Bio-derived cyclic bicarbonate monomers and isocyanate-free poly(hydroxy urethane)-based hot-melt adhesives / polymers therefrom

Abstract

The present disclosure relates to bio-derived cyclic carbonate based monomers of formula I and preparation processes thereof. The disclosure also relates to sustainable and isocyanate-free poly(hydroxy urethane) based hot-melt adhesives / polymers of formula II and its preparation thereof using said bio-derived cyclic carbonate based monomers.

Description

[0001] BIO-DERIVED CYCLIC CARBONATE MONOMERS AND ISOCYANATE-FREE POLY(HYDROXY URETHANEj-BASED HOT- MELT ADHESIVES / POLYMERS THEREFROM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a bio-derived cyclic carbonate-based monomer of Formula I. Particularly, present invention relates to sustainable and non-isocyanate polyurethanes [NIPUs] based hot-melt adhesives / polymer of Formula II. More particularly, present invention relates to a process for the preparation of hot-melt adhesives / polymer of Formula II using said bio-derived cyclic carbonate-based monomer of formula I.

[0004] BACKGROUND OF THE INVENTION

[0005] Adhesives play essential role in both industry and everyday life. When compared with other adhesives, hot-melt adhesives show promising next-generation green adhesives due to their solvent-free nature, which avoids emissions of volatile organic compounds, characterized by their solid state at low temperatures while presenting low viscosity and good flowing above this temperature. They provide great bond strengths in shorter periods upon cooling, and they are relatively easy to handle and economical. Thus, hot-melt adhesives are used in many applications, including automotive industry, packaging, bookbinding, shoe making, textiles, and labeling of bottles, disposable products, stamps, and envelopes. Indeed, global hot- melt adhesive market is projected to reach USD 9.46 billion by 2022.

[0006] Among polymers for hot melt adhesives, polyurethanes are versatile class of polymers which find applications in elastomers, foams, coating, biomedical devices, etc. Polyurethanes (PUs) are popular considering better low-temperature properties and greater flexibility (refer Alvaro Gomez-Lopez et al., ACS Polym. Au 2022,2, 3, 194-207). Further, it provides excellent adhesion on surfaces that are difficult to adhere, such as low-surface roughness materials. Global PU hot-melt adhesive market is at USD 1300 million in 2021 and projected to reach USD 2500 million by 2030. The principal monomers for synthesis of polyurethanes are diol / polyol and diisocyanates. Conventional polyurethanes are synthesized by reacting isocyanates with polyols, alternatively dicarbonates react with diamines to give polyhydroxyurethanes. Some of the monomers used for PU synthesis are moisture sensitive and pose various other challenges. Unfortunately, all these starting materials for synthesis of polyurethanes are mostly derived from fossil resources and also involve the usage of hazardous chemicals such as isocynates. Therefore, the development of polyurethanes that are sustainable from various perspectives such as environmental, health, and economic is a major challenge.

[0007] The majority of synthetic polymers are derived from non-renewable resources and nearly half of the packaging material ends up in landfills, and one-third escapes the collection system resulting in economic and energy losses. Further, the growing environmental concerns due to the increased concentration of CO2 in the atmosphere and continuous depletion in fossil resources focused a tremendous interest towards the use of CO2 as a feedstock for the production of value-added chemicals. It would be highly advantageous if fossil-carbon-derived polymeric materials could be replaced with those derived from renewable resources. Using CO2 as a renewable feedstock can significantly contribute to reducing CO2 emissions in several industrial sectors, provided that certain conditions are met, particularly the use of renewable sources of energy to drive the processes involved. CO2 is used to synthesize different polymers such as polyhydroxyurethanes, polycarbonates, polyureas and cyclic carbonates. Cyclic carbonates derived from CO2 can be reacted with amines for developing poly(hydroxyl urethanejs (PHUs). However, the structure of PHUs differs from classical PUs due to the presence of both primary and secondary hydroxyl groups in the main chain of polymers. Hydroxyl groups provide additional benefits to the PHU system, such as post functionalization, improved hydrogen bonding, enhanced adhesion forces, and miscibility between phases. Even though few studies highlighted partial utilization of sustainable resources for developing PHUs, most materials required for cyclic carbonate development and the diamine, still depended on fossil fuels. Furthermore, the data are scarce on bio-based precursors for synthesizing PHUs suitable for adhesive application.

