Patent Description:
The space exploration and the search of life in other celestial bodies has suffered an exponential increase in the last <NUM> years. Technological advances have made it possible to set objectives and achieve goals that were unthinkable before <NUM>, the date on which the first successful satellite, Sputnik <NUM>, was launched. This event launched the space race, and with it, a large number of missions that have explored planets, satellites and comets from our galaxy.

The beginning of these contacts brought with it concern about the possible contamination produced in the visited bodies (Forward contamination), and that received in the return missions (Backward contamination). To study how to minimize the effect of these processes and issue recommendations the COSPAR (Committee on space research) was formed in <NUM>. Its resolutions were ratified by the United Nations in the "External Space Treaty" of <NUM>. Space agencies have adopted these recommendations in their procedures and the Planetary Protection protocols are strictly followed in all space missions. The cleaning procedures and the control systems for biological, molecular and particle contamination are very rigorous and are present in all phases of the mission: design, manufacture, assembly, integration, testing, storage, transportation, preparation for launch, launch and orbit.

Especially sensitive to cross contamination are the scientific missions in situ whose objective is the search for life precursors. The analytical equipment shipped aboard the rovers and probes are increasingly sensitive and the detection range is becoming smaller (ppb). A natural pollution, or accidental, produced by the material transported from the Earth in a mission can produce a false positive in the search for life precursors, where biological traces as simple as C-H, C-O or C-N links are looked for.

Advances in polymer technology have allowed to improve the mechanical and thermal properties, which together with its lightness, has made polymers very interesting candidates for spatial use as structural materials. As functional materials its use is even more widespread: wiring, adhesives, plastic connectors, lubricants or gaskets that are present in any mission.

However, the simple signals of the mentioned links could be detected in a large number of the polymers, which are the fundamental basis of their composition, and in case of contamination, produce a false positive in the analysis of the samples.

<CIT> and <CIT> relate to taggant fibers made of polymers selected from polyolefins for enhanced protection and security when said fibers are used in documents such as land titles, currency, passports and other documents of value. <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, disclose different isotopically labelled polymer materials. Whether these materials are suitable for the detection of material contamination, degradation, or wear under industrial or space environments is unknown.

The present invention provides a material which allows the detection of any contamination or degradation or wear of said material in a simple and very reliable way. The inventors of the present invention have found that an isotopically marked functional material can be traced and, moreover, that its different components can be traced so as to identify if there has been any contamination or degradation of the material in general or of any of its components in particular.

In a first aspect, the present invention relates to the use of a material comprising a synthetic functional polymer and optionally at least one functional additive in the detection of material contamination or degradation or wear, wherein said material is marked with at least one isotope, wherein the isotope or isotopes are present in a functional component of the material and wherein the at least one isotope is selected from <NUM>H, <NUM>C, <NUM>N, <NUM>O,<NUM>O, <NUM>Si, <NUM>Si, <NUM>S, <NUM>S, <NUM>S, <NUM>Cl, wherein said material is a space material or an industrial material, preferably wherein the industrial material is a material to be used in a clean room. Said functional component or components of the material where the isotope or isotopes are present is not used in the material for marking said material but has another function in said material other than marking the material, such as a structural function, or a function such as that of a plasticizer, a flame retardant, a filler, an antioxidant, a metal scavenger, a UV protector, a photostabilizer, a heat stabilizer, an impact modifier, etc. Thus, the marked functional component is not present in the material only for the purpose of labelling or tagging the material.

In a preferred embodiment of the first aspect, the present invention relates to the use of a material comprising at least one synthetic functional polymer and optionally at least one functional additive in the detection of material contamination or degradation or wear, wherein said material is marked with at least one isotope, wherein the isotope or isotopes are present in a functional component of the material, and wherein the at least one isotope is selected from <NUM>H, <NUM>C, <NUM>N, <NUM>O, <NUM>O, <NUM>Si, <NUM>Si, <NUM>S, <NUM>S, <NUM>S, <NUM>Cl, wherein said material is a space material or an industrial material, preferably wherein the industrial material is a material to be used in a clean room. These isotopes form covalent bonds in organic compounds.

In a preferred embodiment of the first aspect, the material comprises more than one component and the same isotope is used for marking different components.

In another preferred embodiment of the first aspect, the material comprises more than one component and wherein a different isotope is used for marking different components.

In a preferred embodiment of the first aspect, the isotope is introduced in a specific position in a monomer of the synthetic polymer.

The term "functional" as used herein means that the synthetic polymer or the additive's purpose or function is not exclusively marking the material, that is, the synthetic polymer or additive has a function other than marking the material. For example, the function of the synthetic polymer may be structural. For example, the function of the additive may be a plasticizer, a flame retardant, a filler, an antioxidant, a metal scavenger, a UV protector, a photostabilizer, a heat stabilizer, or an impact modifier. The term "functional" as used herein should not be understood as "functional group" but as explained above.

