WO2016195854A1 - Topochemical formation of ordered graphite-polymer nanocomposites - Google Patents

Abstract

Layered host-polymer nanocomposites comprising an ordered nanoscale combination of layered host sheets with polymeric guest galleries have been prepared with many different inorganic hosts, but no such materials have previously been obtained from graphite. The present disclosure provides a method for the generation of ordered graphite-polyether nanocomposites with polymer nanolayers contained between graphene sheets using a topochemical approach. The present disclosure further provides a method for reductively intercalating alkali metal cation-polyether complexes into graphite either by direct reaction of graphite, alkali metal, and polyether (molecular weight up to 6,000) with an electrocatalyst or using a solvent that supports electride formation. Structural characterization of products using powder X-ray diffraction, Raman spectroscopy, and thermal analyses provide the first clear evidence for ordered polymer-graphite nanocomposites which contain reduced graphene sheets separated by polymer nanolayers.

Description

TOPOCHEMICAL FORMATION OF ORDERED GRAPHITE-POLYMER

NANOCOMPOSITES

Field of the Invention

[0001] The present invention relates to the field of

nanocomposites and, more particularly, to a method for

generating ordered graphite-polymer nanocomposites with pol nanolayers contained between graphene sheets using a

topochemical approach.

Background of the Invention

[0002] Layered host - polymer nanocomposites have been prepared from many materials combinations - the hosts include the layered smectite clays, M02, MS2, Mo03 and MPS3 and the polymers include polylactide, poly (vinyl pyrrolidone) , linear polyethylenimine, poly(vinyl alcohol), and poly ( ethylene oxide) . The nanocomposites may be ordered, retaining co-planarity of inorganic host layers with intercalate galleries opened for the polymers, or they may be disordered, with delaminated inorganic nanosheets dispersed into a polymer matrix. Because nanoscale materials combinations often display significant property changes from their native constituents, nanoscale materials are currently used as, or are candidates for, applications such as enhanced structural materials, gas barriers, and thermal or fire resistant components.

[0003] Previous reports on forming graphite-polymer

nanocomposites include the in situ polymerization of vinyl co- intercalates. However, the products were highly disordered, precluding strong evidence for the nanocomposite structure.

Additionally, structural data could not conclusively demonstrate the presence of polymer galleries in the previously reported graphite intercalation compounds (GICs) or the dispersion of graphene nanosheets into the polymer matrix. The donor-type GICs such as KC8 are well known as polymerization catalysts, and have also been shown to uptake the polymerizable co-intercalates ethylene, styrene and butadiene. However, the differentiation of bulk, surface-adsorbed or intercalated polymer remains a challenge for materials derived using prior known methods.

[0004] Nanocomposites containing graphite or graphene sheets are of interest for electrochemical applications where graphitic or other carbons are presently employed. Even though solvent co-intercalation into graphite will require large volume changes on charge/discharge, the chemistry has recently been shown to be highly reversible. Graphite-polymer nanocomposites, with higher molecular weight polymers retained in galleries, could undergo similar redox chemistry without the associated volume or phase changes. Graphite-polymer nanocomposites, with higher molecular weight polymers retained in galleries may also display other attractive properties, such as high conductivity for intercalate ions .

Summary of the Inven

[0005] A need exists for a method for generating ordered graphite-polymer nanocomposites with nanoscale polymer layers

(nanolayers) contained between graphene sheets using a

topochemical approach. Accordingly, in one embodiment the present invention includes a composition of matter comprising a nanocomposite including individual graphene sheets and a polymer separating the graphene sheets. The graphene sheets retain stacking coherence. [0006] In another embodiment, the present invention includes a method of separating the graphene sheets in graphite with polymer intercalate by providing graphite, providing a polymer, providing an electropositive metal, combining the graphite, polymer, and electropositive metal with an electrocatalyst in a sealed container, and maintaining the sealed container at an elevated temperature.

[0007] In another embodiment, the present invention includes a method of separating the graphene sheets with polymer

intercalate by providing graphite, providing a polymer,

providing ethylenediamine, providing an electropositive metal, combining the graphite, polymer, electropositive metal, and ethylenediamine with an electrocatalyst in a sealed container, and maintaining the sealed container at an elevated temperature.