[0008] References may be made to Journal “Synthesis of isosorbide based polyurethanes: An isocyanate free method” by V. Besse et al., in March 2013 Reactive and Functional Polymers, pp. 588-594, which discusses synthesis of isocyanate free polyurethanes. New bio based isosorbide dicyclocarbonates from isosorbide are prepared and then polyhydroxyurethanes (PHUs) were synthesized by a cyclocarbonate-amine step growth poly addition with four commercial diamines. This publication only covered homo -polymers, which are created when a single cyclic monomer reacts with various diamines (primarily fossil-derived) to produce polyhydroxy urethanes. The polymer synthesis specifically copolymers prepared in the present invention has not been disclosed. Present invention discloses the development of a reusable bio-based HMA with a high bio content of 88-90%, biodegradability, and tunable adhesive nature was developed as a possible alternative to conventional petroleum-based hot melt adhesives.

[0009] References may be made to Journal “Green Chemistry Letters and Reviews, Volume 14, 2021 - Issue 3”, which discusses the biobased Isosorbide compound as an advantageous competitor of petroleum-derived components in the synthesis of polymers.

[0010] References may be made to Journal “J. Mater. Chem. A, Pages 1233-1243” which discloses lignin derived vanillin. A spiro diacetal epoxy resin prepared from this vanillin was proved to be readily degradable under mild acidic conditions while maintaining stability under neutral or basic conditions and showing outstanding thermal stability. The present invention discloses prepare new vanillin-derived cyclic decarbonates which produces new monomers and polymers as described hereunder.

[0011] References may be made to Journal “Bio-based non-isocyanate poly(hydroxy urethane)s (PHU) derived from vanillin and CO2” by Fanjul-Mosteirfn, N., et al., in May 2023 Materials Advances, Volume 4, Page 2437-2448”, which discusses development of non-isocyanate poly (hydroxy urethanes) (PHU) based on 5- membered cyclic carbonates. First, three different vanillin-derived bis-cyclic carbonates were synthesized and then each monomer was reacted with two different bis-amines to yield six different PHUs. This document uses different starting materials from that of the present invention (a dimer of vanillin carbonate).

[0012] The proposed disclosure will aid in developing methodologies to utilize CO2 and natural molecules from agricultural products as primary raw materials for the design and synthesis of functional monomers and biodegradable polyurethanes suitable for adhesive application. Further, the ease of developing PHUs from renewable resources will add an advantage when subjected to both industrial and medical applications.

[0013] The non-isocyanate part is developed from a series of inexhaustible natural compounds derived from sugar molecules (isohexides) and lignin (Vanillin) (e.g. Maxence Fache et al., Green Chem., 2014,16, pages 1987-1998), since they have gathered much attention as a renewable starting material for commercial polymer production due to relative stability, rigidity, chirality, nontoxicity, and large scale industrial production. The influence of the molar composition of blends of dicyclic carbonates, as well as the nature thereof, on the adhesion properties, is being addressed. The bio derived optional substrates are vanillin or isosorbide. They react with various (second) substrates such guaiacol or its derivatives or other compounds to provide a variety of monomers, which are then polymerized by reacting with a variety of diamines.

[0014] Hence, a need still exists for to envisage different central challenges of our time for sustainable use of raw materials, utilization of non-toxic precursors, strategies for fighting climate change, transitioning from conventional to renewable sources of materials, and their applicability as the adhesive, when compared to commercial products, which has not been discussed in any of the prior documents discussed herein above.

[0015] Based on the above it is desired to address the above-mentioned disadvantages or other shortcomings or at least provide a useful alternative.

[0016] OBJECTS OF THE INVENTION Main object of the present invention is to provide a bio-derived cyclic carbonate- based monomer of Formula I.

