WO2017041082A1 - Compositions including ligninsulfonate and methods of forming and compositions including un-alkylated lignin - Google Patents

Abstract

Compositions such as polymers that include a ligninsulfonate component. Methods of formin ligninsulfonate containing compositions. Compositions such as polymers that include un- alkylated lignin.

Description

COMPOSITIONS INCLUDING LIGNINSULFONATE AND METHODS OF FORMING AND COMPOSITIONS INCLUDING UN- ALKYLATED LIGNIN

GOVERNMENT FUNDING

This invention was made with government support under 2011-67009-20062 awarded by the United States Department of Agriculture (USD A) NIFA Sustainable Bioenergy Research Program; and AFRI Competitive Grant no. 2011-68005-30416 awarded by the United States Department of Agriculture (USD A) NIFA Sustainable Bioenergy Research Program; and 115808 G002979 awarded by the Washington State University Northwest Advanced Renewables Alliance. The government has certain rights in the invention.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application Serial No.

62/214,291, filed September 4, 2015 and U.S. Provisional Patent Application Serial No.

62/215,017, filed September 6, 2015, each of which is incorporated herein by reference thereto.

SUMMARY

Disclosed herein are compositions such as polymers that include a ligninsulfonate component.

Also disclosed herein are methods that include obtaining a ligninsulfonate salt, the ligninsulfonate salt including a ligninsulfonate component and a counter ion component;

replacing at least some of the counter ion component with a proton to obtain a protonated ligninsulfonate; and forming a polymer from at least the protonated ligninsulfonate.

Disclosed herein are polymers that include lignin, more specifically non-alkylated lignin. The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows tensile behavior of methylated ball-milled lignin (MBML)-based polymeric materials, [i] 100% MBML-based plastic; blends of 85% MBML with [ii] 15% poly(ethylene glycol) (PEG), [iii] 15% poly(ethylene oxide-b-l,2-butadiene) (EB) and [iv] 15% poly(trimethylene glutarate) (PTMG).

FIG. 2 shows tensile behavior of polymeric materials based on ligninsulfonate methylated with dimethyl sulfate (sMLS) or dimethyl sulfate followed by diazomethane (dMLS). [i] 100% sMLS; blends of 85% sMLS with [ii] 15% poly(trimethylene glutarate) (PTMG) and [iii] 15% polycaprolactone (PCL); [iv] blend of 85% dMLS with 15% PTMG cast stepwise at 115°, 125°, 135° and then 150°C (Before methylation, LS M_w = 9600, M_w/M_n = 5).

FIGs. 3A and 3B show tensile behavior of ligninsulfonate (LS)-based polymeric materials, [i] 100% LS; [ii] blend of 90% LS with 10% PEG, Mn 400 Da; blends of 85% LS with [iii] 15%) polycaprolactone (PCL), [iv] 15% poly(trimethylene succinate) (PTMS), and [v] 15% poly(trimethylene glutarate) (PTMG) (Before methylation, LS M_w = 9600, M_w/M_n = 5) (FIG. 3A) ; and tensile behavior of polymeric materials based on unmethylated ligninsulfonate (LS) and on ligninsulfonate methylated with dimethyl sulfate (sMLS), both alone and in blends with 15 wt% poly(trimethylene glutarate) (PTMG). (Before methylation, LS M_w = 7100, M_w/M_n = 3 8) (FIG. 3B)

FIGs. 4A to 4F show X-ray powder diffraction patterns of uncast and cast polymeric materials based on unmethylated and methylated ligninsulfonates. (FIG. 4A) uncast and (FIG. 4B) cast unmethylated ligninsulfonate (LS); (FIG. 4C) uncast and (FIG. 4D) cast ligninsulfonate methylated with dimethyl sulfate (sMLS); (FIG. 4E) uncast and (FIG. 4F) cast ligninsulfonate successively methylated with dimethyl sulfate and diazomethane (dMLS). The x-ray diffraction patterns of the amorphous polymeric materials were analyzed by fitting two Lorentzian functions I(x) = I(0)/(1 + x2/hwhm2), x = 2Θ - 20k, where I(x) is the scattered intensity at x from the Bragg angle 20k for the peak, 20 is the scattering angle, and hwhm is the half-width at the half- maximum of the peak. FIGs. 5A to 5D show packing of macromolecular entities in ligninsulfonate (LS)-based polymeric materials cast at 115° and then 150°C. Tapping-mode AFM amplitude images of ultramicrotome-cut surfaces of (FIG. 5A) unmethylated LS, (FIG. 5B) LS methylated with dimethyl sulfate (sMLS), (FIG. 5C) LS successively methylated with dimethyl sulfate and diazomethane (dMLS); (FIG. 5D) corresponding height image of dMLS surface (material cast stepwise at 115°, 125° and 150°C). (Before methylation, LS M_w = 9600, M_w/M_n = 5).

FIG. 6 shows correlation between toughness and elongation-at-break (sb) for methylated ball-milled lignin-based polymeric materials blended with 0-30% w/w miscible components: DEG, diethyl glutarate; EBE, poly(ethylene oxide-b-l,2-butadiene-b-ethylene oxide); PBA, poly(butylene adipate); PEG, poly(ethylene glycol); PES, poly(ethylene succinate); etc. The symbols o denote data points that are not included in the linear regression analysis; they represent tensile behavior that embodies substantial plastic deformation.

FIG. 7 shows correlation between tensile strength (omax) and modulus (E) of methylated ball-milled lignin-based polymeric materials blended with 0-30% w/w miscible components: EBE, poly(ethylene oxide-b-l,2-butadiene-b-ethylene oxide); PEG, poly(ethylene glycol); and TBBP-A, 3 , 3 ', 5 , 5 '-tetrabromo-bi sphenol- A.

FIG. 8 shows the relationship between tensile strength (omax) and elongation-at-break (Δε %) for ligninsulfonate-based polymeric materials alone and in blends with miscible components: LS, ligninsulfonate; PEG, poly(ethylene glycol); PTMG, poly(trimethylene glutarate); PTMS, poly(tri-methylene succinate); sMLS, ligninsulfonate methylated with dimethyl sulfate; PCL, polycaprolactone; PE, polyethylene; and PS, polystyrene (In these materials, the molecular weight distribution of the ligninsulfonate before methylation is characterized by M_w = 9600, M_w/M_n = 5).

FIG. 9 shows the tensile behavior of unmethylated ball-milled lignin-based polymeric materials composed of the lignin preparation alone (100% BML); corresponding blends with 2% poly(ethylene oxide-£-l,2-butadiene-£-ethylene oxide) (EBE), 5% poly(trimethylene glutarate) (PTMG) and 5% tetrabromobisphenol A (TBBP-A). DETAILED DESCRIPTION

Lignosulfonates

Lignins are found in the cell-walls of all vascular plants; as a class, they represent the second most abundant group of biopolymers on earth. The profitable conversion of

lignocelluloses from plants to liquid biofuels and commodity organic chemicals depends on the value added to the co-product lignins. The cleavage of such lignin derivatives to low-molecular- weight compounds may look like a reasonable possibility, but resistance to degradation and broad range of products formed can dampen enthusiasm for such undertakings.

For the past 50 years, an erroneous working hypothesis about the macromolecular lignin configuration has diverted attention from the propriety of formulations for plastics with very high lignin contents. In 1960, the hydrodynamic behavior of ligninsulfonates was interpreted as indicating that the constituent high molecular weight lignin species are crosslinked microgels. At that time, it was not thought that the hydrodynamic compactness of lignin macromolecules could arise from noncovalent interactions between the aromatic substructures. Even 30 years ago, softwood delignification could still be evaluated through an elaboration of Flory-Stockmayer theory that sought to analyze lignin dissolution in terms of crosslinked-gel degradation processes. Just three years ago, lignin macromolecules were adamantly described as hyper- branched. Of course, crosslinking and hyper-branching create rigid macromolecular structures that would lead to brittle materials in the absence of intervening soft segments along the polymer chains. For these reasons, incorporation limits of 40% for lignins in plastics have seldom been exceeded.

Furthermore, ligninsulfonates, when formed through pulping or other such processes, are most often in the form of salts. Typically, the ligninsulfonate is associated with a counter ion, for example either sodium (Na⁺) or calcium (Ca⁺). In this form, the ligninsulfonate component has a net negative charge. The individual ligninsulfonate components would be electrostatically repulsed by other ligninsulfonate components. As such, one of skill in the art would not think they could be incorporated into polymers.

