Non-isocyanate polyurethanes from bio-based polyols

Abstract

Bio-based polymer precursors and non-isocyanate polyurethanes (NIPU) and non-isocyanate polyurethane foams (NIPUF) that can be formed from the precursors, and methods of synthesizing the precursors and polyurethane products, are described. The bio-based polymer precursors are formed by functionalizing a bio-based polyol, such as lignin, with a cyclic carbonate. The bio-based polyol starting material does not require pre-processing, and can include kraft lignin. The NIPU / NIPUF can be synthesized by a ring-opening curing reaction of the cyclic carbonate of the bio-based polyol precursor with a diamine. The carbonate and diamine can constitute a non-toxic, bio-based carbonate.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 034,584, filed on June 4, 2020, which is incorporated herein by reference in its entirety.

[0003] background

[0004] Polyurethane is one of the six most produced polymers in the world and is widely used in the automotive, furniture, construction, coatings, and home appliance industries, among many others, due to its beneficial properties, including lightweight, high impact resistance, and good insulation. This versatility is largely due to the ease and efficiency with which polyols react with diisocyanates to produce polyurethane materials with properties ranging from flexible to rigid, including polyurethane foam. Unfortunately, because the formation pathway of diisocyanates utilizes the deadly gas phosgene, the use of diisocyanates has placed polyurethane at the top of the list of 50 most toxic polymers. Furthermore, diisocyanates have been designated "CMR" (carcinogenic, mutagenic, and reproductive toxin) by the European Community and have received similar warnings in the United States.

[0005] In recent decades, the demand for the synthesis of environmentally friendly materials has grown, supported by the green chemistry movement, and there has been a growing interest in replacing petroleum-derived chemicals with biomass-derived precursors. The toxicity associated with petroleum resources and the expectation of reducing overall carbon emissions from industrial processes have led to efforts supporting the concept of biorefining, in which natural materials are used as feedstocks for the production of chemicals and materials. With the initial success of cellulosic ethanol production, including the benefits of lowering the average selling price of ethanol (MESP) to compete with petroleum-derived fuels, the growing demand for valuations of other biomass sources, and particularly the lignin components of biomass, has gained momentum.

[0006] One promising approach to lignin valuation is through polymer synthesis, which could replace traditional petroleum-based polymer production pathways by utilizing lignin (the world's richest source of aromatic carbon). A literature review of lignin-derived polymers has proposed several innovative methods using green chemistry. Unfortunately, the widespread use of lignin in polymer formation is often hampered by its low reactivity, heterogeneity, and the necessity of extensive purification and / or functionalization to ensure materials achieve quality comparable to current petroleum-based standards. Therefore, although lignin can be used as a renewable feedstock, typical schemes still utilize harmful, toxic, petroleum-derived solvents and reagents, thus reducing bio-based carbon content and the renewability of lignin-based polymer formulations.

[0007] The incorporation of lignin into polyurethanes and polyurethane foams is a well-studied subject, demonstrating that lignin can be used to replace traditional polyols used in reactions with diisocyanates. However, challenges remain. For example, to synthesize lignin-based polyurethane foams with properties similar to conventional materials, propylene oxide has been used to simultaneously liquefy lignin and extend nascent hydroxyl groups to generate more reactive lignin-derived precursors. The toxicity and explosion risks associated with propylene oxide have led researchers to seek more benign lignin functionalization pathways. Furthermore, lignin-derived polyurethane foams still require the use of diisocyanate-based precursors.

[0008] Although non-foamed, non-isocyanate polyurethanes derived from lignin have been produced, these attempts have resulted in materials that are too brittle to be mechanically characterized or too chemically inert to yield meaningful results.

[0009] What is needed in the field are bio-based precursors derived from bio-based polyols, such as lignin- or other natural material-based precursors that can be used to form non-isocyanate polyurethane (NIPU) and non-isocyanate polyurethane foam (NIPUF). NIPU and NIPUF exhibiting high bio-based carbon content and excellent physical properties comparable to their isocyanate counterparts would be of great benefit to the field.

[0010] Overview

[0011] According to one embodiment, a bio-based precursor is disclosed, the precursor comprising a functionalized bio-based polyol, the functionalization including cyclic carbonate functionality. The bio-based precursor may contain cyclic carbonate functional groups at a concentration of about 1.8 mmol of cyclic carbonate or greater per gram of total polyol. Furthermore, the bio-based precursor may have a high bio-based carbon content, for example, about 95% or higher, as determined, for example, by radiocarbon dating according to ASTM D6866-20.

[0012] A novel NIPU is also disclosed, comprising a reaction product of a bio-based precursor and a diamine as described. The NIPU includes hard segments and soft segments, the hard segments comprising the bio-based precursor reaction product and the soft segments comprising the diamine reaction product. The diamine may be a fatty acid-based diamine, for example, a fatty acid polyvalent diamine with 100% bio-based carbon content, and the polyurethane may have a bio-based carbon content of about 90% or greater. In one embodiment, the NIPU may be NIPUF. The NIPU may possess excellent physical properties, such as a final strength of about 10 MPa or greater, a final strain of about 10 MPa or greater, and / or a tensile modulus of about 135 MPa or greater, as determined according to ASTM D638. In the case of foam, NIPUF may exhibit about 100 kg / m³. 3 Or even larger, for example from approximately 110 kg / m 3 Approximately 130 kg / m 3 Density and / or compressive strength of approximately 80 kPa or greater at 10% strain.

[0013] Methods for forming precursors and methods for forming NIPU / NIPUF using the precursors are also disclosed. The methods may include chain extension reactions of a bio-based polyol with a first organic carbonate, and in one embodiment, a non-toxic bio-based organic carbonate, to form an oxyalkylated polyol. Next, the methods may include transesterification reactions of the oxyalkylated polyol with a second organic carbonate to insert a cyclic carbonate structure onto the polyol backbone and form a bio-based precursor. The chain extension reaction can be carried out at relatively low temperatures, such as about 160°C or lower, for a relatively short period of time, such as about 2 hours or less, and the transesterification reaction can be carried out at about 100°C or lower for about 5 hours or less.

[0014] Polyurethane forming methods may include reacting a bio-based precursor with a diamine, such as a bio-based polyvalent diamine, during a ring-opening polymerization reaction. NIPUF can be formed by adding a blowing agent, such as a bio-based blowing agent, during the polymerization reaction. Brief description of the attached diagram

[0016] The full and enabled disclosure of the subject matter of the invention is set forth in more detail in the remainder of the specification, including with reference to the accompanying drawings, including its best mode of presentation to those skilled in the art, in which:

[0017] Figure 1 This is a flowchart of one implementation scheme for the formation process of bio-based NIPU.

[0018] Figure 2 The reaction scheme of one implementation of NIPU is presented.

[0019] Figure 3 The reaction of oxyalkylated lignin with glycerol carbonate and subsequently with dimethyl carbonate (cyclic carbonated lignin) is presented. 1 H NMR.

[0020] Figure 4 FTIR of lignin and functionalized lignin precursors was presented.

[0021] Figure 5 The sulfate lignin and functionalized lignin precursors formed according to the disclosed method are presented. 31 PNMR.

[0022] Figure 6 Presented a cyclic carbonated lignin-based precursor formed according to the disclosed method 13 C NMR.

[0023] Figure 7 A reaction scheme is provided for cyclic carbonated lignin with different stoichiometric amounts of diamine curing agents that leads to changes in crosslinking density.

[0024] Figure 8 The curing rheology of the NIPU reaction mixture is presented.

[0025] Figure 9A The unfolded diagrams of the carbonyl regions of FTIR of cured NIPU materials cured at different temperatures are presented.

[0026] Figure 9B FTIR of NIPU materials formed with different reaction stoichiometry and compared with cyclic carbonated (CC) lignin precursors is presented.

[0027] Figure 9C The FTIR unfolded diagrams of carbonyl and aromatic regions of cured NIPU samples formed with different reaction stoichiometry are presented.

[0028] Figure 10 Solid-state NMR of NIPU samples formed with different reaction stoichiometry compared to CC lignin precursors is presented.

[0029] Figure 11 The results of uniaxial tensile tests on NIPU materials formed with different reaction stoichiometry are presented.

[0030] Figure 12 Thermogravimetric analysis of NIPU materials formed with different reaction stoichiometry is presented.

[0031] Figure 13 DSC thermograms of the second heating cycle of NIPU materials formed with different reaction stoichiometry are presented.

[0032] Figure 14 The dynamic mechanical analysis of the NIPU sample is presented, showing the storage modulus and Tanδ curve.

[0033] Figure 15 The shape memory properties of NIPU material are shown.

[0034] Figure 16 SEM images of NIPU foams as described herein are provided, including foams with predominantly closed-cell contents formed by reaction with a stoichiometric amount of diamine (left); foams with an open-cell morphology formed by reaction with an excess of diamine (middle); and foams with densities of ~300 kg / m³ as described. 3 A photo of a bubble (right).

[0035] Figure 17 A reaction mechanism for forming bio-based NIPUFs as described herein is provided.

[0036] Figure 18 FTIR analysis is provided for the formation of sebacic bis-cyclocarbonate as described in this paper for NIPUF.

[0037] Figure 19 FTIR analysis of NIPUF formed from a mixture of two different bio-based precursors as described herein is provided.

[0038] The repeated use of reference characters in this specification and accompanying drawings is intended to indicate the same or similar features or elements of the invention.

[0039] Detailed Explanation

[0040] Reference will now be made in detail to various embodiments of the disclosed subject matter, one or more examples of which are set forth below. Each embodiment is provided by way of explanation rather than limitation of the subject matter. Indeed, it will be apparent to those skilled in the art that various modifications and changes may be made to this disclosure without departing from the scope or spirit of the subject matter. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce yet another embodiment.

[0041] This disclosure relates to bio-based polymer precursors and NIPU and NIPUF that can be formed from these precursors, as well as methods for synthesizing the precursors and polyurethane products. More specifically, NIPU / NIPUF can be synthesized via a ring-opening curing reaction of a bio-based cyclic carbonate with a diamine. The bio-based precursors can be formed by functionalizing a bio-based polyol with a cyclic carbonate. The bio-based polyol can include lignin-based polyols and / or polyols derived from: bio-based processes, such as processing fatty acids from algal, animal, or plant sources; bacterial processes that produce mixtures or selective amounts of diols; and the production of diols such as ethylene glycol derived from bio-based carbohydrates; etc. The polyol component can include a mixture of bio-based polyols and conventional (non-bio-based) polyols. In those embodiments where the polyols include lignin-derived polyols, the lignin starting material does not require preprocessing and may include sulfate lignin. The carbonate and diamine can constitute a non-toxic bio-based carbonate.

[0042] The NIPU / NIPUF formation method comprises a design for compatibility of bio-based precursors with diamines to produce non-isocyanate polyurethane products exhibiting properties comparable to more conventional isocyanate-based materials. In some embodiments, the method allows the use of biomass as both a bio-based precursor and a curing agent to form NIPU and NIPUF. The beneficial properties of biomass-derived products are thought to be due to the high reactivity observed between the cyclic carbonate and diamine precursors, leading to rapid gelation of the reaction mixture. NIPU / NIPUF products can exhibit a biphasic polymer structure with tunable properties based on the addition of a curing agent or other polymerizing agent. The simplicity and non-toxicity of the approach overcome some major obstacles associated with biomass-derived chemical components such as lignin, including low reactivity, solubility, and compatibility with curing agents, and the avoidance of forming excessively brittle structures as seen with previously known methods and materials.