[0017] Yet another object of the present invention is to provide a process for the preparation of bio-derived cyclic carbonate based monomer of formula I.

[0018] Another object of the present invention is to provide sustainable and isocyanate- free poly(hydroxy urethane) based hot-melt adhesives / polymer of Formula II.

[0019] Yet another object of the present invention is to provide a process for the preparation of hot-melt adhesives / polymer of Formula II using said bio-derived cyclic carbonate based monomer of formula I.

[0020] Yet another object of the present invention is to replace fossil-carbon-derived polymeric materials with those derived from renewable resources.

[0021] Yet another object of the present invention is to utilize Carbon dioxide (CO2) as a renewable feedstock for the development of value-added chemicals by environmentally friendly methods.

[0022] Yet another object of the present invention is to develop bio-derived mono and dicarbonate cyclic ring which can be a used as an alternative to isocyanate for the synthesis of poly hydroxy urethanes.

[0023] Yet another object of the present invention is to provide polyurethanes that are sustainable from various perspectives such as environmental, health, and economic. Yet another object of the present invention is to provide sustainable and isocyanate- free poly(hydroxy urethane) based hot-melt adhesives.

[0024] Yet another object of the present invention is to provide a method for replacing fossil-carbon-derived polymeric materials with those derived from renewable biomass.

[0025] Still another object of the present invention is to provide a facile, economical and industrially applicable method for developing PHUs from renewable resources for use in both industrial and medical applications

[0026] Yet another object of the present invention is to envisage different central challenges for sustainable use of raw materials, utilization of non-toxic precursors, strategies for fighting climate change, transitioning from conventional to renewable sources of materials, and their applicability as the adhesive, when compared to commercial products.

[0027] SUMMARY OF THE INVENTION

[0028] Accordingly, the present invention provides a polymer of formula II n is in the range of 2.5 to 4.5.

[0029] In an embodiment of the present invention, in the polymer of Formula II, R’ and

[0030] R1 are absent, and R2 is either In an embodiment of the present invention, the polymer is selected from the group consisting of: i. Polymer of formula IIA ii. Polymer of formula IIB

[0031] Formula IIB wherein n is in range of 2.5 to 4.5; and iii. Polymer of formula IIC Formula IIC wherein n is in range of 2.5 to 4.5.

[0032] In yet another embodiment, the present invention provides a process for the synthesis of polymer of formula II comprising the steps of: a) reacting a bio derived substrate with an alkylating agent, followed by an aqueous base and a phase transfer catalyst at a temperature ranging between 40°C to 100°C for a time period ranging from 2h to lOh to obtain alkenes derivative; b) reacting a bio derived substrate with pentaerythritol in the presence of an acid at a temperature ranging from 70°C to 150°C for a time period ranging from 2h to 20h to obtain diol derivative; c) contacting the alkene derivative as obtained instep (a) / diol derivative as obtained in step (b) with an oxidizing agent and a base at 0°C to obtain an epoxide; d) reacting the epoxide as obtained in step (c) with 10-30 bar of CO2 at a temperature ranging from 70°C to 150°C for a time period ranging from lOh to 30h and further contacted with a catalyst in the presence of a solvent to obtain corresponding monomer of Formula I; e) reacting at least one cyclic monomer of formula I with a diamine in a ratio ranging between 1:4 to 4: 1 in the presence of a strong base or a solvent at a temperature range of 50°C-120°C for a time period of 15-30 hrs to obtain polymer of formula II.

[0033] In yet another embodiment of the present invention, the process is carried out at preferably at a temperature range of 80-100°C for a time period of 15-25 hrs.

[0034] In yet another embodiment of the present invention, the bio-derived substrates are selected from vanillin, isosorbide or a combination thereof.

[0035] In yet another embodiment of the present invention, oxidizing agent used is elected from ozone, epichlorohydrin or mixture thereof.

[0036] In yet another embodiment of the present invention, the catalyst used is Tetrabutylammonium bromide [TBAB].

[0037] In yet another embodiment of the present invention, diamine is a fatty acid-derived diamine; the fatty acid derived diamine is Priamine and the strong base is 1,5,7- Triazabicyclo- [4.4.0]-dec-5-ene.