Brief Description of the Drawings

[0008] FIGs. la-lb illustrate ex situ powder X-ray

diffraction (PXRD) patterns from various products;

FIGs. 2a-2b illustrate structures and data relating to the bilayer structure;

FIGs. 3a-3b illustrate a thermal analysis plots of nanocomposite products;

FIGs. 4a-4b illustrate additional data relating to nanocomposite products;

FIG. 5 illustrates Raman spectra showing the G band shift in various GICs;

FIGs. 6a-6c illustrate additional thermal analysis plots of nanocomposite products; and FIG. 7 illustrates additional Raman spectra showing the low D/G band intensity, or no discernible D-band, in various

Detailed Description

[0009] Throughout this disclosure, the present invention is described in one or more embodiments in the following

description with reference to the figures, in which like

numerals represent the same or similar elements. While the invention is described in terms of the best mode for achieving the invention's objectives, it will be appreciated by those skilled in the art that it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and their equivalents as supported by the following disclosure and drawings.

[0010] Layered host-polymer nanocomposites comprising an ordered nanoscale combination of layered host sheets with polymeric guest galleries have been prepared with many different inorganic hosts, but no such materials have previously been obtained from graphite. There are several synthetic approaches to forming nanocomposites, including (1) intercalation of monomeric precursors followed by in situ polymerization, (2) layered host exfoliation followed by sorption of polymer and reassembly of the nanocomposites (either using a solvent or in a solvent-free "melt-intercalation" process), (3) direct

topochemical intercalation of the polymer between host layers, or (4) templated growth of the inorganic layers on the polymer.

[0011] The production of nanocomposites derived from polymers and graphite or graphene is a special case and presents special challenges. Graphite has a high chemical potential for oxidation (¾ 4.5-5.0 V vs Li(m)/Li+) and low chemical potential (¾ 0.2-1.0 V vs Li(m)/Li+) for reduction, precluding the use of most chemical solvents and stable intercalates that can be applied with other hosts. Furthermore, graphene sheet

flexibility results in the unique stack ordering effect called staging that allows the sheet charge density to remain

relatively constant during intercalation. The staging

phenomenon interferes with attempts to accomplish host

delamination via redox titration. One with skill in the art will appreciate the challenges of a template approach given the conditions for graphene sheet formation. The template approach is unlikely to succeed with organic polymers given the high temperatures (>500°C) required to crack molecular precursors such as alkanes.

[ 0012 ] The isolation and characterization of single-sheet graphene has sparked much interest and progress, but the

delamination of graphite into nanosheet colloids is not as straightforward as with many other layered materials. Graphite oxide (GO) does not have the remarkable electronic properties of graphene, but is far more amenable to solution-phase processing, hence one strategy has been to first employ GO as the host during nanocomposite preparation, and to then reduce the GO layers back to graphene. For example, GO can be dispersed into polar solvents and thus undergo solution-phase processing.

Related approaches have employed chemically and thermally pretreated graphite (including thermally exfoliated graphites, graphenes, graphite oxide, or reduced graphene oxide) to

generate nanocomposite materials with dispersed graphene

nanosheets . [0013] The present disclosure provides methods for generating ordered graphite-polyether nanocomposites with polymer

nanolayers contained between graphene sheets using a

topochemical approach. Graphite-polyether nanocomposites may be used for electrochemical applications where graphite is

currently used. For example, for use as an anode in reversible charge-storage devices. Graphite-polyether nanocomposites may be used for electronic applications where graphite is currently used. For example, as a conducting additive in composites.

Graphite-polyether nanocomposites may be used for applications where other layered sheet nanocomposites are used. For example, in packaging, or as a structural component. Graphite has the advantage of being electrically conductive and resistant to oxidation or reduction.

[0014] The present disclosure explores the co-intercalation of linear and branched amine co-intercalation and the formation of new GICs with expanded and unusual intercalate conformations and arrangements. Subsequent ion exchange rapidly and

quantitatively generates well-ordered GICs with intercalates as large as (CI 8H37 ) 2N (CH3 ) 2+ (molar mass = 551 D) . The present disclosure teaches the incorporation of oligomeric or polymeric constituents via similar topochemical reactions using a direct or ion-exchange approach. The present disclosure also teaches that direct reductive intercalation of oligo and polyethers can lead to similar products. As reported below, both methods generate ordered graphite-polymer nanocomposites.