[0043] Bio-based precursors can provide non-isocyanate formation pathways where sufficient reactivity not only ensures impressive mechanical properties but also cures during the foaming reaction period required to produce lightweight NIPUFs. Furthermore, materials and methods can provide for the formation of NIPUs and NIPUFs containing very high bio-based carbon content. For example, bio-based precursors can have a bio-based carbon content of about 95% or more, or in some embodiments about 98% or more. In some embodiments, the NIPU or NIPUF formed from the bio-based precursor can have a bio-based carbon content of about 90% or more, about 92% or more, or about 95% or more. The bio-based carbon content can be calculated based on known procedures; for example, by using the procedure of Pan et al. (Biomacromolecules 12, 2416-2428 (2011)) to correlate the total amount of biorenewable carbon with the total amount of carbon present in the formulation. In some embodiments, the bio-based carbon content can be determined, for example, by radiocarbon dating according to ASTM D6866-20.

[0044] In one embodiment, the disclosed method can be used to form NIPU or NIPUF entirely from bio-based materials. For example, Figure 1 One embodiment of the formation process is presented, which can utilize entirely bio-based starting materials. As illustrated, animal-based starting materials can be derived from animal processing / rendering plants, such as in the cattle raising / harvesting industry or any other animal processing facility, including but not limited to the processing of cattle, pigs, chickens, fish, sheep, etc., and combinations of animal-derived raw materials. Animal processing facilities can also provide organic materials for forming organic carbonates for producing bio-based precursors, and fatty acids for producing fatty acid-based diamine curing agents. Starting materials can also be derived from plant processing and algae harvesting.

[0045] The process can utilize lignin-containing raw materials, such as those obtained from wood processing operations that produce bio-based polyol components. However, it should be understood that the disclosed methods can obtain lignin starting materials from any lignocellulosic biomass source material (including both woody and non-woody sources). Woody lignocellulosic biomass can be derived from forests, agriculture, or any other source, and can include hardwood and / or softwood source materials. For example, fast-growing tree species such as hybrid willow (Salix) and poplar, which have been developed for production in agricultural sites, can be utilized.

[0046] Agricultural systems can be sources of non-woody lignin or other polyol biomass materials. Agricultural systems can produce several different types of non-woody lignocellulosic biomass materials, primarily including cellulose materials such as plant leaves and materials with higher lignin content such as stems and straw. For example, the harvesting of grains, vegetables, and fruits can provide lignocellulosic polyol biomass materials. Agricultural residues, including field residues and processing residues, can provide lignocellulosic polyol biomass materials. Field residues include materials left in the field after crop harvest and can include, but are not limited to, straw and stalks, leaves, and seed pods. Processing residues, such as husks, seeds, bagasse, and roots, include those materials left after processing the crop into the desired form. Examples of agricultural residue source materials can include, but are not limited to, rice straw, wheat straw, corn stover, and bagasse.

[0047] Other waste streams, such as municipal waste, construction waste, and sawmill waste, can provide lignocellulosic polyol biomass sources. For example, in some implementation schemes, yard waste and holiday waste can provide lignocellulosic polyol sources.

[0048] Perennial and annual grasses can provide sources of lignocellulose polyols. Examples of grass-based materials include, but are not limited to, switchgrass (Panicum virgatum), miscanthus spp. Anderss., canary grass (Phalaris arundinacea), giantreed (Arundo donax L.), alfalfa (Medicago sativa L.), sorghum (Sorghum bicolor) and pennisetum (Pennisetum purpureum).

[0049] Vegetable oils can be sources of bio-based polyols for producing bio-based precursors. Edible oils such as soybean oil, rapeseed oil, corn oil, cottonseed oil, and olive oil can be sources of bio-based polyols. Bio-based polyols can also be derived from more sustainable non-edible oils such as castor oil, mahua oil, or perilla oil. Animal lipids and / or algal lipids can also be used as sources of bio-based polyols; for example, in oil refining processes where fatty acids are produced from triglycerides. Bacterial processes can also produce polyols that can be further functionalized. Carbohydrates, such as naturally occurring carbohydrates (e.g., C3 to C12 carbohydrates), can also be sources of polyols (e.g., diols) produced through known reduction reactions.

[0050] In one embodiment, lignin-containing feedstock can be used to form bio-based precursors. For example, industrial lignin obtained through a sulfate pulping process (which has been considered too difficult to process in many previously known attempts at bio-based chemical processing) can be used to form lignin-based precursors. For example, lignin feedstock can be obtained from sulfate pulping, which is produced by precipitation of the lignin-containing fraction in black liquor. In such embodiments, the precipitate can include the lignin feedstock used in the disclosed method. Such a black liquor precipitation process can separate a portion of the impurities contained in the black liquor, such as ash, metals, hemicellulose, etc., from the lignin feedstock. For example, the black liquor can undergo carbon dioxide acidification and / or sulfuric acid acidification to precipitate the lignin feedstock, leaving impurities in the remaining liquid fraction. Of course, such precipitation treatment is not limited to sulfate black liquor source materials. In another embodiment, an alkaline liquor obtained from processing source materials such as agricultural residues (e.g., corn stalks) can be pretreated by acidification with an inorganic or organic acid, which can precipitate the lignin-containing feedstock, leaving impurities in the remaining alkaline liquor.

[0051] Advantageously, in one embodiment, lignin raw materials that have not undergone further processing can be utilized, such as sulfate lignin with a relatively high polydispersity index that has not undergone fractionation or depolymerization preprocessing. Using such raw materials not only reduces the cost of the polyurethane forming process but also increases the bio-based carbon content of the polyurethane prepared by this process. For example, bio-based polyol raw materials can have a polydispersity index of about 2 or greater, or in some embodiments, a polydispersity index of about 3 or greater.

[0052] As used herein, the polydispersity index (PDI) is a measure of the molecular weight distribution in a given polymer sample. The calculated PDI is the weight-average molecular weight divided by the number-average molecular weight. It indicates the distribution of individual molecular weights in the polymer sample. The PDI has a value equal to or greater than 1, but as polymer chains approach a uniform chain length, the PDI approaches one (i.e., 1).

[0053] Number-average molecular weight (M) n The molecular weight of n polymer molecules is readily calculated by those skilled in the art and typically refers to the common arithmetic mean or average of the molecular weights of the individual macromolecules. It is determined by measuring the molecular weights of n polymer molecules, summing their weights, and dividing by n, as expressed by the following formula:

[0054]

[0055] Where N i It is the molecular weight M iThe number of molecules. The number-average molecular weight of a polymer can be determined by gel permeation chromatography and all colligative methods, such as vapor pressure osmotic pressure determination or end-group determination.

[0056] "weight-average molecular weight" (M w (This is) readily calculable by a person skilled in the art, and generally refers to:

[0057]

[0058] Where N i It is the molecular weight M i The number of molecules. Weight-average molecular weight can be determined by light scattering, small-angle neutron scattering (SANS), X-ray scattering, gel permeation chromatography, and sedimentation rate.

[0059] Polyol raw materials can be processed to form cyclic carbonated bio-based precursors, which can then be used for the ring-opening reaction of the cyclic carbonates of the precursors with a diamine curing agent to form polyurethane. Bio-based precursors can be formed by reacting the polyol raw material or its reaction product with one or more carbonates. This can be achieved by etherifying and carboxylating both the aromatic and aliphatic hydroxyl groups of the polyol raw material, thereby enhancing the reactivity of the bio-based polyol precursor with the curing agent.

[0060] In one embodiment, organic carbonates can be used to form bio-based precursors instead of metal carbonates because organic carbonates can have a bio-based origin, exhibit non-toxicity, and can utilize mild reaction conditions. Furthermore, unwanted homopolymerization of propylene oxide (typically used to produce more reactive lignin precursors) can be avoided by using well-controlled reactions with organic carbonates.

[0061] Cyclocarbonated bio-based precursors can be formed via a two-step reaction process. The first step involves the formation of an oxyalkylated polyol. According to this first reaction, the aliphatic and aromatic hydroxyl groups of the polyol feedstock can react with an organic carbonate to incorporate susceptible ether and carbonyl groups into the polyol backbone, while simultaneously terminating the chain-extending precursor in the 1,2-diol. Figure 2 In one embodiment, the organic carbonate may be a bio-based carbonate derived from natural resources, rather than a petroleum-based carbonate, which can increase the bio-based carbon content of the bio-based precursor and the bio-based carbon content of the polyurethane product formed from the precursor.

[0062] like Figure 1As indicated in the text, in one embodiment, glyceryl carbonate can be used to obtain a cyclic carbonate group, and the glyceryl carbonate can be derived from bio-based glycerol obtained from animal fats. Bio-based glycerol, such as that produced from vegetable oils, can also be used to form bio-based glyceryl carbonates. For example, glycerol can be obtained from natural resources by hydrolysis reactions as known in the art. Hydrolysis is a known process involving reacting vegetable oils or animal fats with water to break down the vegetable oils or animal fats into free fatty acids and glycerol. Optionally, a catalyst can be used in the reaction. Furthermore, the reaction may include applying heat to accelerate the reaction. Next, the bio-based glycerol can be reacted with dialkyl carbonates, such as... Figure 1 The diagram shows the reaction of dimethyl carbonate or cyclic alkylene carbonates to form bio-based glycerol carbonates.

[0063] like Figure 2 As illustrated in the figure, in one embodiment, the glycerol carbonate reactant can be used for an oxyalkylation reaction. However, this first step of the precursor formation process is not limited to functionalizing polyols such as lignin with glycerol carbonate, and other organic carbonates can be optionally utilized. For example, the functionalizing agent can be a cyclic organic carbonate having the following general structure:

[0064]

[0065] Where R is H, or a C1 to C18 alkyl or a C1 to C19 alcohol.

[0066] Examples of cyclic organic carbonates may include, but are not limited to, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate or 2,3-butylene carbonate, and combinations of cyclic organic carbonates.

[0067] The organic carbonates used in the oxyalkylation of polyol feedstocks are not limited to cyclic organic carbonates, and alternatively, acyclic carbonates, as well as combinations of cyclic and acyclic carbonates, may be used. For example, acyclic organic carbonates may include, but are not limited to, dimethyl carbonate or other dialkyl carbonates. Examples of organic carbonate reactants may include, but are not limited to, dimethyl carbonate, diethyl carbonate, di(n-propyl) carbonate, di(isopropyl) carbonate, di(n-butyl) carbonate, di(sec-butyl) carbonate, di(tert-butyl) carbonate, or dihexyl carbonate.

[0068] Based on the hydroxyl content of the polyol, the organic carbonate of the oxyalkylation reaction step can typically be provided in an amount from about 5 equivalents to about 15 equivalents; for example, in one embodiment, the organic carbonate is provided in an amount of about 10 equivalents, depending on the hydroxyl content of the polyol.