Ligninsulfonates, lignosulfonates, lignosulfonate or sulfonated lignin all refer to the same compound (CAS number 8062-15-5). For the sake of clarity, ligninsulfonate will be used throughout. Ligninsulfonates are water soluble anionic poly electrolyte polymers that are byproducts from the production of wood pulp using sulfite pulping. Ligninsulfonates have a relatively broad range of molecular mass (e.g., they are polydisperse). Molecular masses from 1000 to 140,000 daltons have been reported from softwood ligninsulfonates with lower values typical for hardwoods. Ligninsulfonates can be formed using the Howard process to produce calcium ligninsulfonate (CAS 904-76-3). Ligninsulfonates can also exist as sodium

ligninsulfonate (CAS 8061-51 -6), magnesium ligninsulfonate or ammonium ligninsulfonate. Various extraction methods, including ultrafiltration and ion-exchange for example can be utilized to obtain ligninsulfonates from pulp liquids.

Disclosed herein are compositions or polymers that include a ligninsulfonate component. Also disclosed are methods for forming compositions or polymers. Such methods can include steps of protonating ligninsulfonate components that include a counter ion. This step can also be described as exchanging the positive counter ion for a proton.

Disclosed compositions, or disclosed polymers can include a ligninsulfonate component. Ligninsulfonate component can include any compound that includes a ligninsulfonate backbone. A ligninsulfonate backbone can be described as an oligomeric or polymeric structure derived from a lignin molecule that possesses attached sulfonic acid or sulfonate groups. If the hydrogen atom of a sulfonic acid group or negative charge of a sulfonate group is replaced with an alkyl group, the ligninsulfonate can be referred to as an alkylated ligninsulfonate. Moreover, if the hydrogen atom of any aromatic or aliphatic hydroxyl group on a ligninsulfonate molecule is replaced with an alkyl group, the ligninsulfonate can also be referred to as an alkylated ligninsulfonate.

It should also be understood that ligninsulfonate components disclosed and utilized herein can include alkylated ligninsulfonates. The phrase "alkylated ligninsulfonate" as utilized herein can refer to any type of ligninsulfonate, be it a native ligninsulfonate or a chemically modified ligninsulfonate, in which at least some hydrogen atoms of hydroxyl groups have been replaced with an alkyl group.

In some embodiments, alkylation, alkylating, or alkylated ligninsulfonate, can refer to replacing at least some hydrogens of hydroxyl groups, for example free hydroxyl groups, on the ligninsulfonate with an alkyl group (for example any alkyl group). Stated another way, alkylation changes hydroxyl groups (-OH groups) (e.g., free hydroxyl groups) to alkoxy groups (-0(CH₂)nCH₃, where n can range from 0 to 3, for example) (e.g., free alkoxy groups). The hydroxyl groups that are modified can be free hydroxyl groups, the phenolic hydroxyl group, or any combination thereof. In some embodiments, each hydroxyl that is part of any sulfonate (which would convert the sulfonic acid groups to alkyl sulfonate ester groups) is not included in the group of hydroxyl groups that can be alkylated. In some embodiments, alkylation can be done with methyl groups (CH₃, where n equals zero), ethyl groups (CH₂CH₃, where n equals one), propyl groups ((CH₂)₂CH₃, where n equals two), or butyl groups (CH₂)₃CH₃, where n equals three). In some embodiments, ligninsulfonate utilized in disclosed compositions can be methylated, ethylated, or a combination thereof for example.

In some embodiments, any extent of alkylation can be utilized. In some embodiments, the alkylation can be substantially complete (for example, at least 98% of the free hydroxyl groups can be converted to alkoxy groups). In some embodiments, the amount of alkylation can be almost any amount, for example at least 95%, at least 90%, at least 85%>, at least 75%, at least 50%), at least 40%, or any number in between. As more of the ligninsulfonate is alkylated, the hydrogen bonding in the ligninsulfonate polymer will be decreased. In some embodiments, it is not clear to what extent the aliphatic hydroxyl groups are alkylated even though the aromatic hydroxyl groups are thought to be substantially or even in some embodiments completely derivatized.

Alkylation increases the weight of the ligninsulfonate polymer in comparison to the non- alkylated version. This is true because alkylation removes a hydrogen atom (atomic weight about 1 g/mol) and replaces it with an alkyl group. In embodiments where the alkyl group is a CH₃ group (molecular weight of about 15 g/mol), this increases the molecular weight of the ligninsulfonate polymer by about 14 g/mol for each hydrogen replaced with a methyl group. As such, an alkylated lignin will have a lower ligninsulfonate weight percent in a final composition than does its corresponding un-alkylated ligninsulfonate counterpart in the same composition.

In some embodiments where the alkylation will be methylation, various methods can be utilized to at least partially methylate the ligninsulfonate. In some embodiments, any

electrophilic methyl source can be utilized. Examples can include, iodomethane, dimethyl sulfate, dimethyl carbonate, methyl triflate, and methyl fluorosulfonate for example. In some embodiments, a nucleophilic methyl source can be utilized. Examples can include

diazomethane, methyllithium and Grignard reagents for example. Similar reagents can be used in instances where the ligninsulfonate is to be ethylated, propylated, or butylated for example. Disclosed ligninsulfonate components can also include ligninsulfonate that include a counter ion. The ligninsulfonate component can be referred to as a ligninsulfonate salt.

Illustrative examples of counter ions can include sodium and calcium for example. Disclosed compositions or polymers can include ligninsulfonate salts, ligninsulfonate salts that have had at least some of the counter ions replaced with hydrogens (e.g., at least some protonated

ligninsulfonate), or any combination thereof.

In some embodiments, a ligninsulfonate component can refer to a mixture of

ligninsulfonate components in which some of the sulfonic acid groups are protonated and some are in their sulfonate form with an accompanying counterion.

Ligninsulfonate components can also refer to mixtures of ligninsulfonates, un-alkylated ligninsulfonate that has counter ion(s) (e.g., un-alkylated ligninsulfonate salts), un-alkylated ligninsulfonate that is protonated (e.g., un-alkylated protonated ligninsulfonate), alkylated ligninsulfonate that is protonated (e.g., alkylated protonated ligninsulfonate), alkylated ligninsulfonate that has counter ion(s) (e.g., alkylated ligninsulfonate salts), or any combination thereof.

Ligninsulfonate salts can be obtained from various processes involving cellulosic material. For example, calcium bisulfite pulping of forest-harvest residuals (e.g, Douglas fir, etc.) can produce a product that includes calcium ligninsulfonate salts and sodium bisulfite pulping of forest-harvest residuals (e.g, Douglas fir, etc.) can produce a product that includes sodium ligninsulfonate salts. The Howard process, for example, can be utilized to produce calcium lignosulfonate. Products of such processes can be further processed in order to purify and/or concentrate the ligninsulfonate salts.

In some embodiments disclosed compositions include at least some protonated ligninsulfonates (whether alkylated or un-alkylated), in some embodiments disclosed

compositions include more protonated ligninsulfonates than ligninsulfonate salts (based on moles) (whether alkylated or un-alkylated), and in some embodiments disclosed compositions include substantially all protonated ligninsulfonates (whether alkylated or un-alkylated). In some embodiments, disclosed compositions include at least 50% protonated ligninsulfonates based on the total of protonated ligninsulfonate and ligninsulfonate salts. In some embodiments, disclosed compositions include at least 75% protonated ligninsulfonates based on the total of protonated ligninsulfonate and ligninsulfonate salts. In some embodiments, disclosed compositions include at least 90% protonated ligninsulfonates based on the total of protonated ligninsulfonate and ligninsulfonate salts. In some embodiments, disclosed compositions include at least 95% protonated ligninsulfonates based on the total of protonated ligninsulfonate and ligninsulfonate salts.

Also disclosed herein are methods. Such methods can include a step of obtaining a ligninsulfonate salt. The ligninsulfonate salt can be described as above, as including a ligninsulfonate component and a counter ion component. The ligninsulfonate salt can be obtained in any way. For example, a product from a previously carried out method or process to form and/or isolate a ligninsulfonate containing composition from a source (e.g, some plant matter) can be obtained. The product, so obtained, may or may not be further processed to isolate and/or concentrate the ligninsulfonate component. The starting product of disclosed methods can include more compounds or materials than simply the ligninsulfonate salt (e.g., the starting product can include solvent(s), by products from a previous process, original

components from the starting material, added materials, or any combination thereof). Such additional components can be removed, the concentration decreased, maintained, the

concentration increased, or any combination thereof before the starting product is utilized in a disclosed method. In an illustrative embodiment, the product of calcium or sodium sulfite pulping of Douglas fir forest-harvest residuals can be filtered (e.g., ultrafiltered) to use as a starting material for a disclosed method.

