WO2016040228A1

WO2016040228A1 - Enhanced cellulosic materials

Info

Publication number: WO2016040228A1
Application number: PCT/US2015/048790
Authority: WO
Inventors: Giuseppe Trigiante
Original assignee: Humanitarian Scientific Llc
Priority date: 2014-09-08
Filing date: 2015-09-08
Publication date: 2016-03-17

Abstract

The present invention describes methods of treating cellulosic materials to enhance mechanical properties of said cellulosic materials and/or to provide coatings on said cellulosic materials.

Description

ENHANCED CELLULOSIC MATERIALS BACKGROU D OF THE INVENTION

FIELD OF THE INVENTIO

(0001 J The present invention relates generally to methods of treating celluiosic-compound containing ma terials, and more specifically to methods of modifying the mechanical properties of cellulose-based materials, including modifying of ceilulosic surfaces, where such modified cellulose-based materials are useful environmentally friendly replacements for products containing oil-based plastics.

BACKGROUND INFORMATION

(0002) Naiiocelhilose or Microfibrillated cellulose (MFC) is a physical derivative of cellulose obtained via partial enzymatic digestion and high pressure extrusion of cellulose pulp. MCF properties include a heightened viscosity for the same water content, where the presence of nanoscaSe crystals of cellulose allow MFC to retain optical transparency when dried into films. These films also display a superior mechanical resistance compared to dried, products directly obtained from pulp,

(0003) As such, MCF represents an ideal candidate to replace petroleum based plastics, namely polyethylene, in the packaging industry with significant economic and environmental benefits, since MCF is derived from a renewable source and is itself recyclable, compostabie and biodegradable,

(0 0 j However, MCF has a potential weakness which prevents its immediate and widespread use; it is fragile, it exhibits a high degree of brittieness and a tendency to fracture at stress points, thereby compromising useful barrier function. While not being bound by theory, this fragility is due, in part, to the crystallimty of the stmcture at the nanoraolecular scale, which crystal Unity imparts excessive hardness io the structure and creates stress points under deformation.

[0005) Cellulose consists of a hierarchical arrangentent of a linear polymer of glucose into rigid nanofibrils which eventually associate into higher orders of structure still maintaining linearity and rigidity. Θ 06] The process by which the material is generated is aimed at separating the insoluble fibers of cellulose in a metas table-solution, into nanofibrils onl a few nm in width. In this state, the solution resembles a gel, such as those obtained with soluble polysaccharides. However, this state is thermodynamical^'ly unstable as cellulose has a natural tendency to form crystals in the form of long aggregate fibers of hydrogen bonded fibrils.

[00071 When the gel is allowed to dry, ih fibrils rebind in a random orientation forming a mesh held together by hydrogen bonds, yielding a material of high strength (comparable to aluminum) and good gas barrier properties. The small dimensions of the solid units allow visible wavelengths though and render the material clear.

(Θ008) The fact that each fibril is rigid and tightly bonded to its neighbors is the reason for the rigidity of the structure as a whole and its weakness to strain. It would be desirable to modify this material in such a way as to preserve its optical and environmental friendliness properties while obviating to its intrinsic fragility.

1O00&I In addition, many advantages of cellulose are countered by the hydrophificity of th material, which shows high affinity for water and can easily absorb large amounts of it (see, e.g., Aalin et a.L Langmuir (2009) 25(1 3):76?5-?685). While this is a benefit for applications such as absorbents and tissues, it ^'becomes an issue when the safe packaging of watery material (e.g., foodstuffs) is required. Long term storage of food, especially ready made meals which contain a significant amount of water, is made problematic in cellulose trays as they would first become soggy and then ultimately disrupt under the hydration of their fibers.

JOw O j This problem is usually addressed in the industry by coating the cellulose fiber with some kind of hydrophobic organic material, for example a resin or a polymer, which would physically shield the underlying hydrophiiie cellulose from the water in the contents. Materials such as PVC are routinely used for this puipose and are physically attached (i.e., spray coated) on the surfaces to he treated. 0OJ ί I A similar problem is encountered when sealing foodstuff in its container by means of a film. This film requires even more stringent properties than the container itself. On top of the resistance to mechanical stress, the film, must be thin enough to be peeled off, should ideally be transparent, heat resistant, and impermeant to gases such as CO> and oxygen, non toxic, and hydrophobic. Again, plastic in the form of polymers and resin is the present solution of the industry, jO l 2] New materials have been designed which are either derived from natural sources or semi-synthetic sources and therefore are renewable and/or biodegradable. Materials such as poly- lactic acid (PLA) and poly hydroxyalkanoate (ΡΙ-ΙΆ) are the present golden standard for

biodegradable "plasties." However, they suffer the drawbacks of heat instability which severely limit their use in the packaging industry, where there is a need for coatings that are amenable to heat sealing.