[0069] Oxyalkylation reactions can utilize catalysts as known in the art. In one embodiment, the catalyst can be a non-metallic catalyst, such as a non-metallic bio-based catalyst. Examples of non-metallic catalysts for oxyalkylation reactions include, but are not limited to, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), triethylamine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxophosphacyclopentane, etc. Typically, depending on the hydroxyl content of the polyol, a catalyst in an amount of about 0.1 equivalents or less can be used; for example, in one embodiment, about 0.05 equivalents of catalyst is used.

[0070] The reaction of organic carbonates with polyols can be highly temperature-sensitive. For example, at temperatures close to sulfate pulping conditions (around 170°C), ether linkages throughout the lignin structure can be disrupted, triggering a series of reactions involving highly reactive lignin segments. Therefore, conditions for oxyalkylation reactions, including catalyst loading, reaction temperature, and reaction time, have been developed to balance the condensation of the polyol structure (which can reduce the hydroxyl content and increase the molecular weight of the polyol) with the hierarchical separation of the polyol skeleton (resulting in lower molecular weight derivatives). A desirable balance has been found to be achieved by conducting the oxyalkylation chain extension reaction at relatively low temperatures for a relatively short duration, typically at around 160°C or lower, or from around 130°C to around 155°C, for example, around 150°C in some embodiments, for a duration from around 1 hour to around 2 hours, or around 1.5 hours in some embodiments. The use of higher temperatures and / or longer reaction times has been found to result in excessive polycarbonate condensation and generally unprocessable materials.

[0071] During the oxyalkylation reaction, the molecular weight of the polyol starting material can be reduced, which is evidence of the good balance between condensation and fractionation that can be achieved through this reaction. For example, the weight-average molecular weight (M0.05) of the oxyalkylated polyol... w ) can be the weight-average molecular weight (M) of the polyol in the raw material. w Approximately 90% or less of the content of M; for example, approximately 80% or less, or approximately 70% or less. In some embodiments, the M of the oxyalkylated polyol... w It can be M of polyol raw materials w From approximately 50% to approximately 70%.

[0072] Following the oxyalkylation step, the oxyalkylated polyol having a 1,2-diol functionalized structure can be further processed to insert a cyclic carbonate structure into the backbone. This can be carried out via an exchange reaction of the oxyalkylated polyol with a second organic carbonate. The organic carbonate used in the exchange reaction can be the same as or different from the organic carbonate used in the oxyalkylation reaction. For example, in one embodiment, a cyclic organic carbonate (e.g., glyceryl carbonate) can be used in the oxyalkylation step, and a non-cyclic carbonate, such as dimethyl carbonate, can be used in the exchange reaction to insert a 5-membered cyclic carbonate structure into the backbone of the polyol. Of course, other combinations of carbonate reactants as previously described can also be utilized.

[0073] Based on the hydroxyl content of the polyol, the organic carbonate for the transesterification step can typically be provided in amounts from about 3 equivalents to about 10 equivalents; for example, in one embodiment, the organic carbonate is provided in an amount of about 5 equivalents, depending on the hydroxyl content of the polyol.

[0074] Similar to the initial oxyalkylation reaction, bio-based precursors can be provided through strict control of catalyst loading, reaction temperature, and reaction time. These precursors can exhibit a high content of highly reactive functional groups that can be used for curing during polyurethane polymerization. For example, basic catalysts can be used, including but not limited to alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, or lithium hydroxide; salts of alkali metals and weak acids such as sodium carbonate and potassium carbonate; and basic salts such as trisodium phosphate.

[0075] Alkali metal alkoxides, such as sodium methoxide, potassium ethoxide, and sodium ethoxide; organic bases, such as quaternary ammonium bases, including mixed alkyl-dimethyl-benzyl ammonium hydroxide, alkyl-trimethyl ammonium hydroxide, and tetraalkyl quaternary ammonium hydroxides, such as tetramethyl ammonium hydroxide and hexadecyl dimethyl benzyl ammonium hydroxide; or alkali metal sucrates or alkali metal raffinates, such as sodium sucrose and sodium raffinate. Additionally, metals such as tin and zinc can be used as catalysts for transesterification reactions.

[0076] Based on the hydroxyl content of the polyol, the catalyst for the transesterification reaction step can typically be provided in an amount of about 1 equivalent or less; for example, in one embodiment, the catalyst is provided in an amount from about 0.2 equivalents to about 0.7 equivalents, or about 0.4 equivalents, depending on the hydroxyl content of the polyol.

[0077] The transesterification cyclic carbonate insertion reaction can be carried out at a temperature of about 100°C or lower, or from about 60°C to about 90°C, for example about 75°C in some embodiments, and last for a period of time from about 3 hours to about 6 hours, or about 4 hours in some embodiments.

[0078] It should be understood that bio-based cyclic carbonate precursors formed according to other methods can be used in the disclosed processes and products, for example, in combination with bio-based cyclic carbonate precursors formed according to the two-step oxyalkylation / transesterification process described above, with other bio-based cyclic carbonate precursors, with other non-bio-based precursors, or as the sole cyclic carbonate precursor in a polyurethane forming process, if desired. For example, in some embodiments, straight-chain or branched cyclic carbonate precursors formed from bio-based polyfunctional acids (e.g., dicarboxylic acids) can be used to form polyurethanes with specific properties.

[0079] In some embodiments, cyclic carbonates can be provided by reacting an acid, such as a bio-based organic acid, with a carbonate, such as a bio-based glycerol carbonate as described above. For example, fatty acids, triglycerides, polyols, or the like, such as those derived from animal or plant sources as previously discussed, such as vegetable oils like soybean oil, rapeseed oil, corn oil, cottonseed oil, olive oil, castor oil, hemp seed oil, or perilla oil, algae oil, animal fats, or animal oils, can be processed to form straight-chain or branched-chain acids, such as C4 to C10 straight-chain or branched bio-based acids, which can then be reacted with a carbonate to form a cyclic carbonate precursor, which can be used together with one or more other bio-based precursors, such as lignin-based precursors, to form polyurethanes with distinctive properties.

[0080] Bio-based precursors can be highly reactive. For example, in one embodiment, the bio-based precursor may have a cyclic carbonate content of about 1.8 mmol or more per gram of total polyol, such as from about 1.8 mmol to about 2.25 mmol of cyclic carbonate per gram of starting polyol, or about 2 mmol of cyclic carbonate per gram of polyol. Furthermore, the cyclic carbonates can be readily accessed by the curing agent during the polyurethane forming process, as evidenced by the molecular weight of the bio-based precursor, which may be lower than the molecular weight of the polyol raw material used to form the precursor. For example, the M of the bio-based precursor... w It can be the M of the polyol in the raw material. w The percentage ranges from about 70% to about 95%, or in some embodiments from about 80% to about 90%, such as about 85%. For example, in some embodiments, the bio-based precursor may have a weight-average molecular weight of about 15,000 or less, about 14,500 or less, or about 14,000.

[0081] Similarly, the number-average molecular weight (M) of bio-based precursors n The number average molecular weight (M) of the polyols in the raw materials can be lower than that of the raw materials. n For example, M, a bio-based precursor n It can be M of polyol raw materials nApproximately 90% or less; for example, approximately 80% or less, or approximately 70% or less. In some embodiments, the precursor M... n It can be M of polyol raw materials n The percentage ranges from about 50% to about 70%. For example, in some embodiments, the bio-based precursor may have a number average molecular weight of about 4,000 or less, about 3,500 or less, or about 3,400.

[0082] Compared to polyol raw materials used as precursor bases, the lower molecular weight of the precursor can have specific advantages because it allows the precursor to be dissolved in the curing agent with a small amount of solvent, such as a green solvent like dimethyl sulfoxide (DMSO). As previously mentioned, bio-based precursors can also exhibit very high bio-based carbon content, such as about 95% or higher; for example, in those embodiments where one or more carbonates are derived from bio-based sources.

[0083] To form polyurethane using bio-based precursors, the diamine can react with one or more precursors and be incorporated as a soft segment into the entire NIPU structure, while the one or more bio-based precursors are incorporated as a hard segment. In one embodiment, the diamine can be a bio-based diamine, and in a particular embodiment, it is a polyvalent fatty acid-based (e.g., dimer) diamine. In one embodiment, the diamine component can contain 100% bio-based carbon, such as a 100% bio-based carbon fatty acid dimer diamine. Advantageously, in one embodiment, the polyurethane formation scheme can be performed without using any polyol chain extenders or petroleum-based chain extenders, which can increase the bio-based carbon content of the formed polyurethane.

[0084] In one embodiment, the diamine component can be represented by the following structure:

[0085]

[0086] R1 may include C1 to C20 straight-chain alkyl groups.

[0087] In one embodiment, the diamine component can be a polyvalent diamine represented by the following structure:

[0088]

[0089] Where A is a tetravalent saturated hydrocarbon residue and can be a straight-chain structure or a cyclic structure; for example, a C1 to C4 straight-chain structure, R2 and R3 are alkylene groups, such as C1 to C20 alkylene groups, and R4 and R5 are straight-chain alkyl groups, such as C1 to C20 straight-chain alkyl groups.

[0090] For example, but not limited to, R2 and R3 can be selected from methylene, ethylene, propylene, butylene, pentylene, etc., and can be the same as or different from each other. R4 and R5 can be selected from, but not limited to, methyl, ethyl, propyl, butyl, pentyl, etc., and R4 and R5 can be the same as or different from each other.

[0091] In some embodiments, one or more carbon chains of the diamine can be relatively long; for example, C14 to C18 alkyl chains. The aliphatic nature of the carbon chains present in the diamine structure can provide soft segments for the NIPU / NIPUF structure and can mitigate the brittle and rigid properties of the aromatic skeleton of the bio-based precursor.

[0092] In one embodiment, the diamine can be a bio-based diamine derived from fatty acids. For example, and as... Figure 1 As indicated in the document, bio-based fatty acid dimer diamines can be formed through the reductive ammonolysis of dimer fatty acids produced as a byproduct of animal processing. As used herein, the term "fatty acid" generally refers to naturally occurring and synthetic monobasic fatty acids having a hydrocarbon chain of 8 to 24 carbon atoms. Fatty acids can include saturated acids, olefinic unsaturated acids, and alkynyl unsaturated acids.

[0093] Diamines can be diamines of polyvalent fatty acids. As used herein, the term "polyvalent fatty acid" generally refers to dimeric fatty acids, trimeric fatty acids, and higher polymers of fatty acids, respectively. Saturated fatty acids, olefinic unsaturated fatty acids, and alkynyl unsaturated fatty acids are typically polymerized using slightly different techniques, but due to the functional similarity of the polymer products, they are often referred to as "polyvalent fatty acids."

[0094] For example, saturated fatty acids can be polymerized at elevated temperatures using a peroxide catalyst such as di-tert-butyl peroxide to form polyvalent fatty acids, such as dimer fatty acids. Exemplary saturated fatty acids that can be used to form fatty acid diamines include branched-chain and straight-chain acids, such as caprylic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, isopalmitic acid, stearic acid, arachidic acid, docosanoic acid, and tetracosanoic acid.