Disclosed methods can include steps of protonating ligninsulfonate components that include a counter ion, or stated another way replacing at least some of the counter ion component with a proton. Any known or typical methods of replacing counter ions with protons can be utilized herein. Illustrative methods include, for example, interaction of the ligninsulfonate salt with an ion exchange resin (e.g., in a column, in a bed of resin, in combination with a resin in a solution, etc.), ultrafiltration of the ligninsulfonate salt with (dilute) aqueous acid through a low- molecular weight cutoff membrane, or combinations thereof. In some specific illustrative methods, a ligninsulfonate salt can interact with an ion exchange resin in an alcohol solution (e.g., a methanol solution), or some other solution. In some specific illustrative methods, ligninsulfonate salts, which may have been previously purified, can be mixed with methanol and then interact with an ion exchange resin. In some specific illustrative methods, ligninsulfonate salts, which may have been previously purified, can be mixed with methanol and then that solution can be run through a column containing an ion exchange resin. Specific, but non- limiting examples of ion exchange resins include those sold under the AMBERLITE® name from Sigma-Aldrich Co. LLC (St. Louis, MO) such as AMBERLITE® IR120 hydrogen form (Sigma-Aldrich, St. Louis, MO).

Once at least some of the counter ions on the ligninsulfonate have been replaced by hydrogens to form at least some protonated ligninsulfonate, the next step includes forming a composition with the protonated ligninsulfonate. More specifically, the protonated

ligninsulfonate can be formed into a polymer. This can be accomplished with the protonated ligninsulfonate alone or by combining the protonated ligninsulfonate with a secondary component, for example, either in the presence or absence of a solvent. The step of forming a polymer may or may not be followed by or simultaneous with a step of forming an article from the polymer. This step can be accomplished using solvent casting, melt blending followed by extrusion, compression molding or injection molding. In methods such as solvent casting, for example, a composition can include one or more than one solvent that can be chosen based on, at least in part, the ability of the solvent(s) to form a blend of the protonated ligninsulfonate and optional secondary component(s).

Disclosed polymers that include lignosulfonate components can also include other secondary components. Disclosed polymers can also include more than one secondary component. A secondary component can also be characterized as a plasticizer, for example. One or more secondary components, if utilized, can be chosen in order to alter properties of a 100 wt% ligninsulfonate component containing polymer. In some embodiments, a secondary component can be chosen based on the ability of the chemical structure of the secondary component to interact with or affect functional groups or substructures of the ligninsulfonate component in a way that positively affects the properties of the ligninsulfonate component. It should also be noted that low molecular weight components within the ligninsulfonate component polymer could also act as plasticizers for the ligninsulfonate component polymer.

In some embodiments, virtually any secondary component could be utilized in disclosed compositions. Secondary component(s), if utilized, could be chosen based on various different properties, including, for example the ability of the secondary component to interact with the ligninsulfonate component polymer, relative cost of the secondary component(s), mechanical properties of the secondary component(s) or mechanical properties the secondary component(s) imparts to the ligninsulfonate component, non-mechanical properties (e.g., renewability, biodegradability, or others), or combinations thereof. In some embodiments, a secondary component(s) can be chosen based on the ability of the secondary component(s) to form a miscible blend with the ligninsulfonate component.

Illustrative secondary components can include for example polymers such as

poly(ethylene oxide), poly(ethylene glycol), poly(trimethylene glutarate) (PTMG),

polycaprolactone, poly(trimethylene succinate), and other main-chain aliphatic polyesters.

Exemplary secondary components can also include small molecules such as diethyl adipate, and 3,3',5,5'-tetrabromobisphenol A, for example. It should be noted that polymeric, monomeric, oligomeric and small molecule secondary components other than those exemplified herein are also envisioned herein. In some embodiments, a possible secondary component can include chitin or chitosans.

In some disclosed compositions, various amounts of ligninsulfonate component can be utilized. In some embodiments, compositions can include at least 50 weight percent (wt%) based on the total dry weight of the composition. Components in disclosed compositions can be described by the weight of the component based on the total dry weight of the total composition. The dry weight of the composition can be further described by the total weight of all of the components except any solvent that may be added to effect various methods of forming an article. In some embodiments, the total weight of a composition can include the weight of the ligninsulfonate component and any secondary component(s). In some embodiments, compositions can include at least 75 wt% ligninsulfonate component based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 80 wt% ligninsulfonate component based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 85 wt% ligninsulfonate component based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 90 wt% ligninsulfonate component based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 95 wt% ligninsulfonate component based on the total weight of the composition (without any solvent(s)). In some embodiments, disclosed compositions can include substantially all ligninsulfonate component, or 100 wt% of the total composition. Disclosed compositions can be formed into articles, for example polymeric articles using known and as yet heretofore unknown methods. For example, solvent casting, melt blending followed by extrusion, or compression molding. In methods such as solvent casting, for example, a composition can include one or more than one solvent that can be chosen based on, at least in part, the ability of the solvent(s) to form a blend of the ligninsulfonate component(s) and optional secondary component(s).

Articles formed from disclosed compositions can be formed into or used as any type of structure including for example block structures (regular or irregular), sheet structures, fiber structures or film structures. Properties of the formed article that may be relevant or of interest may vary depending on the type of structure and the purpose for which the article is to be used. Exemplary properties that may be relevant can include, for example mechanical properties such as tensile strength, elongation at break, ductility, plastic deformation, bending characteristics, and melt rheology.

In some embodiments, disclosed articles or materials can have tensile strengths of at least about 30 MPa. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have tensile strengths of at least about 40 MPa. In some

embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have tensile strengths of at least about 50 MPa. In some embodiments disclosed articles or materials (e.g., those formed from disclosed compositions) can have tensile strengths of at least about 60 MPa. In some embodiments disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 1.5%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 3%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 5%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 7%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of about 10% or greater.

Examples Objects and advantages are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

All chemicals were obtained from Aldrich, Inc. (or a similar commercial provider) and were used without further purification unless otherwise noted.

Example 1

Methods

Ball Milled Lignin Preparation

Jack pine 1.5 cm3 sapwood blocks were ground in a Wiley mill to a 40-mesh particle size. The resulting wood meal was Soxhlet-extracted with acetone for 48 h. The dry extractive- free wood meal was then milled in a cooled vibratory ball mill under N2 for 48 h. A 40 g quantity of the ball-milled wood meal was suspended and stirred in dioxane-water (96:4 v/v) three consecutive times over 96 h. The extracts were centrifuged (3000 rpm, Beckman J6B, 30 min) and thereafter the solvents were removed by rotary evaporation. The lignin isolated was systematically purified by treatment with 9: 1 :4: 18 v/v/v/v pyridine/acetic acid/water/chloroform whereupon, after solvent removal, the remaining material was dissolved in 2: 1 v/v

dichloroethane/ethanol and precipitated with ether. The carbohydrate content of the resulting product was so low that any monosaccharides liberated through acid catalysis could not be detected by standard chromatographic means.

Methylation of lignin preparations with dimethyl sulfate

The lignin preparation prepared as above was dissolved (about 20 g/L) in aqueous 60% dioxane containing 0.10 molar (M) NaOH. Dimethyl sulfate (Aldrich, Inc.) was added at a level of 2 mL/g lignin to the solution under N₂. The pH of the mixture kept falling as a result of hydroxyl-group methylation. Solution containing 2.0 M NaOH and corresponding amounts of dioxane were repeatedly added to dissolve any precipitates formed during methylation and to adjust the pH of the mixture to a value between 12.5 and 13.5. When the pH remained constant upon basification, the same amount of dimethyl sulfate was again added. This overall procedure was repeated 4 times. Upon the 5th addition of dimethyl sulfate and aqueous dioxane containing 2.0 M NaOH, the mixture, after incubation, was neutralized with aqueous 0.5 M H₂SO₄. The dioxane was removed exhaustively at neutral pH by rotary evaporation at about 35° C. The residue was washed with distilled water until complete removal of sulfate was accomplished and the product was air-dried. The partially methylated product was further methylated by diazomethane as described below.

