SENSOR BASED ON A POLYOLEFIN MATRIX AND A SENSING COMPOUND

Abstract

A sensor comprising a randomly functionalised polyolefin having functional groups, a sensing compound and optionally a polar solvent, wherein the polyolefin has a crystallinity between 0 and 35%, as determined with DSC, and wherein the amount of monomeric moieties comprising functional groups is at least 0.1 mol %.

Claims

1. A sensor comprising: a randomly functionalised polyolefin having functional groups, a sensing compound comprising at least one of a pH indicator, or a redox indicator, and optionally a polar solvent, wherein the functionalised polyolefin has a crystallinity between 0 and 35%, as determined with differential scanning calorimetry, and wherein an amount of monomeric moieties having a functional group ranges between 0.1 and 5 mol %, as determined with .sup.1H NMR.

2. The sensor according to claim 1, wherein the functionalised polyolefin has hydroxyl (—OH), carboxylic acid (—COOH), amine and/or thiol functionalities.

3. The sensor according to claim 1, wherein the functionalised polyolefin is a functionalised low-density polyethylene, or a functionalised linear low-density polyethylene, or a functionalised very low density polyethylene, or a functionalised ethylene-propylene rubber, or a functionalised polypropylene, or a functionalised propylene-α-olefin copolymer, or a combination thereof.

4. The sensor according to claim 1, wherein the functionalised polyolefin further comprises a comonomer of 1-butene, 1-hexene, 1-octene, or a combination thereof.

5. The sensor according to claim 1, wherein the density of the functionalised polyolefin in the sensor is below 0.89 g/ml.

6. The sensor according to claim 1, wherein the functionalised polyolefin comprises a functionalised polyethylene, and the melt temperature (T.sub.m) (according to DSC) of the sensor is below 100° C.

7. The sensor according to claim 1, wherein the functional groups of the functionalised polyolefins are protic functional groups.

8. The sensor according to claim 1, wherein the sensor comprises hydrogen bonding enhancing agents, which hydrogen enhancing agents are polyols, polyamines, polyacids, polyethers, polyesters, polycarbonates, polyamides, polyurethanes, polyureas, polysaccharides, polypeptides and/or combinations of at least two of said hydrogen bond enhancing agents.

9. The sensor according to claim 1, wherein the sensor comprises a polar solvent, and wherein the polar solvents comprises water, an alcohol, formic acid, acetic acid, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, ethyl acetate, propylene carbonate or a combination thereof and wherein an amount of the polar solvent ranges between 0 and 50 wt % relative to the weight of the sensor.

10. The sensor according to claim 1, wherein the sensing compounds comprises at least one of methyl red, phenolophthalein, thymol blue, bromocresol purple, alpha-naphtholbenzein, methylene blue, thionine, Indophenol, diphenylaminesulfonic acid, Indigo carmine, or N,N-diphenylbenzidine.

11. The sensor according to claim 1, wherein the sensor is a thin films, sheets, or circles or wherein the sensor is attached to a substrate, wherein the substrate is a microporous film, a non-porous film, or a multilayer material.

12. (canceled)

13. Smart packaging material containing the sensor according to claim 1.

14. The sensor according to claim 1, wherein the functionalised polyolefin comprises a functionalised polypropylene, and the melt temperature (T.sub.m) (according to DSC) of the sensor is below 125° C.

15. The sensor according to claim 7, wherein the protic functional groups are —OH groups, —COOH groups, or a combination thereof.

16. The sensor according to claim 7, wherein the protic groups are partially or fully deprotonated to obtain a polyolefinic ionomeric system.

17. The sensor according to claim 8, wherein an amount of the hydrogen bond enhancing agent is from 0.01 to 10 wt. %, based on the combined weight of the amorphous functionalised olefine and the hydrogen bond enhancing agent.

18. The sensor of claim 9, wherein an amount of the polar solvent ranges between 5 and 25 wt % relative to the weight of the sensor.

19. The sensor of claim 8, wherein the amount of hydrogen bond enhancing agent is from 0.01 to 10 wt. %, based on the combined weight of the amorphous functionalised olefin copolymer and the hydrogen bond enhancing agent.

Description

FIGURES

[0065] FIG. 1 shows a sensor, based on a functionalised atactic polypropylene containing methyl red as the active sensing compound, as prepared and after being exposed to sparkling water and ammonia.