[0095] Polyvalent fatty acids, such as dimer fatty acids, can be converted into corresponding dionitriles by reacting them with ammonia under nitrile-forming conditions as known in the art. The dionitriles can then be purified by vacuum distillation or other suitable methods. After such purification, the dionitriles can be hydrogenated to form dimer diamines, which can also be purified by vacuum distillation or other suitable methods.

[0096] Of course, the diamine used for reaction with bio-based precursors is not limited to fatty acid diamines or fatty acid dimer diamines, and other diamines known in the art can be used, although the use of such diamines may reduce the bio-based carbon content of the polyurethane product, depending on the raw materials used to form the diamine. Examples of diamines that can be utilized include, but are not limited to, ethylenediamine, 1,2-propanediamine and 1,3-propanediamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, 1,2-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, decamethylenediamine, N,N'-dibutylhexamethylenediamine, N,N'-dimethylhexamethylenediamine, N,N'-dihexylhexamethylenediamine, 1,12-dibutylaminododecane, 1,10-dibutylaminodecane, N,N'-di(dodecyl)hexamethylenediamine, N,N'-dibutylbutyldiamine, N,N'-dibutylethylenediamine, N,N'-diisobutylbutyldiamine, and combinations thereof. As a commercial example, Priamine... TM (As can be found from Croda Japan Co., Ltd.) was mentioned.

[0097] As in traditional polyurethane forming schemes, the relative amount of diamine curing agent used with the bio-based precursor can vary. For example, a stoichiometric amount of diamine can lead to the maximum amount of crosslinking, while excess diamine can terminate the crosslinking reaction by generating amine-terminated derivatives, such as... Figure 7 The diagram is shown in the illustration.

[0098] The catalyst used in the curing reaction can typically be a typical catalyst used in standard amounts, for example, about 1 equivalent or less, about 0.5 equivalents or less, or about 0.3 equivalents or less, depending on the cyclic carbonate content of the system, such as from about 0.05 equivalents to about 0.2 equivalents or about 0.1 equivalents in one embodiment. In one embodiment, an organic catalyst such as TBD, as previously mentioned, can be used in the polyurethane forming reaction.

[0099] As previously mentioned, the reaction conditions found in the formation of bio-based precursors have produced sufficiently small functionalized precursor molecules that allow for easy compatibility with diamines, such as fatty acid-based diamines. Compared to previously known methods (e.g., dissolving in polyols or polypropylene oxide, significantly reducing the bio-based carbon content of the cured material; or using chlorinated solvents and toxic solvents such as dichloromethane, tetrahydrofuran, or dioxane), this approach can be an extremely environmentally friendly method for producing soluble bio-based precursors.

[0100] One or more bio-based precursors disclosed herein can also react with a diamine curing agent in rapid kinetics; for example, in some embodiments, the gelation time of the uncatalyzed system is about 15 minutes or less, about 10 minutes or less, or about 8 minutes; and in some embodiments, the gelation time of the catalyzed system is about 10 minutes or less, about 5 minutes or less, or about 3 minutes.

[0101] In some implementations, the curing reaction temperature can typically be about 120°C or higher, for example, about 150°C, for the complete conversion of cyclic carbonate groups to urethane binders. Lower reaction temperatures are possible; however, they may result in some unreacted groups, and therefore, lead to NIPU materials with lower performance.

[0102] NIPU formed using stoichiometric amounts of curing agent (a 1:1 ratio of cyclic carbonate groups to amine units on the diamine) can exhibit final strength values ​​from about 10 MPa to about 25 MPa, final strain values ​​from about 10% to about 50%, and tensile modulus from about 135 MPa to about 450 MPa. Tensile properties can be determined according to ASTM D638. Using a higher proportion of diamine curing agent allows for the incorporation of a larger proportion of diamine soft segments into the polymer structure, resulting in an increase in final strain and a corresponding decrease in modulus.

[0103] NIPU can also have high density, for example, about 1000 kg / m³. 3 This is independent of the relative amount of curing agent used in the curing reaction. The NIPU formed as described can also be thermally stable, having a loss temperature of 5% wt from about 300°C to about 350°C, for example, about 330°C. As previously discussed, the NIPU formed as described can also have a high bio-based carbon content, such as about 90% or more.

[0104] By examining the average molecular weight between crosslinks, excellent compatibility with bio-based precursors is evident. For example, in polyurethanes formed from stoichiometric amounts of diamines, the average molecular weight between crosslinks can be approximately equal to the molecular weight of the diamine curing agent (regardless of M). w Or M n In embodiments using excess diamine, the average molecular weight between crosslinks will increase due to the incorporation of a larger amount of amine-terminated polyol material interacting via hydrogen bonding.

[0105] The superior kinetics of the curing reaction of bio-based precursors allow for the formation of NIPUFs because the curing reaction between the cyclic carbonate functionalization of the bio-based precursors and the diamine can proceed within a timeframe equivalent to that of a foaming reaction. As is known, the gel time of polyurethanes is a very important aspect of their processability and ability to cure within a timeframe comparable to that of a foaming reaction. Rheology can indicate the gel time of the polymer by monitoring the sharp increase in the elastic modulus and the crossover point between the elastic modulus and the storage modulus; the crossover point is the point where the reaction mixture exhibits solid-like mechanical properties rather than liquid-like mechanical properties.

[0106] The rapid gelation time of the previously disclosed system is surprising given the expected low reactivity between cyclic carbonates and diamines. The rapid reaction time of the disclosed method provides evidence of the ability to successfully prepare more reactive precursors using organic carbonates as benign agents. Without wishing to be limited to any particular theory, this is thought to be due to the precursor formation process, which extends the nascent hydroxyl groups beyond the structure of polyol skeletons, such as complex polyol structures like lignin skeletons, preventing the cyclic carbonate groups from spatially hindering their participation in the curing reaction.

[0107] To prepare NIPUF, the curing reaction can be incorporated with a physical or chemical foaming agent. Typically, any physical or chemical foaming agent as known in the art can be used, including but not limited to physical foaming agents such as supercritical CO2 or sodium bicarbonate, or chemical foaming agents such as poly(methylhydrosiloxane) (PMHS). With the foaming agent, the curing agent can react with the foaming agent to release hydrogen and cause foaming.

[0108] In one embodiment, NIPUF can be formed by using a delayed addition of a blowing agent. In this method, a crosslinking reaction can be allowed to proceed in the NIPU formulation for a period of time, such as from about 1 minute to about 2 minutes, after the combination of the bio-based precursor and the curing agent, before the addition of the blowing agent, and then foaming begins. As described, a delayed addition method is not required to generate NIPUF, and in other embodiments, the blowing agent can be added together with the addition of the curing agent (or before the addition of the curing agent).

[0109] As is known in conventional polyurethane foam processing, the amount of blowing agent incorporated can vary, with higher amounts typically resulting in lower density foam. Furthermore, the properties of the blowing agent (e.g., chemical / physical properties) and the reactants used in the chemical foaming reaction can influence the preferred amount of blowing agent. However, generally, blowing agent can be added in amounts from about 1 vol% or less, for example, about 0.5 vol%, relative to the volume of the reaction mixture to provide a relatively low density foam, such as about 100 kg / m³. 3 Or smaller, approximately 50 kg / m3 Or smaller, or in some implementations about 30 kg / m 3 Or even smaller, for example from about 50 kg / m 3 Approximately 80 kg / m 3 Or in some implementation schemes, from approximately 70 kg / m 3 Approximately 100 kg / m 3 Foaming agents can typically be added in amounts of about 1% by volume or higher relative to the volume of the reaction mixture to provide higher density foam, such as about 100 kg / m³. 3 Or even larger, for example, about 100 kg / m 3 Approximately 900 kg / m 3 Approximately 100 kg / m 3 Approximately 500 kg / m 3 Approximately 105 kg / m 3 Approximately 150 kg / m 3 Or in some implementation schemes, approximately 110 kg / m 3 Approximately 130 kg / m 3 .

[0110] In one embodiment, compared to the volume of the reaction mixture in which a further diamine curing agent is added to the blowing agent in stoichiometric proportions, the use of PMHS chemical blowing agent in amounts from about 1 vol% to about 3 vol% can provide NIPUF formed using a lignin-based precursor as the sole cyclic carbonate precursor of the polyurethane, which has a strength from about 200 kg / m³. 3 Approximately 350 kg / m 3 The density of the foam. The foam density value can be determined according to ASTM D1622.

[0111] The properties of NIPUF can also be modified by selecting precursors, curing agents, etc., as known in the art. For example, NIPUF with desired and targeted properties can be provided by combining highly branched precursors, such as lignin-based precursors, with linear precursors, such as linear cyclic carbonate precursors.

[0112] The viscosity of the NIPUF reaction mixture is an important parameter that allows gas bubbles to coalesce during the foaming reaction, thereby increasing the porosity of the sample. The viscosity of the reaction mixture can vary depending on the type and amount of solvent used in the reaction mixture. Advantageously, the disclosed materials can form a reaction mixture with a desired viscosity at relatively low solvent add-in amounts. For example, the reaction mixture may include a solvent at a ratio of about 1.5 mL per gram of bio-based precursor or less, such as about 1.3 mL per gram of bio-based precursor in some embodiments. There are no particular limitations on the solvent used, but in one embodiment, a non-toxic solvent such as dimethyl sulfoxide (DMSO) can be used, which can increase the safety and environmental performance of the product.

[0113] The viscosity of the reaction mixture can also affect the formation of open-cell and closed-cell foams, with lower viscosity reaction mixtures leading to the formation of more open-cell structures. Specifically, as the lamellar layer becomes thinner due to the lower viscosity reaction mixture, more cellular rupture occurs. The viscosity of the reaction mixture can be altered by changing the solvent content and by changing the amount of diamine curing agent. For example, a higher content of a low-viscosity diamine curing agent in the reaction mixture (which is beneficial for utilizing chemical foaming agents such as PMHS that react with diamines) can reduce the viscosity of the reaction mixture, resulting in an increase in open-cell contents in NIPUF.

[0114] The disclosed NIPUF can achieve or exceed the typical expected threshold of commercial rigid PUFs at 10% strain. For example, the NIPUF as described can exhibit a compressive strength of about 80 kPa or greater at 10% strain (as can be determined according to ASTM D1621), or in some embodiments about 100 kPa or greater, such as from about 110 kPa to about 170 kPa at 10% strain.

[0115] The bio-based NIPUF disclosed herein can also exhibit other desirable qualities. For example, in some embodiments, the NIPUF can exhibit an Asker C hardness of about 20 to about 30, such as from about 21 to about 29, from about 22 to about 27, or about 25 as determined by ASTM 2240.

[0116] In some implementations, bio-based NIPUFs can also exhibit desirable strength qualities, for example, from about 2 kg / cm². 2 Approximately 10 kg / cm 2 Such as from about 3kg / cm 2 Approximately 8kg / cm 2 Or approximately 5kg / cm 2The tensile strength, such as that determined according to ASTM D3574E; in some embodiments, the tear strength, such as that determined according to ASTM D3574F, ranging from about 1 kg / cm to about 5 kg / cm, such as about 2 kg / cm; and in some embodiments, the split strength, ranging from about 0.1 kg / cm to about 3 kg / cm, such as about 0.2 kg / cm to about 2 kg / cm, or about 0.5 kg / cm.