[0013] One problem with the present coatings is that they are too thin. Previous processes involve derivaiixation of the hydroxy! groups on the cellulose surface with a fatty acid chloride. This derivatkation results in a monomolecular layer on the cellulose, however, the reaction can only be used once.

| ΘΜ4| What is needed is a method that allows fo the generation of various coating thicknesses using a more flexible approach. The present invention provides environmentally friendly solutions to reduce inherent fragility and provide for better surface coatings.

SUMMARY OF THE INVENTION ft⁾{il5] The present disclosure relates to a variant of the production process of MFC films and materials aimed at disrupting the direct and exclusi ve aggregation of rigid components into a mesh and -interspersing them with flexible polymers equally suitable at forming hydrogen bonds, equally transparent and biodegradable but not forming linear aggregates (e.g., gums).

]0016j in addition, the present disclosure relates to coating processes based on the chain opening polymerization reaction of cyclic esters (lactones.) of fatty acids, including the use of aluminum or yttrium catalysts, and comprises the use of an initiator under mild conditions, lit a related aspect, the hydroxyl attacks and opens the lactone forming an ester bond and leaving an exposed hydroxyl which may further react with lactone molecules resulting in an extending chain. The resulting plastic (poiycaprolactone) is ecofriend!y and heat scalable, it is also hydrophobic and pro vides a water barrier function.

[00:17] In a further related aspect, the initiator may be a cellulose hydroxykted surface ha sang a chain built on it, where the reaction is terminated by addition of an acyl chloride which "caps" the chain, with, an acyl group. Appropriate choice of toning and acyl chloride amounts will yield various chain lengths hence thickness of the film.

[00! 8] In embodiment, a method of coating a cellulose containing surface is disclosed including eoniaciiig one or more cyclic esters of hydrocarbons with the hydroxy! groups on a cellulose surface in the presence of an aluminum of yttrium catalyst to covaiently attach a polyester moiet on the surface of said cellulose; and reacting the contacted surface with an electrophilic chain terminator, where the resulting modified surface exhibits increased water contact angle relative to a non-treated surface.

[0019] In one aspect, the electrophilic chain terminator is an acyl chloride. In another aspect, the electrophilic chain terminator is a linear CIO to C50 acyl chloride.

[Θ92Θ] in another aspect, the reaction scheme is as follows;

wherein R is an alkyl group and a is 10-40. in a related aspect, the acyl chloride is present at a ratio of about .1:0.01, about 0.5:0.02, or about 0.1:0.033 to the lactone. 002J 1 in another aspect, an aprotic base as catalyst, and acid buffer is added to the polyeaproSactone and acyichiori.de. In a related aspect, the aprotic amine is present at a ratio of about 0.5:0.00.1 , about 0.2:0.01 , or about 0.1 :0.02 to the lactone. In a further related aspect, the aprotic base is selected from the group consisting of pyridine, trialky laroines, bicycJic amines, and combinations thereof. la another aspect, a composition, comprisin a surface treated by the method above is disclosed. [0022} In one aspect, the resulting modified surface exhibits a water contact angle greater than about 60'^", in another aspect, the cellulose is microfibrillated cellulose (MFC), In a farther aspect, the method further comprises mixing of a gum with the resulting MFC, whereby the resulting coated surface exhibits at least a two fold increas in tensile strength as compared to the non- treated surface. In a related aspect, the mixing is carried out at between about 50* C and about 100° C.

[0023] in one embodiment, a solid eellukise-eontainiug material is disclosed, where at least a portion of the hydroxy! groups available on the surface of the solid cellulose-containing material are attac hed directly via a first ester bond to an open chain deri vative of a cyc lic ester, where additional, open, chain derivatives of the sam cyclic esters are attached to each other by ester bonds to form a polymer, where the oxygen atoms contained in the hydroxy! groups available at the end of the polymer are attached directly via an ester bond to the carbon atom of the acyl group of an alkanoic acid derivative having the formula:

K-CO- where R is a straight-chain, branched-ehain, or cyclic aliphatic hydrocarbon .radical having from 10 to 40 carbon atoms, where the surface of the resulting esierified solid cellulose-containing material exhibits a water contact angle of between 60° to about ! 20 \ and where the portion of the hydroxyl groups esierified on the surface of the cel!olose-containing material is greater than 40%.

