the fluorocarbon polymer could be a co-polymer, where at least one unit comprises the formula - [CFl2CRi(C(0)0(CH2) x (CF2) y CF3)]-, or both units could comprise that formula, but differing in at least one of Ri, x and y.
  • the Raman substrate of the first aspect provides a means for undertaking Raman spectroscopy of materials that are not strongly SERS active, such as the explosives RDX and PETN.
  • the fluorocarbon polymer may be a polymer comprising, or assembled/generated from, the monomer 1H, 1H, 2H, 2FI-perfluorodecyl acrylate (PFAC-8) or the monomer 1H, 1H, 2H, 2H- perfluorooctyl acrylate (PFAC-6), either by itself or in combination with a linking chemical moiety, for example divinyl adipate, or a different second monomer or fluorocarbon monomer, which may be generated at/on the surface of any suitable support material using plasma polymerisation, to generate the Raman substrate.
  • PFAC-8 the monomer 1H, 1H, 2H, 2FI-perfluorodecyl acrylate
  • PFAC-6 monomer 1H, 1H, 2H, 2H- perfluorooctyl acrylate
  • a linking chemical moiety for example divinyl adipate
  • a different second monomer or fluorocarbon monomer which may be generated at/
  • fluorocarbon polymers generated from PFAC-8 or PFAC-6 by plasma polymerisation are capable of concentrating, supporting and enabling crystallisation of particular agents at its surface, using numerous solvents.
  • the extent of concentration and quality of crystallisation is proportional to the possible improved sensitivity achieved, and the quality of the Raman spectra produced.
  • a fluorocarbon polymer generated from PFAC-6 or PFAC-8 not only prevents spreading of the materials to be analysed over the substrate surface, but thereby also enables or aids crystallisation, thus focussing and concentrating the materials in addition to the crystallisation.
  • Substrates coated with a polymer comprising, or assembled from, PFAC-6 or PFAC-8, or coated with polymerised PFAC-6 or PFAC-8 are capable of producing a Raman signal through the Raman effect as a result of the concentration and crystallisation of material at the surface.
  • Crystallisation can be further optimised by careful selection of the solvents from which to crystallise the materials.
  • the support material of the Raman substrate may be selected from numerous possibilities.
  • the Applicant has in particular found that the substrate does not need to be or include a metal, such as gold, a feature essential for SERS, but could be any material.
  • the support material could be plastic, fabric, glass, metal, or combinations thereof.
  • the support material may be nickel.
  • the surface of the substrate may be textured, as texturing of the surface has been shown to lower the surface energy at the surface.
  • the solvent for crystallisation of explosives could be any suitable organic solvent, though the solvent should be one that enables good crystallisation on the Raman substrate surface, such as acetone, methanol, or ethanol. Acetone is particularly advantageous for detecting explosives.
  • the present invention provides a method for detecting the presence of a material in a sample using Raman spectroscopy comprising i. crystallising the sample on a Raman substrate according to the first aspect of the invention with an appropriate solvent; ii. undertaking Raman spectroscopy on the crystallised sample to generate a Raman spectrum, and iii. interrogating the Raman spectrum to determine whether the material is present in the sample.
  • the material is an explosive, for example TNT, RDX or PETN.
  • TNT the appropriate solvent may be any organic solvent, though in a preferred embodiment would be ethanol, methanol, acetone or isopropanol.
  • Suitable solvents for RDX and PETN also include ethanol, acetone, methanol and isopropanol.
  • the present invention provides a method of manufacturing a Raman substrate comprising undertaking plasma polymerisation deposition of a perfluoroalkyl acrylate monomer in the presence of a support material suitable for Raman spectroscopy.
  • the plasma polymerisation deposition may comprise deposition of the perfluoroalkyl acrylate monomer by itself, or in combination with a linking chemical moiety, for example divinyl adipate, or in combination with a different second monomer or fluorocarbon monomer, which may be a different perfluoroalkyl acrylate monomer.
  • the support material may be plastic, fabric, glass, metal, or combinations thereof. In one embodiment the support material is nickel. The support material may be smooth or roughened, or textured.
  • the plasma polymerisation deposition may be pulsed plasma deposition.
  • the perfluoroalkyl acrylate monomer may be any of the monomers discussed for the first aspect of the present invention.
  • Figure 1 is four Raman spectra, each of a 10 mI_ droplet of RDX at the following concentrations in the solvent acetone; 1 mg/ml (A), 100 pg/ml (B), 10 pg/ml (C) and 1 pg/ml (D) on nickel (support material) coated with a fluoropolymer of PFAC-8 (coated by pulsed plasma polymerisation).