[0117] In some embodiments, the bio-based NIPUF may exhibit elongation, such as greater than about 50%, for example from about 50% to about 150%, from about 75% to about 125%, or about 100% in some embodiments. The tensile elongation value can be determined according to ASTM 3574E.

[0118] In some embodiments, the bio-based NIPUF may exhibit desirable compressive properties, such as compressive deformation from about 5% to about 40%, from about 10% to about 30%, or about 20%; shrinkage rate less than about 5%, such as from about 0.5% to about 3%, or about 1%; and elasticity from about 20% to about 50%, such as from about 25% to about 40%, or from about 28% to about 32%. The compressive properties, shrinkage rate properties, and elasticity properties can be determined according to ASTM 3574, such as ASTM 3574N and ASTM 3574H.

[0119] Among other benefits, the high bio-based carbon content NIPU and NIPUF described herein exhibit excellent recyclability. Without wishing to be limited to any particular theory, it is believed that the use of organic carbonates in the initial chain extension reaction of polyol feedstocks not only extends the newly formed hydroxyl groups but also generates additional ether and carbonyl groups on the polyol backbone. These ether and carbonyl groups can act as “molecular zippers” in subsequent chemical recycling steps, providing a pathway not only to decompose the resulting polyurethane in the degradation reaction but also to recover a significant amount of precursor material, thus providing a circular lifecycle for the reuse of recycled precursors in the same or other applications. For example, using hydrolysis recycling technology, including processing at temperatures from about 200°C to about 250°C for reaction periods lasting from about 1 hour to 6 hours, bio-based NIPU / NIPUF can be treated to recover from about 60 wt.% to about 85 wt.% of lignin and convert from about 60 wt.% to about 75 wt.% of total polyurethane waste material. The combined hydrolysis / glycolysis recycling technology can utilize a reaction system comprising: a stabilizer such as ethylene glycol, formaldehyde, or bio-based alcohol in an amount of about 5 wt.% to 20 wt.% (e.g., 10 wt.%), and an alkaline catalyst such as potassium hydroxide solution in an amount of about 0.05 M to about 2.5 M (e.g., 1 M to 2 M), at a reaction temperature of about 200 °C to about 250 °C, for a reaction period of about 1 hour to 6 hours. Bio-based NIPU / NIPUF can be treated to recover from about 70 wt.% to 100 wt.% lignin and convert from about 70 wt.% to about 95 wt.% of total polyurethane waste material. Furthermore, natural degradation pathways present in the structure of polyols such as lignin have been shown to produce unique handles that can undergo chemical transformation and degradation through applied hydrolysis.

[0120] The presence of two phases in the polymer structure can also lead to shape memory properties in both NIPU and NIPUF, as described. Shape memory polyurethanes can be useful in sensors, actuators, smart materials, and many other applications. Shape memory polymers typically contain hard segments responsible for the permanent shape of the sample, while soft segments allow the sample shape to remain above the polymer's T0. g Deformation occurs when the temperature drops below T. g Furthermore, when the external stress is released, the sample retains its deformed shape due to the interaction between the soft polymer chains.

[0121] The utilization of waste products, using renewable biomass as a raw material in polymer synthesis and chemical conversion technologies, can create a truly renewable polyurethane lifecycle. In addition to environmental benefits, the use of low-cost waste feedstocks can increase the economic prospects of these materials. Furthermore, due to the "tunability" of the disclosed physical properties (including flexibility, stiffness, strength, etc.) of the materials, they can be used in any of a wide variety of end-use applications, such as, but not limited to, packaging (e.g., food packaging, cushioning, flexible packaging); building materials (e.g., structural foams, insulation, sealants); transportation materials (e.g., transport container insulation, supports, sealants); packaging materials; vehicle materials (e.g., roof liners, seat cushions, insulation); personal care products (e.g., joint wraps and supports, shoe inserts and liner); furniture (e.g., seating materials, cushions, fillings); and so on.

[0122] The present disclosure can be better understood by referring to the embodiments described below. Example

[0123] Materials and methods

[0124] Sulfate lignin is produced by Domtar under the trade name " "Lignin" is available. It is a low-ash lignin (~1%) and is dried before use. The curing agent is produced by Croda under the trade name "Priamine". TM 1074” available. Priamine TM It is a dimer diamine with an amine value of 209 mg KOH / g. Glyceryl carbonate (DMC) was purchased from Spectrum Chemical or InKemia Green Chemicals with a minimum purity of 90%. Dimethyl carbonate (>99.0%), dimethyl sulfoxide-d6 (DMSO-d6, 99.96 atomic % D), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 98%), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD, 98%), 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxophosphacyclopentane (95%), 1,3,5-trioxane (>99%), cholesterol (>99%), chromium acetylacetone (III) (97%), and poly(methylhydrosiloxane) (PMHS) were purchased from Millipore Sigma. The DMSO (99%) used in the reaction was purchased from VWR.

[0125] Infrared spectroscopy by Thermo Scientific TM Nicolet TM6700 spectrometer, from 500 cm⁻¹ -1 -4500cm -1 Using 16 scans, at 2cm -1 Spectral resolution was maintained during collection. All NMR experiments were performed using a Bruker Avance 300MHz spectrometer. The NMR was conducted after dissolving 30 mg of lignin sample in 0.55 ml of DMSO-D6. 1 1H NMR. 32 scans were performed using a spectral width of 5342 Hz. 13 C10 NMR was performed by dissolving 70-80 mg of lignin sample in 0.55 mL of DMSO-d6, using 50 μL of 15 mg / mL trioxane solution as an internal standard. Chromium acetylacetone (III) was used as a relaxant, with a spectral window of 18-110 Hz and 20,000 scans. Phosphorylation was performed in a 1.6 / 1 solution of pyridine and chloroform-d using 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxophosphazenecyclopentane as a phosphorylating agent, according to an established procedure. 31 P NMR analysis was performed. Cholesterol was used as an internal standard, and Cr(III) was used as a relaxant. CP / MAS SS was performed using a Bruker AV3-400 instrument at a spectrometer frequency of 100 MHz and a magic angle spinning frequency of 10 kHz. 13 C10 NMR. Molecular weight of the lignin precursor was measured using GPC (Alliance GPCV 2000), with two columns in tandem: first, Waters... HT5, followed by an Agilent PolarGel-L column. Lignin was dissolved at 1 mg / mL in N,N-dimethylformamide in 0.05 mL of lithium bromide. The mobile phase was filtered using a 0.2 mm nylon filter. PEG calibration standards were used with a Waters differential refractometer. Lignin samples were detected at 280 nm using a Waters 2487 UV-Vis detector.

[0126] Tensile tests were performed on canine bone-shaped samples generated in a silicon mold, and the tests were conducted on an Instron 1125R at 5 mm / min using a 1 kN load cell. Compression tests were performed on a 5582 with a compression rate of 10 mm / min using a 1 kN load cell. Samples were cut from a conical mold into cubes approximately 25 mm × 25 mm × 10 mm in size (depending on the rise height). The moduli of both tensile and compressive samples were calculated based on the initial slope of the stress-strain diagram. The average values ​​of three to five samples used for tensile testing and five samples used for compression testing were calculated and used for statistical analysis, with errors reported as standard deviations. Dynamic mechanical analysis was performed on a TA Instruments Q800 DMA in single cantilever mode using a fiber / membrane tension clamp. Temperature scans were performed from -50°C to 150°C at a frequency of 5 Hz and 0.3% of the maximum strain.

[0127] Thermogravimetric analysis (TGA) was performed on a TA Instruments Q5000 under a nitrogen and air mixture, with a heating rate of 20 °C / min from 25 °C to 600 °C. Dynamic scanning calorimetry (MSC) was performed on a TA Instruments Q20 during a hot-cold-hot cycle at 5 °C / min, purged with nitrogen at 50 mm / min. The glass transition temperature was calculated based on the midpoint of the slope change of heat flux relative to temperature. Curing rheology was studied on a Discovery HR-2 rheometer (TA Instruments) using a 25 mm parallel plate geometry. Increases in loss and storage modulus were observed using time-scan under isothermal conditions of 80 °C, 1% strain, and an angular frequency of 10 radians / second.

[0128] Example 1

[0129] Non-toxic glycerol carbonate (GC) was used as both a solvent and reagent in the oxyalkylation of sulfate lignin. Sulfate lignin (6.1 mmol OH / g) was mixed with 10 equivalents of GC (MW = 118.09 g / mol) in a round-bottom flask, based on the hydroxyl content of the lignin. 0.1 equivalents of catalyst were added, and the reaction was carried out at 150 °C under a nitrogen atmosphere for 1.5 h. When the reaction was complete, the mixture was allowed to return to room temperature, and the product was precipitated in a diluted HCl solution until the pH reached below 2. The precipitated lignin product was washed with acidified water, filtered, and dried overnight under vacuum using P₂O₅.

[0130] Oxyalkylated sulfate lignin (OKL) with a 1,2-diol functionalized structure underwent a transesterification reaction with dimethyl carbonate (DMC) to insert a 5-membered ring carbonate structure into the lignin backbone. OKL (4.7 mmol / g) was dissolved in DMSO, and 5 equivalents of DMC were added along with 0.4 equivalents of K₂CO₃ catalyst. The reaction was carried out at 75 °C under nitrogen for 4 hours. After the reaction was complete, the product was precipitated, filtered, and dried as described above.

[0131] The reaction of lignin-derived OH groups with organic carbonates occurs at both the carbonyl and alkyl carbons, forming carbonate and ether linkages, respectively. Spectroscopic evidence ( Figure 3 , Figure 4 This supports the incorporation of chain-extended lignin macromonomers containing two types of susceptible groups, producing molecular handles that can be used for chemical recycling in subsequent polymers. Figure 3 The peak at 3.5 ppm is due to the addition of methylene groups in the oxyalkylation chain, while the peak at 4-5 ppm refers to the protons in the cyclic carbonate ring. Figure 4 As shown, the functionalization (oxyalkylation) of sulfate lignin with glycerol carbonate results in CO stretching (1000 cm) corresponding to the etherified chain. -1 -1100cm -1 The increase in signal intensity, and the increase in signal intensity in the carbonyl region reflecting the presence of both straight-chain and branched cyclic carbonates (1700 cm⁻¹, respectively). -1 1720cm -1 The subsequent reaction with dimethyl carbonate resulted in a significant increase in the cyclic carbonate peak, which is a result of the ring-closed transesterification reaction.

[0132] The characteristics of the starting sulfate lignin, intermediate OKL, and cyclic carbonated lignin (CCL) are shown in Table 1 below.