The expression "present in a functional component of the material" also means that the component of the material which is isotopically marked has a function other than marking the material. For example, when the component that is isotopically marked is the synthetic polymer, this polymer may be a structural component, useful for its mechanical properties, or a functional component, useful for its chemical, magnetic, electronic properties, etc., and this polymer will be useful for other reasons than for being marked.

The term "component" as used herein means any constituting part of a larger whole, any constituent. In the present description, the term "component" refers to the material and, therefore, refers to any constituting part of the material.

The term "marked", or "marking" as used herein means that the material in general and the marked component in particular, comprise a different isotopic ratio than the isotopic ratio present in the medium or environment where the material is used. For example, for space material to be used in Mars, the isotopic environment in the material will be different than the isotopic environment in Mars. For space material to be used in the Moon, the isotopic environment in the material will be different than the isotopic environment in the Moon. For a prosthetic material to be used in the human body, the isotopic environment in the material will be different than the isotopic environment in the human body. The skilled person is fully aware of how to prepare the materials of the present invention, once the particular isotopic environment for the material has been chosen (see for example <NPL>;<NPL>; <NPL>; <NPL>; <CIT>; <NPL>; <NPL>;<NPL>;<NPL>).

The terms "labelled" and "marked" are used interchangeably in the present description.

The expression "isotopic environment" as used herein refers to the percentage of each isotope of each chemical element in a certain physical environment, i.e. in a certain planet, satellite, etc. The expression "different isotopic environment" as used herein means that upon detecting the percent of a certain isotope of a certain chemical element in the material and in a particular natural environment, different percentages will be obtained. For example, for a material marked with <NUM>H (deuterium) to be used in Mars, its minimum mark will be <NUM> times the abundance of <NUM>H in Mars, which is <NUM> % of the Hydrogen atoms in the marked component of the material will be <NUM>H.

For example, the plasticizer dioctyl phthalate (DOP) can be added in a <NUM> weight % to the composition of a material comprising a synthetic polymer. If DOP is marked at the <NUM> % of a set atomic position, this means that this component of the material is marked and if it degasifies, the degraded component will be detected because of the different signals generated by this <NUM>% of marked positions.

The present invention allows to have different marking in each component which allows to identify the component which is suffering degradation.

A material can be <NUM>% traceable if all of its components are marked and each one is marked using a specific marking, which can be associated to a specific component or material upon detection.

The expression "industrial material" as used herein refers to any material suitable for industrial applications. Materials suitable for industrial applications must be validated according to the characteristics of the specific field of use. Two examples of industrial material are:.

The expression "space material" as used herein refers to any material suitable for a space mission. Materials suitable for space missions must be validated according to the requirements of each mission in terms of space environment effects, such as vacuum, heat, thermal cycling, radiation, debris, etc. and in terms of induced space environment effects, such as contamination, secondary radiations and spacecraft charging. These space environment effects are defined by the external physical world for each mission: atmosphere, meteoroids, energetic particle radiation, etc. The induced space environment is that set of environmental conditions created or modified by the presence or operation of the item and its mission. The space environment also contains elements which are induced by the execution of other space activities (e.g. debris and contamination).

In a preferred embodiment of the first aspect, at least <NUM> % of the atoms of the chemical element of the isotope are marked, in respect of the total number of atoms of that chemical element in the marked component of the material. Preferably, at least <NUM> % of the atoms of the chemical element of the isotope are marked, in respect of the total number of atoms of that chemical element in the marked component of the material. More preferably, at least <NUM> % of the atoms of the chemical element of the isotope are marked, in respect of the total number of atoms of that chemical element in the marked component of the material. In a more preferred embodiment, at least <NUM> % of the atoms of the chemical element of the isotope are marked, in respect of the total number of atoms of that chemical element in the marked component of the material. In an even more preferred embodiment, at least <NUM> % of the atoms of the chemical element of the isotope are marked, in respect of the total number of atoms of that chemical element in the marked component of the material. In another embodiment, at least <NUM> % of the atoms of the chemical element of the isotope are marked, in respect of the total number of atoms of that chemical element in the marked component of the material. The minimum marking of the material will depend on the technique intended to be used for detection and its sensitivity.

In a preferred embodiment of the first aspect, the isotopic mark is detected by FTIR, Raman, GC/MS, RMN-H, RMN-C, UV-visible spectroscopy. The isotopic mark is detected by any analytical technique that can detect the differences between the natural isotopic environment and the induced isotopic environment in the material. Preferably, the isotopic mark is detected by FTIR, Raman, GC/MS, RMN-H, RMN-C and/or UV-visible spectroscopy. More preferably, the isotopic mark is detected by Raman or GC/MS.