[0038] In yet another embodiment of the present invention, the solvent used in step (d) is selected from the group consisting of di ethyl ether, hexane, DCM, chloroform, methanol, ethyl acetate or acetone.

[0039] In yet another embodiment of the present invention, the catalyst used in step (d) is selected from Tetrabutylammonium bromide or TBAB.

[0040] In yet another embodiment of the present invention, the solvent used in step (e) is selected from the group consisting of dimethylformamide (DMF), dimethylsulfoxide (DMSO), N-Methyl Pyrrolidone (NMP), phenols, or a mixture thereof.

[0041] In yet another embodiment of the present invention, the polymer is a poly(hydroxyl urethane) s (PHUs).

[0042] In yet another embodiment, the present invention provides a bio-derived cyclic carbonate-based monomer of Formula I

[0043] Formula I wherein

[0044] In an embodiment of the present invention, the monomer is a dicarbonate or a monocarbonate cyclic monomer selected from isosorbide dicarbonate (ISO-DC) or divanillin- spiro-dicarbonate (DVS-DC).

[0045] In another embodiment, the present invention provides for the synthesis of a monomer of formula I comprising the steps of: a) reacting a bio-derived substrate with an alkylating agent, followed by an aqueous base and a phase transfer catalyst at a temperature ranging between 40°C to 100°C for a time period ranging from 2h to lOh to obtain alkenes derivative; b) reacting a bio-derived substrate with pentaerythritol in the presence of acid at a temperature ranging from 70°C to 150°C for a time period ranging from 2h to 20h to obtain a diol derivative; c) contacting the alkene derivative as obtained instep (a) / diol derivative as obtained in step (b) with an oxidizing agent and a base at 0°C to obtain an epoxide; d) reacting the epoxide as obtained in step (c) with 10-30 bar of CO2 at a temperature ranging from 70°C to 150°C for a time period ranging from lOh to 30h and further contacted with a catalyst in the presence of a solvent to obtain corresponding monomer of Formula I.

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Fig. 1 represents the DSC 2ndheating curves of non-isocyanate polyurethanes [NIPUs],

[0048] Fig. 2 represents the TGA thermograms of NIPUs.

[0049] Fig. 3 represents the GPC chromatograms of NIPUs.

[0050] Fig. 4 represents the Lap shear strength of NIPUs on the aluminium substrate. The error bars show the standard deviation of each sample set which includes 5 samples. Fig. 5 represents1H NMR spectrum of (a) NIPU 1-0, (b) NIPU3-40, and (c) NIPU6- 100, before and after degradation using 1 mol / L HC1. (d) weight loss of the NIPUs at different times (under 1 mol / L HC1).

[0051] Fig. 6 represents syntheses of ISO-DC from bio-renewable isosorbide; wherein (a) Allyl bromide, aq. NaOH, 65°C, 5 h; (b) Oxone, NaHCO3, 0°C, 7 h; (c) CO2, 30 bars, TBABB, 100°C, 24 h.

[0052] Fig. 7 represents the synthesis of DVS-DC from bio-renewable vanillin and Pentaerythritol; wherein (a) p-TSA, DMF-Pet Ether, refluxed, 12 h; (b) Epichlorohydrin, TBAB, 70°C, 3 h, aq. NaOH; (c) CO2, 30 bars, Acetone, 100°C, 24 h.

[0053] Fig. 8 represents synthetic routes for bio-based NIPUs.

[0054] DETAILED DESCRIPTION OF THE INVENTION

[0055] Present invention relates to a bio-derived cyclic bicarbonate monomer of formula I, wherein at least one of the substrate is obtained from biological / natural source.

[0056] The monomer is a dicarbonate or a monocarbonate cyclic monomer.

[0057] The biological sources are derived from sugar molecules and lignin.