[0133] Table 1

[0134]

[0135] The reagent equivalent in the reaction with GC was measured using the total hydroxyl content. An initial reaction using 10 equivalents of GC and 0.1 equivalents of catalyst DBU at 170°C for 3 hours typically yielded a black, glassy material exhibiting polycarbonate condensation properties between KL and GC. Lowering the temperature to 150°C while maintaining the same reaction time still resulted in a material that was substantially insoluble and unprocessable. However, reducing the reaction time to 1.5 hours and the catalyst loading to 0.05 equivalents yielded a product that was completely soluble in DMSO and could be characterized and used in further synthetic efforts. The reaction of GC with sulfate lignin was observed to be highly temperature-sensitive, and as expected, near sulfate pulping conditions (170°C), the ether linkages of the entire lignin structure were disrupted, triggering a series of reactions involving highly reactive lignin fragments. Increased exothermic gas (CO2) was observed at higher catalyst loadings and longer reaction times, indicating further GC reactions on the lignin framework. Because lignin polyols have much higher solubility in aqueous media, it becomes increasingly difficult to recover lignin after such a reaction.

[0136] Evidence for the complete reaction of aromatic hydroxyl groups with GC comes from 31 P NMR confirmed this by the disappearance of the aromatic signal from 136ppm-144ppm. Figure 5 A new peak appeared in the aliphatic region at 145.5 ppm–146.5 ppm, corresponding to the conversion of aromatic hydroxyl groups to newly formed aliphatic hydroxyl groups. Interestingly, when the reaction was completed at 120 °C, evidence of incomplete reaction was observed through the persistence of aromatic hydroxyl groups in the 137 ppm–140 ppm range. Unfortunately, due to side reactions during the oxyalkylation step, the use of… 31 Direct quantitative grafting of chains via PNMR is impossible.

[0137] Table 1 shows that the molecular weight of OKL is slightly lower than that of unfunctionalized sulfate lignin, and the hydroxyl content is correspondingly lower. In addition to the reaction of aromatic hydroxyl groups, the transformation of natural aliphatic hydroxyl groups can be observed through the formation of new, sharp peaks in the aliphatic region between 147 ppm and 148 ppm. Figure 5 Given the evidence of successful functionalization of aliphatic and aromatic hydroxyl groups, and the solubility and processing capability of the samples at 150 °C for 1.5 h, these conditions were used for all subsequent synthetic work.

[0138] 1 H NMR also confirmed the successful insertion of the oxyalkylated chain, with a spike at 3.7 ppm, which was associated with the disappearance of alkyl protons in the newly grafted carbon chain and phenolic protons at 8 ppm–10 ppm in the unfunctionalized lignin. Figure 3 Even during the first stage with GC, the signal of cyclic carbonate protons (4 ppm–5 ppm) still appears in this region, most likely a result of transesterification with excess GC in the reaction mixture. Quantification is difficult because the newly formed peaks of the oxyalkylated chains overlap with existing signals from unreacted lignin. However, for the peaks from the oxyalkylated chains… Figure 3 The total signal of all hydrogens associated with the methylene and methoxy regions between 3.5 ppm and 4.5 ppm was integrated, and this result was compared with the aromatic signal present in the range of 8 ppm to 10 ppm, with an average addition of 12 additional hydrogen atoms per aromatic group. A reasonable correlation was made with the amount of hydrogen contained in each grafted chain of GC (5), and with 2 grafted glycerol chains per aromatic unit. This result supports the findings of other teams that the reaction of lignin with organic carbonates is controlled to such an extent that extended polyglycerol chains do not form under normal reaction conditions. In this analysis, 13 C10 NMR does not provide sufficiently high resolution to conduct a more quantitative study of the amount of alkyl chains added to the lignin structure.

[0139] OKL's FTIR spectrum ( Figure 4 This demonstrates successful grafting of oxyalkylation chains at 1100 cm⁻¹ in association with CO stretching. -1 -1200cm -1 The signal increases in the region, and due to the OH-terminated groups, at 3500 cm⁻¹ -1 The total OH signal increased. The carbonyl region of the oxyalkylation precursor showed interesting results. ~1725 cm⁻¹ -1 The side peaks at 1795 cm⁻¹ indicate the formation of carbonyl groups, witnessing the formation of the linear carbonate linker between the lignin hydroxyl groups and GC. Cyclic carbonate groups (CC) can also be observed after the reaction with GC, such as at 1795 cm⁻¹. -1 The peaks at the specified locations confirm the presence of both etherified and carboxylated groups in the oxyalkylation chain, successfully functionalizing lignin with the extended hydroxyl groups used in the second step for cyclocarbonation.

[0140] The diol present in the lignin structure is converted into a cyclic carbonate group through a subsequent reaction with dimethyl carbonate. Figure 2 The successful reaction was detected by FTIR at 1795 cm⁻¹. -1 Enhancement of the CC peak ( Figure 4 ),as well as 1 The hydrogen associated with the carbonate ring showed a significant increase in ¹H NMR at 4.5 ppm–5.5 ppm. Figure 3 This was confirmed by applying [method / method]. The quantification of the CC group was achieved through the application of [method / meth 13 C NMR, by comparing the characteristic peak of cyclic carbonate at 155 ppm with the characteristic peak of the internal standard (trioxane) at 90 ppm (C NMR). Figure 6 The lignin derivatives containing a concentration of C-C groups of 2.05 mmol / g ± 0.05 mmol / g lignin were quantitatively analyzed.

[0141] Example 2

[0142] The precursors formed as described above are used to form NIPU. The formation reaction involves adding a diamine as a cured product, including a sample using a fatty acid-based dimerizing agent containing 100% renewable carbon. The diamines examined include hexamethylenediamine (HMD), decamethylenediamine (DMD), and... 1074. The supplier did not provide proprietary information. The molar mass of the diamine is given, but the reported amine value is included (209 mg KOH / g). Using Equation 1 and the amine value, the molar mass of the diamine can be determined... The molecular weight of the diamine was calculated to be 537 g / mol.

[0143] MW = 56100 × (number of H atoms in the amine) ÷ (amine value × number of H atoms per N atom) (1)

[0144] NIPU materials were formed by mixing CCL with diamines in different stoichiometric ratios (CC:amine - 1:1, 1:1.5, 1:2) to investigate the differences in crosslinking density and mechanical properties provided by different reaction mixtures. A small amount of DMSO was used to aid in the dissolution and compatibility of the two components, and 0.1 equivalents of the organic catalyst TBD were used to ensure complete reaction between the CC groups and the amines.

[0145] The kinetics of the curing reaction were studied by monitoring the gelation time of the reaction mixture at 80°C using a parallel plate rheometer. Figure 8 As shown, for approximately 6.5 minutes Uncatalyzed sample and catalyzed sample after approximately 1.5 minutes. The system exhibits a sharp increase in elastic modulus. Given the 1.5-minute time required to reduce the geometry of the rheological apparatus and initiate the procedure, the gelation time for the uncatalyzed system is 8 minutes, while the gelation time for the catalyzed system is 3 minutes. The observed rapid kinetics confirm the production of highly reactive lignin precursors using a non-toxic protocol.

[0146] The reaction conditions and results for different diamines are summarized in Table 2 below. Solubility was tested using DMSO, CDCl3, DMF, THF, m-cresol, and TFAc anhydride.

[0147] Table 2

[0148]

[0149] Due to the highly crosslinked nature of NIPU and the enhanced hydrogen bonding resulting from the additional hydroxyl groups formed during the ring-opening reaction during curing, the synthesized materials mostly exhibit complete insolubility in common organic solvents, as well as in treatments with hexafluoroisopropanol and trifluoroacetic anhydride. Therefore, the extent of polymerization was monitored by FTIR observation at 1795 cm⁻¹. -1 The CC peak at 1700cm -1 CNO stretching conversion of urethane carbonyl group. Figure 9A This shows the curing process as temperature increases, using... FTIR development of the carbonyl region of the NIPU sample formed from the product. The sample cured at 80°C showed unreacted cyclic carbonate groups in the structure, while increasing the curing temperature to 110°C showed a smaller proportion of unreacted groups. When the curing temperature was increased to 150°C, the cyclic carbonate groups were observed to be completely converted to urethane groups. Therefore, the maximum curing temperature of 150°C was selected for subsequent synthesis work.

[0150] A series of samples with varying stoichiometry of the curing agent were prepared. Samples were synthesized using CC lignin:amine ratios of 1:1, 1:1.5, and 1:2. CC lignin (2.0 mmol / g cyclic carbonate) was dissolved in DMSO in a 20 mL scintillation bottle. Dimeric diamines (MW = 537 g / mol, functionality = 2) were added according to different stoichiometric ratios of CC groups to amine functional groups (CC:amine 1:1, 1:1.5, 1:2). DMSO was added in the following ratio: 1.3 mL DMSO: 1 g CC lignin. The reaction mixture was gently heated to allow dissolution and mixing of the two components, and then poured into a preheated mold and subjected to curing at 80 °C for 4 hours, 150 °C for 4 hours, and 80 °C for 2 hours.

[0151] FTIR ( Figure 9B ; Figure 9C The image shows all NIPU samples observed at 1795 cm⁻¹. -1 The cyclic carbonate peak at 1700 cm⁻¹ is completely converted to the peak at 1700 cm� -1 The carbamate carbonyl peak at 1640 cm⁻¹ and the peak at 1640 cm⁻ -1 The side peak at 1600 cm⁻¹ indicates the presence of urea groups in the structure. The presence of urea groups at a curing temperature of 150°C is not surprising and is common in conventional polyurethanes formed via diisocyanate reactions. -1 and at 1500cm -1 The large peaks at this location are caused by the aromatic skeleton bands of lignin and are typically hidden at approximately 1500 cm. -1 The discovery of NH deformation. The incorporation of aliphatic diamines was witnessed through the following: the addition of cyclocarbonate-modified lignin precursors at 3500 cm⁻¹. -1 The OH stretching at 3300cm was replaced. -1 NH stretching at the location, and as concentrated at 2900 cm -1 There was a significant increase in the methylene signal in the two nearby peaks.

[0152] The bio-based content of the samples was calculated based on the procedure of Pan et al. (Biomacromolecules 12, 2416-2428 (2011)) by correlating the total amount of biorenewable carbon with the total amount of carbon present in each NIPU formulation. The lignin carbon content (65%) was estimated using publicly available data from elemental analysis of sulfate lignin (Forests 10, (2019)). The carbon content of the dimer diamine (80%) was estimated based on the molecular weight and the estimated molecular structure, as the manufacturer did not provide the precise structure. The only non-renewable carbon content present in the polymer structure was based on the incorporation of cyclic carbonate structures from reactions with organic carbonates. Despite the existence of bio-based pathways for their synthesis, glycerol carbonate and dimethyl carbonate are currently still synthesized from petroleum feedstocks. Table 3 below shows the results using… The high biomass content obtained from lignin-derived NIPU is achieved. As the ratio of CC lignin to curing agent becomes more stoichiometric, the biomass content decreases with increasing weight percentage of the cyclic carbonate component. The cyclic carbonate component is based on the information reported above. 13 The C NMR is calculated based on the assumption that there is an average of one grafted glycerol chain for each cyclic carbonate group.

[0153] Table 3

[0154]

[0155] Advantageously, when using bio-based sources for cyclic carbonate reagents, it is possible to obtain materials with 100% renewable bio-based carbon content. For example, testing of NIPU foam formed from a 1:1 ratio of CC and lignin using radiocarbon analysis according to ASTM D6866-20 revealed a content of 100 pMC (modern carbon percentage).