[0024| In a related aspect, the cellulose-containing material is tnicroiibriliated cellulose (MFC).

[0025] in another embodiment, a method of preparing a nanoceilulose composi tion is disclosed including mixing microfibri!lated cellulose (MFC) and a gum; heating the mixture until a substantially homogenous mixture is formed: and drying said mixed MFC and. gum into a sheet, where the resulting combination exhibits increased thickness compared to a nanoceilulose composition comprising the MFC alone.

10026] In. one aspect, the resulting composition exhibits an. increase in. tensile strength of at least 1.2 fold. In another aspect, the gum includes agarose, gel!ao, k-earageenan, agar-agar, alginate, glucoraannan, and combinations thereof. [0027) in one aspect, the gum is present in an amount from 5% to 40% by weight, and the MFC is present i an amount, of between about 0.5% to about 3% by weight. In another aspect, a composition is disclosed prepared by t e above method.

BRIEF DESCRIPTION OF THE DRAWINGS

(0028] FIG. 1 shows the structure of a typical cell ulose vs. gum bond.

(0029] FIG. 2 shows graph of thickness o f MFC and agarose-MFC (Ag-MFC).

(0030] F!G. 3 shows tensile strength of Ag-MFC.

(0031] FIG. 4 show a photograph of a coated MFC surface.

(0032] FIG. 5 shows test swatches for MFC Generic 2 (left before, right after treatment).

(0033] FIG. 6 shows test swatches for MFC surface coated with myristoic acid groups (left before, right after treatment).

DETAILED DESCRIPTION OF THE INVENTION

[003 1 Before the present composition, methods, and methodologies are described, it is to be understood that this invention is not limited to particular compositions, methods, and

experimeriial conditions described, as such compositions, methods, and conditions may vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is no intended to be limiting, since the scope of the present invention will be limited only in tbe appended claims.

(0035] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include piurai -references unless the context clearly dictates otherwise. Thus, for example, references to "a deriviiizing agent" includes one or more derivitrang agents, and/or compositions of the type described herein whieh will become apparent to those persons skilled in the art upo reading this disclosure and so forth.

[0036) Unless defined otherwise, all technical and scientific terms used herein have tbe same meaning as commonly understood by one of ordinar skill in the art to which this invention belongs. Any methods and materials similar or equivalent to those described herein may be used in the practice or testing of the iiwentlon, as it will be understood thai modifications and

variations are encompassed within the spirit arid, scope of the instant disclosure.

[Θ037] It is well known that esters are organic molecules with a high biodegradability as bacteria! enzymes readily break them down. They are however relatively stable to physical agents such as heat.

[0038] As used herein, "celMosic" means natural synthetic or semisynthetic materials that can be molded or extruded into objects or films or filaments, which may be used for making such objects or films or filaments, that are structurally and functionally similar to cellulose, e.g., coatings and adhesives (e.g., earboxymethylceliulose}. In another example, cellulose, a complex carbohydrate

that is composed of glucose units, which forms the main constituent of the cell wail in most plants, is eelluiosic.

[0039] As used herein, "hydrophobicity" means the property of being water-repellent, tending to repel and not absorb water.

{^'0040] As used herein, "cellulose-containing material" means a compositio which consists essentially of cellulose. For example, such material may include, hot is not limited to, a carton for food storage, a bag for food storage, a bottle for carbonated liquid storage, a bottle for non- carbonated liquid storage, film for wrapping food, a garbage disposal container, a food handling implement, a fabric fibre (e.g., cotton or cotton blends), a water storage and conveying implement, alcoholic ornon alcoholic drinks, an outer casing or screen for electronic goods, an internal or external piece of furniture, a curtain and upholstery,

{0041] As used herein "biodegradable," including grammatical variations thereof means capable of bein broken down especially into innocuous products by the action of living things (e.g., by microorganisms).

[0042] As used herein, "neat" means there is substantially no other molecule present in the substance inc luding the absence of a solvent.