[0058] The present invention provides a process for synthesis of bio-derived cyclic bicarbonate monomer of formula I comprising the following steps: a) a bio derived substrate is effected to react with functional groups to form its diol or alkenes derivative; b) contacting the diol / alkene derivative with an oxidizing agent and a base at 0°C to obtain an epoxide; and c) subjecting the epoxide to chemical fixation of CO2 to obtain mono and dicarbonate cyclic ring-based compounds of formula I.

[0059] The bio derived substrates are vanillin and / or isosorbide.

[0060] The alkene is obtained by reacting the bio derived substrate with an alkylating agent, followed by the aqueous base and a phase transfer catalyst. This process step is effected at a temperature ranging from 40°C to 100°C for a time period ranging from 2h to lOh. The process is effected at a temperature ranging from 65°C for a time period ranging of 6 hr.

[0061] The diol is obtained by reacting the bio derived substrate with pentaerythritol in the presence of an acid. This process step effected at a temperature ranging from 70°C to 150°C for a time period ranging from 2h to 20h. Preferably, the process is effected at a temperature ranging from 105 °C for a time period ranging of 15 hr. The second step involves contacting diol / alkene derivative with oxidizing agent and base at 0°C to obtain epoxide. Various oxidizing agents or combination thereof may be used in epoxidation reaction. Examples of oxidizing agents that may be suitable for use in present process include but are not limited to ozone, epichlorohydrin or mixture of any of these.

[0062] The epoxide is reacted with CO2 under ambient conditions of temperature and pressure to obtain corresponding mono and dicarbonate cyclic ring. This process step is effected at a temperature ranging from 70°C to 150°C for a time period ranging from lOh to 30h.

[0063] The amount of CO2 added is 10-30 bar. Preferably, the process is effected at a temperature ranging from 100°C for a time period ranging of 24 hr. In a more preferred embodiment 10-30 bar of CO2 is added.

[0064] Further, the epoxide is contacted with a catalyst in the presence of a solvent. Various solvents such as di ethyl ether, hexane, DCM, chloroform, methanol, ethyl acetate etc may be used. In preferred embodiment of the disclosure acetone is used as a solvent.

[0065] A number of catalysts or combination thereof may be employed in the process. In the preferred embodiment Tetrabutylammonium bromide or TBAB is used in the process.

[0066] The monomer was precipitated in cold water, and further purified in organic solvents. Various solvents such as di ethyl ether, hexane, DCM, chloroform, methanol, ethyl acetate etc may be used. Examples of solvents that may be suitable for use in the present process include but not limited to DCM, petroleum ether or a mixture of any of these.

[0067] The present disclosure provides a synthetic polymer of formula II comprising at least one monomer unit of formula I.

[0068] The n value in said polymers of formula II is preferably in the range of 2.97 to 4.39.

[0069] The present disclosure relates to synthetic polymer of formula IIA comprising at least one monomer unit of formula I. The formula IIA is represented by:

[0070] Formula IIA wherein

[0071]

[0072] The present disclosure relates to synthetic polymer of formula IIB comprising at least one monomer unit of formula I. The formula IIB is represented by:

[0073] Formula IIB wherein n is in range of 2.5 to 4.5.

[0074] The present disclosure relates to synthetic polymer of formula IIC comprising at least one monomer unit of formula I. The formula IIC is represented by: wherein n is in range of 2.5 to 4.5.

[0075] The present disclosure relates to synthetic polymer of formula II comprising at least one monomer unit of formula I. In some embodiments similar monomers may be polymerized to form the polymer. In other embodiments two different monomers may be polymerized to form the polymer. In preferred embodiments, the polymer is a poly(hydroxyl urethane)s (PHUs). The present disclosure relates to a process for synthesis of polymer of formula II comprising the following steps: a) At least one cyclic monomer is reacted with a diamine in the presence of a strong base to afford the polymer; b) At least one cyclic monomer is reacted with diamine in the presence of a solvent; c) the process is carried out at a temperature range of 50-120°C for a time period of 15-30 hrs.

[0076] In some embodiments, the diamine is a fatty acid-derived diamine.

[0077] A number of organic or inorganic bases may be employed in the process. In preferred embodiments, the base used is 1,5,7-Triazabicyclo- [4.4.0] -dec-5-ene.