Methylation with diazomethane

The diazomethane used was prepared by distilling it from Diazald (Aldrich, Inc.) in an aqueous base-chloroform mixture. A 30 mL volume of chloroform was added to a cold biphasic mixture composed of 30 mL aqueous 1 g/mL KOH and 30 mL 2-ethoxyethanol in a 250 mL clear-seal -joint distilling flask from the Diazald kit. The chloroform-aqueous KOH-2- ethoxyethanol mixture was magnetically stirred and heated in a water bath at about 80°C. When the first drop of chloroform appeared at the collecting end of the condenser in the apparatus, 150 mL 0.1 g/mL Diazald in chloroform was slowly introduced into the mixture in the distilling flask over a period of about 15 to 20 min, and then an additional 75 mL volume of fresh chloroform was added to the boiling mixture. The diazomethane was collected together with chloroform in a receiving flask under ice. The cold diazomethane-chloroform solution was mixed with 1 g of the lignin preparation that had been methylated with dimethyl sulfate and pre-dissolved in chloroform. The mixture was kept in the dark overnight. In order to discharge the unreacted diazomethane, the mixture was extracted with 0.5 M H₂SO₄ five times and thoroughly washed with distilled water. After sufficient centrifugation at 3000 rpm, the clear chloroform layer was dried with anhydrous Na₂S0₄ and filtered. The chloroform was removed by rotary evaporation.

The above methylation procedures were utilized to afford complete methylation of lignin preparations and lignin derivatives. However, less thorough methylation would also result in useful lignin-based materials, although in certain instances there could be significant differences in the mechanical properties of the blends produced or in the blend compositions employed.

Ligninsulfonate preparation

Ligninsulfonate was received in a solution of sulfite spent liquor which had been produced from forest residues primarily (-90%) or almost completely composed of Douglas fir wood. This solution had been ultrafiltered through a 200 kDa nominal-molecular-weight-cutoff membrane and retained by a 4 kDa membrane before shipment.

Ligninsulfonate samples were prepared by exhaustive ultrafiltration in water through a 1 kDa nominal-molecular-weight-cutoff membrane followed by freeze-drying of the solution with pH adjusted to 7.5. Prior to further processing, the ligninsulfonate was protonated with Amberlite IR120 (Sigma-Aldrich) in methanol which, after filtration, was subsequently removed by rotary evaporation.

Methylation of ligninsulfonate with dimethyl sulfate

A quantity of 3.6 g ligninsulfonate in 600 mL aqueous 50% dioxane was methylated with 25 mL dimethyl sulfate (Sigma-Aldrich) at pH -13. The pH of the mixture kept falling as a result of hydroxyl-group methylation. A solution containing 4.0 M NaOH and a corresponding amount of dioxane were repeatedly added to maintain the pH of the mixture at a value between 12.5 and 13.5. When the pH remained constant upon basification, the same amount of dimethyl sulfate was again added. This overall procedure was repeated 4 times. When the reaction was deemed complete, the solution mixture was neutralized with aqueous 0.1 M H₂S0₄. The dioxane was removed by rotary evaporation, whereupon the resulting solution was subjected to ultrafiltration in water through a 1 kDa nominal-molecular-weight-cutoff membrane. After brief centrifugation to remove traces of insoluble material, the retentate was freeze-dried.

Methylation of methylated ligninsulfonate with diazomethane

About 1.8 g partially methylated ligninsulfonate was protonated using Amberlite IR120 in -150 mL methanol before the sulfonic acid groups were methylated in chloroform with diazomethane prepared as previously described. The reaction mixture was allowed to proceed in the dark for -16 h, and the entire procedure was repeated until methylation was complete. The volume of the reaction mixture (-2 L) was reduced to -500 mL by rotary evaporation. About 300 mL acidified water (pH 4.1) was introduced to discharge any residual diazomethane. After exhaustive washing with distilled water, the methylated ligninsulfonate solution was dried with sodium sulfate, and the chloroform removed under reduced pressure.

Solution casting

A 0.6 g quantity of ball-milled lignin or ligninsulfonate with or without other blend components was dissolved in 4.0 mL dimethyl sulfoxide (DMSO) in a 10 x 20 mm Teflon mold at 50° or 80°C, respectively. After degassing under reduced pressure in a vacuum oven at 50°C for 15 min, the ball-milled lignin test pieces were produced by solution-casting at 150° for a day and then 180°C for 3 h. The ligninsulfonate-based blend-component solutions were degassed in a similar way at 80°C for 15 min, and the corresponding test pieces were formed by solution- casting typically at 115°C for 24 h and then 150°C for a further 24 h.

Size-exclusion chromatography (SEC) The molecular weight distribution of BML was determined by eluting through Sephadex G100 (Sigma-Aldrich) in aqueous carbonate-free 0.10 M NaOH. The SEC profile was monitored spectrophotometrically at A280 and calibrated with paucidisperse

polystyrenesulfonate fractions (American Polymer Standards, Mentor, OH). The elution profile exhibited no excluded peak. The weight- and number-average molecular weights of LS were determined under conditions that have been previously described.

NMR analysis

Quantitative 13C NMR spectra were recorded with a 600 MHz Varian Inova instrument using a 5 mm HCN cold probe. Weights amounting to -0.2 g BML, MB ML and sMLS were individually dissolved in 1 g DMSO-d6, while -0.1 g dMLS was similarly dissolved in the same solvent. A 90° pulse width, 1.4 s acquisition time and 12 s relaxation delay were employed in collecting 10,000 scans from each solution. Chemical shifts were referenced to DMSO (39.51 ppm). The 2D Q-HSQC spectra of BML and MBML were obtained from 5% solutions in DMSO-d6 using a 700 MHz Bruker Avance instrument with a 5 mm TXI cryoprobe.

Tensile tests

The solid rectangular test pieces were filed into dog-bone-shaped specimens of which the typical dimensions were 5 mm in width, 8 mm in length between shoulders and -1 mm in thickness. The tensile behavior of each ligninsulfonate-based plastic specimen was

characterized by means of a stress-strain curve measured with an Instron model 5542 unit fitted with a 500 N static load cell. Serrated jaws were used to hold all test pieces in place. No tensile test was initiated until the load reading had become stable. A crosshead speed of 0.05 mm min-1 was employed with specimen gauge lengths of 7-8 mm. Young's modulus (E) and the stress (omax) and strain (εσ, max) at fracture were calculated on the basis of initial sample dimensions.

Differential scanning calorimetry (DSC)

DSC measurements were performed with a Q2000 instrument (TA Instruments) equipped with Refrigerated Cooling System 90. Samples weighing -8 mg were sealed with a lid in an aluminum pan after flushing with N₂ for 15 h in a glove-box. Each unmethylated or singly- methylated ligninsulfonate preparation was pre-scanned from 40° to 170°C at 10°C min-1. The second scan was carried out from -90° to 165°C at a heating rate of 10°C min-1. The glass- transition temperature would have been identified as the half-height point in the glass-transition region of the DSC thermogram, had the requisite feature been present. X-ray powder diffraction

X-ray diffraction patterns were obtained in a 5° - 36° range of the diffraction angle, 2Θ (where Θ is the angle of the 1.542 A incident beam), with a Bruker AXS D5005 diffractometer operating in the reflection mode using Cu Ka radiation and a diffracted-beam monochromator. Powdered unmethylated and methylated ligninsulfonate samples were compressed onto a zero- background holder and 0.06° step-size scans were taken with 18 s dwell times. The diffraction patterns generated by these amorphous unmethylated and methylated ligninsulfonates (FIG. 4A- F) were fitted to sums of two Lorentzian functions with respect to a fixed algebraic baseline identified for each complete pattern to lie below that for the experimental data. The

contributions from the two peaks to any overall diffraction pattern are consequently proportional to the Lorentzian peak-area sections above the experimental baseline.

Atomic force microscopy (AFM)

After sectioning and trimming, the unmethylated and methylated ligninsulfonate-based materials were individually mounted in a specimen-holder fitted with a double-D clamp (Mager Scientific, Dexter, MI). The surface of each specimen was smoothed using a 45° glass blade for ultramicrotome-cutting with a 1 μπι step-size on a Leica EM UC6 apparatus to produce successive layers. The resulting surface was burnished further, using a 100 - 300 nm step-size several times, and immediately subjected to AFM scanning. The AFM experiments were carried out with a Bruker Nanoscope V multimode 8 scanning-probe microscope employed in a tapping mode for generating tip-oscillation-amplitude images. The monolithic silicon probe (ArrowTM NCR, NanoWorld AG, Switzerland) chosen for this work featured a 160^m-long cantilever holding a tetrahedral tip 10 - 15 μπι in height with a typical radius of curvature less than 10 nm. AFM scans were recorded with a Nanoscope 8.15 unit (Bruker) while online plane-fitting for images was turned off. Gwyddion software was used to process and analyse the AFM images. The center-to-center distances between adjacent nodular features in the amplitude images (FIG. 5A-C) were measured manually.

