WO2019220081A1 - Hydroxyde à double couche modifié en surface - Google Patents

Hydroxyde à double couche modifié en surface Download PDF

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Publication number
WO2019220081A1
WO2019220081A1 PCT/GB2019/051295 GB2019051295W WO2019220081A1 WO 2019220081 A1 WO2019220081 A1 WO 2019220081A1 GB 2019051295 W GB2019051295 W GB 2019051295W WO 2019220081 A1 WO2019220081 A1 WO 2019220081A1
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Prior art keywords
double hydroxide
layered double
ldh
amo
modifier
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PCT/GB2019/051295
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English (en)
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Dermot O'hare
Chunping CHEN
Jean-Charles BUFFET
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Scg Chemicals Co., Ltd.
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Publication of WO2019220081A1 publication Critical patent/WO2019220081A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/16—Preparation of alkaline-earth metal aluminates or magnesium aluminates; Aluminium oxide or hydroxide therefrom
    • C01F7/162—Magnesium aluminates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/32—Thermal properties
    • C01P2006/37—Stability against thermal decomposition

Definitions

  • the present invention relates to surface modified layered double hydroxides, as well as to processes for making the surface modified layered double hydroxides, and their uses in composite materials.
  • LDHs Layered double hydroxides
  • WO 99/24139 discloses the use of LDHs to separate anions including aromatic and aliphatic anions.
  • a method of preparing LDHs with a specific surface area of at least 125 m 2 /g was reported (WO2015/144778), the method comprising slurrying a dispersion of a water-wet LDH in an aqueous-miscible organic (AMO) solvent, followed by recovery and drying of the so-called AMO- LDH.
  • AMO-LDHs suffer from a high moisture uptake capacity compared with conventionally-prepared LDHs and as a result can be difficult to process and incorporate into composite materials.
  • M is at least one charged metal cation
  • M’ is at least one charged metal cation different from M
  • z is 1 or 2;
  • y is 3 or 4;
  • X is at least one anion
  • n is the charge on anion(s) X
  • a is equal to z(1-x)+xy-2;
  • L is an organic solvent capable of hydrogen-bonding to water
  • step c) mixing the layered double hydroxide of formula (I) provided in step a) with the modifier provided in step b);
  • step c) wherein the mixing in step c) is conducted in the presence of less than or equal to 100% by weight of a solvent, relative to the total weight of the layered double hydroxide and the modifier.
  • a modified layered double hydroxide obtainable, obtained or directly obtained by a process defined herein.
  • a composite material comprising a modified layered double hydroxide as defined herein dispersed throughout a polymer.
  • (m-nC) or "(m-nC) group” used alone or as a prefix, refers to any group having m to n carbon atoms.
  • alkyl as used herein includes reference to a straight or branched chain alkyl moieties, typically having 1 , 2, 3, 4, 5 or 6 carbon atoms. This term includes reference to groups such as methyl, ethyl, propyl (n-propyl or isopropyl), butyl (n-butyl, sec-butyl or tert-butyl), pentyl (including neopentyl), hexyl and the like. In particular, an alkyl may have 1 , 2, 3 or 4 carbon atoms.
  • alkenyl as used herein include reference to straight or branched chain alkenyl moieties, typically having 2, 3, 4, 5 or 6 carbon atoms.
  • This term includes reference to groups such as ethenyl (vinyl), propenyl (allyl), butenyl, pentenyl and hexenyl, as well as both the cis and trans isomers thereof.
  • alkynyl as used herein include reference to straight or branched chain alkynyl moieties, typically having 2, 3, 4, 5 or 6 carbon atoms.
  • the term includes reference to alkynyl moieties containing 1 , 2 or 3 carbon-carbon triple bonds (CoC). This term includes reference to groups such as ethynyl, propynyl, butynyl, pentynyl and hexynyl.
  • alkoxy as used herein include reference to -O-alkyl, wherein alkyl is straight or branched chain and comprises 1 , 2, 3, 4, 5 or 6 carbon atoms. In one class of embodiments, alkoxy has 1 , 2, 3 or 4 carbon atoms. This term includes reference to groups such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, pentoxy, hexoxy and the like.
  • (m-cC)alkoxyl(m-nC)alkyl means a (m-nC)alkoxyl group covalently attached to a (m-nC)alkylene group, both of which are defined herein.
  • aryl as used herein includes reference to an aromatic ring system comprising 6, 7, 8, 9 or 10 ring carbon atoms.
  • Aryl is often phenyl but may be a polycyclic ring system, having two or more rings, at least one of which is aromatic. This term includes reference to groups such as phenyl, naphthyl and the like.
  • aryl(m-nC)alkyl means an aryl group covalently attached to a (m-nC)alkylene group, both of which are defined herein.
  • carrier as used herein includes reference to an alicyclic moiety having 3, 4, 5, 6, 7 or 8 carbon atoms.
  • the group may be a bridged or polycyclic ring system. More often cycloalkyl groups are monocyclic. This term includes reference to groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, bicyclo[2.2.2]octyl and the like.
  • carbocyclyl(m-nC)alkyl means a carbocyclyl group covalently attached to a (m-nC)alkylene group, both of which are defined herein.
  • heterocyclyl means a non-aromatic saturated or partially saturated monocyclic, fused, bridged, or spiro bicyclic heterocyclic ring system(s).
  • Monocyclic heterocyclic rings contain from about 3 to 12 (suitably from 3 to 7) ring atoms, with from 1 to 5 (suitably 1 , 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur in the ring.
  • Bicyclic heterocycles contain from 7 to 17 member atoms, suitably 7 to 12 member atoms, in the ring.
  • Bicyclic heterocyclic(s) rings may be fused, spiro, or bridged ring systems.
  • heterocyclic groups include cyclic ethers such as oxiranyl, oxetanyl, tetrahydrofuranyl, dioxanyl, and substituted cyclic ethers.
  • Heterocycles containing nitrogen include, for example, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, tetrahydrotriazinyl, tetrahydropyrazolyl, and the like.
  • Typical sulfur containing heterocycles include tetrahydrothienyl, dihydro-1 , 3-dithiol, tetrahydro-2/-/- thiopyran, and hexahydrothiepine.
  • heterocycles include dihydro-oxathiolyl, tetrahydro-oxazolyl, tetrahydro-oxadiazolyl, tetrahydrodioxazolyl, tetrahydro-oxathiazolyl, hexahydrotriazinyl, tetrahydro-oxazinyl, morpholinyl, thiomorpholinyl, tetrahydropyrimidinyl, dioxolinyl, octahydrobenzofuranyl, octahydrobenzimidazolyl, and octahydrobenzothiazolyl.
  • the oxidized sulfur heterocycles containing SO or SO2 groups are also included.
  • examples include the sulfoxide and sulfone forms of tetrahydrothienyl and thiomorpholinyl such as tetrahydrothiene 1 , 1 -dioxide and thiomorpholinyl 1 ,1 -dioxide.
  • heterocyclyl groups are saturated monocyclic 3 to 7 membered heterocyclyls containing 1 , 2 or 3 heteroatoms selected from nitrogen, oxygen or sulfur, for example azetidinyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidinyl, morpholinyl, tetrahydrothienyl, tetrahydrothienyl 1 , 1 -dioxide, thiomorpholinyl, thiomorpholinyl 1 , 1 -dioxide, piperidinyl, homopiperidinyl, piperazinyl or homopiperazinyl.
  • any heterocycle may be linked to another group via any suitable atom, such as via a carbon or nitrogen atom.
  • heterocyclyl(m-nC)alkyl means a heterocyclyl group covalently attached to a (m-nC)alkylene group, both of which are defined herein.
  • heteroaryl as used herein includes reference to an aromatic heterocyclic ring system having 5, 6, 7, 8, 9 or 10 ring atoms, at least one of which is selected from nitrogen, oxygen and sulphur.
  • the group may be a polycyclic ring system, having two or more rings, at least one of which is aromatic, but is more often monocyclic.