[6043] As used herein, "water contact angle" means the angle measured through a liquid at which a liquid/vapor interface meets a solid surface. It quantifies the wettability of the sol id surface by the liquid. The contact angle is a reflection of how strongly the liquid and solid molecules interact with each other, relative to how strongly each Interacts with its own kind. On many highly hydrophilic surfaces, water droplets will exhibit contact angles of f) degrees to 30 degrees. Generally, if the water contact angle is larger than. 90 degrees, the solid, surface is considered hydrophobic .

(0044] As used ^'herein, "water vapour permeability" means^' breathabi!ity or a textile's ability to transfer moisture. There are at least two different measurement methods. One, the MVT Test (Moisture Vapour Transmission .Rate) in accordance with ISO 15496, describes the water vapor pemieabilitv (WVP) of a fabric and therefore the degree of perspiration transport to the outside air. The measurements determine how many grams of moisture (water vapor) pass through a ^'square mete -of fabric in 24 ^'hours (the higher the level, the higher the breathability).

(0045] As used herein, "oxygen permeability" means the degree to which a polymer allows the passage of a gas or fluid. Oxygen permeability (Ok) of a material is a function of the dtffusivity (D) (i.e., the speed at which oxygen molecules traverse the mate-rial) asid the solubility (k) (of the amount of oxygen molecules absorbed, per volume, in the material). Values of oxygen permeability (Dk) typically fall within the range 1.0-150 x 10^*" (cm^"' .ml 0₂)/(s ml nimlig). A semi-logarithmic relationship has been demonstrated between hydroget water content and oxygen, permeability (Unit: Barrer unit). The international Organization for Standardization (ISO) has specified permeability usin the SI unit hectopascal (hPa) for pressure. Hence Dk^:::T0^"! ' (cm ml 0 )i(s ml hPa). The Barrer unit can be converted to h^'Pa unit by mul iplying it by the constant 0.75.

(0046] i embodiments, the invention may include a variant of the production process of MFC films and materials aimed at disrupting the direct and exclusive aggregation of rigid components into a mesh and interspersing them with, flexible polymers equally suitable at forming hydrogen bonds, equally transparent and biodegradable but. not forming linear aggregates. These compounds are known in the art as "gums" and, in spite of the very varied chemical nature, have common biological origins and physicochemica!. characteristics.

(00471 The gums are all also polysaccharides like cellulose that is polymers of a sugar but. the main difference lies in the bond which links the sugars together. Whereas in cellulose all the bonds are "β" as in FIG. 1 , top, in other polysaccharides and gums there are also "a" bonds. As can be seen, the former bond accounts for a linear distribution of the glucoses whereas the latter forces a nonlinear (i.e., spiral, coil or other) structure. The fact that gums also contain branching points in their chains enhances this "amorphous" structure.

[0048} It is self evident that a nonlinear structure is more amenable to deformation than a linear one. in fact, this is why gums are used as thickeners and gelling agents in a. large variety of applications, from th cosmetic to the food and even research fields.

[0049] Another important feature of the gums is thai they are, at the molecular level, very similar to cellulose and therefore potentially completely mixable with it: in fact, they have a high density of hydroxy I groups able to form strong bonds with cellulose. Moreover, they are of natural origin and completely biodegradable.

[0050) In embodiments, the invention includes mixing MFC in the watery gel state with a polysaccharide gum gel, in variable amount, prior to the drying phase. This ensures thai when the final, mesh is formed it contains mostly cellulose nanofibrils but interspersed with gam molecules so as to allow the fibril mesh to deform under stress, up to a point where the gum molecules themselves are fully stretched and oppose any further deformation. The net result is to add flexibility to resilience and obtain a material with superior tensile strength and retained optical aud environmental benefits. In embodiments, gum is present in an amount from 5% to 40% by weight and the MFC is present in an amount of between about 0.5% to about 3% by weight. In a preferred embodiment, the gum. to MFC ratio is 1 :4.

[0051 j Another bene fit is the reduced density of the material, due to the lower density of the less organized gum molecules. This makes the resulting material lighter and stronger per unit mass.

[0052] Typical gums which can be used in the process include, but are not limited to, agarose, geilan, k-carrageenan. agar-agar, alginate, glueonmnnan, and combinations thereof.

[0053] In embodiments, methods of coating MFC surfaces are disclosed. In a related aspect, the coating on cellulose heat, seal able. In a related aspect, the coating on cellulose is hydrophobic.