Results

The weight- and number-average molecular weights of the ball milled lignin (BML) were determined using size-exclusion chromatography to be 2300 and 750, respectively, under conditions that have been previously described. No detectable monosaccharides were released from this preparation as a result of acid-catalyzed hydrolysis. The quantitative ¹³C-NMR spectrum of the BML (as a 20% solution in DMSO-d6) was very similar to that previously reported for spruce milled wood lignin. The 5C 55.6 ppm C-3 methoxyl peak area, when multiplied by 6.12, amounted to 99.3% of the spectral area in the aromatic range (-108-156 ppm), indicating that the BML was composed almost entirely of guaiacyl units.

After consecutive methylation with dimethyl sulfate and diazomethane, the proportion of aromatic methoxyl groups (centered around 55.5 and 56.6 ppm) increased by 31% owing to the manifestation of these groups on C-4 of the methylated ball-milled lignin (MB ML). This increase is identical to the estimated phenolic hydroxyl group frequency in spruce milled wood lignin. The effect is consistent with the observed shift of a conspicuous portion of the 5C 147.4 aromatic C-4 BML feature to 148.5 ppm in the MB ML.

Methylation also gave rise to aliphatic methoxyl signals centered around 5C 58.5 with a ~4-fold smaller peak appearing at 58.2 ppm; together these amounted to an area equivalent to 31%) of the original aromatic C-3 methoxyl substituents. These aliphatic methoxyl groups are bound, in part, to C-γ of β-Ο-4 ethers, and indeed the corresponding C-β around 5C/5H ~ 84.3/4.3 in the HSQC spectrum of BML shifted to 5C/5H 82.3/4.4 after methylation.

The blend-compositions were chosen to create an initial framework for the materials being compared. As far as methylated ball-milled lignin-based materials are concerned, the casting conditions have a significant effect on tensile behavior: in the absence of other blend components, the more volatile lignin-derived oligomers (produced under the lignin-isolation conditions themselves) act as plasticizers. When cast at 150 °C, the methylated ball-milled lignin (MBML) alone exhibits a tensile strength of 43 MPa with 5% elongation-at-break (FIG. 1). Such a result compares very favorably with polystyrene and clearly refutes the likelihood of crosslinking in lignins. All of the phenolic and many of the aliphatic hydroxyl groups in the ball- milled lignin are methylated under the derivatization conditions employed; this simple step reduces the brittleness of the cast materials substantially. Blending of MBML with 15%> poly(ethylene glycol) leads to a tensile strength of 52 MPa with elongation-at-break above 6%>. However, 15%> levels of poly(ethylene oxide-b-l,2-butadiene) or poly(trimethylene glutarate) do not individually improve the tensile behavior of 85%> MBML-based polymeric materials (FIG. 1).

The purity of the ligninsulfonate in the spent liquor (obtained from a process of calcium bisulfite pulping of Douglas fir forest-harvest residuals that had been carried out for approximately 6 h at 145°C in the presence of approximately 6.6% (w/w) total S0₂ (with respect to wood) under conditions previously described by J.Y. Zhu, M. S. Chandra, F. Gu, R. Gleisner, R. Reiner, J. Sessions, G. Marrs, J. Gao and D. Anderson, Bioresour. Technol., 2015, 179, 390- 397), was increased 2-fold by consecutive ultrafiltration through 200 kDa and 4 kDa nominal molecular weight cutoff membranes. The resulting 87% pure ligninsulfonate held in the 4 kDa- membrane retentate was employed to develop formulations for polymeric materials with high ligninsulfonate contents. By means of size-exclusion chromatography, this polyanionic lignin derivative was found to possess weight- and number-average molecular weights of 7.1-9.6 kDa and 1.9 kDa respectively.

The ligninsulfonate (LS) was methylated either with dimethyl sulfate alone or consecutively with dimethyl sulfate and diazomethane. The peak-areas in the quantitative 13C- MR spectra of the singly and doubly methylated derivatives (sMLS and dMLS as 20% and 10%) solutions, respectively, in DMSO-d6) were scaled in relation to the corresponding aromatic spectral features (107-156 ppm) in keeping with the protocol for the BML and MBML analyses. After multiplying the overall 5C 55.5 peak-area by 6.12, it was evident that the C-3 and C-4 methoxyls along with the methyl sulfonate groups in the sMLS contributed, on average, 1.39 methyl groups altogether to each sMLS monomer unit. Comparison with the corresponding ratio for MBML here reveals that a substantial number of the sulfonic acid groups had already been methylated by dimethyl sulfate. This proportion increased significantly as a result of subsequent methylation by diazomethane, whereupon the 5C 55.5 peak-ratio rose to 1.45. Reaction of sMLS with diazomethane also raised the frequency of aliphatic methoxyl groups in dMLS: the relative area of the signal centered around 5C 58.4-58.5 ppm increased from 0.19 to 0.30. Interestingly, this final value for dMLS is almost identical to the corresponding ratio for MBML.

Casting the singly-methylated ligninsulfonate (sMLS) alone resulted in a material that exhibited a 28 MPa tensile strength with 5% elongation-at-break (FIG. 2). An outcome like this suggests that certain simple sMLS blends should be capable of matching polyethylene in their tensile behavior. However, a sMLS-based material cast with 15%> w/w poly(trimethylene glutarate) suffered a >10% reduction in tensile strength, although the corresponding blend with 15%) w/w polycaprolactone supported a 40% improvement in elongation-at-break (FIG. 2).

A particularly interesting result was encountered with the doubly-methylated

ligninsulfonate (dMLS). A dMLS-based blend with 15% w/w poly(trimethylene glutarate) manifested a 24 MPa tensile strength with 11% elongation-at-break (FIG. 2). Evidently, the reduction in intermolecular hydrogen bonding that accompanies complete phenolic hydroxyl and sulfonic acid group methylation can reduce the brittleness of certain ligninsulfonate-based polymeric material blends quite appreciably.

The impact of the various noncovalent forces (hydrogen bonding, electron correlation, dipolar interactions) on the ductility of LS-based materials is difficult to predict at this stage in reference to any particular blend composition. For example, an unmethylated (M_w 9.6 kDa, M_n 1.9 kDa) LS-based blend with 15% w/w poly(trimethylene glutarate) has manifested a tensile strength near 35 MPa with 7% elongation-at-break, even though the solution-cast material based on LS alone did not exceed 22 MPa in tensile strength with 3.5% elongation-at-break (FIG. 3A). Yet, the corresponding LS-based blends with 15% w/w polycaprolactone and 15%

poly(trimethylene succinate) individually exhibited tensile strengths of 26 and 30 MPa, respectively, at 5% and 6% elongations-at-break (FIG. 3A). On the other hand, with another unmethylated ligninsulfonate (LS) preparation (M_w 7.1 kDa, M_n 1.9 kDa), a blend incorporating 15%) PTMG resulted in a material with 47 MPa tensile strength and 7% elongation-at-break

(FIG. 3B). After methylation with dimethyl sulfate, the sMLS (methylated ligninsulfonate derivative) blend incorporating 15% PTMG resulted in a material with 46 MPa tensile strength and 10%) elongation-at-break (FIG. 3B). Both of these (unmethylated and methylated) ligninsulfonate-based blends with 15% PTMG surpass polystyrene in tensile behavior.

The arrangements of the aromatic rings among chain segments in the unmethylated and methylated LS-based materials are reflected in their X-ray powder diffraction patterns. Before and after casting, the diffuse scattered intensities may be typically described as sums of two overlapping Lorentzian peaks with maxima centered at equivalent Bragg spacings (d) of 3.9 - 4.2 A and 5.8 - 6.1 A (FIGs. 4A-4F). In accordance with previous X-ray powder diffraction analyses of paucidisperse kraft lignin fractions, the two distributions of separation distances can be respectively attributed to distinct series of co-facial and edge-on arrangements of interacting aromatic rings. The contributions to the decrease in energy from the noncovalent forces that stabilize the two kinds of configurations have been estimated to be 7 - 11 and ~4 kcal/mol, respectively, at the M05-2X/6-31+G(d,p) level of density of functional theory.