[0078] In some embodiments, the diamine is a fatty acid-derived diamine. In other embodiments the diamine may be any organic amine. In more preferred embodiments the fatty acid derived diamine is Priamine.

[0079] In step (b), various polar solvents such a, dimethylformamide (DMF), dimethylsulfoxide (DMSO), NMP, phenols, etc may be used. Examples of solvents that may be suitable for use in the present process include but not limited to N- Methyl Pyrrolidone, Dimethyl Formamide or a mixture of any of these.

[0080] After cooling, the polymer was precipitated in cold water, and further purified in organic solvents. Various solvents such as di ethyl ether, hexane. DCM, chloroform, methanol, ethyl acetate etc may be used. Examples of solvents that may be suitable for use in the present process include but not limited to DCM, petroleum ether or a mixture of any of these.

[0081] The ratio between the cyclic monomer and the diamine is in ratio of 1:2 or 1:3 or 1 :4 or 2: 1 or 3 : 1 or 4: 1. In preferred embodiment of the disclosure, the ratio between the cyclic monomer and the diamine is in ratio of 1: 1. The process is carried out at a temperature range of 50-120°C for a time period of 15-30 hrs. The process is carried out at a temperature range of 80-100°C for a time period of 15-25 hrs. In more preferred embodiments, the process is carried out at 80 °C for 24 h.

[0082] Polyurethanes which are mostly derived from fossil resources and also involve the usage of hazardous chemicals such as isocaynates. The present disclosure utilizes renewable resources such as biomasss along with CO2 for synthesizing monomers which can finally lead to the synthesis of polyhydroxyurethanes.

[0083] Present invention discloses a process for synthesis of monomer of formula I. Vanillin / isosorbide will be chemically modified through its more reactive functional groups and the key reaction pathway is the conversion of vanillin / isosorbide to its alkenes / epoxide derivative followed by chemical fixation of CO2 to modified vanillin / isosorbide derivatives to derive corresponding mono and dicarbonate cyclic ring. Thus developed cyclic dicarbonate-based monomers from CO2 will act as an alternative of isocyanate for polyhydroxyurethane synthesis. The reactivity of cyclic dicarbonate was investigated by reacting with series of diamine and obtained Mnvarying from 1500-5500 g / mol and Mwvarying from 2000-10000 g / mol depending on the diamine used.

[0084] The polymer is used as an alternative adhesive to traditional petroleum-based adhesives. The polymer exhibits high shear strength.

[0085] The synthetic polymer may be used in as a hot melt adhesive. Synthetic polymer is used as an alternative adhesive to traditional petroleum-based adhesives. In more preferred embodiments, the polymer exhibits high shear strength.

[0086] BIOLOGICAL MATERIAL USED

[0087] Vanillin (>98%) and Isosorbide (>98%) were purchased from the TCI Chemicals, Toshima, Kita-Ku, Tokyo, Japan.

[0088] EXAMPLES Following examples are given by way of illustration and therefore should not be construed to limit the scope of the invention.

[0089] Materials: Vanillin (>98%), Isosorbide (>98%), Pentaerythritol (>98%), Allyl bromide (>98%), Tetrabutylammonium bromide (TBAB, >98%), Potassium peroxymonosulfate (Oxone), and l,5,7-triazabicyclo-[4.4.0] dec-5-ene (TBD, >98%) were purchased from the TCI Chemicals, Toshima, Kita-Ku, Tokyo, Japan. Priamine 1074 was provided by the CRODA, India. Epichlorohydrin (>99%) and Para-toluene sulfonic acid monohydrate (pT.SA.H2O) were procured from Sigma Aldrich. Sodium hydroxide pellets (NaOH, 98%) were supplied from the S D fine chemicals. Sodium sulfate (anhydrous, >99.5%, AR) was purchased from Leonid chemicals. Dimethyl sulfoxide (DMSO-de, 99.80% D) and Chloroform (99.80% D) were purchased from Eurisotop. CO2 gas cylinder (99.5%) was obtained from the Vadilal chemical. Sodium bicarbonate (NaHCCh) was procured from SRL chemicals. N-methyl pyrrolidinone (NMP), and Dimethylformamide (DMF) were distilled over CaH under a nitrogen atmosphere and stored over molecular sieves (4A). All chemicals were used as received unless specified.