[6054] In embodiments, an MFC gel and gum are first heated prior to the mixing stage. While not being bound by theory, this may facilitate the disruption of existing hydrogen bonds and assist in the formation of intermolecular bonds between the cellulose and the gum chains. In a related aspect, the heating temperature may be about 50° C to about 60* C, about 60° C to about 70° C, about 70° C to about 80° C, about 80° C to about 9i C, and about 90° C to about 100° C. In a .related aspect, heating may be carded out between, about 50° C to about 1 00" C. jO SSj The MFC and gum are bonded by hydrogen bonds so no covalent bonds are involved. In one aspect; once a sheet is formed a layer of solution of another polymer may be added, where the solution is allowed io dry to form another sheet. As such, there is no need to "rewet" the second surface as the hydroxyls groups are still on the surface for MFC-gum interaction. Such composite layered materials may comprise 1 to 2 additional layers, 2 to 3 additional layers, 3 to 4 additional layers, and up to 10 additional layers. In. a related aspect, such layering would provide additional flexibility to structures, including, but not limited to increased resistance to tearing and increased tensile strength, without necessarily increasing elasticity due to the rigidity of the MFC layer. jW⁾56 j The extension reaction, started by a nucleopfai^'Uc hydroxy!, cannot include another hydroxy! (hence no second MFC surface or gum). The capped chain (supra) is utrreactive and will not further crosslink (which is a benefit for the material's iner properties), in embodiments, the reaction may be allowed to occur between two layers of MFC or cellulose, which reactions do not include an acyl chloride as a terminator, hut a dlacyi chloride (C!-CO-R-CO-Cl). This reagent will react with two extending chains from the different surfaces, and crosslink them. In a related aspect the result would be a layer of poly caprolac tone sandwiched between cellulose, where the resulting structure would behave like a PE-cardboard composite with higher water barrier function, wouid remain biodegradable, and exhibit increased flexibility and tensile strength. In further related aspect, such a reaction as described above, may include tri- and tetraacyl chlorides (as from branched chain polycarboxylic acids) that would Intensify the crosslinks. The reaction condition would be as recited, supra.

[Θ057] in embodiments, the cellulose-containing material (or ce!lulosic) and gum composition comprises alternating layers of gum and cellulose-containing material w here the cellulose- containing material can form none, one or both of the outer layers of the composition. In embodiments the outer surface of the cellulose-containing material of the composition can be derivitized by treating with a cellulose-containing (or cellulosic) material by applying to the surface a composition containing an a!kanoie acid derivative having the formula (1):

R-CO-X Formula (1) Θ 58] where R. is a straight-chain, branched-chain, or cyclic aliphatic hydrocarbon radical having from 6 to 50 carbon atoms, and where X is CI, Br, 1 or 0(CO)O. , a base, and a first solvent, heating the applied composition on the surface; rinsing the surface with a second solvent; and drying the rinsed surface; where the composition esterifies at least a portion of the hydroxy! groups available via the cellulose of the material. In general, i has been found that acyl groups containing fewer than about 6 carbon atoms in chain length do not produce satisfactory waier-repellency. Accordingly, chain lengths greater than 6 carbon atoms may be used to practice the invention as disclosed, in embodiments, chain lengths may be 8-50, 10-40, and 10-30 carbon atoms. In embodiments, the carbon atom chain length may be 10-20 carbon atoms.

[0059] In embodiments, the cellulose and gum composition comprises gum-cellulose containing material gum- cellulose-containing material-gum, cellulose-containing material - gum-cell ulose-con tai nbig maieri ai .

J0060] In embodiments, a method as disclosed herein is based on the chain opening polymerization reaction of cyclic esters (lactones) of fatty acids. This reaction may be carried out using aluminum or yttrium catalysts, requiring a raicleophilie initiator (e.g., an alcohol) under mild conditions.

[0061} The hydroxy! attacks and opens the lactone forming an ester bond and leaving an exposed hydroxy! which can further .react with lactone molecules resulting in an extending chain. The resulting plastic (po!ycaproiactone) is ecofriendiy, heat sea!able and ready to use. 00621 in a related aspect, the alcohol initiator is replaced with a cellulose hydroxylated surface having the chain built on it, where the reaction is terminated by addition of an acyi chloride which "caps" the chain with an acyl group. Appropriate choice of timing and acyl chloride amount will yield various chain lengths hence thickness of the film. In a related aspect, a non-nucleopht!ic base such as pyridine, may be added in the capping reaction.

[0063) The reaction scheme is as follows:

(Scheme 1 ) where R is an acyl group n - .1 -20.