EXPERIMENTAL SECTION

General Considerations

[0066] All manipulations were performed under an inert dry nitrogen atmosphere using either standard Schlenk or glove box techniques. Pentamethyl heptane (PMH) and heptane were employed as solvents for PP-based sensors and polymerisation experiments and were supplied by Brenntag Netherlands. 1-Hexene was purchased from Sigma Aldrich and was distilled over a sodium/potassium alloy with benzophenone as an indicator under inert atmosphere. Toluene, methanol, D-mannose, methylene blue, potassium hydroxide, methyl red were purchased from Sigma Aldrich, 10-undecene-1-ol, 10-undecenoic acid and 3-buten-1-ol were purchased from Sigma Aldrich and dried under an inert atmosphere using standard distillation techniques. Methylaluminoxane (MAO, 30 wt. % solution in toluene) was purchased from Chemtura. Diethyl zinc (DEZ, 1.0 M solution in toluene) and triisobutyl aluminium (TiBA, 1.0 M solution in hexanes) were purchased from Sigma Aldrich. (C.sub.5Me.sub.4(SiMe.sub.2NtBu)TiCl.sub.2) catalyst was prepared according to literature procedure described in Organometallics 1990, 9, 867-869 and Chem. Ber. 1990, 123, 1649-1651 and rac-Me.sub.2Si(2-Me-4-Ph-Ind).sub.2ZrCl.sub.2 was purchased from MCAT GmbH, Konstanz, Germany.

Synthesis of iPP-co-hexene-co-C.SUB.11.OH (Entry 3, Table 1)

[0067] The polymerisation reaction was carried out in a 2 L stainless steel reactor. Prior to the polymerisation, the reactor was washed with 1.5 L heptane containing TiBA (1.0 M solution in toluene, 2 mL) at 150° C. Subsequently, heptane (1.5 L), TiBA (1.0 M solution in toluene, 2.0 mL), MAO (15 wt. % solution in toluene, 2.0 mL), TiBA protected 10-undecen-1-ol (20 mmol) and 1-hexene (160 mmol) were introduced into the reactor and stirred at 300 rpm at 50° C. The reactor was vented off, the temperature was raised to 80° C. and the solvent was saturated with propylene (5 bar). In a glovebox, a stock solution of Me.sub.2Si(2-Me-4-Ph-Ind).sub.2ZrCl.sub.2 catalyst in toluene (5 mL) was prepared and the MAO activated catalyst solution (0.6 μmol) and DEZ (1.0 M solution in toluene, 0.5 mL) were transferred into the reactor using an overpressure of nitrogen. The propylene pressure was maintained constant during the polymerisation time (40 min). At the end of the polymerisation, the propylene feed was stopped and the residual propylene was vented off. The reaction mixture was quenched with acidified isopropanol (300 mL, 2.5 wt. % of acetic acid), filtered and washed with demineralised water. The resulting powder was dried in a vacuum oven under reduced pressure at 60° C. overnight.

[0068] A similar procedure was applied in propylene copolymerisation with 10-undecenoic acid (entry 10, Table 1) using Me.sub.2Si(2-Me-4-Ph-Ind).sub.2ZrCl.sub.2 and propylene copolymerisation with 3-buten-1-ol (entries 2-4, Table 2), 10-undecen-1-ol (entry 5, Table 2) and 10-unedecenoic acid (entry 6, Table 2) using [C.sub.5Me.sub.4SiMe.sub.2NtBu]TiCl.sub.2 catalysts (Table 2).

Preparation of PP-Based pH Sensor

[0069] PP-co-1-hexene-co-C.sub.11OH (1 g, Table 1, entry 6) was dissolved in PMH (60 mL) containing Irganox 1010 (10 mg) at 90° C. for 1 h. Subsequently, to the polymer solution, 60 mL of demineralised water was added and the suspension was gently stirred. Than an alcohol/water (30/20 v/v) mixture, containing methyl red (5.0 mL, 0.0037 mmol), was introduced and stirred for 1 h at 90° C. and was subsequently allowed to cool to room temperature under stirring. The PP-co-1-hexene-co-C.sub.11OH, containing methyl red was filtered, dried at 60° C. in the vacuum oven for 24 hours. All the sample plaques were prepared via compression-molding using PP ISO settings on LabEcon 600 high-temperature press (Fontijne Presses, the Netherlands). Then, the compression-molding cycle was applied: heating to 210° C., stabilising for 5 min with no force applied, 5 min with 100 kN normal force and cooling down to 40° C. with 15° C./min and 100 kN normal force. The above-described procedure was applied for all the materials listed in Tables 1-2. The OH and COOH functionalised samples revealing higher crystallinity level than 35% (entries 8-9, Table 1) and non-functionalised PP samples (entry 11, Table 1) did not reveal significant affinity to the sensing compound and no clear colour change could be observed when exposing these samples to acidic or basic conditions.