  • the lower line shows a 5 s integration time, the middle line a 10 s integration time and the higher line a
  • Figure 3 is four Raman spectra, each of a 10 pL droplet of TNT at the following concentrations in the solvent acetone; 1 mg/ml (A), 100 pg/ml (B), 10 pg/ml (C) and 1 pg/ml (D) on nickel (support material) coated with a fluoropolymer of PFAC-8 (coated by pulsed plasma polymerisation).
  • the lower line shows a 5 s integration time, the middle line a 10 s integration time and the higher line a 20 s integration time.
  • Spectra were collected using a 785 nm laser excitation;
  • Figure 4 is two overlaid Raman spectra, a Raman spectrum for bulk PETN from a library, and a Raman spectrum for PETN (1 mg/ml; 5 pi) in methanol crystallised on a Raman substrate having a smooth nickel support material coated with plasma polymerised PFAC-8;
  • Figure 5 is two overlaid Raman spectra, a Raman spectrum for bulk PETN from a library, and a Raman spectrum for PETN (1 mg/ml; 5 pi) in methanol crystallised on a Raman substrate having a textured nickel support material coated with plasma polymerised PFAC-8;
  • Figure 6 is two overlaid Raman spectra, a Raman spectrum for bulk PETN from a library, and a Raman spectrum for PETN (1 mg/ml; 5 pi) in methanol crystallised on a p-RIM substrate;
  • Figure 7 is two overlaid Raman spectra, a Raman spectrum for bulk RDX from a library, and a Raman spectrum for RDX (1 mg/ml; 5 pi) in ethanol crystallised on a Raman substrate having a smooth nickel support material coated with plasma polymerised PFAC-8;
  • Figure 8 is two overlaid Raman spectra, a Raman spectrum for bulk RDX from a library, and a Raman spectrum for RDX (1 mg/ml; 5 pi) in ethanol crystallised on a Raman substrate having a textured nickel support material coated with plasma polymerised PFAC-8;
  • Figure 9 is two overlaid Raman spectra, a Raman spectrum for bulk RDX from a library, and a Raman spectrum for RDX (1 mg/ml; 5 mI) in ethanol crystallised on a m-RIM substrate;
  • Figure 10 is two overlaid Raman spectra, a Raman spectrum for bulk TNT from a library, and a Raman spectrum for TNT (1 mg/ml; 5 mI) in methanol crystallised on a Raman substrate having a textured nickel support material coated with plasma polymerised PFAC-8;
  • Figure 11 is two overlaid Raman spectra, a Raman spectrum for bulk TNT from a library, and a Raman spectrum for TNT (1 mg/ml; 5 mI) in methanol crystallised on a m-RIM substrate;
  • Figure 12 is a Raman spectrum for TNT (lmg/ml; 5 m I) in acetone crystallised on a m-RIM substrate;
  • Figure 13 is a Raman spectrum for TNT (lmg/ml; 5 mI) in acetone crystallised on a Raman substrate having a smooth nickel support material coated with plasma polymerised PFAC-8;
  • Figure 14 is a Raman spectrum for bulk TNT from a library
  • Figure 15 is a Raman spectrum for RDX (lmg/ml; 5 mI) in ethanol crystallised on a m-RIM substrate;
  • Figure 16 is a Raman spectrum for RDX (lmg/ml; 5 mI) in ethanol crystallised on a Raman substrate having a smooth nickel support material coated with plasma polymerised PFAC-8;
  • Figure 17 is a Raman spectrum for bulk RDX from a library;
  • Figure 18 is a Raman spectrum for PETN (lmg/ml; 5 mI) in methanol crystallised on a m-RIM substrate;
  • Figure 19 is a Raman spectrum for PETN (lmg/ml; 5 mI) in methanol crystallised on a Raman substrate having a smooth nickel support material coated with plasma polymerised PFAC-8;
  • Figure 20 is a Raman spectrum for bulk PETN from a library;
  • Figure 21 is Raman spectra for RDX (100 mg/ml) in acetone, ethanol, and methanol crystallised on a Raman substrate coated with plasma polymerised PFAC-6 [in the presence of a fixed volume percentage of divinyl adipate (DVA)]; and
  • DVA divinyl adipate
  • Figure 22 is a Raman spectrum for RDX (lO pg/ml) in methanol crystallised on a Raman substrate coated with plasma polymerised PFAC-6 [in the presence of a fixed volume percentage of divinyl adipate (DVA)].