The materials of the present invention are characterized physico-chemically analysing their TGA, DSC, degree of crystallinity, glass transition temperature, gel permeation chromatography (GPC), FTIR, Raman and H-NMR. The degradation/contamination/wear of the materials of the present invention can be detected by means of the same analytical techniques used in the rover of the Exomars <NUM> mission: Raman, GC/MS, etc. For example, the analytical techniques used in Martian rovers to search organic life signatures are gas chromatography with mass spectroscopy (GC/MS), laser desorption with mass spectroscopy (LD/MS) and Raman spectroscopy.

For those materials to be used in space, said materials will undergo the relevant spatial validation tests, required for all materials that participate in space missions, and which are determined by the type of mission, the function of the component, and its exposure to environmental agents.

For the materials described in the present invention, the rules of the ESA (European Space Agency) have been followed, and the validation tests have been those determined by the following standards:.

In a preferred embodiment of the first aspect, the synthetic polymer is an addition polymer or a condensation polymer. Preferably, the synthetic polymer is a polyolefin, a polyester, a polyurethane, a polyimide, a polyacrylate, a polysiloxane, a polyepoxide, a fluorinated polymer or a combination thereof. more preferably, the synthetic polymer is polyethylene (PE), polyethylene terephthalate (PET), polyamide (PA), ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyetheretherketone (PEEK), polyethersulphone (PES), polysulfone, polyetherimide (PEI) or a copolymer o terpolymer thereof.

Examples of synthetic bioabsorbable polymers that may be used for prosthetic materials are polyglycolide, or polyglycolic acid (PGA), polylactide, or polylactic acid (PLA), poly ε-caprolactone, polydioxanone, polylactide-co-glycolide, e.g., block or random copolymers of PGA and PLA, and other commercial bioabsorbable medical polymers. Preferred is spongy collagen or cellulose.

In a preferred embodiment of the first aspect, the material is a plastic, an adhesive, a coating, a varnish, a tape, a film, a paint, an ink, a lubricant, a potting, a sealant, a foam, a rubber, a wire or a cable.

In a preferred embodiment of the first aspect, the material is used as a calibrator for a Raman spectrometer.

In a preferred embodiment of the first aspect, the material is comprised in a composite material. Preferred composite materials comprise at least one of carbon fibre, polyethylene, polypropylene, nylon or kevlar. Preferably, the composite material comprises a binder and reinforcement fibres and/or particles. Said binder and/or reinforcement fibres and/or particles could be also polymeric.

In a preferred embodiment of the first aspect of the present invention, the material comprises different components and all the marked components are marked with the same isotope.

In order to provide a better understanding of the invention, the following is a detailed explanation of some of the preferred embodiments of the invention, which is provided to give an illustrative example of the invention but which, by no means, should be considered to limit the same.

As an example of isotopically labelled structural or functional material for the application of space contamination detection, PET polymers (Polyethylene terephthalate) have been synthesized and have the same technical characteristics as the PET used as the calibrator of the Raman spectrometer that will go aboard the Exomars. These polymers have been synthesized starting from:.

The synthesis has been carried out by additive polymerization (polycondensation in interface), in a two-phase system composed of an organic and an inorganic phase, with the following conditions:.

The monomers were added in a staggered manner in two independent phases. The interfacial polymerization proceeded then in the following way:.

The ratio of isotopically labelled polymer was graduated by employing different mixtures of the monomers and their deuterated analogues. For the example, <NUM> different compositions were made:.

The purification of the resulting material was carried out in the following manner:.

After this purification, it was necessary to carry out a bakeout to release the non-crosslinked monomers, and the residues of additives and solvent, typical in materials for space use.

Over a solution of <NUM> to <NUM> of NaOH (<NUM> mol/L) in water, <NUM> to <NUM> mol of a mixture of ethyleneglycol and ethylene-d<NUM> glycol (ratio from <NUM> to <NUM> %; total concentration <NUM> mol/L) was added under stirring at a moderate speed. Subsequently, <NUM> mol-% of phase transfer catalyst (for example, tetrabutylammonium bromide) dissolved in <NUM> to <NUM> liters of water were added. A mixture of terephthaloyl chloride and terephthaloyl-d<NUM> chloride (ratio from <NUM> to <NUM> %; molar ratio diol/diacid chloride <NUM>:<NUM>) was dissolved in chloroform (ratio water/chloroform <NUM>:<NUM>). The organic phase was then added over the aqueous layer under vigorous stirring and mixing continued for <NUM> to <NUM> minutes. Acetone was added to the reaction vessel and the polymer was filtered off and washed with acetone to remove unreacted monomers. The material was subsequently washed three times with water and then filtered off. The final product was dried to constant weight in a vacuum oven at <NUM>.