[0090] Method: The chemical structure of the molecules was determined by and13C NMR spectroscopy using a Bruker Advance 500 MHz spectrometer equipped with a QNP z-gradient probe at room temperature. The infrared spectra (IR) were recorded on Bruker alpha Fourier transform infrared spectroscopy (FTIR) spectrometer where 48 scans were recorded in a frequency range of 4000-500 cm-1at a resolution of 4 cm-1. The high-resolution mass spectrometer (ThermoFisher Scientific) was used to detect the molecular weight of compounds. Their data was acquired from a hybrid Quadrapole Q-Exactive orbitrap fitted with an ACCELA PDA detector. Gel permeation chromatography was employed to analyzed the molecular weight of PHUs using viscotek GPC max (VE 2001) with a refractive index as a detector (Figure 3). The measurements were done in DMF (DMF plus lithium bromide IgL1) as an eluent at 1 mL / min. and using the DT6000M column at 50°C. Molecular weights were estimated relative to polymethyl methacrylate standards. The glass transition temperature was analyzed on a DSC-Q10 system from TA instruments (Figure 1). For each sample, two cycles were performed in the range between -70 and 150°C at 10°C min1under a nitrogen atmosphere (Figure 2). The glass transition temperature (Tg) was determined from a second heating cycle. Thermogravimetric studies were performed using a TGA-STA 6000 (Perkin Elmer) at a heating rate of 10 °C / min from 50°C to 900°C under a nitrogen atmosphere. The adhesive properties of synthesized PHUs were investigated at room temperature using an Instron 33R4204 (Load cell-lOKN) with a displacement rate of 1 mm.min1. The lap shear test was performed on aluminium substrates having dimensions of 54 mmx20 mmxl.55 mm (L*W*T). 200 mg of polymer materials were applied on the substrate surface by maintaining the adhesive contact area of 300 mm2(20 mm x 15 mm). Further, the adhesive specimen was prepared by melting at 130°C for 30min. After that, they were let to cool at room temperature overnight before the test. The measurements of each sample were repeated at least five times. The type of failure was also reported after the test on the basis of visual inspection. The lap shear strength was determined by the following formula, r = F / A where: r = lap-shear strength (N.mm-2or MPa), F = maximum shear force (N), and A = contact area of the adhesive joints (300 mm2)

[0091] Oscillatory rheological experiments were conducted using a stress-controlled rheometer (Physica MCR 301, Anton Paar, Austria) to investigate the viscoelastic properties of NIPUs. These polymers were exposed to sinusoidal oscillatory shear stress to examine their visco-elastic behaviors utilizing a parallel plate setup (plate diameter, 25 mm). Strain sweep tests were carried out from 1 to 10% strain at a fixed temperature (135 °C) and frequency (1 rad / s). Frequency sweep tests ranged from 0.5 to 500 rad / s at a steady temperature (135 °C) and strain (2.5%). Additionally, temperature ramp tests were conducted from 5 to 160 °C, maintaining a constant frequency (10 Hz) and strain (2.5%). The resulting values for storage modulus, loss modulus, tan delta, and complex viscosity were recorded and graphically represented. Mechanical tensile tests were also performed at room temperature using an Instron 5944 (Load cell: 1 KN) at a rate of 20 mm.min1. Dog- bone-shaped specimens, measuring a total length of 2.8 cm and a width of 1.2 cm (with the narrow section measuring 1.5 cm in length and 0.6 cm in width), were analyzed. The young modulus, tensile strength, and elongation at break were determined from the mean values of at least five samples. The error is reported as one standard deviation.