[0156] To further investigate the chemical structure of the synthesized NIPU, solid-state (SS) NMR was employed, taking into account the material's insolubility in common solvents used for conventional NMR preparation. SS NMR provided superior structural characterization of NIPU 1:1 and NIPU 1:2 compared to the CC lignin precursor. Figure 10Structural assignment was performed based on literature reports. The reaction of CC lignin with an aliphatic dimer diamine showed a shift of the cyclic carbonate carbonyl group present at 155 ppm (d) to the urethane-bonded carbonyl group at a slightly lower field (d'). At the α position of the urethane bond is an aliphatic CN bond, which appears at 40 ppm when the diamine is crosslinked, and at 39 ppm when the diamine is a chain-terminated substance (“free”). NIPU 1:2 showed a higher “free” CN bond signal than NIPU 1:1 because excess curing agent limited the amount of crosslinking available during the reaction by generating amine-terminated lignin. The signal of the cyclic carbonate carbon ac in CC lignin became condensed after curing, indicating a more similar chemical environment for the CO carbon and COH (a'-c') carbon after curing. Further away from the upfield, a methylene signal appeared at 30 ppm, reflecting the incorporation of the long-chain dimer diamine. The signal from NIPU 1:2 was stronger in this region than that from NIPU 1:1, reflecting a larger amount of curing agent added to the reaction mixture. Overall, ss NMR confirmed the successful reaction of CC lignin and the curing agent, and indicated relevant structural features associated with different stoichiometry of the reaction mixture.

[0157] Tensile tests were performed on canine-bone shaped samples using a 1 kN load cell and a crosshead speed of 5 mm / min. Samples were tested using curing agent ratios of 1:1, 1:1.5, and 1:2 (CC lignin:amine) to explore changes in mechanical properties with varying crosslinking density. The results reported in Table 4 below show that a maximum final strength value of 20.9 MPa was obtained when a stoichiometric ratio (1:1) was used between CC lignin and diamine. Stoichiometric samples did show some difficulty when clamped during tensile testing. However, adding a slight excess (no more than 0.25 mol fraction) of diamine prior to curing allowed for less cracking during analysis, with no observable difference in tensile strength. Higher proportions of diamine (NIPU 1:1.5 and 1:2) incorporated a larger proportion of fatty acid-based soft segments into the polymer structure, resulting in an increase in final strain and a corresponding decrease in modulus. When the ratio of amine groups to CC groups increased to 2 (NIPU 1:2), a significant increase in final strain and a decrease in modulus were observed, indicating that the sample was more elastic. By inserting long-chain diamine molecules into each CC group, the NIPU 1:2 sample represents the highest theoretical amount of soft-segment incorporation in the polymer structure. Figure 7 , Figure 10The decrease in final tensile strength and modulus was supplemented by the results of DMA analysis, which showed a reduction in the crosslinking density of NIPU 1:2 in DMA. Overall, the tensile test results confirmed the molecular structure determination by ssNMR, which revealed a higher incorporation of soft segments (aliphatic diamines) in the NIPU 1:2 samples, leading to a significant increase in the elasticity of these materials. Representative stress-strain curves for each sample are presented below. Figure 11 middle.

[0158] Table 4

[0159] NIPU Final tensile strength (MPa) Final strain (%) Tensile modulus (MPa) 1:1 20.9±3.6 10.7±2.8 400.6±86.0 1:1.5 15.8±2.2 13.0±4.0 307.7±45.3 1:2 12.2±0.54 38.9±7.5 137.3±23.8

[0160] Thermal analysis of NIPU revealed that it is a material with similar thermal stability to commercial polyurethanes. (TGA analysis) Figure 12 This reveals the 5% weight loss temperature (T) above 300°C. 5％ Thermal decomposition follows a typical two-step mechanism, as revealed by the curve for the first derivative with respect to weight loss. Figure 13 The first derivative shows that the urethane bond dissociates at approximately 350°C, followed by rapid decomposition of the lignin and diamine components.

[0161] DSC results showed that, within the typical temperature range of -20°C to 200°C for thermosetting crosslinked materials, there were no peaks indicating melting or crystallization events. Figure 13 The glass transition temperature was measured based on the change in slope observed in the second heating curve of the DSC thermogram. As expected, a higher loading of aliphatic curing agent resulted in a more pronounced transition from the glass state, while T... g The temperature was decreased from 94 °C for NIPU 1:1 to 84 °C for NIPU 1:2. These results are in good agreement with the glass transition temperature found from DMA analysis. DMA was performed from -50 °C to 150 °C at a fixed frequency (1 Hz), revealing the properties of the crosslinked material. The peaks in the Tanδ plot correspond to the T values ​​of the polymer network. g Correlation (α-relaxation) was observed, and a decrease in temperature from 99°C for NIPU 1:1 to 91°C for NIPU 1:2 samples was observed. Figure 14 An additional maximum was found at approximately 75 °C in NIPU 1:2, derived from relaxation associated with the dimer diamine, while at higher temperatures, this maximum was associated with the lignin macromolecular structure. Therefore, the DMA plot reflects a biphasic material with a broad transition region between 0 °C and 100 °C.

[0162] Using viscoelastic polymer theory, it is possible to measure the crosslinking density and the molecular weight of the crosslinked products by utilizing the rubber plateau found in the storage modulus after the α-relaxation temperature in DMA. The rubber plateau can be measured at T...α+20 It was found that, located after the broad transition from the vitrification region... Figure 14 Crosslinking density (V) e The result can be obtained from Equation 2:

[0163]

[0164] in

[0165] E' is in T α+20 The elastic modulus,

[0166] R is the constant of the gas law, and

[0167] T is T α+20 .

[0168] The crosslinking density of each sample is shown in Table 5 below, and it can be seen that the crosslinking density decreases with increasing soft segment incorporation from NIPU 1:1 to NIPU 1:2. High crosslinking was observed, resulting in exceptionally high storage modulus (~14 MPa-20 MPa) in the region of the rubber plateau.

[0169] The average molecular weight (Mc) of the crosslinked material can be obtained using data from a rubber platform and Equation 3:

[0170]

[0171] in

[0172] ρ is the density of the polymer.

[0173] T is T α+20 ,and

[0174] E' is in T α+20 The elastic modulus.

[0175] Using this relationship, the average molecular weight of the crosslinked components in the NIPU 1:1 sample was calculated to be 536.9 g / mol, which precisely corresponds to the molecular weight of the dimer diamine used in the curing reaction (537 g / mol). When an excess of diamine was used in NIPU 1:1.5 and NIPU 1:2, the average crosslinked molecular weight increased due to the incorporation of a larger amount of amine-terminated lignin material interacting via hydrogen bonding.

[0176] Table 5

[0177]

[0178] Given the T of the NIPU sample gLocated at approximately 100°C, the shape memory effect of the sample was tested by heating and curing NIPU in an oven set to 105°C for 10 minutes, followed by cooling to room temperature, which induced a semi-circular deformation. Figure 15 As shown, the NIPU material can maintain its deformation after cooling to room temperature and exhibits reversibility in returning to its pre-deformed shape upon reheating. This effect was observed for all NIPU samples, regardless of the stoichiometry of the curing agent, confirming the two-phase nature of these samples and their ability to act as shape memory materials.

[0179] Example 3

[0180] A chemical foaming agent was added to the reaction mixture as described above to investigate its ability to process NIPU foam. 1 g of CC lignin was dissolved in 1.3 mL of DMSO in a 20 mL scintillation bottle. Dimeric diamines were added based on the molar mass and density (0.9 g / mL) of the diamine, according to CC:amine group ratios of 1:1 and 1:2. PMHS was added based on volume fractions of 1.5% and 3.0% of the total reaction mixture. The corresponding amount of diamine was added based on the 90% mass content of hydrosiloxane units in the PMHS. The mixture was stirred for 1 minute and added to a conical aluminum mold with a base diameter of 30 mm. The foam was cured at 150 °C for 12 hours. Upon completion, the product was cut into 25 mm × 25 mm square segments and subjected to compression tests. Poly(methylhydrosiloxane) was added to react with the diamine curing agent to release hydrogen and induce foaming. Through iterative processes, it was found that a DMSO:1g CC lignin ratio of 1.3ml was the optimal condition to support foam rise during the curing process. PMHS was initially added at different volume percentages relative to the reaction mixture to form the lowest density foam. It was found that a volume of 3% PMHS produced a consistent sample with the highest rise height and lowest density compared to the volume of the reaction mixture. Additional diamine was added stoichiometrically to react with PHMS to allow for consistent reaction stoichiometry. Two reaction mixtures corresponding to NIPU 1:1 and NIPU 1:2 were used for the foaming reaction with 3% volume PMHS. An additional material was prepared with 1.5% PMHS for comparison.

[0181] Table 6 shows the results of physical and mechanical tests on NIPU foam. The density of all formulations was set at 241 kg / m³. 3 -337kg / m 3The high-density foam region between NIPU 1:1 and NIPU 1:2 showed negligible density differences; however, significant differences in properties were observed depending on the amount of foaming agent added during processing. Using 3% PMHS clearly produced a lower-density foam with a correspondingly lower compressive modulus.

[0182] The compression test results in Table 6 show that the foam made from stoichiometric amounts of diamine (NIPU 1:1) has a compressive strength greater than 100 kPa at 10% strain. Mechanical tests clearly show that using stoichiometric amounts of curing agent results in greater compressive strength and a comparable modulus than the NIPU 1:2 sample, revealing that using excess diamine in the NIPU 1:2 sample does not provide a net gain in terms of properties. The compression tests of these foams are consistent with general principles, observing increased compressive strength in materials with higher crosslinking density (NIPU 1:1 vs. NIPU 1:2) and apparent density (1.5% PMHS vs. 3.0% PMHS).

[0183] Table 6

[0184]

[0185] SEM analysis was used to examine the structural morphology of NIPU foam. Figure 16 Images of the lowest density foam with 3% PMHS are shown. NIPU 1:1 foam primarily contains closed-cell contents of 1 mm length or less (left), while the NIPU 1:2 sample contains more open-cell contents with larger pore lengths of 2 mm (center). Given that both NIPU 1:1 and NIPU 1:2 have a density of approximately 1000 kg / m³, the non-porous NIPU material has a density of approximately 1000 kg / m³. 3 Density, porosity of foamed materials The volume expansion (φ) can be calculated using equations 4 and 5 respectively:

[0186]

[0187] φ=(ρ f / ρ m (5)

[0188] in

[0189] ρ m It is the density of the original material, and

[0190] ρ f It refers to the density of the foamed material.

[0191] The results shown in Table 6 reflect a volume increase of more than four times during the foaming reaction, corresponding to a porosity value of approximately 0.75.

[0192] Example 4

[0193] In NIPU formulations, lignin-based precursors as described above are used in conjunction with linear bio-based cyclic carbonates (dicyclic decyl carbonate).

[0194] Dicyclic decanoate can be synthesized from sebacic acid (a derivative of castor oil) or sebacyl chloride and bio-based glycerol carbonate using known processes. This linear cyclic carbonate is added in different feed ratios than lignin-derived cyclic carbonates and reacted with diamines and blowing agents as previously described to form a range of NIPU foams with different properties. In general, the addition of dicyclic decanoate has been found to impart a softer foam quality, which is thought to be achieved by incorporating linear chains between the rigid lignin backbone.