  • This term includes reference to groups such as pyrimidinyl, furanyl, benzo[b]thiophenyl, thiophenyl, pyrrolyl, imidazolyl, pyrrolidinyl, pyridinyl, benzo[b]furanyl, pyrazinyl, purinyl, indolyl, benzimidazolyl, quinolinyl, phenothiazinyl, triazinyl, phthalazinyl, 2H-chromenyl, oxazolyl, isoxazolyl, thiazolyl, isoindolyl, indazolyl, purinyl, isoquinolinyl, quinazolinyl, pteridinyl and the like.
  • heteroaryl(m-nC)alkyl means a heteroaryl group covalently attached to a (m- nC)alkylene group, both of which are defined herein.
  • halogen or“halo” as used herein includes reference to F, Cl, Br or I. In a particular, halogen may be F or Cl, of which Cl is more common.
  • fluoroalkyl is used herein to refer to an alkyl group in which one or more hydrogen atoms have been replaced by fluorine atoms.
  • fluoroalkyl groups include -CHF 2 , -CH 2 CF 3 , or perfluoroalkyl groups such as -CF 3 or -CF 2 CF 3 .
  • substituted as used herein in reference to a moiety means that one or more, especially up to 5, more especially 1 , 2 or 3, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of the described substituents.
  • optionally substituted as used herein means substituted or unsubstituted.
  • substituents are only at positions where they are chemically possible, the person skilled in the art being able to decide (either experimentally or theoretically) without inappropriate effort whether a particular substitution is possible.
  • amino or hydroxy groups with free hydrogen may be unstable if bound to carbon atoms with unsaturated (e.g. olefinic) bonds.
  • substituents described herein may themselves be substituted by any substituent, subject to the aforementioned restriction to appropriate substitutions as recognised by the skilled person.
  • the present invention provides a process for forming a modified layered double hydroxide comprising the steps of:
  • M is at least one charged metal cation
  • M’ is at least one charged metal cation different from M
  • z is 1 or 2;
  • y is 3 or 4;
  • X is at least one anion
  • n is the charge on anion(s) X
  • a is equal to z(1-x)+xy-2;
  • L is an organic solvent capable of hydrogen-bonding to water
  • step c) mixing the layered double hydroxide of formula (I) provided in step a) with the modifier provided in step b);
  • step c) wherein the mixing in step c) is conducted in the presence of less than or equal to 100% by weight of a solvent, relative to the total weight of the layered double hydroxide and the modifier.
  • the inventors have determined that the surface modification of conventionally-prepared LDHs is hindered by a number of factors. Principally, the presence of large amounts of water in the conventionally-prepared LDH significantly reduces the efficiency of the reaction between the surface modifying agent and the hydroxyl functional groups located on the surface of the LDH. In particular, rather than reacting with the available hydroxyl groups on the LDH, the surface modifying agent may react preferentially with the complexed water. Moreover, the presence of water is likely to give rise to an increased number of unwanted side- reactions, thus generating undesirable by-products which results in the generation of impure materials.
  • the inventors discovered a method of preparing LDHs with a specific surface area of at least 125 m 2 /g (WO2015/144778); the method comprising slurrying a dispersion of a water-wet LDH in an aqueous-miscible organic (AMO) solvent, followed by recovery and drying of the so-called AMO-LDH. Nevertheless, such AMO-LDHs suffer from a high moisture uptake capacity compared with conventionally-prepared LDHs and as a result can be difficult to process and incorporate into composite materials.
  • AMO-LDHs Nevertheless, such AMO-LDHs suffer from a high moisture uptake capacity compared with conventionally-prepared LDHs and as a result can be difficult to process and incorporate into composite materials.
  • AMO-LDHs AMO-LDHs
  • organosilane modifiers by a mixing process carried out in the absence or near-absence of solvent, leads to a modified AMO-LDH having both good surface area and significantly reduced moisture uptake capacity.
  • the process according to this invention also offers benefits in terms of scalability and environmental impact due to the avoidance of solvents.
  • the surface modified LDHs of the invention can be used in a variety of applications, wherein conventionally-prepared hydrophilic LDHs would be unsuitable.
  • a layered double hydroxide of formula (I) wherein when z is 2, M is Mg, Zn, Fe, Ca, Sn, Ni, Cu, Co, Mn or Cd or a mixture of two or more of these, or when z is 1 , M is Li.
  • z is 2 and M is Ca, Mg, Zn or Fe. More suitably, z is 2 and M is Ca, Mg or Zn.
  • a layered double hydroxide of formula (I) wherein when y is 3, M’ is Al, Ga, Y, In, Fe, Co, Ni, Mn, Cr, Ti, V, La or a mixture thereof, or when y is 4, M' is Sn, Ti or Zr or a mixture thereof.
  • y is 3. More suitably, y is 3 and M’ is Al.
  • M’ is Al.
  • a layered double hydroxide of formula (I) wherein x has a value according to the expression 0.18 ⁇ x ⁇ 0.9.
  • x has a value according to the expression 0.18 ⁇ x ⁇ 0.5. More suitably, x has a value according to the expression 0.18 ⁇ x ⁇ 0.4.
  • a layered double hydroxide of formula (I) which is a Zn/AI, Mg/AI, Zn,Mg/AI, Mg/AI,Sn, Mg/AI,Ti, Ni/Ti, Mg/Fe, Ca/AI, Ni/AI or Cu/AI layered double hydroxide.
  • halide e.g., chloride
  • X B, C, N, S, P: e.g.
  • anionic surfactants such as sodium dodecyl sulfate, fatty acid salts or sodium stearate
  • anionic chromophores and/or anionic UV absorbers, for example 4- hydroxy- 3- 10 methoxybenzoic acid, 2-hydroxy-4 methoxybenzophenone-5-sulfonic acid (HMBA), 4-hydroxy-3-methoxy-cinnamic acid, p-aminobenzoic acid and/or urocanic acid.
  • the anion X is an inorganic oxyanion selected from carbonate, bicarbonate, hydrogenphosphate, dihydrogenphosphate, nitrite, borate, nitrate, sulphate or phosphate or a mixture of two or more thereof. More suitably, the anion X is an inorganic oxyanion selected from carbonate, bicarbonate, nitrate or nitrite. Most suitably, the anion X is carbonate.
  • a layered double hydroxide of formula (I) wherein, M is Ca, Mg, Zn or Fe, M’ is Al, and X is carbonate, bicarbonate, nitrate or nitrite.
  • M is Ca, Mg or Zn, M’ is Al, and X is carbonate, bicarbonate, nitrate or nitrite. More suitably, M is Ca, Mg or Zn, M’ is Al, and X is carbonate.
  • a layered double hydroxide of formula (I) is provided wherein M is Mg, M’ is Al and X is carbonate.
  • a layered double hydroxide of formula (I) is provided with the formula Mg q AI-CC>3, wherein 1.8 £ q £ 5, and preferably wherein 1.8 £ q £ 3.5.
  • a layered double hydroxide of formula (I) is provided wherein the layered double hydroxide of formula (I) is a Mg3AI-CC>3 layered double hydroxide.
  • a layered double hydroxide of formula (I) is provided which is a Mg 4 AI- CO 3 layered double hydroxide.
  • a layered double hydroxide of formula (I) which is a MgsAI- CO 3 layered double hydroxide.
  • a layered double hydroxide of formula (I) which is a Mg2ZnAI-CC>3 layered double hydroxide.
  • the organic solvent, L, present in formula (I) may have any suitable hydrogen bond donor and/or acceptor groups, so that it is capable of hydrogen-bonding to water.
  • Hydrogen bond donor groups include R-OH, R-NH 2 , R 2 NH
  • AMO refers to aqueous-miscible organic solvents, such as ethanol, methanol and acetone.
  • AMO is used to refer to solvents which are capable of hydrogen-bonding to water and as such, other organic solvents with limited aqueous miscibility (such as ethyl acetate) are also envisaged within the scope of an‘AMO’, for example when used in the term‘AMO-LDH’.