[0015] Polymer candidates for GIC co-intercalation are reductively stable to < 0.7-1.0 V vs Li/Li+. Polymer candidates should also be strong Lewis bases so to provide favorable energetics for co-intercalation by strongly solvate alkali metal cations as opposed to ion desolvation (as occurs when charging Li-ion batteries anodes to form binary LiC6) . Poly (ethylene glycol) (PEG), and poly (ethylene oxide) (PEO) , are ether-group abundant candidates with Na+ binding constants linearly

proportional to chain length, and both PEG and PEO form

nanocomposites layered hosts. Accordingly both PEG and PEO were chosen as targets for study. Methylated derivatives, poly

(ethylene glycol) dimethyl ethers (PEGDME) , CH30 (CH2CH20) nCH3, were used for lower molecular weight reagents to avoid chemical reduction of end groups.

[0016] The co-intercalation of small ethers with alkali metal cations to form GICs is established; there are reports for (1) tetrahydrofuran (THF) and derivatives 2-methylTHF, 2,5- dimethylTHF; (2) diethylether and t-butylmethyl ether; (3) dialkoxymethanes and dialkoxyethanes ; (4) the macrocyclic

"2.2.2-cryptand" ; and (5) diglyme and diethylene glycol dimethyl ether. Most of the above referenced GICs, i.e., examples 1-4, were obtained by direct reduction of graphite by alkali metals in the etheric solvent, the latter case, example 5, used

electrochemical reduction.

[0017] The present invention provides a method of formulating GICs using either (1) the direct reaction of graphite, polymer, Na (m) and electrocatalyst above the polymer melting point, or (2) graphite, polymer, and Na (m) in ethylenediamine (en) . The latter combination without polymer rapidly generates

[Na (en) 1.0] C15, which in turn exchanges polymer co-intercalate for en in the galleries. Products from (1) and (2) are

identified as D-GIC-n and E-GIC-n, respectively, where n

indicates the average polymer molecular weight. The G in the identification indicates that SPl graphite was used to produce the GIC. The G' indicates that synthetic graphite with 1 μπι particle diameter was used. For example, D-GIC-1,000 is an ordered graphite-polyether nanocomposites with polymer nanolayers contained between graphene sheets with an average polymer molecular weight of 1,000 formed from the direct

reaction of graphite, polymer, Na (m) and electrocatalyst above the polymer melting point. E-GIC-2,000 is an ordered graphite- polyether nanocomposites with polymer nanolayers contained between graphene sheets with an average polymer molecular weight of 2,000 formed from a solution of graphite, polymer, and Na (m) in en .

[ 0018 ] Using SP-1 graphite with an average particle diameter of ¾100 μπι, D-GIC-n products with n < 1, 000 are produced which are dark blue. While using SP-1 graphite, D-GIC-n products with n > 1,000 are produced which are dull-black. FIGs. la-lb illustrate ex situ PXRD patterns from products of direct, as shown in FIG. la, and exchange, as shown in FIG. lb, reactions. FIG. la shows from bottom to top, reactions using

dimethoxyethane, PEDGME with Mw = 250, 500, 1000, 2000, and graphite. D-GIC-1000 shows a nanocomposite phase with Miller indices indicated. In FIG. lb, E-GIC-2000 products with

reactant PEGDME / graphite (P/G) ratios of 1, 2, 3, 4, are shown along with [Na (en) 1.0] C15 (at bottom) . For P/G= 3 and 4, peaks from a nanocomposite phase and [Na (en) 1.0] C15 are observed. In both FIGs. la and lb, an asterisk (*) indicates peaks from the native polymer. Miller indices (hkl) are included only for peaks ascribed to new GIC products. The present disclosure demonstrates, as shown in FIG. la, using PXRD, that the product obtained using dimethoxyethane (DME) is a stage 1 GIC, stage n indicates that n graphene layers separate intercalates, with a basal repeat, di = 0.73 nm, and a gallery expansion of Ad = di - 0.335 nm = 0.40 nm, indicating a gallery monolayer. Products with the lower molecular weight PEGDMEs, MW 500, show no identifiable new phases, but have weak and broadened graphite (002) peaks, suggesting bulk graphite intercalation occurs.

However, the diffraction patterns obtained indicate only higher stage and disordered structures were produced. Topochemical intercalation proceeds to some extent. However, the products are unstable under the conditions explored. In contrast, D-GIC- 1,000 shows a new well-ordered GIC phase with di = 1.164 nm. The calculated Ad = 0.83 nm is similar to those observed for PEO-containing nanocomposites with other inorganic hosts.