Preparation of PP-Based Oxygen Sensor

[0070] PP-co-1-hexene-co-C.sub.11OH (1 g, Table 1, entry 6) was dissolved in toluene (60 mL) containing Irganox 1010 (10 mg) at 100° C. for 1 h. The solution was stirred under reduced pressure to remove oxygen traces. Subsequently, to the polymer solution 20 mL of D-mannose (0.1 M aqueous solution) and methylene blue (0.1 g, 0.03 mmol) and KOH (0.1 M aqueous solution) were added to obtain a colourless solution. All the manipulations were carried out under nitrogen atmosphere. The mixture was stirred at 100° C. for 1 h and subsequently allowed to cool to room temperature under stirring. Afterwards, the polymer containing oxygen sensor was recovered by solvent evaporation under reduced pressure. Upon exposing the polymer to air, the colour of the material turned blue.

[0071] The OH and COOH functionalised samples revealing higher crystallinity level than 35% (entries 8-9, Table 1) and non-functionalised PP samples (entry 11, Table 1) did not reveal significant affinity to the sensing compound and no clear colour change could be observed when exposing these samples to air.

Analytical Techniques

[0072] .sup.1H NMR Characterisation.

[0073] The percentage of functionalisation was determined by .sup.1H NMR analysis carried out at 130° C. using deuterated tetrachloroethane (TCE-d.sub.2) as the solvent and recorded in 5 mm tubes on a Varian Mercury spectrometer operating at a frequency of 400 MHz. Chemical shifts are reported in ppm versus tetramethylsilane and were determined by reference to the residual solvent protons.

[0074] High Temperature Size Exclusion Chromatography (HT-SEC).

[0075] The molecular weights, reported in kg/mol, and the PDI were determined by means of high temperature size exclusion chromatography, which was performed at 150° C. in a GPC-IR instrument equipped with an IR4 detector and a carbonyl sensor (PolymerChar, Valencia, Spain). Column set: three Polymer Laboratories 13 μm PLgel Olexis, 300×7.5 mm. 1,2-Dichlorobenzene (o-DCB) was used as eluent at a flow rate of 1 mL.Math.min-1. The molecular weights and the corresponding PDIs were calculated from HT SEC analysis with respect to narrow polystyrene standards (PSS, Mainz, Germany).

[0076] Differential Scanning Calorimetry (DSC).

[0077] Thermal analysis was carried out on a DSC 0100 from TA Instruments at a heating rate of 5° C..Math.min.sup.−1. First and second runs were recorded after cooling down to ca. −20° C. The melting temperatures reported correspond to second runs. The degree of crystallinity was derived from the DSC data by the comparison of the enthalpy of fusion measured at the melting point of the synthesized polymers and the enthalpy of fusion of a totally crystalline polymer measured at the equilibrium melting point (for more details for example see Polymer 2002, 43, 3873-3878).

[0078] The enthalpy of fusion of a totally crystalline polypropylene is reported to be 207.1 J/g, while the enthalpy of fusion of a totally crystalline polyethylene is 293.6 J/g.