  • L is selected from acetone, acetonitrile, dimethylformamide, dimethyl sulphoxide, dioxane, ethanol, methanol, n-propanol, isopropanol, tetrahydrofuran, ethyl acetate, n-butanol, sec-butanol, n-pentanol, n-hexanol, cyclohexanol, diethyl ether, diisopropyl ether, di n-butyl ether, methyl tert-butyl ether (MTBE), tert-amyl methyl ether, cyclopentyl methyl ether, cyclohexanone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl isoamyl ketone, methyl n-amyl ketone, furfural, methyl format
  • L is selected from acetone, ethanol, ethyl acetate, and a mixture of two or more thereof.
  • L is ethanol.
  • a layered double hydroxide of formula (I) wherein M is Mg, M’ is Al, X is carbonate and the L is ethanol or acetone.
  • b has a value according to the expression 0 ⁇ b£7.5.
  • b has a value according to the expression 0 ⁇ b£5.
  • b has a value according to the expression 0 ⁇ b£3.
  • b has a value according to the expression 0 ⁇ b£1 (e.g. 0.2 ⁇ b£0.95).
  • c has a value according to the expression 0 ⁇ c ⁇ 7.5.
  • c has a value according to the expression 0 ⁇ c ⁇ 5.
  • c has a value according to the expression 0 ⁇ c£1.
  • c has a value according to the expression 0 ⁇ c£0.5.
  • the layered double hydroxide of formula (I) provided in step a) has a BET (as determined by N 2 adsorption) specific surface area of at least 40 m 2 /g.
  • the AMO-LDH has a BET specific surface area of at least 70 m 2 /g. More suitably, the AMO-LDH has a BET specific surface area of greater than 125 m 2 /g. Even more suitably, the AMO-LDH has a BET specific surface area of at least 180 m 2 /g. Yet more suitably, the AMO-LDH has a specific BET surface area of at least 240 m 2 /g. Yet more suitably, the AMO-LDH has a BET specific surface area of at least 275 m 2 /g. Most suitably, the AMO-LDH has a BET specific surface area of at least 300 m 2 /g.
  • the layered double hydroxide of formula (I) provided in step a) has a BET (N 2 ) pore volume of at least 0.3 cm 3 /g.
  • the AMO-LDH has a BET pore volume of at least 0.4 cm 3 /g. More suitably, the AMO-LDH has a BET pore volume of at least 0.5 cm 3 /g. Yet more suitably, the AMO-LDH has a BET pore volume of at least 0.75 cm 3 /g. Most suitably, the AMO-LDH has a BET pore volume of at least 0.9 cm 3 /g.
  • the layered double hydroxide of formula (I) provided in step a) has a loose bulk density of less than 0.5 g/mL.
  • the AMO- LDH has a loose bulk density of less than 0.35 g/mL. More suitably, the AMO-LDH has a loose bulk density of less than 0.25 g/mL.
  • the AMO-LDH has a tap density of less than 0.5 g/mL. Tap densities are calculated by standard testing method (ASTM D7481-09) using a graduated cylinder. The powder was filled into a cylinder and a precise weight of sample (m) was measured.
  • the AMO-LDH has a tap density of less than 0.4 g/mL. More suitably, the AMO-LDH has a tap density of less than 0.35 g/mL. Yet more suitably, the AMO-LDH has a tap density of less than 0.27 g/mL.
  • the layered double hydroxide of formula (I) provided in step a) is prepared by a process comprising the steps of
  • step II contacting the water-washed, wet precipitate of step I) with a solvent L, as defined for formula (I).
  • the term“water-washed wet precipitate of formula (II)” used in step (I) will be understood to define a material having a composition defined by formula (II) which has been precipitated out of a solution of reactants and has subsequently been washed with water and then dried and/or filtered to the point that it is still damp.
  • the water-washed wet precipitate is not allowed to dry prior to it being contacted with the solvent according to step (II), since to do so results in the formation of highly agglomerated, stone-like particles of LDH, whose low surface area renders them inferior for surface modification using the types of modifiers described herein.
  • the wet precipitate may have a moisture content of 15 to 60 % relative to the total weight of the wet precipitate.
  • step (I) may be pre-formed.
  • step (I) may be prepared as part of step (I), in which case step (I) comprises the following steps:
  • step (ii) ageing the layered double hydroxide precipitate obtained in step (i) in the reaction mixture of step (i);
  • step (iii) collecting the aged precipitate resulting from step (ii), then washing it with water and optionally a‘solvent’ as defined hereinbefore for formula (I);
  • the ammonia-releasing agent used in step (i) may increase the aspect ratio of the resulting LDH platelets.
  • Suitable ammonia-releasing agents include hexamethylene tetraamine (HMT) and urea.
  • HMT hexamethylene tetraamine
  • the ammonia-releasing agent is urea.
  • the amount of ammonia releasing agent used in step i) may be such that the molar ratio of ammonia-releasing agent to metal cations (M + M’) is 0.5:1 to 10:1 (e.g. 1 :1 to 6:1 or 4:1 to 6:1).
  • the precipitate is formed by contacting aqueous solutions containing cations of the metals M and M’, the anion X 11 , and optionally an ammonia-releasing agent, in the presence of a base being a source of OH (e.g. NaOH, NH 4 OH, or a precursor for OH formation).
  • a base being a source of OH (e.g. NaOH, NH 4 OH, or a precursor for OH formation).
  • the base is NaOH.
  • the quantity of base used is sufficient to control the pH of the solution above 6.5.
  • the quantity of base used is sufficient to control the pH of the solution at 6.5-13. More suitably, the quantity of base used is sufficient to control the pH of the solution at 7.5-13. Yet more suitably, the quantity of base used is sufficient to control the pH of the solution at 9-11.
  • step (ii) the layered double hydroxide precipitate obtained in step i) is aged in the reaction mixture of step (i) for a period of 5 minutes to 72 hours at a temperature of 15-180°C (e.g. 18-40°C).
  • step (ii) the layered double hydroxide precipitate obtained in step (i) is aged in the reaction mixture of step (i) for a period of 1 to 72 hours. More suitably, in step (ii), the layered double hydroxide precipitate obtained in step (i) is aged in the reaction mixture of step (i) for a period of 5 to 48 hours. Most suitably, in step (ii), the layered double hydroxide precipitate obtained in step (i) is aged in the reaction mixture of step (i) for a period of 12 to 36 hours.
  • step (ii) the layered double hydroxide precipitate obtained in step (i) is aged in the reaction mixture of step (i) at a temperature of 80-150°C. More suitably, in step (ii), the layered double hydroxide precipitate obtained in step (i) is aged in the reaction mixture of step (i) at a temperature of 90-140°C.
  • Step (ii) may be performed in an autoclave.
  • step (iii) the aged precipitate resulting from step (ii) is collected, then washed with water and optionally a solvent as defined hereinbefore for formula (I) until the filtrate has a pH in the range of 6.5-7.5.
  • step (iii) comprises washing the aged precipitate resulting from step (ii) with a mixture of water and solvent at a temperature of 15-100°C (e.g. 18-40°C).
  • the solvent is selected from ethyl acetate, ethanol and acetone.
  • the quantity of solvent in the washing mixture is 5-95% (v/v), preferably 30-70% (v/v).
  • step II) the water-washed wet precipitate is contacted with a solvent L by dispersing said precipitate in the solvent L to produce a slurry.
  • the preparation process comprises a further step III) of maintaining the slurry resulting from step II).
  • the slurry produced in step II) and then maintained in step III) contains 1-100 g of water-washed wet precipitate per 1 L of solvent L.
  • the slurry produced in step II) and maintained in step III) contains 1 -75 g of wate r- washed wet precipitate per 1 L of solvent L.
  • the slurry produced in step II) and maintained in step III) contains 1 -50 g of water- washed wet precipitate per 1 L of solvent L.