[<MN> ] While not ^'being bound by theory, the thickness of the coating as disclosed is

independent of the amount of cyclic ester reagent, and instead relies on the length of the alky! chain R and the amount of acyl chloride, as there is no physical absorption, of the coating on the substrate, but a chemical linking reaction, which may foe variable, on the hydroxy! layer of the surface. The second capping step (i.e., reaction of poiycaprolactone with RCOCI) may be carried out as described in U.S. Pub. No. 20150.148532 and 20130345415, herein incorporated by reference in their entireties.

[0065] In embodiments, where the process and composition relates to coating processes based on the chain opening polymerization reaction of cyclic esters (lactones) of fatty acids, including the use of aluminum or yttrium catalysts, and comprises the use of an initiator under mild, conditions the resulting poiycaprolactone chain ma be terminated by addition of an diacyl chloride (Cl-CO-R-CO-C!) which "caps" the chain with an acyl group. The diacyl chloride will react wi h two extending chains, from the same or different surfaces, and crosslink result in cross Unking. The result poiycaprolactone sandwiched between cellulose containing materia! will have higher water barrier function, increased flexibility and tensile strength as compared to aon treated cellulose based material. In embodiments,, the acylchioride can be tri- and teiraacy! chlorides (as from branched chain polycarboxylic acids), these would increase the crosslinks, i.e., would intensify the crosslinks. Reaction conditions and reagents for the chain, termination reaction are the same as disclosed for esterifi cation of the alkanoic acid derivative of formula (I) to cellulose. is from 6 to 50 carbon atoms. Chain lengths greater than 6 carbon atoms may be used to praciice the invention as disclosed, In embodiments, chain lengths may be 8-50, 10-40, and 10-30 carbon atoms. In embodiments, the carbon atom chain length may be 10-20 carbon atoms.

|0066| in embodiments, eellulose-po!ycaprolactone composition comprises alternating layers of poiycaproiaetone and cellulose-containing material is disclosed, wherein the capping reaction covalently bonds the polycaprolactone and cellulose-containing material,, and wherein, the cellulose-containing material may form none, one or both of the outer Savers of the composition. In embodiments, the outer surface can. be esterified with the derivative of formula (I).

[0067] No special preparation of the material is necessary in practicing this invention, except thai the surface to be treated should be clean and free of di t and excess moisture, in

embodiments, normally air-dried material which contains a few percent adsorbed moisture may be used. In some embodiments, material may be dried prior to treatment (e.g., at 1 1 Q^¾€ for a few minutes) to remove most of the adsorbed moisture.

10068] Depending on the source, the cellulose may be nanoeellulose, cellulose nanofibres, whiskers or microfibril, microfibrillated, cotton or cotton blends, or nanofibril cellulose. f 01)69) in embodiments, the amount of coating applied is sufficient to completely cover at least one surface of a cellulose-containing material. For example, in embodiments, the coating may be applied to the complete ou ter surface of a container, the complete inner surface of a container, or a combination thereof. In other embodimen ts, the complete ripper surface o a film may be covered by the coating, or the complete under surface of a. film may be covered by the coating, or a combination thereof. In some embodiments, the lumen of a device/instrument may be covered by the coating or the outer surface of the device/instrument may be coveted by the coating, o a combination thereof. In embodiment, the amount of coating applied is sufficient to partially cover at least one surface of a cellulose-containing material. For example, only those surfaces exposed to the ambient atmosphere are covered by the coating, or only those surfaces that are not exposed to the ambient atmosphere are covered by the coating. As will be apparent to one of skill in. the art, the amount of coating applied will, be dependent on the use of the material to be covered.

|ββ?β] Any suitable coating process may be used to deliver any of various the coatings applied in the course of practicing this aspect of the method, in embodiments, coating processes include immersion, spraying, painting,, and any combination of any of these processes, alone or with other coating processes adapted for practicing the methods as disclosed.

(Θ0711 hi general, longer chain acid derivatives give greater impermeability, other factors such as depth of cellulose treated being- equal. The degree of impermeability can be measured through various techniques known to the skilled in the art such as moisture vapor transmission rate or water contact angle measurement.

[0072] In embodiments, the cyclic ester or cyclic ester/catalyst combination may be sprayed on the material to be derivatized. and optionally heated to about 80° io aboirt 210" C, about 100° to about 150° C or about 1 ί 0° to about 130° C for a vanable period (e.g., for about 1 mm to about 2.5 hours, from about 15 m to about 3 hours or from about I hours to about 3 hours). The surface may then be rinsed with detergent (surfactant) and water or a solvent (e.g., acetone) and dried again, A surfactant may be an ionic (catioaic and anionic) surfactant, a non-ionic surfactant, or a combination thereof.