  • the explosives PETN and RDX are particularly difficult to detect using surface enhanced Raman spectroscopy (SERS) - they are not strongly SERS active. These materials are usually applied to a Raman substrate in an organic solvent, and then dried. Research was thus undertaken to investigate minimising the spread of the organic solvent on the substrate, which could then concentrate the explosive material on the surface. A number of materials were investigated, including the commercial available m-RIM slide, which has a stainless steel support material coated with Teflon. The Applicant also investigated potential novel Raman substrates, including several support materials (e.g. plastic, glass, metal) coated with fluorocarbon polymers, and especially a fluorocarbon polymer generated through plasma polymerisation deposition with the monomer PFAC-8.
  • SERS surface enhanced Raman spectroscopy
  • the base (support material) of a new Raman substrate was prepared from a nickel sheet, which in this case was electroformed for 55 amp hours (AH) in a nickel sulfamate tank, from a silver-coated 8 x 10" glass plate.
  • the nickel sheet was cut, in this case using a Coherent Talisker laser in 355 nm UV mode, max power input 4W at 200 kHz with a pulse duration of 15 ps.
  • the substrate was machined at full power on continuous loops until it had fully cut through the thickness of the substrate.
  • the surface was hatched with the laser at 25% power at four different angles, and then cut on full power for continuous loops until it had fully cut through the substrate.
  • Plasma treatment was carried out in an inductively coupled glass cylindrical glow discharge reactor (10 cm diameter, 4.3x10 3 m 3 volume, base pressure typically better than 1x10 2 mbar).
  • the reactor was connected to a two stage Edwards rotary pump via a liquid nitrogen cold trap with a thermocouple pressure gauge inline.
  • a monomer tube containing lH,lH,2H,2H-perfluorodecyl acrylate (PFAC-8, Fluorochem, UK) was purified by freeze-thaw cycles prior to use and attached to the air inlet side of the reactor. All connections were grease free.
  • An L-C matching unit was used to minimise the standing wave ratio (SWR) of the transmitted power between the 13.56 MHz RF generator and the electrical discharge.
  • SWR standing wave ratio
  • a base substrate (support material; Nickel sheet) was placed in the centre of the reactor.
  • the chamber was then evacuated to the base pressure of the apparatus, typically 1 x 10 2 mbar, and the chamber was heated to 32°C.
  • the PFAC8 vapour was introduced into the reactor.
  • the reactor was purged with the vapour for five minutes, and then the RF generator was switched on to create a 40 W continuous wave plasma, for 30 s.
  • the pulse generator was then turned on, in this case at a pulsing sequence of 40ps on, 20ms off. Once the plasma deposition had recovered, as indicated by an input power of 40 W and a stable pulse envelope (confirmed using an oscilloscope), the deposition was allowed to run for 20 min.
  • the RF generator was switched off and the reactor purged for 2 minutes with monomer vapour, prior to being evacuated back to base pressure. Once base pressure was reached the vacuum chamber was isolated from the pump and the system was brought up to atmospheric pressure to allow the new Raman substrate to be removed.
  • the DSA is capable of measuring contact angles of liquids/solvents on surfaces. The surface tension, and surface free energy, is then calculated from the contact angles measured between the liquid/solvent droplets and the surface. This approach was used to measure the surface free energy of the Raman substrate for crystallisation.
  • the Applicant compared the m-RIM slide to a potential substrate comprising a nickel support material coated with a fluoropolymer generated from PFAC-8 through plasma polymerisation. Three contact angle measurements were taken for each liquid/solvent used, and the average of these three measurements was used for the calculation of the surface free energy. The lower the surface free energy, the higher the repellency from the surface, and thereby the greater the concentration effect prior to crystallisation.
  • the contact angles for the PFAC-8 derived fluoropolymer substrate were 113.8 degrees, 82.0 degrees, 108.2 degrees, and 104.6 degrees, for water, n-hexadecane, ethylene glycol and diiodo methane respectively, with a total surface free energy (Total Interfacial Tension - IFT), based on the contact angles for all four solvents on this surface, of 8.3 mN/m. From these results it is apparent that there is a huge difference in the surface free energies of the commercial m-RIM substrate, and the PFAC-8 derived substrate. These results also show that there is more scope to use a wider variety of solvents with the PFAC-8 derived substrate, and also that material in a particular solvent of choice will be concentrated into a smaller area due to the better repellency on the surface of this substrate.
  • acetone the favoured solvent for crystallisation of all three of RDX, PETN and TNT, does not generate a droplet on the m-RIM slide, and samples applied to this surface in acetone instead wetted the surface.
  • the new substrate is thus also advantageous because of the variety of solvents that can be applied to it, and especially acetone when interrogating samples that may contain explosives.
  • the explosive material PETN (1 mg/ml; 5 mI) in methanol was crystallised on three different Raman substrates, and Raman spectra were generated for each of them, and compared to each other and to a library spectrum of the bulk explosive.