Ethylene and ethylene-d<NUM> were introduced at different ratios and at a moderate flow to a stirred solution containing a <NUM> to <NUM> mixture of TiCl<NUM> and AlEt<NUM> in hexanes under N<NUM> atmosphere. When the reaction mixture became thick, the mixture was hydrolyzed by addition of several amounts of ethanol. The resulting material was subsequently washed several times with ethanol, filtered and dried.

The PET polymer was marked using deuterium in the <NUM>% of the hydrogen atomic positions of both precursor monomers (ethylenglycol-d4, and terephthaloyl chloride-d4).

In order to detect/identify the marked PET, different techniques were used:.

Raman spectroscopy is a non-destructive technique that does not need the previous preparation of the sample.

For this study the Raman spectrometer used was a RAMAN Horiba XPlora with Laser: <NUM> (Green) and Confocal microscope 10x.

We found that the isotopic substitution of deuterium (<NUM>H) instead of protium (<NUM>H) in the <NUM>% of hydrogen positions (aliphatic and aromatic) in PET caused little differences in many of the detected signals, but in those in which the hydrogen interaction was higher, the shift of the signals was more notorious and easy to differentiate in the marked sample. Some examples of the most representative were the following:.

Only the deuterated signals (Table <NUM>) appeared in the spectrum, clearly differentiated from the analogous protium examples that did not appear in that case. The ratio of the intensity of equivalent signals must be proportional to the ratio of the marked:non-marked positions.

In the case of <NUM>% of marked positions in both precursor monomers, the protium and deuterium signals will appear in the spectrum with same intensity, but keeping the shift that allows to differentiate.

<NUM> of the powdered <NUM>% marked PET was dissolved in <NUM> of acetone for HPLC (≥<NUM>%).

The GC/MS system used was a Varian Saturn <NUM>. The parameters of the method were:.

<NUM>µl of the PET/acetone solution was injected directly in the <NUM> injector of the GC, using a <NUM>µl Hamilton syringe.

As it happened in the Raman study, only the mass of the deuterated fragments (table <NUM>) appeared in the chromatogram.

The +<NUM>(M/z) caused by every deuterium introduced instead of a protium has an accumulative effect, and in the PET case, the <NUM> marked position generates a +<NUM> (M/z) for the molecular ion, and at least +<NUM>(M/z) in the most of identification fragments:.

In the case of <NUM>% of marked positions in both precursor monomers, the protium and deuterium signals appear in the chromatogram with same intensity. Since the isotopic differences do not affect significantly the interaction of compounds with the chromatographic column, the separation was not possible (even for longer and soft methods) and the retention time was almost the same.

To solve this, the GC/MS systems allows the selective plot of the preferred masses. Protium and deuterium signals (table <NUM>) could be plotted separately and compare the number of accumulated counts of every species.

The ratio of the intensity of the accumulated counts of the masses detected must be proportional to the ratio of the marked:non-marked positions.

Three additives of common polymeric use are presented as examples of identification by GC/MS. The methodology of study and identification will be the same as for PET:.

The +<NUM>(M/z) caused by every deuterium introduced instead of a protium has an accumulative effect, and in the Dioctyl-Phthalate-d<NUM> (DOP) case, the <NUM> marked positions generates a +<NUM> (M/z) for the molecular ion, and at least +<NUM>(M/z) in the most of identification fragments:.

Decamethyltetrasiloxane is used as adsitive in adhesives and lubricants.

The +<NUM>(M/z) caused by every deuterium introduced instead of a protium has an accumulative effect, and in the decamethyltetrasiloxane-d<NUM> case, the <NUM> marked positions generates a +<NUM> (M/z) for the molecular ion, and at least +<NUM>(M/z) in the most of identification fragments:.

Benzotriazole is used as UV photostabilizer.

The +<NUM> (M/z) caused by every deuterium introduced instead of a protium has an acumulative effect, and in the Benzotriazole-d<NUM> case, the <NUM> marked positions generates a +<NUM> (M/z) for the molecular ion, and at least +<NUM>(M/z) in the most of identification fragments:.

Claim 1:
Use of a material comprising a synthetic functional polymer and optionally at least one functional additive in the detection of material contamination or degradation or wear, wherein said material is marked with at least one isotope, wherein the isotope or isotopes are present in a functional component of the material, wherein the term "functional" has the meaning as defined in the description, and wherein the at least one isotope is selected from <NUM>H, <NUM>C, <NUM>N, <NUM>O, <NUM>O, <NUM>Si, <NUM>Si, <NUM>S, <NUM>S, <NUM>S, <NUM>Cl, wherein said material is a space material or an industrial material, preferably wherein the industrial material is a material to be used in a clean room.