(00731 I^'« embodiments the reaction is conducted in the presence of an acyl chloride in a molar ratio of about. 1 :0l _» or about 0.5:0.2 or aboirt 0.1 0.33 to the lactone . The acyl chloride has a chain length of about 5 to 70 carbon atoms, preferably 10 to 50 carbon atoms.

[Θ074] In embodiments the reaction also contains an aptotic base as catalyst to both the extension and capping reactions, and to neutralize the hydrochloric acid released during the capping reaction. This base present in the ratio of 0.5:0.00! , or about 0.2 to 0.01 or about 0.1 to 0.02 to the lactone. Exainpies of such bases are bu t are not limited to pyridine, trialkylamines, bic-yelic amines.

|0β?5] It will be apparent to one of skill io the art that the selection of cellulose to be treated, the reaction temperature (or vapor pressure), and the exposure time are process parameters that may be optimized by routine experimentation to suit any particular application for the final product.

|Θ076) in embodiments, materials treated according to the presently disclosed procedure display a complete biodegradahi!ity as measured by the degradation in the environment under microorganismal attack. [0077] Jn embodiments, materials treated according to the presently disclosed procedure display moisture vapor transmission rates of 1 to K)„ preferably 0, 1 to 5 and more preferably .01. to 1 g/nrVday. in embodiments, materials treated according to the presently disclosed procedure display water contact angles of 60 degrees to 135 degrees or preferably 90 degrees to 120 degrees.

[00781 Various methods are available to define and test biodegradatelity including the shake- flask method (ASTM E l 279 - 89(2008)) and the Zahn-We!lens test (OEC.D TG 302 B).

[Θ079] Materials suitable for treatment by the process of this invention include various forms of cel l ulose, such as cotton fibers, plant fibers such as flax, wood fibers, regenerated cellulose (rayon and cellophane), partially alkylated cellulose (cellulose ethers), partially esterifsed cellulose (acetate rayon), and other modified cellulose materials which have a substantial portion of their hydroxy! groups a vailable for reaction. As sta ted above, the term "cellulose" includes all of these .materials and others of similar polysaccharide structure and having similar properties. Among these the relatively novel materia! micmfibrillated cellulose (nanoceliulose) (as defined e.g. in US patent US4374702 and application 20090221 812, herein, incorporated by .reference in their entireties) is particularly suitable for this application as it can form transparetU films of high specific resistance, in other embodiments, celluloses may include but are not limited to, cellulose triacetate, cellulose propionate, cellulose acetate propionate, cellulose acetate boiyrate, nitrocellulose (cellulose nitrate), cellulose sulfate, celluloid, methylcelluiose, ethy!cellulose, ethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, ethyl hydroxyethyl cellulose. carboxymethyi

cellulose, and combinations thereof..

[0080] The modification of the cellulose as disclosed may increase its tensile strength and flexibility, thereb further widening its spectrum of use. Ail biodegradable and partially biodegradable products made from or by using the modified, cellulose disclosed in. this application are within the scope of the disclosure,

[00811 Among the possible applications of the coating technology such items include, but are not limited to, paper, cardboard, containers for all purpos such as boxes, trays, shopping bags, pipes and water conduits, food grade disposable cutlery, plates and bottles, screens for TV and mobile devices, clothing (e.g., cotton or cotton blends.) and medical devices to be used on the body or inside It such as corUraceptives. Also, the coaling technology as disclosed may be used on furniture and upholstery, outdoors camping equipment and the like.

[0082] The following examples are intended to illustrate but not limit the invention.

EXAMPLES

Example 1. Enhancing the mechanical properties of nanocellulose using gelling polysaccharides.

[0083] As an example agarose-MFC was prepared, which material is obtained by the combinat ion of agarose (i.e., "Ag", a strong gelling gum) and MFC in a 1 :4 ratio and subsequent drying into sheets. The material thickness and tensile strength per unit mass are reported below in Figures 2 and 3.

Example 2. Biocomposiabilny assay on MFC and coated MFC.

[Θ084] Method; two -samples were cut; from sheets derived from MFC Generic- 2 (Innventia, Sweden) one of which (Sample I) had been surface coated with myristoic acid groups using the reaction Scheme 1 (see above). A coated MFC surface is shown in FIG, 4.