TABLE-US-00001 TABLE 1 Copolymerisations of propylene, 1-hexene and TiBA-pacified 10-undecen-1-ol and 10-undecenoic acid using isospecific catalyst..sup.[a] M.sub.n C10═COOH C.sub.11═OH.sup.[b] C.sub.10═COOH.sup.[b] 1-hexene Yield (kg/mol) or C11═OH 1-hexene.sup.[d] T.sub.m.sup.[e] x.sub.c.sup.[e] # (mmol) (mmol) (mmol) (g).sup.[c] (PDI) (mol. %).sup.[d] (mol. %) (° C.) (%) 1 5 n.a. 160 137.5 35.6 0.16 n.d. 118.7 24.7 (2.1) 2 20 n.a. 80 36.0 56.9 0.5 n.d. 123.3 30.2 (2.2) 3 20 n.a. 160 39.6 63.9 0.6 n.d. 107.4 18.9 (2.2) 4 30 n.a. 160 35.4 73.2 0.8 2.1 106.5 17.6 (2.1) 5 40 n.a. 160 73.5 58.9 0.6 2.1 104.4 13.2 (2.2) 6 40 n.a. 40 50.6 55.3 1.0 1.2 123.7 26.5 (2.1) 7 50 n.a. 160 72.5 53.0 0.7 2.2 101.7 11.5 (2.0) 8 5 n.a. 16 24.7 40.0 0.13 0.8 146.8 40.4 (2.3) 9 12 n.a. n.a. 49.8 60.4 0.4 n.a. 148.8 44.2 (2.1) 10 n.a. 30 160 72.2 67.3 0.12 2.6 110.6 24.5 (2.1) 11 n.a. n.a. n.a. 59.1 45.2 n.a. n.a. 156.0 52.0 (2.1) .sup.[a]Conditions: rac-Me.sub.2Si(2-Me-4-Ph-Ind).sub.2ZrCl.sub.2 = 0.6 μmol, heptane = 1.5 L, propylene = 5 bar, reaction temperature = 80° C., reaction time = 40 min, MAO (15 wt % solution in toluene, 2 mL), DEZ (1.0M solution in toluene) = 0.5 mL, TiBA (1.0 M solution in toluene) = 2 mL. .sup.[b]C.sub.11═OH is 10-undecen-1-ol and was pacified using 1.0 equiv. of TiBA (1.0M solution in toluene), C.sub.10═COOH is 10-undecenoic acid and was pacified using 2.0 equiv. of TiBA (1.0M solution in toluene) .sup.[c]The yield was obtained under non-optimised conditions and determined using the weight of polymer obtained after filtration and drying in vacuum oven overnight at 60° C.. .sup.[d]10-undecen-1-ol or 10-undecenoic acid incorporation level as determined by .sup.1H NMR and 1-hexene incorporation was determined using 13C NMR. .sup.[e]Determined by DSC. X.sub.c is determined by dividing the enthalpy of fusion of the polymer sample by 207.1 and multiplying by 100%.

TABLE-US-00002 TABLE 2 Copolymerisations of propylene with TiBA-pacified 10-undecen-1-ol, 10-undecenoic acid and 3-buten-1-ol using non-isospecific catalyst. al C.sub.4═OH.sup.[b] C.sub.11═OH.sup.[b] C.sub.10═COOH.sup.[b] Com. incorp..sup.[d] M.sub.n # (mmol) (mmol) (mmol) Yield.sup.[c] (mol %) (kg .Math. mol.sup.−1) PDI 1 n.a. n.a. n.a. 136 n.a. 57.2 2.7 2  5 n.a. n.a. 55 0.11 44.6 2.2 3 10 n.a. n.a. 41 0.33 59.6 2.6 4 15 n.a. n.a. 46 0.38 62.3 2.3 5 n.a. 15 n.a. 33 0.23 77.2 2.4 6 n.a. n.a. 5 28 0.10 41.7 2.3 .sup.[a][C.sub.5Me.sub.4SiMe.sub.2NtBu]TiCl.sub.2 (2 μmol), heptane = 1.5 L, propylene = 5 bar, reaction temperature = 50° C., reaction time = 40 min, MAO (15 wt % solution in toluene, 4 mL), TiBA (1.0M solution in toluene, 2 mL). .sup.[b]C.sub.4═OH and C.sub.11═OH are 3-buten-1-ol and 10-undecen-1-ol, respectively and were pacified with 1.0 equiv. of TiBA (1.0M solution in toluene), C.sub.10═COOH is 10-undecenoic acid and was pacified using 2.0 equiv. of TiBA (1.0M solution in toluene). .sup.[c]The yield was obtained under non-optimised conditions and determined using the weight of polymer obtained after filtration and drying in a vacuum oven overnight at 60° C.. .sup.[d]3-buten-1-ol, 10-undecen-1-ol and 10-undecenoic acid incorporation levels as determined by .sup.1H NMR. Those samples were found amorphous as determined by DSC.