Accordingly, new material D-GIC-1,000 is ascribed to an ordered structure with single graphene sheets separated by bilayers containing Na+ and PEGDME co-intercalate, confirmed by the observed ID gallery electron density map, see FIG. 2b. FIG. 2a is a schematic diagram of M-PEG (DME) -GIC bilayer structure.

FIG. 2b is a ID-electron density map generated from Na-PEGDMElk- GIC diffraction data showing the gallery bilayers.

CO- ΔΡ GALLERY COMPOSITION PACKING POMAIN

INTERCAL (NM) TYPE FRACTION SIZE

ATE (NM)

Na PME 0 40 monolayer N/A N/A N/A

Li PEGPME- 0 81 bilayer [Li (CH₂CH₂0) 3 4] C25 0 32 37

lk

Na PEGPME- 0 83 bilayer [Na ( CH2 CH2O ) 2 δ] Cl3 0 49 37

lk

K PEGPME- 0 89 bilayer [K(CH₂CH₂0) 2 .6 ] C11 0 52 27

lk

Na PEGPME- 0 83 bilayer [Na ( CH2 CH2O ) 1 4] C9 0 40 39

2k

Na PEG-6k 0 84 bilayer [Na ( CH2 CH2O ) 2 4] Cio 0 60 30

Table 1. Structural and compositional data for synthesized GICs—all products were first stage, with single graphene sheets between polymer bilayers [0019] The domain size obtained from PXRD peak widths is shown in Table 1. FIGs. 3a-3b show dTGA curves with calculated peaks. FIG. 3a shows Na-PEGDMElk-GIC . FIG. 3b shows Na-PEG6k- GIC. The dTGA plots of reaction products of FIGs. 3a-3b show two overlapping peaks. The lower temperature peak is attributed to polymer in the GIC phase, and the higher temperature peak is attributed to excess unreacted polymer. FIGs. 3a-3b show

Gaussian simulation of the subject dTGA peaks with a coefficient of determination R2 equal to 0.988.

[0020] The sodium mass % in the GIC products was obtained by ascribing the residual mass at 800°C under 02 flow as Na20. The product after the subject processing was colorless or white, indicating that the graphitic carbons or polymer residues had been volatilized by oxidation. The sodium mass contents thus derived were 2.82 and 3.16 mass % for samples Na-PEGDMElk-GIC and Na-PEG6k-GIC, respectively.

[0021] The graphite mass % in the products was obtained from the mass residual at 650°C under N2 flow, Ar for Li products. From the experimentally determined mass %, the mass of Na

(determined above) was subtracted. The graphitic contents were calculated as 21.3 and 18.9 mass % for Na-PEGDMElk-GIC and Na- PEG6k-GIC, respectively.

[0022] The domain size indicates a well-ordered stacking structure with about 30 coherent units per domain. Products D- GIC-2,000 and those with higher molecular weight polymer do not indicate nanocomposite formation with SP-1 graphite. However, when using synthetic graphite, with a domain size of ¾l-2 μπι, product D-G' IC-6, 000, again showed a well-ordered nanocomposite with Ad = 0.83 nm similar to that described above. When D-GIC-n and E-GIC-n possess a number of graphene sheet polymer pairs, or coherent units per domain, of greater than two, the products are said to possess stacking coherence. The higher viscosity and lower diffusion rates for longer polymer chains create a kinetic restriction for direct intercalation of high Mw polymers; the dissolution of PEG into the electride solution facilitates a more rapid reaction. The combination of en and alkali metals with graphite generates [Na(en)y]Cx, accordingly [Na(en)y]Cx forms first and then PEG is exchanged for the en co-intercalate.

[0023] The direct reaction products, e.g., D-GIC-90, D-GIC- 1,000, and D-G' IC-6, 000, suggest a kinetic limitation for the larger polymer co-intercalates. Accordingly, reactions with en were also explored using co-intercalate exchange reactions. E- GIC-1,000 prepared with different polymer/graphite ratios shows, for P/G ≤ 2, only [Na (en) 1.0] C15 and no nanocomposite phase, as shown in FIG. lb. With P/G = 3, a nanocomposite phase appears and that new phase is the only one observed at P/G = 4,

indicating full exchange of en for polymer. The calculated gallery expansion, Ad = 0.83 nm, and the sharp PXRD peaks again indicate the presence of polymer nanolayers in a well-ordered nanocomposite .