  • the slurry produced in step II) and maintained in step III) contains 1 -30 g of water- washed wet precipitate per 1 L of solvent L.
  • step III the slurry produced in step II) is maintained for a period of time.
  • the slurry is stirred during step III).
  • the slurry in step III), is maintained for a period of 0.5 to 120 hours (e.g. 0.5 to 96 hours).
  • the slurry is maintained for a period of 0.5 to 72 hours. More suitably, in step III), the slurry is maintained for a period of 0.5 to 48 hours. Even more suitably, in step III), the slurry is maintained for a period of 0.5 to 24 hours. Yet more suitably, in step III), the slurry is maintained for a period of 0.5 to 24 hours.
  • the slurry is maintained for a period of 1 to 8 hours. Alternatively, in step III), the slurry is maintained for a period of 16 to 20 hours).
  • the LDH resulting from step III) may be isolated by any suitable means, including filtering, filter pressing, spray drying, cycloning and centrifuging.
  • the isolated AMO-LDH may then be dried to give a free-flowing powder.
  • the drying may be performed under ambient conditions, in a vacuum, or by heating to a temperature below 60°C (e.g. 20 to 60°C).
  • the AMO-LDH resulting from step III) is isolated and then heated to a temperature of 10-40°C in a vacuum until a constant mass is reached.
  • the LDH may be dried by heating at 50°C -200°C, such as 100°C -200°C, for example 150°C -200°C.
  • the layered double hydroxide provided in step a) (AMO-LDH) comprises less than 50% by weight of solvent L, relative to the weight of the layered double hydroxide. In an embodiment, the layered double hydroxide provided in step a) (AMO-LDH) comprises less than 25% by weight of solvent L, relative to the weight of the layered double hydroxide. In an embodiment, the layered double hydroxide provided in step a) (AMO-LDH) comprises less than 10% by weight of solvent L, relative to the weight of the layered double hydroxide. In an embodiment, the layered double hydroxide provided in step a) (AMO-LDH) is provided as a dry solid.
  • the organosilane modifier used in step b) of the process may have a structure according to formula (II) shown below: ijj
  • each Ri is independently hydrogen or an organofunctional group
  • each Y is independently absent, or is a straight or branched organic linker
  • each R 2 is independently hydrogen, halo, hydroxy, carboxy, (1-4C)alkyl or a group -OR 3 , wherein R 3 is selected from (1-6C)alkyl, aryl(1-6C)alkyl,
  • heteroaryl(1-6C)alkyl cycloalkyl(1-6C)alkyl, heterocyclyl(1-6C)alkyl and (1- 6C) al koxy( 1 -4C) al kyl .
  • At least one R 2 is not hydrogen or (1-4C)alkyl.
  • q is 1.
  • the organofunctional group is selected from acrylate, methacrylate, mercapto, aldehyde, amino, azido, carboxylate, phosphonate, sulfonate, epoxy, glycidyloxy, ester, halogen, hydroxyl, isocyanate, phosphine, phosphonate, alkenyl (e.g. vinyl), aryl (e.g. phenyl), cycloalkyl, heteroaryl and heterocyclyl (e.g. morpholinyl).
  • the organofunctional group is selected from halo, epoxy, glycidyloxy, mercapto, alkenyl and aryl. Yet more suitably, the organofunctional group is selected from epoxy, glycidyloxy, mercapto, alkenyl and aryl.
  • Y is a hydrocarbylene linker group containing 1 or more carbon atoms, wherein the linker optionally contains one or more atoms selected from O, N, S and Si within the linker, and wherein the linker is optionally substituted with one or more groups selected from hydroxyl, halo, haloalkyl, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)alkoxy, aryl, aryl(1-4C)alkyl, heteroaryl, heteroaryl (1-4C) alkyl, cycloalkyl, heterocyclyl, -Si(R 2 )3 and NR x R y , wherein R 2 is as defined hereinbefore, and R x and R y are each independently hydrogen or (1-4C)alkyl.
  • Y is a hydrocarbylene linker group containing 1-10 carbon atoms, wherein the linker optionally contains one or more atoms selected from O, N and S within the linker, and wherein the linker is optionally substituted with one or more groups selected from hydroxyl, halo, haloalkyl, (1-6C)alkyl, (2-6C)alkenyl, (1-6C)alkoxy, aryl, aryl(1-4C)alkyl, heteroaryl, heteroaryl(1- 4C)alkyl and NR x R y , wherein R x and R y are each independently hydrogen or (1-4C)alkyl.
  • Y is absent.
  • the organosilane modifier is selected from the group consisting of 3- aminopropyltriethoxysilane, (3-glycidyloxypropyl)triethoxysilane, (3-glycidyloxypropyl)- trimethoxysilane (3-mercaptopropyl)-triethoxysilane, triethoxyvinylsilane, triethoxyphenylsilane, trimethoxy(octadecyl)silane, vinyl-tris(2-methoxy-ethoxy)silane, g-methacryloxy- propyltrimethoxysilane, g-aminopropyl-trimethoxysilane, b(3,4-epxycryclohexyl)- ethyltrimethoxysilane, g-mercaptopropyltrimethoxysilane, (3-aminopropyl)triethoxysilane,
  • the organosilane modifier is selected from the group consisting of 3- aminopropyltriethoxysilane, (3-glycidyloxypropyl)triethoxysilane, (3-glycidyloxypropyl)- trimethoxysilane, (3-mercaptopropyl)triethoxy-silane, triethoxyvinylsilane, trimethoxy- methylsilane, triethoxyoctylsilane, trichloro(octadecyl)-silane and triethoxyphenylsilane.
  • the organosilane modifier provided in step b) is provided as a neat organosilane.
  • the neat organosilane may be a liquid or a low melting point solid.
  • step b) includes the steps of melting the organosilane to provide a liquid organosilane modifier.
  • Step c) comprises mixing the layered double hydroxide of formula (I) provided in step a) with the modifier provided in step b), wherein the mixing in step c) is conducted in the presence of less than or equal to 100% by weight of a solvent, relative to the total weight of the layered double hydroxide and the modifier.
  • a solvent for the avoidance of doubt, and purely as an example, if 1 g of AMO-LDH is mixed with 0.5 g of modifier, then 100% by weight of a solvent would be 1.5 g of solvent.
  • Step c) may be conducted in air or under an inert atmosphere (e.g. under a N 2 blanket). In an embodiment, step c) is conducted under an inert atmosphere.
  • the mixing in step c) is conducted in the presence of less than 100% by weight of a solvent relative to the total weight of the layered double hydroxide and the modifier.
  • the mixing in step c) is conducted in the presence of less than or equal to 50% by weight of a solvent relative to the total weight of the layered double hydroxide and the modifier.
  • the mixing in step c) is conducted in the presence of less than 10% by weight of a solvent relative to the total weight of the layered double hydroxide and the modifier.
  • the solvent which may be present in step c), may be the same solvent as the solvent Y present in the AMO-LDH provided in step a), or it may be a different solvent.
  • the mixing in step c) is conducted with substantially no solvent, or no solvent present.
  • the mixing in step c) is conducted using more than 5% by weight modifier, relative to the weight of layered double hydroxide. [0086] In an embodiment, the mixing in step c) is conducted using more than 10% by weight modifier, relative to the weight of layered double hydroxide.
  • the mixing in step c) is conducted using more than 20% by weight modifier, relative to the weight of layered double hydroxide.
  • the mixing in step c) can be carried out by a variety of means.
  • the mixing may be achieved by manual (e.g. grinding in a pestle and mortar) or automated means (such as a vortex mixer or fluidised bed mixer).
  • the mixing in step c) is carried out by means of vapour treatment, a dry mixer, a vortex mixer, or by milling the layered double hydroxide in the presence of the modifier.
  • the mixing in step c) is carried out by means of a vortex mixer.
  • the mixing in step c) may be carried out in an open vessel (such as a pestle and mortar, or an open batch mixer), or in a closed vessel (such as a sealed tube in a vortex mixer).