The co-facial arrangements of interacting aromatic rings presumably occupy the inner regions of the macromolecular entities in the unmethylated and methylated LS, while the edge- on orientations are more prevalent among the peripheral chain segments. In the cast materials, the proportions of the two contrasting configurations of interacting aromatic rings is determined, in part, by the requirements for continuity between adjoining macromolecular species. There is a notable decrease in the proportion of edge-on arrangements of aromatic rings as a direct result of casting all three LS-based materials (FIGs. 4A-F). In the case of the unmethylated LS, the Lorentzian peak emanating from the edge-on configurations disappeared altogether during casting. Evidently, the contours of the stable co-facial arrangements of aromatic rings in the cast material can match one another without the persistence of A- or nm-scale voids between adjacent macromolecular entities.

Fresh surfaces of the cast unmethylated and methylated LS-based materials were created by ultramicrotome-cutting with a 45° glass blade. The procedure was carried out (between ambient and -60°C) at a temperature above which the surface features showed some likelihood of coalescing or otherwise undergoing deformation. Atomic force microscopy (AFM) was employed in the tapping mode to probe the surfaces of the three cast (LS, sMLS and dMLS) materials represented in terms of the respective tip-oscillation amplitude images (FIGs. 5A to 5C) and, for confirmatory purposes, the corresponding height images (exemplified in FIG. 5D).

Adjacent local maxima in the nodular surface features of the LS-, sMLS- and dMLS- based materials are separated by 12.2 ± 3.2, 16.7 ± 4.3 and 20.3 ± 5.5 nm, respectively. These distances mirror the ranges of the effective diameters characterizing the macromolecular entities of which the unmethylated and methylated LS-based materials are composed. It is unlikely that LS-methylation would engender covalent formation of larger macromolecular entities, and thus the increase in diameter of these species is more likely to arise from coalescence during casting. The probability of coalescence rests on the molecular-weight dependence of the intermolecular interactions between the individual LS components. In this respect, it seems that the

macromolecular entities in the cast sMLS- and dMLS-based materials are (in three dimensions) approximately 2- and 4-fold larger, respectively, than those making up the unmethylated LS. Such a situation could occur, for example, if the strongest noncovalent interactions between the methylated LS components were to involve the intermediate rather than higher chain lengths.

The question naturally arises as to whether the dimensions of the constituent

macromolecular entities in the cast unmethylated and methylated LS-based materials are reasonable in relation to any previous estimates. A 2010 study of the track-etched-membrane fractionation of an industrial kraft lignin sample at 0.01 gL-1 in aqueous solution concluded that over 60% and 70%, respectively, of the supra-macromolecular solute species were below 30 nm in size at pHs 7.0 and 9.5 (Russ. J. Appl. Chem. 2010, 83, 1281-1283). The similarity of these results to those presently reported for LS-based materials is particularly striking because the supra-macromolecular kraft lignin species had undergone expansion as a result of their dissolution/suspension in aqueous solution.

In relation to the actual surface topologies of the LS-based materials, the AFM images in FIGs. 5A to 5D have been convoluted in regard to the smoother traces produced with the <10 nm tip radius of the instrument probe. This limitation will not, however, impose an appreciable error on the values of the separation distances between peak maxima.

The first comparative survey of unmethylated and methylated ligninsulfonate-based polymeric materials has been shown here. The new materials are composed of macromolecular entities with 9-15 nm dimensions. Simple blends with small quantities (<15%) of miscible low- Tg polymers, for example, can surpass polystyrene in tensile behavior. Such findings are promising.

There are two notable aspects to the properties of the unmethylated and singly- methylated ligninsulfonate-based materials. First, their differential scanning calorimetric thermograms are without features that could be related to a glass-transition temperature.

Evidently the prominent domains that encompass co-facially disposed aromatic rings among the constituent macromolecular species (FIGs. 4A to 4F) cannot accommodate sufficient chain- segmental motion.

Second, the unmethylated and singly-methylated ligninsulfonate-based materials do not, after casting, dissolve in water despite the original solubility of the components in aqueous solution. Thus, pronounced physicochemical changes have taken place at elevated temperatures that have either dramatically increased the pKa's of the buried sulfonic acid groups or resulted in the formation of sultones (cyclic sulfonate esters) and/or intermolecular sulfonate esters.

Example 2

Ball-milled lignin was isolated from Jack pine as previously described above in Example 1. The purified sample was successively methylated with dimethyl sulfate in alkaline aqueous dioxane and then with diazomethane in chloroform as in Example 1 above. Ligninsulfonate was received as a sample in spent sulfite liquor produced (primarily or exclusively) from Douglas fir residues as described above in Example 1.

After ultrafiltering the spent sulfite liquor in water through a 1 kDa nominal-molecular- weight-cutoff membrane and adjusting the pH to 7.5, the retentate was freeze-dried. The ligninsulfonate was protonated with Amberlite IR120 in methanol to produce unmethylated material for casting. Phenolic-hydroxyl-group methylation was carried out with dimethyl sulfate in aqueous 50% dioxane. Upon completion, the dioxane was removed and the resulting solution (upon pH-adjustment) was subjected to ultrafiltration in water through a 1 kDa membrane prior to freeze-drying. Before casting, the partially methylated ligninsulfonate was again protonated using Amberlite IR120 in methanol.

Solution casting of the methylated ball-milled lignin and (separately) unmethylated or methylated ligninsulfonate (with or without blend components) in DMSO was carried out in teflon molds at 150°C (for the former samples) or typically stepwise at 1 15° and then 150°C (for the latter samples) as discussed in Example 1 above. After filing, the resulting pieces were subj ected to tensile tests as described above in Example 1.

Results

It is readily demonstrable that plastics consisting solely of methylated ball-milled lignins (MBMLs) can exhibit tensile behavior that surpasses many commercial polymeric materials including polystyrene (46 MPa tensile strength, 2.2% elongation-at-break). Small quantities (5- 10%) w/w) of miscible blend components as unassuming as poly(ethylene glycol) can enhance tensile behavior considerably.

When comparing the tensile behavior of MBML-based materials containing 0-30% w/w miscible blend components, a linear relationship persists between toughness and elongation-at- break (FIG. 6) in the absence of substantial plastic deformation. On the other hand, the somewhat weaker correlation between tensile strength and modulus (FIG. 7) is less affected by the ductility of the MBML-based plastics.

Unmethylated softwood ligninsulfonate (LS) samples blended individually with 10%> w/w poly(ethylene glycol) or various aliphatic polyesters at 15%> w/w incorporation levels exhibit a range of tensile behavior that, with small adjustments, could approach polyethylene (30 MPa, 9% elongation-at-break) (FIG. 8). These results embody a trend that, through blend formulations based on other unmethylated or methylated ligninsulfonate samples, are capable of surpassing the tensile strength of polystyrene (FIG. 3B). Phenolic-hydroxyl-group methylation of the LS only brings about a small improvement in the tensile strength of the resulting sMLS.

In polymeric materials with the highest attainable lignin-derivative contents, the constituent macromolecular species are associated complexes that are assembled from individual components as a result of strong noncovalent forces between lignin substructures. Interacting aromatic rings within the interiors are cofacially offset with respect to one another, while those in the peripheral domains of the complexes are often positioned in edge-on arrangements. X-ray powder diffraction reveals that continuity between adjoining complexes is established though their peripheral domains during the casting of lignin-based polymeric materials. Atomic force microscopy of freshly ultramicrotome-cut surfaces reveals that the macromolecular entities in the MB ML- and LS-based materials have dimensions of 9-16 nm and 9-15 nm, respectively.

The polymeric materials respectively composed of MBML and LS alone share remarkable similarities. The constituent macromolecular species possess almost identical dimensions despite the differing molecular weight distributions of these dissimilar lignin derivatives. Contrary to initial expectations, the cast MBML-based plastic is insoluble in DMSO while the cast SL-based material is insoluble in water. The physicochemical changes accounting for these observations await elucidation.

Thus, embodiments of compositions including ligninsulfonates are disclosed. The implementations described above and other implementations are within the scope of the following claims. One skilled in the art will appreciate that the present disclosure can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation.