[0024] FIG. 4a shows ex situ PXRD patterns of direct reaction products using Li, Na or K metal and PEGDME-lk. FIG. 4b shows gallery expansion for these GICs vs. ionic radii of the alkali cations. As shown in FIGs. 4a-4b, Li, Na, and K reactions using the direct method with PEGDME-lk all generate new single phase GICs with a linear response of gallery expansion vs. alkali metal ionic radius. The slope of the plot, ¾1.3, confirms that more than a single cation-containing layer contributes to the gallery expansion.

[0025] Raman spectra are sensitive to graphene layer charge; donor-type GICs display an E2g (G band) peak shift to higher wavenumber due to occupancy of in-plane antibonding orbitals. For example, a 12-14 cm-1 shift has been reported for LiC6.

FIG. 5 illustrates Raman spectra showing the G band shift in obtained GICs. Native graphite, in the bottom spectrum, shows a peak at 1576 cm-1. FIG. 5 shows a blue shift to 1596-1601 cm-1 for GICs with PEGDMEs. FIG. 5 shows the G band peak for

graphite at 1576 cm-1, and the nanocomposite products show G band peaks at 1596-1601 cm-1, indicating the presence of reduced graphene sheets. D/G band ratios also confirm that graphene sheets do not accumulate defects during the above referenced reactions .

[0026] The packing fractions, i.e., the fraction of occupied space within the expanded galleries, are calculated from the compositional and structural data by applying equation (1) : packing fraction = ( VM + y· 0.0493 nm3 ) / (0.0261 nm2 · χΔο!) (1)

[0027] The calculation uses the cationic volumes VLI = 0.0016, a = 0.0060, and VK = 0.0110 nm3 and the van der Waals volume of one -CH2CH20- repeat unit (0.0493 nm3), with x indicating the number of graphitic carbons per negative layer charge, and y indicating the molar ratio of -CH2CH20- units to sodium cation in the stated compositions.

[0028] The present disclosure provides for a simple gravity separation method allowing polymer to flow out of samples maintained at 60°C for 6 h to remove excess polymer after reaction. The nanocomposite products are obtained in admixtures with the polymer reagents. Nevertheless, accurate nanocomposite phase compositions are obtained using thermal analyses. FIGs. 6a-6c show thermal analysis, including TGA and derivative TGA, plots of nanocomposite products under N2 flow. FIGs. 6a-6c include a trace for the starting polymer for comparison. FIG. 6a shows PEGDME-lk. FIG. 6b shows PEGDME-2 k . FIG. 6c shows PEG-6k. The curves are compared with those for the PEGDME reagent used. TGA and dTGA show two loss features in all GIC products, a loss at temperature close to that with the native polymer, plus a lower-temperature loss at approximately 250- 320°C ascribed to degradation of the polymer co-intercalate in the GIC. Previous studies have similarly shown a catalytic effect for graphite compounds where intercalates and co- intercalates thermally degrade at lower temperature. The low- temperature peak areas were evaluated to determine co- intercalate contents in the GIC phase. Metal cation content was determined by thermolysis under oxygen flow, where at 800°C the carbon is volatilized as C02 leaving only Li20, Na20 or K20. From the above referenced data, nanocomposite compositions are derived, as shown in Table 1, above. By combining the

compositions and GIC gallery expansions, gallery packing

fractions of 0.41-0.60 were obtained, see Table 1. From these results, GICs have similar gallery dimensions, but somewhat less densely packed polymer bilayers, than PEO nanocomposites with MPS3 (packing fraction = 0.72-0.83), or Na-montmorillonite

(packing fraction = 0.68.

[ 0029 ] The domain size along the stacking direction (c-axis) for each product was determined using the modified Scherrer relation for the first 3-4 low angle (001) reflections observed in PXRD. The (003) reflection generally has a shoulder peak due to excess crystalline polymer and was not used in the

calculations. Table 2 shows the data for one sample: β (rad) Θ (rad) Ln (l/cos9) ίηβ

0.00384 0.06631 0.00220 -5.5624

0.00368 0.13266 0.00883 -5.6041

0.00394 0.26704 0.03609 -5.5355

0.00429 0.33632 0.05765 -5.4507

1. β is full width at half maximum (FWHM) .

2. Θ is the peak position.