  • the mixing in step c) is carried out in an open vessel.
  • the mixing in step c) is carried out in a closed vessel.
  • the modified AMO-LDH product resulting from step c) may be subjected to a further drying step.
  • the process for forming a modified layered double hydroxide comprises a further step of:
  • step d) thermally treating the modified layered double hydroxide resulting from step c) at a temperature of 15-200 °C.
  • step d) the thermal treatment is carried out at 100-200 °C.
  • step d) the thermal treatment is carried out under vacuum at a temperature of 15-200 °C.
  • step d) the thermal treatment is carried out under vacuum at a temperature of 15-60 °C.
  • step d) the thermal treatment is carried out for 2-24 hours.
  • step d) the thermal treatment is carried out for 10-16 hours.
  • the present invention provides a modified layered double hydroxide obtainable, obtained or directly obtained by a process defined herein.
  • a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area (as determined by N 2 adsorption) of at least 40 m 2 /g.
  • the modified layered double hydroxide has a BET surface area of at least 60 m 2 /g. More suitably, the modified layered double hydroxide has a BET surface area of at least 80 m 2 /g. Even more suitably, the modified layered double hydroxide has a BET surface area of at least 100 m 2 /g.
  • a modified layered double hydroxide obtained by a process according to the present invention has a BET (N 2 ) pore volume of at least 0.3 cm 3 /g.
  • the modified layered double hydroxide has a BET pore volume of at least 0.4 cm 3 /g. More suitably, the modified layered double hydroxide has a BET pore volume of at least 0.5 cm 3 /g. Yet more suitably, the modified layered double hydroxide has a BET pore volume of at least 0.75 cm 3 /g. Most suitably, the modified layered double hydroxide has a BET pore volume of at least 0.9 cm 3 /g.
  • a modified layered double hydroxide obtained by a process according to the present invention has a loose bulk density of less than 0.5 g/ml_.
  • the modified layered double hydroxide has a loose bulk density of less than 0.35 g/ml_. More suitably, the modified layered double hydroxide has a loose bulk density of less than 0.25 g/ml_.
  • the modified layered double hydroxide has a tap density of less than 0.5 g/ml_. Tap densities are calculated by standard testing method (ASTM D7481-09) using a graduated cylinder. The powder was filled into a cylinder and a precise weight of sample (m) was measured.
  • the modified layered double hydroxide has a tap density of less than 0.4 g/mL. More suitably, the modified layered double hydroxide has a tap density of less than 0.35 g/mL.
  • a modified layered double hydroxide obtained by a process according to the present invention has a moisture uptake level of less than 20 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • the modified layered double hydroxide has a moisture uptake level of less than 15 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • the modified layered double hydroxide has a moisture uptake level of less than 10 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • a modified layered double hydroxide obtained by a process according to the present invention has a contact angle greater than or equal to 60°. Reference made herein to contact angles will be understood by one of ordinary skill in the art to refer to the contact angle of water. Suitably, the modified layered double hydroxide has a contact angle greater than or equal to 80°.
  • a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 40 m 2 /g and a moisture uptake level of less than 20 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours. In an embodiment, a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 60 m 2 /g and a moisture uptake level of less than 20 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 80 m 2 /g and a moisture uptake level of less than 20 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 40 m 2 /g and a contact angle of greater than or equal to 60°. In an embodiment, a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 60 m 2 /g and a contact angle of greater than or equal to 60°. In an embodiment, a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 80 m 2 /g and a contact angle of greater than or equal to 60°.
  • a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 100 m 2 /g and a contact angle of greater than or equal to 60°. In an embodiment, a modified layered double hydroxide obtained by a process according to the present invention has a BET surface area of at least 100 m 2 /g and a contact angle of greater than or equal to 80°.
  • the present invention also provides a composite material comprising a modified layered double hydroxide as defined herein dispersed throughout a polymer.
  • LDHs have a variety of interesting properties that make them attractive materials for use as fillers in polymeric composites. However, given that conventionally-prepared LDHs are only dispersible in aqueous solvents, the preparation of polymer-LDH composite materials using polymers that are soluble in organic solvents has been restricted.
  • the modified LDHs of the invention have increased dispersibility in a range of organic solvents. This allows the preparation of a homogenous mixture of modified LDH, polymer and solvent, which can be processed into a LDH- polymer composite material, wherein the modified LDH is uniformly dispersed throughout the polymeric matrix.
  • the polymer is selected from polypropylene, polyethylene, polyvinyl chloride, polyvinylidene chloride, polylactic acid, polyvinyl acetate, ethylene vinyl alcohol, ethylene vinyl acetate, acrylonitrile butadiene styrene, polymethyl methacrylate, polycarbonate, polyamide, an elastomer, or mixtures of two or more of the aforementioned.
  • the polymer is a biopolymer.
  • a process for forming a modified layered double hydroxide comprising the steps of: a) providing a layered double hydroxide of formula (I):
  • M is at least one charged metal cation
  • M’ is at least one charged metal cation different from M
  • z is 1 or 2;
  • y is 3 or 4;
  • X is at least one anion
  • n is the charge on anion(s) X
  • a is equal to z(1-x)+xy-2;
  • L is an organic solvent capable of hydrogen-bonding to water
  • step c) mixing the layered double hydroxide of formula (I) provided in step a) with the modifier provided in step b);
  • step c) wherein the mixing in step c) is conducted in the presence of less than or equal to 100% by weight of a solvent, relative to the total weight of the layered double hydroxide and the modifier.
  • M is Mg, Zn, Fe, Ca, Sn, Ni, Cu, Co, Mn or Cd or a mixture of two or more of these, or when z is 1 , M is Li.
  • M’ is Al, Ga, Y, In, Fe, Co, Ni, Mn, Cr, Ti, V, La or a mixture thereof, or when y is 4, M 1 is Sn, Ti or Zr or a mixture thereof.
  • M’ is Al.
  • the layered double hydroxide is a Zn/AI, Mg/AI, Mg,Zn/AI, Mg/AI,Sn, Mg/AI,Ti, Ca/AI, Ni/Ti or Cu/AI layered double hydroxide.
  • X is an anion selected from at least one of halide, inorganic oxyanion, or an organic anion (e.g. an anionic surfactant, an anionic chromophore or an anionic UV absorber).
  • step II contacting the water-washed, wet precipitate of step I with a solvent L as defined for formula (I).
  • a solvent L as defined for formula (I).
  • step b) the modifier is provided as a neat organosilane.
  • q is 1 , 2 or 3;
  • each Ri is independently hydrogen or an organofunctional group
  • each Y is independently absent, or is a straight or branched organic linker; and each R 2 is independently hydrogen, halo, hydroxy, carboxy, (1-4C)alkyl or a group -OR 3 , wherein R 3 is selected from (1-6C)alkyl, aryl(1-6C)alkyl, heteroaryl(1- 6C)alkyl, cycloalkyl(1-6C)alkyl, heterocyclyl(1-6C)alkyl and (1-6C)alkoxy(1- 4C) alkyl.
  • organofunctional group is selected from acrylate, methacrylate, mercapto, aldehyde, amino, azido, carboxylate, phosphonate, sulfonate, epoxy, glycidyloxy, ester, halogen, hydroxyl, isocyanate, phosphine, phosphonate, alkenyl, aryl, cycloalkyl, heteroaryl and heterocyclyl.
  • organosilane modifier is selected from the group consisting of 3-aminopropyltriethoxysilane, (3- glycidyloxypropyl)triethoxysilane, (3-mercaptopropyl)triethoxysilane, triethoxyvinyl- silane, triethoxyphenylsilane, trimethoxy(octadecyl)silane, vinyl-tris(2-methoxy- ethoxy)silane, g-methacryloxypropyltrimethoxysilane, g-aminopropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl)ethyltrimethoxysilane, g-glycidoxypropyltrimethoxysilane, g- mercaptopropyltrimethoxysilane, (3-aminopropyl)triethoxysilane,
  • step c) The process according to any one of statements 1 to 17, wherein the mixing in step c) is conducted with no solvent present.