Non-Alkylated Lignin Lignin provides structure to plant cell-wall materials and is the component responsible for the strength of wood against mechanical stress for example. Lignin is a highly abundant biopolymeric material (second only to cellulose) and can be derived from, for example, wood via processes that have been used for many years. Lignin is an amorphous, polyphenolic

macromolecule with a complex structure. Despite extensive investigations, the complex and irregular structure of lignin is not completely understood. The physical and chemical properties of lignin can vary depending upon the wood and plant species, the botanical origin, and the region from which the wood or plant material is harvested, and the process by which the lignin is isolated.

Useful lignin components may be obtained from a number of plant-based lignin- removing processes, including the kraft, organosolv, steam explosion, soda, autohydrolysis extraction processes, and mechanical milling followed by extraction. Lignins from these sources are readily available. For example, kraft lignin derivatives are by-products of the principal process employed in the United States for chemically convening wood chips into pulp for making paper. Instead of burning the kraft lignin derivative as fuel in the pulp mill, it may be used to prepare disclosed compositions.

Lignin macromolecules are composed of para-hydroxyphenylpropane units linked together through six or seven different carbon-oxygen or carbon-carbon bonds. Depending on the source of the lignin, the individual aromatic rings differ according to the frequency (zero, one or two) of attached methoxyl groups.

Also disclosed herein are polymers that include non-alkylated lignin. Disclosed compositions can utilize lignin in various forms, both native and chemically modified. For example, disclosed compositions can utilize native lignin (not chemically modified). In some embodiments, any form of lignin can be utilized. Useful lignin components may be obtained from a number of plant-based lignin-removing processes, including the kraft, organosolv, steam explosion, soda, autohydrolysis extraction processes, and mechanical milling. Lignins from these sources are readily available. For example, kraft lignin derivatives are by-products of the principal process employed in the United States for chemically converting wood chips into pulp for making paper. Instead of burning the kraft lignin derivative as fuel in the pulp mill, it may be used to prepare disclosed compositions.

In some embodiments, disclosed compositions can utilize native lignins. Native lignin refers to lignin that has not been chemically cleaved. Native lignin can include lignin that has been mechanically cleaved however. One method of isolating lignin from its starting product (for example, wood of some sort) includes milling along with inert balls followed by extraction. Such lignin can be referred to as ball milled lignin (referred to herein as "BML"). Various known and heretofore unknown methods and processes of obtaining BML can be utilized to obtain native lignin that can be utilized in disclosed compositions. In some embodiments, mechanical methods other than ball milling can also be utilized assuming that they do not chemically cleave a substantial amount of bonds in the lignin. In some embodiments, methods other than ball milling can also be utilized assuming that they do not chemically cleave the majority of the inter-unit bonds in the lignin.

Disclosed compositions include non-alkylated lignin. Non-alkylated lignin is lignin in which no free hydroxyl groups present in the native lignin have been alkylated by chemical means. Non-alkylated lignin and lignin are different mostly in the frequency of hydrogen bonding between the lignin components and non-lignin components.

Disclosed polymers that include non-alkylated lignin can also include other secondary components. Disclosed polymers can also include more than one secondary component. A secondary component can also be characterized as a plasticizer, for example. One or more secondary components, if utilized, can be chosen in order to alter properties of a 100 wt% non- alkylated lignin containing polymer. In some embodiments, a secondary component can be chosen based on the ability of the chemical structure of the secondary component to interact with or affect functional groups or substructures of the non-alkylated lignin in a way that positively affects the properties of the non-alkylated lignin. It should also be noted that low molecular weight components within the non-alkylated lignin polymer could also act as plasticizers for the non-alkylated lignin polymer.

In some embodiments, virtually any secondary component could be utilized in disclosed compositions. Secondary component(s), if utilized, could be chosen based on various different properties, including, for example the ability of the secondary component to interact with the non-alkylated lignin polymer, relative cost of the secondary component(s), mechanical properties of the secondary component(s) or mechanical properties the secondary component(s) imparts to the non-alkylated lignin, non-mechanical properties (e.g., renewability, biodegradability, or others), or combinations thereof. In some embodiments, a secondary component(s) can be chosen based on the ability of the secondary component(s) to form a miscible blend with the non-alkylated lignin.

Illustrative secondary components can include for example polymers such as

poly(ethylene oxide), poly(ethylene oxide-b-l,2-butadiene), poly(ethylene oxide-b-1,2- butadiene-b-ethylene oxide), poly (ethylene glycol), poly(trimethylene glutarate),

polycaprolactone, poly(trimethylene succinate), and other main-chain aliphatic polyesters. Exemplary secondary components can also include small molecules such as diethyl adipate, and 3,3',5,5'-tetrabromobisphenol A, for example. It should be noted that polymeric, monomeric, oligomeric and small molecule secondary components other than those exemplified herein are also envisioned herein.

In some disclosed compositions, various amounts of non-alkylated lignin can be utilized.

In some embodiments, compositions can include at least 50 weight percent (wt%) based on the total dry weight of the composition. Components in disclosed compositions can be described by the weight of the component based on the total dry weight of the total composition. The dry weight of the composition can be further described by the total weight of all of the components except any solvent that may be added to effect various methods of forming an article. In some embodiments, the total weight of a composition can include the weight of the non-alkylated lignin and any secondary component(s). In some embodiments, compositions can include at least 75 wt% non-alkylated lignin based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 80 wt% non-alkylated lignin based on the total weight of the composition (without any solvent(s)). In some

embodiments, compositions can include at least 85 wt% non-alkylated lignin based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 90 wt% non-alkylated lignin based on the total weight of the composition (without any solvent(s)). In some embodiments, compositions can include at least 95 wt% non- alkylated lignin based on the total weight of the composition (without any solvent(s)). In some embodiments, disclosed compositions can include substantially all non-alkylated lignin, or 100 wt% of the total composition.

The compositions and articles disclosed herein can be considered a significant advance in next-generation plastics with high lignin contents. In some embodiments, disclosed

compositions and articles involve blending with various quantities (for example anywhere from 0 wt% to 25 wt%) of secondary, e.g., miscible polymeric, oligomeric and/or monomeric components. Despite the relative simplicity of disclosed compositions, these new polymer blends embody by far the highest lignin contents of any materials reported with useful mechanical properties.

The economic importance of the disclosed lignin-based plastics may lie in the prospects for "biorefining" lignocellulosic plant materials (including wood) to produce liquid "biofuels" and other commodity organic chemicals. It is generally agreed that biorefineries will require significant value added to the lignin co-products from lignocellulose for increased economic viability. Disclosed compositions take a truly significant step forward toward this goal.

The context in which the disclosed compositions have been derived may be briefly described as follows. The lignin-containing polymeric materials previously disclosed, for example between 1970 and 2000, were limited in their usefulness by the fact that increasing lignin contents resulted in worse mechanical properties, as far as the overall trends were concerned. Generally, materials with lignin contents greater than 35-40% were fatally compromised. Previous work with kraft-lignin-based plastics overcame this limitation and demonstrated the feasibility of incorporating methylated kraft lignin preparations (derived from softwood pulp mills) at 70-75% levels into polymeric-material blends with quite promising behavior as lignin-based plastics.

In some embodiments more than one type of lignin can be utilized in disclosed compositions and materials. In some embodiments native lignin and one or more chemically modified lignin could be utilized in disclosed compositions. For example, in some compositions both native lignin, such as bail milled lignin, and lignosultonates could be utilized in disclosed compositions.

Disclosed compositions can be formed into articles, for example polymeric articles using known and as yet heretofore unknown methods. For example, solvent casting, melt blending followed by extrusion, compression molding or injection molding. In methods such as solvent casting, for example, a composition can include one or more than one solvent that can be chosen based on, at least in part, the ability of the solvent(s) to form a blend of the alkylated lignins and optional secondary component(s).

Articles formed from disclosed compositions can be formed into or used as any type of structure including for example block structures (regular or irregular), sheet structures, or film structures. Properties of the formed article that may be relevant or of interest may vary depending on the type of structure and the purpose for which the article is to be used. Exemplary properties that may be relevant can include, for example mechanical properties such as tensile strength, elongation at break, ductility, plastic deformation, bending characteristics, and melt rheology. In some embodiments, disclosed articles or materials can have tensile strengths of at least about 35 MPa. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have tensile strengths of at least about 40 MPa. In some

embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have tensile strengths of at least about 50 MPa. In some embodiments disclosed articles or materials (e.g., those formed from disclosed compositions) can have tensile strengths of at least about 55 MPa. In some embodiments disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 1.5%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 3%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 5%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of at least about 7%. In some embodiments, disclosed articles or materials (e.g., those formed from disclosed compositions) can have an elongation-at-break of about 10% or greater.