  • the three substrates were a smooth nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 4), a roughened/textured nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 5), and a m-RIM substrate ( Figure 6).
  • the explosive material RDX (1 mg/ml; 5 mI) in ethanol was crystallised on three different Raman substrates, and Raman spectra were generated for each of them, and compared to each other and to a library spectrum of the bulk explosive.
  • the three substrates were a smooth nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 7), a roughened/textured nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 8), and a m-RIM substrate ( Figure 9).
  • the explosive material TNT (1 mg/ml; 5 mI) in methanol was crystallised on two different Raman substrates, and Raman spectra were generated for each of them, and compared to each other and to a library spectrum of the bulk explosive.
  • the two substrates were a roughened/textured nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 10), and a m-RIM substrate ( Figure 11).
  • PFAC-8 plasma polymerised PFAC-8
  • Figure 11 a m-RIM substrate
  • the explosive material TNT (1 mg/ml; 5 mI) in acetone was crystallised on two different Raman substrates, and Raman spectra were generated from a single point for each of them, and compared to each other and to a library spectrum of the bulk explosive (Figure 14).
  • the two substrates were a smooth nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 13), and a m-RIM substrate ( Figure 12).
  • PFAC-8 plasma polymerised PFAC-8
  • Figure 12 m-RIM substrate
  • the explosive material RDX (1 mg/ml; 5 mI) in ethanol was crystallised on two different Raman substrates, and Raman spectra were generated from a single point for each of them, and compared to each other and to a library spectrum of the bulk explosive (Figure 17).
  • the two substrates were a smooth nickel support material that had been coated with plasma polymerised PFAC-8 ( Figure 16), and a m-RIM substrate ( Figure 15).
  • PFAC-8 plasma polymerised PFAC-8
  • Figure 15 m-RIM substrate
  • the material used as the support material could be any suitable material, such as glass, plastic or metal, or even fabric, without having any significant effect on the ability of the Raman substrate (coated with a fluorocarbon polymer, such as poly-PFAC-8) to generate Raman spectra for materials such as TNT, RDX and PETN.
  • a fluorocarbon polymer such as poly-PFAC-8
  • a Raman substrate was prepared in a plasma polymerisation chamber using PFAC-6 in the presence of a fixed volume percentage of divinyl adipate (DVA), used as a linking chemical moiety, and using helium as a carrier gas.
  • the deposition process consisted of a 1 min continuous wave step with 250W power and a pulsed step with 340W power and an RF pulse duty cycle of 0.010%.
  • Aluminium was used as support material for the test substrate and the contact angle of the coated substrate was determined using the Krijss drop shape analyser. Water, n-hexadecane and ethylene glycol were used and gave a total surface free energy (Total Interfacial Tension - IFT), based on the contact angles for the three solvents of 11.2 mN/m.
  • Total Interfacial Tension - IFT Total Interfacial Tension - IFT
  • RDX a ten-fold dilution of a 1 mg/ml solution of RDX was prepared in acetone, ethanol and methanol, and Raman spectra generated using a 785 nm Raman spectrometer, thus a final concentration of 100 pg/ml RDX.
  • RDX could be identified at this concentration, irrespective of the solvent used to apply to the Raman substrate.

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Abstract

L'invention concerne de nouveaux substrats et procédés améliorés de spectroscopie Raman, permettant une détection de matériaux qui sont généralement difficiles à détecter par l'utilisation d'une spectroscopie Raman exaltée de surface (SERS). L'invention concerne donc un substrat Raman comportant une surface comprenant un polymère de fluorocarbone, le polymère de fluorocarbone comprenant des unités monomères d'acrylate de perfluoroalkyle, ou étant assemblé à partir de ces dernières. Le polymère de fluorocarbone peut être généré sur un substrat par le biais d'une polymérisation par plasma du monomère CH2=CR1C(O)O(CH2)x(CF2)yCF3 . Ces substrats Raman constituent un moyen de détection de matériaux qui ne sont pas fortement actifs du point de vue SERS, tels que les explosifs à base de RDX et de PETN.
PCT/GB2021/000076 2020-07-07 2021-06-30 Nouveaux substrats améliorés de spectroscopie raman Ceased WO2022008859A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB2010387.5 2020-07-07
GBGB2010387.5A GB202010387D0 (en) 2020-07-07 2020-07-07 New and improved substrates for raman spectroscopy
GBGB2102465.8A GB202102465D0 (en) 2021-02-22 2021-02-22 New and improved substrates for raman spectroscopy
GB2102465.8 2021-02-22

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TWI596144B (zh) * 2016-10-27 2017-08-21 國立中興大學 高分子薄膜、其製造方法及其應用之抗反射元件與感測元件
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