  • step c) the mixing is carried out by means of vapour treatment, a dry mixer, a vortex mixer, or by milling the layered double hydroxide in the presence of the modifier.
  • step c) is conducted under an inert atmosphere.
  • step d) the thermal treatment is carried out at 100-200 °C.
  • step d) the thermal treatment is carried out under vacuum at a temperature of 15-60 °C.
  • step d) the thermal treatment is carried out for 2-24 hours.
  • a modified layered double hydroxide obtainable by a process according to any one of statements 1 to 26.
  • the modified layered double hydroxide of statement 32 wherein the modified layered double hydroxide has a BET (N 2 ) pore volume of at least 0.75 cm 3 /g.
  • the modified layered double hydroxide of statement 32 wherein the modified layered double hydroxide has a BET (N 2 ) pore volume of at least 0.9 cm 3 /g.
  • the modified layered double hydroxide of statement 37 wherein the modified layered double hydroxide has a loose bulk density of less than 0.35 g/ml_.
  • the modified layered double hydroxide of statement 37 wherein the modified layered double hydroxide has a loose bulk density of less than 0.25 g/ml_.
  • the modified layered double hydroxide of statement 40 wherein the modified layered double hydroxide has a tap density of less than 0.4 g/ml_.
  • the modified layered double hydroxide of statement 40 wherein the modified layered double hydroxide has a tap density of less than 0.35 g/ml_.
  • the modified layered double hydroxide of statement 43 wherein the modified layered double hydroxide has a moisture uptake level of less than 15 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • the modified layered double hydroxide of statement 43 wherein the modified layered double hydroxide has a moisture uptake level of less than 10 wt% of dry LDH, when measured at RH99 at 20 °C for 90 hours.
  • a composite material comprising a modified layered double hydroxide according to any one of statements 27 to 47, dispersed throughout a polymer.
  • Fig. 1 shows the XRD patterns of Examples 2.1 and 2.2 overlaid with AMO-LDH (AMO-LDH- 2); and (b) shows the TGA weight loss curves for Examples 2.1 and 2.2 compared to AMO-LDH.
  • Fig. 2 (a) shows the BET surface area of AMO-LDH (AMO-LDH-2) and Example 2.1 ; and (b) shows the Oil absorption number (OAN) of AMO-LDH (AMO-LDH-2) and Example 2.1.
  • Fig. 3 shows the percentage water uptake of Examples 2.1 and 2.2 and AMO-LDH (AMO-LDH- 2) at various time points during exposure to RH99 at 20°C.
  • Fig. 4 (a) shows solid state 29 Si NMR spectra for Examples 2.1 and 2.2; and (b) shows solid state 27 Al NMR spectra for AMO-LDH (AMO-LDH-2) and Example 2.1.
  • Fig. 5 shows XRD patterns of unmodified AMO-LDH (AMO-LDH-2) and Example 3.1 TEVS- modified AMO-LDHs prepared with 0.1 (P0.1), 0.6 (P0.6), 1.2 (P1.2) and 1.8 (P1.8) ml TEVS per gram AMO-LDH.
  • Fig. 6 shows FT-IR spectra of unmodified AMO-LDH (AMO-LDH-2) and Example 3.1 TEVS- modified AMO-LDHs prepared with 0.1 (P0.1), 0.6 (P0.6), 1.2 (P1.2) and 1.8 (P1.8) ml TEVS per gram AMO-LDH.
  • Fig. 7 shows TGA curves of unmodified AMO-LDH (AMO-LDH-2) and Example 3.1 TEVS- modified AMO-LDHs prepared with 0.1 (P0.1), 0.6 (P0.6), 1.2 (P1.2) and 1.8 (P1.8) ml TEVS per gram AMO-LDH.
  • Fig. 8 shows the percentage water uptake at various time points on exposure to RH99 at 20°C of unmodified 150°C-dried AMO-LDH (AMO-LDH-2) and Example 3.1 TEVS-modified AMO- LDHs prepared with 0.1 (P0.1), 0.6 (P0.6), 1.2 (P1.2) and 1.8 (P1.8) ml TEVS per gram AMO- LDH.
  • Fig. 9 shows TGA curves of unmodified AMO-LDH (AMO-LDH-2) and Example 3.2 TEVS- modified AMO-LDHs prepared with 0.1 (CO.1), 0.6 (C0.6), 1.2 (C1.2) and 1.8 (C1.8) ml TEVS per gram AMO-LDH; and (b) shows the percentage water uptake at various time points on exposure to RH99 at 20°C of unmodified 150°C-dried AMO-LDH (AMO-LDH-2) and Example 3.2 TEVS- modified AMO-LDHs prepared with 0.1 (CO.1), 0.6 (C0.6), 1.2 (C1.2) and 1.8 (C1.8) ml TEVS per gram AMO-LDH.
  • Fig. 10 shows Oil absorption number (OAN) and (b) shows a plot of OAN versus BET surface area of unmodified AMO-LDH (AMO-LDH-2) and Example 3 TEVS-modified AMO-LDHs prepared with 0.1 , 0.6, 1.2 and 1.8 ml TEVS per gram AMO-LDH for both wet-cake (C) and dry- powder (P) methods.
  • OAN Oil absorption number
  • AMO-LDH-2 shows a plot of OAN versus BET surface area of unmodified AMO-LDH (AMO-LDH-2) and Example 3 TEVS-modified AMO-LDHs prepared with 0.1 , 0.6, 1.2 and 1.8 ml TEVS per gram AMO-LDH for both wet-cake (C) and dry- powder (P) methods.
  • Fig. 1 1 (a) shows the XRD patterns of Examples 4A-4D overlaid with AMO-LDH (AMO-LDH-2); and (b) shows the FT-IR spectra of Examples 4A-4D.
  • Fig. 12 (a) shows the measured contact angles of unmodified LDH (AMO-LDH-2) and Examples 4A-4D. The error bars represent the deviation over 3 repeat measurements per sample; and (b) shows a plot of average contact angle and Si/AI molar ratio for Examples 4A-4D.
  • Fig. 13 shows the BET surface area of unmodified LDH (AMO-LDH-2) and Examples 4A, 4B and 4D.
  • Fig. 14 (a) shows the XRD patterns of Examples 5A-5C overlaid with AMO-LDH (AMO-LDH-2); and (b) shows the FT-IR spectra of Examples 5A-5C.
  • Fig. 15 shows the measured contact angles of unmodified LDH (AMO-LDH-2) and Examples 5A- 5C.
  • the error bars represent the deviation over 3 repeat measurements per sample
  • Fig. 16 shows the BET surface area of unmodified LDH (AMO-LDH-2) and Examples 5A-5C.
  • Fig. 17 (a) shows the XRD patterns of Examples 6A and 6B overlaid with AMO-LDH (AMO-LDH-
  • Fig. 18 (a) shows the XRD patterns of Examples 7A and 7B overlaid with AMO-LDH (AMO-LDH-
  • Fig. 19 shows the XRD patterns of Examples 8A and 8B overlaid with AMO-LDH (AMO-LDH- 2); (b) shows the Si/AI molar ratio for Examples 8A and 8B; and (c) shows the BET surface areas of unmodified LDH (AMO-LDH-2) and Examples 8A and 8B.
  • Fig. 20 shows in situ FT-IR spectra recorded after modification of AMO-LDH-2 with TEVS according to Example 9.
  • Fig. 21 shows in situ FT-IR spectra recorded after modification of AMO-LDH-2 with TEOS according to Example 9.
  • Fig. 22 shows in situ FT-IR spectra recorded after modification of AMO-LDH-2 with TMGPS according to Example 9.
  • Fig. 23 (a) shows the XRD patterns of Example 10 overlaid with AMO-LDH (AMO-LDH-2); and (b) shows the FT-IR spectra of Example 10.