3. Linear regression for Ln vs. Ln(l/cos6) gave an intercept of -5.5982.

Table 2. PXRD peak data for Na-PEGDMElk-GIC

[0030] The domain size is determined using equation (2) : exp (L-ΐ β ) o = 0.89λ/ L (2) where the ( ]_ιη β ) ο is the intercept of Ιηβ vs. ln(l/cos6) and λ for Cu K radiation is 0.15406 nm. By combining composition and gallery expansions, gallery packing fractions of 0.41-0.60 are obtained .

[0031] Nanocomposite products exhibit very low Raman D/G band intensity ratios (ID/IG) . FIG. 7 shows spectra for selected products and synthetic graphite. The native synthetic graphite showed ID/IG = 0.26, the Na-PEG6k-GIC product obtained using the subject graphite showed a weaker, broader D-band with ID/IG = 0.08. No discernible D-band intensity was found for Na- PEGDMElk-GIC spectra which was obtained from SP-1 graphite. The D-band peak at ¾1,350 cm-1 indicates sp3 carbon whereas the G- band peak at ¾1,580 cm-1 indicates sp2 carbon. The subject disclosure confirms that the graphene sheets in the

nanocomposite products retain a high degree of graphitization and very low defect concentration, in contrast to the saturated and defected GO/rGO/EG sheets often obtained when GO is used to delaminate the graphene sheets. [0032] FIG. 7 shows Raman spectra of synthetic graphite and nanocomposite samples. D/G band intensity ratios (ID/IG) are calculated for synthetic graphite and Na-PEG6k-GIC sample, while the Na-PEGDMElk-GIC shows no discernible D-band peak.

[0033] The packing fractions show that graphite-polymer nanocomposites have less dense polymer nanolayers than in PEO nanocomposites with MPS3 (packing fraction = 0.72-0.83)6 or Na- montmorillonite (packing fraction = 0.68) .

Example 1 - direct reaction method for generating ordered graphite-polyether nanocomposites with polymer nanolayers contained between graphene sheets :

[0034] 1) Obtain PEGDMEs from Sigma-Aldrich, dimethoxyethane (99+%) from Alfa Aesar, and PEG 6,000 from TCI America;

2) Dry the glassware and graphite reagents at 120°C prior to use;

2) Dry the PEG 6,000 overnight under dynamic evacuation (<10 μπι) ;

3) Combine 250 mg (21 mmol) of graphite (SP-1 grade, Union Carbide Corp., 100 μπι, or Synthetic, Aldrich, 1-2μπι) and 2.0 mL (or 2.0 g if solid) polymer with 80 mg (3.5 mmol) of Na metal (Alfa Aesar, 99.95%) and ¾5 mg naphthalene or phenanthrene electrocatalyst in a sealed glass tube and maintain at 90°C under N2 for 20 h or longer as noted;

4) Isolate products using centrifugation and separation of the solid phase;

5) Dry under vacuum at 60°C for 6 h in inverted test tubes to allow excess polymer to flow away from the samples. Example 2 - ion-exchange reactions method for generating ordered graphite-polyether nanocomposites with polymer nanolayers contained between graphene sheets :

[0035] 1) Obtain PEGDMEs from Sigma-Aldrich, dimethoxyethane (99+%) from Alfa Aesar, and PEG 6,000 from TCI America;

2) Dry the solid reagents overnight under dynamic evacuation (<10 μπι) ;

3) Combine 250 mg (21 mmol) of graphite (SP-1 grade, Union Carbide Corp., 100 μπι, or Synthetic, Aldrich, 1-2μπι) and polymer in the desired mass ratio to 1.0 g of en (Alfa Aesar, 99%) and 100 mg of Na in a sealed glass tube and maintain at 60°C for 20 h with continuous stirring under N2 ;

4) Isolate products using centrifugation and separation of the solid phase;

5) Dry under vacuum at 60°C for 6 h in inverted test tubes to allow excess polymer to flow away from the samples.

[0036] PXRD patterns were acquired using a Rigaku Miniflex II diffractometer with Ni-filtered Cu K radiation (λ= 0.15406 nm) . Samples were loaded in the drybox into airtight sample holders. Measurements were collected at 2Θ = 3-60° at 3°/min. One dimensional electron density maps were generated from PXRD data using a method described previously. Domain sizes were derived from the modified Scherer relation. A TA Q50 thermogravimetric analyzer (TGA) was employed using a heating rate of 10°C/min under flowing N2 or 02 gas. Raman spectra ( resolution=4 cm-1) were obtained using a Witech confocal Raman microscope equipped with a 514 nm laser source. Raman and TGA samples were exposed to ambient conditions for < 1 min.