Examples

Objects and advantages are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

All chemicals were obtained from Aldrich, Inc. (or a similar commercial provider) and were used without further purification unless otherwise noted.

Example 1

Methods

Ball Milled Lignin (BML) Preparation

Jack pine 1.5 cm³ sapwood blocks were ground in a Wiley mill to a 40-mesh particle size. The resulting wood meal was Soxhlet-extracted with acetone for 48 h. The dry extractive-free wood meal was then milled in a cooled vibratory ball mill under N2 for 48 h. A 40 g quantity of the ball-milled wood meal was suspended and stirred in dioxane-water (96:4 v/v) three consecutive times over 96 h. The extracts were centrifuged (3000 rpm, Beckman J6B, 30 min) and thereafter the solvents were removed by rotary evaporation. The lignin isolated was systematically purified by treatment with 9: 1 :4: 18 v/v/v/v pyridine/acetic acid/water/chloroform whereupon, after solvent removal, the remaining material was dissolved in 2: 1 v/v dichloroethane/ethanol and precipitated with ether. The carbohydrate content of the resulting product was so low that any monosaccharides liberated through acid catalysis could not be detected by standard chromatographic means.

A 0.6 g quantity of BML with or without other blend components (as discussed below) was dissolved in 4.0 mL dimethyl sulfoxide (DMSO) in a 10 x 20 mm Teflon mold at 50°C. After degassing under reduced pressure in a vacuum oven at 50°C for 15 min, the BML test pieces were produced by solution-casting at 150° for a day and then 180°C for 3 h.

A100% BML based material, a 98 wt% BML blend with 2 wt% polyethylene oxide-b- 1 ,2-butadiene-b-ethylene oxide) ("EBE"), a 95 wt% BML blend with 5 wt%

tetrabromobisphenol-A ("TBBP-A", a flame retardant), and a 95 wt% BML blend with 5 wt% poly(trimethylene glutarate) ("PTMG") were solution cast.

The solid rectangular test pieces were filed into dog-bone-shaped specimens of which the typical dimensions were 5 mm in width, 8 mm in length between shoulders and ~1 mm in thickness. The tensile behavior of each BML-based plastic specimen was characterized by means of a stress-strain curve measured with an Instron model 5542 unit fitted with a 500 N static load cell. Serrated jaws were used to hold all test pieces in place. No tensile test was initiated until the load reading had become stable. A crosshead speed of 0.05 mm min-1 was employed with specimen gauge lengths of 7-8 mm. Young's modulus (E) and the stress (omax) and strain (εσ, max) at fracture were calculated on the basis of initial sample dimensions.

Results

FIG. 9 shows the tensile behavior of the unmethylated BML and three blends. As seen there, the tensile properties of the 95% BML blend with 5% PTMG (40 MPa strength, 7% elongation-at-break) and the 100% BML-based material (34 MPa strength, 6% elongation-at- break) are "midway" between those of polystyrene (46 MPa strength, 2% elongation-at-break) and polyethylene (30 MPa strength, 9% elongation-at-break). Moreover, the tensile properties of the 95 % BML blend with 5% TBBP-A (54 MPa strength, 7% elongation-at-break) and the 98% BML blend with 2% EBE (58 MPa strength, 9% elongation-at-break) clearly surpass those of polystyrene and polyethylene.

One skilled in the art will appreciate that the articles, devices and methods described herein can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation. One will also understand that components of the articles, devices and methods depicted and described with regard to the figures and embodiments herein may be interchangeable.

All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

As used in this specification and the appended claims, the singular forms "a", "an", and

"the" encompass embodiments having plural referents, unless the content clearly dictates otherwise.

As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. The term "and/or" means one or all of the listed elements or a combination of any two or more of the listed elements.

As used herein, "have", "having", "include", "including", "comprise", "comprising" or the like are used in their open ended sense, and generally mean "including, but not limited to". It will be understood that "consisting essentially of, "consisting of, and the like are subsumed in "comprising" and the like. For example, a conductive trace that "comprises" silver may be a conductive trace that "consists of silver or that "consists essentially of silver.

As used herein, "consisting essentially of," as it relates to a composition, apparatus, system, method or the like, means that the components of the composition, apparatus, system, method or the like are limited to the enumerated components and any other components that do not materially affect the basic and novel characteristic(s) of the composition, apparatus, system, method or the like.

The words "preferred" and "preferably" refer to embodiments that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred

embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure, including the claims. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. or 10 or less includes 10, 9.4, 7.6, 5, 4.3, 2.9, 1.62, 0.3, etc.). Where a range of values is "up to" a particular value, that value is included within the range.

Use of "first," "second," etc. in the description above and the claims that follow is not intended to necessarily indicate that the enumerated number of objects are present. For example, a "second" substrate is merely intended to differentiate from another infusion device (such as a "first" substrate). Use of "first," "second," etc. in the description above and the claims that follow is also not necessarily intended to indicate that one comes earlier in time than the other.

Thus, embodiments of compositions including lignin are disclosed. The implementations described above and other implementations are within the scope of the following claims. One skilled in the art will appreciate that the present disclosure can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation.

Claims

Claims:

1. A polymer comprising:

a ligninsulfonate component.

2. The polymer according to claim 1, wherein the ligninsulfonate is protonated

ligninsulfonate.

3. The polymer according to claims 1 or 2, wherein the ligninsulfonate component comprises alkylated ligninsulfonate.

4. The polymer according to claim 3, wherein the alkylated ligninsulfonate comprises methylated ligninsulfonate.

5. The polymer according to claim 4, wherein the ligninsulfonate is methylated with dimethyl sulfate.

6. The polymer according to claim 5, wherein the methylated ligninsulfonate is further methylated with diazomethane.

7. The polymer according to any one of claims 1 to 6 comprising at least 75 wt% ligninsulfonate component based on the total weight of the composition.

8. The polymer according to any one of claims 1 to 6 comprising at least 85 wt% ligninsulfonate component based on the total weight of the composition.

9. The polymer according to any one of claims 1 to 8 further comprising one or more main- chain aliphatic polyesters.

10. The polymer according to any one of claims 1 to 9, wherein the polymer comprises one or more of poly(ethylene oxide), poly(ethylene glycol), poly(trimethylene glutarate) (PTMG) polycaprolactone, and poly(trimethylene succinate).

11. The polymer according to any one of claims 1 to 9, wherein the polymer further comprises polycaprolactone.

12. The polymer according to any one of claims 1 to 11, wherein the polymer comprises about 85 wt% ligninsulfonate component and about 15% polycaprolactone, based on the total weight of the composition.

13. The polymer according to claim 12, wherein the ligninsulfonate component is at least partially methylated ligninsulfonate.

14. The polymer according to any one of claims 1 to 9, wherein the polymer further comprises poly(trimethylene glutarate) (PTMG).

15. The polymer according to any one of claims 1 to 11 or 14, wherein the polymer comprises about 85 wt% ligninsulfonate component and about 15% poly(trimethylene glutarate) (PTMG), based on the total weight of the composition.

16. The polymer according to claim 15, wherein the ligninsulfonate component is at least partially methylated ligninsulfonate.

17. A method comprising:

obtaining a ligninsulfonate salt, the ligninsulfonate salt comprising a ligninsulfonate component and a counter ion component;

replacing at least some of the counter ion component with a proton to obtain a protonated ligninsulfonate; and

forming a polymer from at least the protonated ligninsulfonate.

18. The method according to claim 17, wherein the step of replacing at least some of the counter ion component with a proton comprises utilizing a cation exchange resin.

19. A polymer compri sing :

non-alkylated lignin.

20. The polymer according to claim 19, wherein the non-alkylated lignin is ball milled lignin (BML).

21. The polymer according to claim 19 or 20 comprising at least 75 wt% non-alkylated lignin based on the total weight of the composition.

22. The polymer according to any one of claims 19 to 21 comprising at least 85 wt% non- alkylated lignin based on the total weight of the composition

23. The polymer according to any one of claims 19 to 22 further comprising one or more main-chain aliphatic polyesters.

24. The polymer according to any one of claim 19 to 23 further comprising one or more of poly(ethylene oxide), poly(ethylene oxide-b-l,2-butadiene), poly(ethylene oxide-b-1,2- butadiene-b-ethylene oxide), poly (ethylene glycol), poly(trimethylene glutarate),

polycaprolactone, poly(trimethylene succinate), and tetrabromobisphenol-A