[0195] The overall formation reaction is shown in Figure 17 middle. Figure 18 The FTIR of the bicyclic decanoate used to form NIPUF is presented. The characteristic peaks of the cyclic carbonate are clearly visible. Figure 19 The FTIR of NIPUF formed from a 50 / 50 bicyclic decanoate / lignin-based cyclic carbonate mixture cured with bio-based diamine is presented. As can be seen, there are no residual cyclic carbonate peaks, providing a complete conversion to 1708 cm⁻¹. -1 Evidence of urethane groups at the site.

[0196] Although certain embodiments of the disclosed subject matter have been described using specific terminology, such description is for illustrative purposes only, and it should be understood that changes and variations may be made without departing from the spirit or scope of the subject matter.

[0197] This invention also provides the following items:

[0198] 1. A bio-based precursor comprising a functionalized polyol, the polyol including a bio-based polyol, the functionalization comprising cyclic carbonate functional groups at a concentration of about 1.8 mmol or greater per gram of polyol, the bio-based precursor having a bio-based carbon content of about 95% or greater as determined by radiocarbon dating according to ASTM D6866-20.

[0199] 2. The bio-based precursor according to Item 1, wherein the bio-based polyol comprises lignin, for example, wherein the lignin comprises sulfate lignin having a polydispersity index of about 2 or greater.

[0200] 3. The bio-based precursor according to Item 1 or Item 2, wherein the bio-based precursor has a weight-average molecular weight of about 15,000 or less, and / or wherein the weight-average molecular weight of the bio-based precursor is about 70% to about 90% of the weight-average molecular weight of the bio-based polyol feedstock used to form the bio-based precursor.

[0201] 4. The bio-based precursor according to any one of items 1-3, wherein the cyclic carbonate functional group comprises a 5-membered cyclic carbonate structure on the backbone of the bio-based polyol.

[0202] 5. A method for forming a non-isocyanate polyurethane, comprising reacting a bio-based precursor, as described in any one of items 1-4, with a diamine curing agent.

[0203] 6. The method according to Project 5, wherein the diamine curing agent comprises fatty acid diamines, such as dimer fatty acid diamines.

[0204] 7. The method according to Project 5 or Project 6, the method further comprising reacting the second bio-based precursor with the bio-based precursor and the diamine curing agent.

[0205] 8. The method according to any one of items 5-7, wherein the reaction is carried out in the presence of a foaming agent, the reaction forming a non-isocyanate polyurethane foam, for example, wherein the foaming agent is combined with the bio-based precursor and the diamine curing agent after a period of time (e.g., from about 1 minute to about 2 minutes) following the combination of the bio-based precursor and the diamine curing agent.

[0206] 9. A method for forming a bio-based precursor as described in any one of items 1-4, the method comprising:

[0207] According to a first reaction, a polyol feedstock is reacted with a first organic carbonate to form an oxyalkylated polyol, said polyol feedstock including a bio-based polyol feedstock, the first reaction being carried out under reaction conditions including a reaction temperature of about 160°C or lower, and a reaction time of about 2 hours or less; and

[0208] The second reaction involves reacting the oxyalkylated polyol with a second organic carbonate to insert a cyclic carbonate structure into the backbone of the oxyalkylated polyol and form the bio-based precursor. The second reaction is carried out under reaction conditions including a reaction temperature of about 100°C or lower and a reaction time of about 5 hours or less.

[0209] 10. The method according to item 9, wherein the polyol raw material comprises lignin, and / or wherein the first organic carbonate comprises a cyclic organic carbonate, such as a cyclic organic carbonate formed by reacting bio-based glycerol with a carbonate.

[0210] 11. The method according to item 9 or item 10, wherein the second organic carbonate is different from the first organic carbonate, for example, wherein the second organic carbonate includes acyclic carbonates.

[0211] 12. The method according to any one of items 9-11, wherein the first reaction reduces the molecular weight of the bio-based polyol feedstock, and / or wherein the bio-based precursor has a molecular weight smaller than that of the bio-based polyol feedstock.

[0212] 13. A non-isocyanate polyurethane comprising a reaction product of a bio-based precursor and a diamine, said bio-based precursor comprising a functionalized polyol, said polyol including a bio-based polyol, said functionalization comprising cyclic carbonate functional groups at a concentration of about 1.8 mmol or greater per gram of polyol, said non-isocyanate polyurethane having a bio-based carbon content of about 90% or greater as determined by radiocarbon dating according to ASTM D6866-20.

[0213] 14. The non-isocyanate polyurethane according to item 13, wherein the diamine includes fatty acid diamines, such as polyvalent fatty acid diamines.

[0214] 15. The non-isocyanate polyurethane according to item 13 or 14, wherein the non-isocyanate polyurethane has one or more of the following properties:

[0215] Approximately 10 MPa or greater final strain,

[0216] Tensile modulus of approximately 135 MPa or greater;

[0217] Approximately 100 kg / m 3 Or a higher density;

[0218] Approximately 150 kg / m 3 Or even lower density;

[0219] Compressive strength of approximately 80 kPa or greater at 10% strain.

[0220] 16. The non-isocyanate polyurethane according to any one of items 13-15, wherein the non-isocyanate polyurethane is a non-isocyanate polyurethane foam.

Claims

1. A bio-based precursor comprising a functionalized polyol and a cyclic carbonate structure inserted into the backbone of the functionalized polyol, the functionalized polyol comprising a functionalized bio-based polyol comprising cyclic carbonate functional groups at a concentration of 1.8 mmol or greater per gram of the functionalized polyol, the bio-based precursor having a bio-based carbon content of 95% or greater as determined by radiocarbon dating according to ASTM D6866-20, wherein the bio-based precursor has a weight-average molecular weight lower than that of the bio-based polyol used to form the bio-based precursor, wherein the functionalized polyol is an oxoalkylated sulfate lignin having a 1,2-diol functionalized structure, the cyclic carbonate structure being a 5-membered cyclic carbonate structure inserted via an exchange-transfer reaction between the oxoalkylated sulfate lignin having a 1,2-diol functionalized structure and dimethyl carbonate.

2. The bio-based precursor of claim 1, wherein the lignin comprises sulfate lignin having a polydispersity index of 2 or greater.

3. The bio-based precursor according to claim 1, wherein the bio-based precursor has a weight-average molecular weight of 15,000 or less, and / or wherein the weight-average molecular weight of the bio-based precursor is 70% to 90% of the weight-average molecular weight of the bio-based polyol feedstock used to form the bio-based precursor.

4. A method for forming a non-isocyanate polyurethane, comprising reacting a bio-based precursor with a diamine curing agent, wherein the bio-based precursor comprises a functionalized polyol and a cyclic carbonate structure inserted into the backbone of the functionalized polyol, the functionalized polyol comprising a functionalized bio-based polyol, the functionalized polyol comprising cyclic carbonate functional groups at a concentration of 1.8 mmol of cyclic carbonate or greater per gram of the functionalized polyol, the bio-based precursor having a structure according to ASTM... D6866-20 has a bio-based carbon content of 95% or greater as determined by radiocarbon dating, wherein the diamine curing agent comprises a fatty acid diamine, wherein the functionalized polyol is an oxoalkylated sulfate lignin having a 1,2-diol functionalized structure, the cyclic carbonate structure is a 5-membered cyclic carbonate structure inserted through an oxoalkylated sulfate lignin having a 1,2-diol functionalized structure via a transesterification reaction with dimethyl carbonate, and wherein the bio-based precursor has a weight-average molecular weight lower than that of the bio-based polyol used to form the bio-based precursor.

5. The method of claim 4, wherein the fatty acid diamine comprises a dimer fatty acid diamine.

6. The method of claim 4, further comprising reacting the second bio-based precursor with the bio-based precursor and the diamine curing agent.

7. The method according to any one of claims 4-6, wherein the reaction is carried out in the presence of a foaming agent, and the reaction forms a non-isocyanate polyurethane foam.

8. The method of claim 7, wherein, after a period of time following the combination of the bio-based precursor and the diamine curing agent, the foaming agent is combined with the bio-based precursor and the diamine curing agent.

9. The method of claim 8, wherein the foaming agent is combined with the bio-based precursor and the diamine curing agent 1 to 2 minutes after the combination of the bio-based precursor and the diamine curing agent.

10. A method for forming a bio-based precursor according to any one of claims 1-3, the method comprising: According to a first reaction, sulfate lignin is reacted with glycerol carbonate to form oxyalkylated sulfate lignin having a 1,2-diol functionalized structure, wherein the first reaction is carried out under reaction conditions including a reaction temperature of 160°C or lower and a reaction time of 2 hours or less; and According to the second reaction, the oxyalkylated sulfate lignin having a 1,2-diol functionalized structure is reacted with dimethyl carbonate to insert a 5-membered ring carbonate structure into the backbone of the oxyalkylated sulfate lignin having a 1,2-diol functionalized structure and to form the bio-based precursor. The second reaction is an ester exchange reaction, and the second reaction is carried out under reaction conditions including a reaction temperature of 100°C or lower and a reaction time of 5 hours or less.

11. The method of claim 10, wherein the first reaction reduces the molecular weight of the bio-based polyol raw material, and / or wherein the bio-based precursor has a molecular weight smaller than that of the bio-based polyol raw material.

12. A non-isocyanate polyurethane comprising a reaction product of a bio-based precursor and a diamine, said bio-based precursor comprising a functionalized polyol and a cyclic carbonate structure inserted into the backbone of said functionalized polyol, said functionalized polyol comprising a functionalized bio-based polyol comprising cyclic carbonate functional groups at a concentration of 1.8 mmol or greater per gram of said functionalized polyol, said non-isocyanate polyurethane having a structure according to ASTM D6866-20 refers to a bio-based carbon content of 90% or greater as determined by radiocarbon dating, wherein the diamine includes a fatty acid diamine, wherein the functionalized polyol is an oxoalkylated sulfate lignin having a 1,2-diol functionalized structure, the cyclic carbonate structure is a 5-membered cyclic carbonate structure inserted via transesterification of the oxoalkylated sulfate lignin having a 1,2-diol functionalized structure with dimethyl carbonate, and wherein the bio-based precursor has a weight-average molecular weight lower than the weight-average molecular weight of the bio-based polyol used to form the bio-based precursor.

13. The non-isocyanate polyurethane of claim 12, wherein the fatty acid diamine comprises a polyvalent fatty acid diamine.

14. The non-isocyanate polyurethane according to claim 12, wherein the non-isocyanate polyurethane has one or more of the following properties: 10 MPa or greater final strain 135 MPa or greater tensile modulus; 100 kg / m 3 Or a higher density; 150 kg / m 3 Or even lower density; Compressive strength of 80 kPa or greater at 10% strain.

15. The non-isocyanate polyurethane according to any one of claims 12-14, wherein the non-isocyanate polyurethane is a non-isocyanate polyurethane foam.

16. The non-isocyanate polyurethane according to any one of claims 12-14, further comprising poly(methylhydrosiloxane).

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