[0037] To the best of the inventor's knowledge, the subject disclosure supports the creation of ordered graphite-polyether nanocomposites with polymer nanolayers contained between graphene sheets with significantly higher average polymer molecular weight than 6,000 as discussed above. Average polymer molecular weights of 96,000 and up to 10 million are envisioned without departing from the scope of the present invention.

Well-ordered GICs containing polyether intercalates are

synthesized via direct reductive intercalation or co-intercalate exchange, providing new simple methods for generating

nanocomposites comprising graphite and oligo or polyethers. The GIC products are first-stage and have intercalate bilayers and metal cations between reduced graphene sheets. If these GICs are applied as electrode materials, these large Mw ether

bilayers remain within galleries and thus reduce the gallery volume changes required during charge/discharge cycling.

[0038] In one embodiment, temperatures and times are changed to generate nanocomposites over reaction or degradation

products. Longer times and or higher temperatures favor

diffusion-limited processes.

[0039] In one embodiment, different electrocatalysts are utilized, including polyaromatic hydrocarbons and derivatives and fullerene and derivatives.

[0040] In one embodiment, different alkali metals or other reductants are utilized, including, but not limited to, Na (m) Li (m) , K (m) , other electropositive metals such as Ba, Ca, Mg and electrochemical reduction.

[0041] In one embodiment, different polymers are utilized including polyamines and functionalized vinyl polymers.

[0042] In one embodiment, other electride formers, or other solvents, are utilized to promote solution phase reactions.

[0043] In one embodiment, the polymer nanolayers may be organized as monolayers, bilayers, multilayers or disordered structures that retain planarity in the encasing graphene sheets .

[ 0044 ] While one or more embodiments of the present invention have been illustrated in detail, the skilled artisan will appreciate that modifications and adaptations to those

embodiments may be made without departing from the scope of the present invention as set forth in the following claims.

Claims

Claims What is claimed:

1. A composition of matter, comprising:

a nanocomposite including,

(a) a plurality of graphene sheets,

(b) a polymer separating the graphene sheets, and

(c) wherein the plurality of graphene sheets retain stacking coherence.

2. The composition of claim 1, wherein the polymer includes an average molecular weight of at least 1,000.

3. The composition of claim 1, wherein the polymer includes an average molecular weight of at least 2,000.

4. The composition of claim 1, wherein the polymer includes an average molecular weight of at least 6,000.

5. The composition of claim 1, wherein the polymer includes poly ethylene glycol, poly ethylene oxide, methylated

derivatives, poly ethylene glycol dimethyl ethers,

CH30 (CH2CH20) nCH3, polyamines, or functionalized vinyl polymers.

6. The composition of claim 1, wherein a number of graphene sheet polymer pairs is greater than five.

7. The composition of claim 1, wherein a number of graphene sheet polymer pairs is greater than twenty.

8. A method of making graphene sheets separated by polymer nanolayers, comprising:

providing graphite;

providing a polymer;

providing an electropositive metal;

combining the graphite, polymer, and electropositive metal with an electrocatalyst in a sealed container; and

maintaining the sealed container at an elevated

temperature .

9. The method of claim 8, further including isolating a product using a physical separation.

10. The method of claim 9, further including drying the product under vacuum.

11. The method of claim 8, wherein the polymer includes an average molecular weight of at least 1,000.

12. The method of claim 8, wherein the polymer includes an average molecular weight of at least 2,000.

13. The method of claim 8, wherein the polymer includes an average molecular weight of at least 6,000.

14. The method of claim 8, wherein the polymer further includes a polymer mixture.

15. A method of making graphene sheets separated by polymer nanolayers, comprising:

providing graphite; providing a polymer;

providing ethylenediamine;

providing an electropositive metal;

combining the graphite, polymer, electropositive metal, and ethylenediamine with an electrocatalyst in a sealed container; and

maintaining the sealed container at an elevated

temperature .

16. The method of claim 15, further including isolating a product using a physical separation.

17. The method of claim 16, further including drying the product under vacuum.

18. The method of claim 15, wherein the polymer includes an average molecular weight of at least 1,000.

19. The method of claim 15, wherein the polymer includes an average molecular weight of at least 2,000.

20. The method of claim 15, wherein the polymer includes an average molecular weight of at least 6,000.

21. The method of claim 15, wherein the polymer further includes a polymer mixture.