  • Fig. 24 shows the measured contact angles of unmodified LDH (AMO-LDH-2) and Example 10. The error bars represent the deviation over 3 repeat measurements per sample.
  • Fig. 25 shows a plot of measured contact angles and Si/AI molar ratios for comparative examples 11.1 to 11.6.
  • AMO-LDH samples were modified by grinding with an organosilane modifier, the grinding was conducted manually in a pestle and mortar.
  • AMO-LDH samples were modified by mixing with an organosilane modifier in a Vortex Mixer, the sample and modifier were placed in a reaction tube, the tube was sealed and mixing was carried out using an Advanced Vortex Mixer (FisherbrandTM ZX3 Vortex Mixer) at a speed of approximately 2800 rpm.
  • an Advanced Vortex Mixer FisherbrandTM ZX3 Vortex Mixer
  • the resulting LDH slurry was dispersed in 200 mL acetone for 17 hours.
  • the LDH slurry was then filtered, washed with 100 mL acetone and dispersed in 100 mL acetone for one hour. This procedure was repeated three times.
  • the resulting LDH was dried overnight in a vacuum oven.
  • the cake was then washed with ethanol (1000 mL).
  • the wet solid was re-dispersed in ethanol (600 mL) and slurried for 1 hour.
  • the slurry was filtered, rinsed with ethanol (400 ml_), and dried in a vacuum oven for 24 hours.
  • Figure 3 demonstrates that the organosilane modifications significantly reduce the moisture uptake compared to unmodified AMO-LDH.
  • Example 2.1 took up more water than Example 2.2, as it had a lower water content to start with (2.6 wt% c.f. 12.7 wt%).
  • Figure 4 shows the solid-state NMR spectra for the 29 Si (Fig. 4a) and 27 Al (Fig. 4b) nuclei.
  • Figure 4a indicates that silane has been grafted onto the AMO-LDH via T3, T2 and T 1 silicone bonding.
  • Figure 4b shows that after silane modification, some octahedral Al has migrated out to form tetrahedral Al, probably in the form of Si-O-AI.
  • Example 3 Synthesis of modified AMO-LDHs - effect of orqanosilane loading
  • AMO-LDH prepared according to AMO-LDH-2 protocol
  • TEVS triethoxyvinylsilane
  • TGA curves in Figure 7 demonstrate the modified samples have reduced moisture content ( ⁇ 2 wt% at 200 °C) compared to unmodified AMO-LDH which has also been dried at 150 °C for 6 h under N 2 (4 wt% at 200 °C).
  • Figure 8 demonstrates that the TEVS modifications significantly reduced the moisture uptake propensity compared to unmodified AMO-LDH, even when a 0.1 ml/g of LDH loading of TEVS was used. Once the loading of TEVS was 0.6 ml/g of LDH or higher, then the moisture uptake did not exceed 15-20 wt% even after 90 hours at RH99.
  • Figure 9(b) demonstrates that the TEVS modifications significantly reduced the moisture uptake propensity compared to unmodified AMO-LDH, even when a 0.1 ml/g of LDH loading of TEVS was used. Once the loading of TEVS was 0.6 ml/g of LDH or higher, then the moisture uptake did not exceed 15-20 wt% even after 90 hours at RH99.
  • Figure 10(a) shows that modified samples have lower OAN values compared to unmodified AMO-LDH.
  • Figure 10(b) illustrates how OAN and BET surface area decrease proportionally as loading of TEVS increases for both dry powder and wet slurry methods.
  • 1.0 g of dried powder AMO-LDH (prepared according to AMO-LDH-2 protocol) was mixed with 0.35 g of triethoxyvinylsilane (TEVS) (35% w/w; 1.8 mmol/g LDH) and ethanol (none (0% w/w) - 4A; 0.85 ml (50% w/w) - 4B; 1.71 ml (100% w/w) - 4C; or 3.41 ml (200% w/w) - 4D)* using a Vortex Mixer for 15 minutes at room temperature. The solid was then dried at 150 ° C for 6 h under N 2 before being isolated.
  • TEVS triethoxyvinylsilane
  • the FT-IR spectra in Figure 1 1 b show for Examples 4A-4D peaks at around 750 and 920-1090 cm -1 which correspond to the vibrations of -Si-C- and -Si-O-M(Si)- from TEVS, and peaks at 1348 and 1531 cm -1 are due to vibration of C0 3 2 from LDH. It is worth noting that the vibration of water from LDH become very weak after the organosilane modifications, indicating reduced water content in the silane-modified samples. Examples 4C and 4D, prepared in the presence of more ethanol, show weaker vibrations from silane compared with 4A and 4B.
  • Figure 12a shows the contact angles of Examples 4A-4D alongside unmodified AMO- LDH (AMO-LDH-2).
  • Organosilane modification of the AMO-LDH with TEVS in a Vortex Mixer results in the LDHs demonstrating larger contact angles.
  • Examples 4A (no ethanol) and 4B (50% w/w ethanol) had the highest contact angles (85-90°) and as the amount of ethanol increased further the contact angle decreased to -75° for Example 4C (100% w/w ethanol) and -40° for Example 4D (200% w/w ethanol).
  • Figure 12b plots the contact angles for Examples 4A-4D with the respective Si/AI molar ratios.
  • Si content and Al content of samples was determined by inductively coupled plasma mass spectrometry (ICP-MS).
  • Samples for ICP-MS (Perkin Elmer Elan 6100DRC) analysis were prepared by digestion in high purity HNO 3 solution (2 h reflux), and dilution with 18.2 megohms Dl water, calibrated using external calibration analysis (a series of standards of known Al concentrations were prepared and measured externally to the samples to produce a linear calibration).
  • Figure 12b indicates that increased Si/AI molar ratio, which is indicative of greater incorporation of organosilane modifier into the AMO-LDH, correlates well with higher contact angle, which is indicative of increased hydrophobicity of the organosilane- modified AMO-LDH.
  • 1.0 g of dried powder AMO-LDH (prepared according to AMO-LDH-2 protocol) was ground with 0.35 g of triethoxyvinylsilane (TEVS) (35% w/w; 1.8 mmol/g LDH) and ethanol (none (0% w/w) - 5A; 0.85 ml (50% w/w) - 5B; or 1.71 ml (100% w/w) - 5C)* in a pestle and mortar for 15 minutes at room temperature. The solid was then dried at 150 ° C for 6 h under N 2 before being isolated.
  • TEVS triethoxyvinylsilane
  • the FT-IR spectra in Figure 14b show for Examples 5A-5C peaks at around 750 and 920-1090 cm -1 which correspond to the vibrations of -Si-C- and -Si-O-M(Si)- from TEVS, and peaks at 1348 and 1531 cm -1 are due to vibration of C0 3 2 from LDH.
  • Figure 15 shows the contact angles of Examples 5A-5C alongside unmodified AMO- LDH (AMO-LDH-2).
  • AMO-LDH-2 unmodified AMO- LDH
  • Organosilane modification of the AMO-LDH with TEVS via a grinding process results in the LDHs demonstrating larger contact angles.
  • AMO-LDH prepared according to AMO-LDH-1 protocol
  • TEVS triethoxyvinylsilane
  • ethanol none (0% w/w) - 6A; or 3.41 mL (200% w/w) - 6B)* using a Vortex Mixer for 15 minutes at room temperature.
  • the solid was then dried at 150 ° C for 6 h under N 2 before being isolated.
  • Figure 17b shows the Si/AI molar ratios of Examples 6A and 6B.
  • 6A non-solvent system
  • 6B contains a much higher amount of the organosilane modifier at the same modifier loading, compared with 6B, which had 200% w/w ethanol present during the mixing process.
  • AMO-LDH prepared according to AMO-LDH-2 protocol
  • TEAPS 3-aminopropyltriethoxysilane
  • ethanol none (0% w/w) - 7A; or 3.41 mL (200% w/w) - 7B)* using a Vortex Mixer for 15 minutes at room temperature.