[0085] The two sampies were buried in vases containing commercial plant compost and left in it for one month with daily watering. Pictures were taken before and after the treatment.

[0086] Results: as seen in FIG. 5 and FIG. 6, the test swatches appear significantly degraded by the action of soil organisms and conditions.

[0087] Conclusions: Both MFC and its coated, derivative appear home compos-table under appropriate conditions.

[0088} Although the invention has been described with reference to the above examples, it will be understood that modifications and variations are encompassed within the spirit and scope of the invention. Accordingly, the invention, is limited onl by the following claims, All references disclosed herein are hereby incorporated by reference in their entireties.

Claims

Ϊ CLAIM:

1 . A method of coating a cellulose containing surface comprising:

contacitig one or more cyclic esters of hydrocarbons with, the hydroxy! groups on a cellulose s urface in the presence of an ali mtrum or yttrium catalyst to covalently attach a polyester moiety on the surface of said cellulose; and

reacting the contacted surface with an electrophi!ic chain terminator,

wherein the resulting modified surface exhibits increased water contact angle relative to a non-treated surface.

2. The method of claim .! , wherein, the electrophilk- chain terminator is an acyl chloride.

3. The method of claim 1, wherein the electrophilk chain terminator is a linear CIO to C5 acyl chloride,

4. The method of claim I , wherein the reaction scheme is as follows:

wherein R is an alky! group and n is 10-40.

5, The method of claim 4, wherein the acyl chloride is present at a. ratio of about \ :0.©! , abont 0.5:0.02, or about 0.1 :0.033 to the lactone.

6. The method of claim I , wherein an aprotic base as catalyst and acid buffer is added to the polycaproiactone and acylehloride. I S

7. The method of claim 6, wherein Ihe aproiic amine is present at a ratio of about 0.5:0.001 , about 0.2:0.0.1 , or about 0.1.-0.02 t the lactone.

8. The method of claim 6, wherein the aprotic base is selected from the group consisting of pyridine, trialfcylamines, bicyclic amines, and combinations thereof.

9. A composition comprising a surface treated by the method of claim ί ,

10. The method of claim I, wherein the resulting modified surface exhibits a water contact angle greater than about 60".

1 1. The method of claim. 1 , wherein the cellulose is microfibriii ed cellulose (MFC).

12. The method of claim 1. , wherein the method further comprises mixing of a gam with the resulting MFC, whereby the resulting coated surface exhibits at least a two fold increase in tensile strength as compared to the non-treated surface.

13. The method of claim 12, wherein ihe mixing is carried out at between about 50° C and about 100° C,

14. A solid cellulose-containing material wherein at least a portion of the hydroxy! groups available on the surface of the solid cellulose-cotitainiug material are attached directly via a first ester bond to an. open chain derivative of a cyclic ester, wherein additional open chain derivatives of the same cyclic esters are attached to each other by ester bonds to form a polymer, wherein the oxygen atoms contained in the hydroxy! groups available at the end of the -polymer are attached directly via an ester bond to the carbon atom of the acyl group of an alkanoic acid derivative having the formula:

R-CO- wherein R is a straight-chain, branched-chain, or cyclic, aliphatic hydrocarbon radical having from 10 to 40 carbon atoms, wherein the surface of the resulting esterified solid cellulose- containing material, exhibits a water contact angle of between 60° to about 120°, and wherein the portion of the hydroxy! groups esterified on the surface of the cellulose-containing material is greater than 40%.

.15. The method of claim 14, wherein the ee!i lose-contamrag material is micro.flbriliated cellulose (MFC).

1 , A method of preparing a nanocelluiose composition comprising:

mixing microfibrillated cellulose (MFC) and a gum;

'heating the mixture until a substantially homogenous mixture is formed; and

drying said mixed MFC and gum into a sheet,

wherein the resulting combination exhibits increased, thickness compared to a nanoceiiulose composition comprising the MFC alone.

17, The method of claim 16, wherein the resulting composition exhibi ts an increase in tensile strength, of at least ! 2 fold.

1 8, The method of claim .1 , wherein said gum is selected from the group consisting of agarose, gellan, k-carageenan, agar-agar, alginate, glucomaunan, and combinations thereof.

19, The method of claim 16, wherein the gum is present in an amount from 5% to 40% by weight, and the MFC is present in. an amount of between about 0.5% to about 3% by weight.

20, A composition prepared by the method of claim 16.