  • the solid was then dried at 150 ° C for 6 h under N 2 before being isolated.
  • Figure 18b shows the Si/AI molar ratios of Examples 7 A and 7B.
  • 7 A non-solvent system
  • 7B contains a higher amount of the organosilane modifier at the same modifier loading, compared with 7B, which had 200% w/w ethanol present during the mixing process.
  • Figure 18c shows the BET surface areas of unmodified AMO-LDH-2 and Examples 7 A and 7B.
  • the surface areas of both 7 A and 7B were significantly reduced by surface modification, with the modified AMO-LDH prepared by solvent-free modification (7 A) having a lower surface area than the equivalent AMO-LDH modified in the presence of 200% w/w ethanol (7B).
  • These results are in line with the Si/AI ratios, indicating that more modifier was incorporated into 7 A than 7B.
  • AMO-LDH prepared according to AMO-LDH-2 protocol
  • TMGS (3-glycidyloxypropyl)trimethoxysilane
  • ethanol none (0% w/w) - 8A; or 3.41 ml_ (200% w/w) - 8B)* using a Vortex Mixer for 15 minutes at room temperature.
  • the solid was then dried at 150 ° C for 6 h under N 2 before being isolated.
  • Figure 19b shows the Si/AI molar ratios of Examples 8A and 8B.
  • 8A non-solvent system
  • 8B contains a much higher amount of the organosilane modifier at the same modifier loading, compared with 8B, which had 200% w/w ethanol present during the mixing process.
  • Figure 19c shows the BET surface areas of unmodified AMO-LDH-2 and Examples 8A and 8B.
  • the surface areas of both 8A and 8B were significantly reduced by surface modification, with the modified AMO-LDH prepared by solvent-free modification (8A) having a lower surface area than the equivalent AMO-LDH modified in the presence of 200% w/w ethanol (8B).
  • Figures 21 and 22 show the FT-IR spectra for the TEOS and TMGPS samples respectively; the vibrations of ethoxy groups in the range of 1090-1200 cm -1 decreased with increasing time. The vibrations of Si-O-Metal/Si-O-Si at around 1000 cm 1 increased with increasing time. The results confirmed that silane has been grafted on LDH surface by reacting hydroxyl group of LDH with ethoxy groups of silane.
  • AMO-LDH prepared according to AMO-LDH-2 protocol
  • FT-IR spectrum of Example 10 in Figure 23(b) shows vibrations from both AMO-LDH and TEVS.
  • the peaks at around 750 and 920-1090 cm -1 are corresponding to the vibrations of - Si-C- and -Si-O-M(Si)- from TEVS, respectively.
  • the peaks at 1348 and 1531 cm -1 are due to vibration of C0 3 2 from LDH. It is worth noting that the vibration of water from LDH became very weak after silane modification, indicating that much less water in the silane modified sample.
  • Figure 24 shows the contact angles of Example 10 alongside unmodified AMO-LDH (AMO-LDH-2).
  • AMO-LDH-2 unmodified AMO-LDH
  • a mixed metal solution was prepared from 9.6 g of Mg(NC> 3 ) 2 -6H 2 0 (37.4 mmol), 4.7 g of AI(N0 3 ) 3 -9H 2 0 (12.5 mmol) in 50 mL of de-carbonated water (Solution A).
  • a second solution contained 2.65 g of Na 2 CO 3 (25.0 mmol) in 50 mL of deionised water (Solution B).
  • the solution A was added drop-wise (58 mL/min) to the Solution B.
  • the system was kept at constant pH 10 by using 4 M NaOH and aged for 16 hours at room temperature.
  • the slurry was then filtered and the filter cake was washed with de-carbonated water until the pH was close to 7.
  • the water- washed Mg3AI-CC>3 LDH was dispersed in water to give a 29% w/v slurry.
  • a mixed metal solution was prepared from 9.6 g of Mg(NC> 3 ) 2 -6H 2 0 (37.4 mmol), 4.7 g of AI(N0 3 ) 3 -9H 2 0 (12.5 mmol) in 50 mL of de-carbonated water (Solution A).
  • the solution A was added drop-wise (58 mL/min) to the Solution B.
  • the system was kept at constant pH 10 by using 4 M NaOH and aged for 16 hours at room temperature.
  • the slurry was then filtered and the filter cake was washed with de-carbonated water until the pH was close to 7 and followed by washing with ethanol. It was then re-dispersed in ethanol and slurried for 1 hour. The slurry was filtered and rinsed with ethanol.
  • the ethanol-treated Mg3AI-CC>3 LDH was dispersed in ethanol to give a 29% w/v slurry.
  • Ethanol-treated AMO Mg 3 AI-C0 3 LDH slurry (29% w/v in ethanol, equal to 1 g of dry LDH) was dispersed into 100 mL of ethanol purged with N2.
  • Triethoxyvinylsilane (TEVS) (2.8 mmol/g LDH) was injected dropwise into the suspension followed by reflux at 80 °C for 18 h. The solid was collected by filtration and washed with ethanol (300 mL) followed by drying for 16 h.
  • TEVS Triethoxyvinylsilane
  • Ethanol-treated AMO Mg 3 AI-C0 3 LDH slurry was dried in vacuum overnight and then thermally treated at 180 °C for 6 h, prior to being dispersed into 100 mL of ethanol purged with N2.
  • Triethoxyvinylsilane (TEVS) (2.8 mmol/g LDH) was injected dropwise into the suspension followed by reflux at 80 °C for 18 h. The solid was collected by filtration and washed with ethanol (300 mL) followed by drying for 16 h.
  • Figure 25 shows the contact angles and Si/AI molar ratios for Examples 1 1.1 to 1 1.6.

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Abstract

L'invention concerne des procédés de fabrication d'hydroxydes à double couche modifiés en surface (LDHs), ainsi que des LDHs modifiés en surface, et leurs utilisations dans des matériaux composites. Les LDHs modifiés en surface selon l'invention sont plus hydrophobes que leurs analogues non modifiés, ce qui permet aux LDHs d'être incorporés dans une grande variété de matériaux, la fonctionnalité intéressante des LDHs pouvant être exploitée.
PCT/GB2019/051295 2018-05-14 2019-05-10 Hydroxyde à double couche modifié en surface WO2019220081A1 (fr)

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CN112978791A (zh) * 2021-03-31 2021-06-18 山东大学 一种含钛层状双金属氢氧化物的制备方法
CN114685082A (zh) * 2020-12-30 2022-07-01 南京博特新材料有限公司 一种核壳杂化型纳米功能材料及其制备方法和应用
CN114717839A (zh) * 2020-12-22 2022-07-08 明基材料股份有限公司 一种具超疏水表面的物品及其制备方法
CN115043439A (zh) * 2022-06-10 2022-09-13 青岛大学 一种特种阴离子插层改性的镍钛双金属氢氧化物及其制备方法和应用

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114717839A (zh) * 2020-12-22 2022-07-08 明基材料股份有限公司 一种具超疏水表面的物品及其制备方法
CN114717839B (zh) * 2020-12-22 2024-02-02 明基材料股份有限公司 一种具超疏水表面的物品及其制备方法
CN114685082A (zh) * 2020-12-30 2022-07-01 南京博特新材料有限公司 一种核壳杂化型纳米功能材料及其制备方法和应用
CN112978791A (zh) * 2021-03-31 2021-06-18 山东大学 一种含钛层状双金属氢氧化物的制备方法
CN112978791B (zh) * 2021-03-31 2022-01-18 山东大学 一种含钛层状双金属氢氧化物的制备方法
CN115043439A (zh) * 2022-06-10 2022-09-13 青岛大学 一种特种阴离子插层改性的镍钛双金属氢氧化物及其制备方法和应用
CN115043439B (zh) * 2022-06-10 2023-11-17 青岛大学 一种特种阴离子插层改性的镍钛双金属氢氧化物及其制备方法和应用

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