[0092] Example 1: Synthesis of Isosorbide dicarbonate (ISO-DC) (Monomer 1)

[0093] Step 1: Synthesis of isosorbide diallyl ether (ISO-DAE)

[0094] In a 250 ml RB flask, 30g of isosorbide (0.2052 mol) was added, and 62.06g of allyl bromide (0.513 mol) was added as the alkylating agent. Next, an aqueous solution of NaOH (20.52 g, 0.513 mol) was added dropwise, and 1.983g of Tetrabutylammonium bromide (TBAB, 6.155 mmol) was added as a phase transfer catalyst. The reaction was performed at 65 oC for 6 h. The crude product was extracted with dichloromethane, dried with anhydrous sodium sulfate, and purified by column chromatography. (26g, yield: 76%).

[0095] 'H-NMR (500 MHz, CDCh) 8 (ppm): 3.57 (t, 1H, isosorbide ring -CH), 3.89-4.05 (m, 5H, isosorbide ring -CH, and Cfh), 3.89-4.05 (m, 3H, CH2-CH=CH2), 4.16- 4.20 (dd, 1H, CH2-CH=CH2), 4.48 (d, 1H, bridgehead -CH), 4.61 (t, 1H, bridgehead -CH), 5.15-5.30 (m, 4H, -CH^CH), 5.82-5.96 (m, 2H, -CH=CH2)

[0096] 13C-NMR (500 MHz, CDCh) 8 (ppm): 69.79-70.47 (-CH2-O, isosorbide ring), 71.59-73.41 (-C=C-CH2-O), 79.43-80.19 (-CH-O, isosorbide ring), 83.75-86.28 (- CH-O, bridgehead), 117.39-117.72 (-CH=CH2-), 134.16-134.49 (-CH=CH2-). FT-IR (cm'1): 2866-2981 (aliphatic -CH stretch), 1647 (C=C stretch), 1260 (isosorbide C-0 stretch), 1023-1137 (isosorbide C-O-C stretch).

[0097] HRMS (ESI) m / z: [M + H]+calculated for CnHisCU: 227.1283; found: 227.1278.

[0098] Step 2: Synthesis of isosorbide diglycidyl ether (ISO-DGE)

[0099] ISO-DAE (20 g, 0.088 mol) was dissolved in a mixture of acetone (161 ml) and DI water (380 ml) and stirred at 0 °C (temperature was maintained using an ice bath). After that, the oxidizing agent Oxone (155 g, 0.251 mol), and sodium bicarbonate (63.08 g, 0.750 mol) were added. The addition of Oxone was done in 3-4 parts. After the completion of the addition, the reaction temperature was maintained at 0 to 5 °C and the reaction was continued for 7 h. Finally, the reaction mixture was filtered on a Buchner funnel. The product was extracted with dichloromethane (19.71 g, yield: 86.33%).

[0100] 'H-NMR (500 MHz, CDCh) 6 (ppm): 2.54-2.61 (m, 2H, epoxy -CH2), 2.75-2.78 (m, 2H, epoxy -CH2), 3.08-3.18 (m, 2H, epoxy -CH), 3.32-3.44 (m, 2H, -O-CH2), 3.75-3.83 (m, 2H, -O-CH2), 3.75-3.80 (t, 1H, isosorbide ring -CH), 3.87-4.01 (m, 5H, isosorbide ring -CH, and CH2), 4.47-4.50 (dd, 1H, bridgehead -CH), 4.60-4.66 (m, 1H, bridgehead -CH).

[0101] 13C-NMR (500 MHz, CDCh) 6 (ppm): 44.02-44.19 (-CH-O, epoxy), 50.53-50.78 (-CH2-O, epoxy), 69.79-70.35 (-CH2-O), 71.07-73.36 (-CH2-O, isosorbide ring), 80.16-80.63 (-CH-O, isosorbide ring), 84.81-86.16 (-CH-O, bridgehead).

[0102] FT-IR (cm4): 2866-2981 (aliphatic -CH / CH2 stretch), 1260 (isosorbide C-0 stretch), 1023-1137 (isosorbide C-O-C stretch), 905 (asymmetric C-0 stretch, epoxy), 832-847 (symmetric C-0 stretch, epoxy)

[0103] HRMS (ESI) m / . [M + H]+calculated for Ci2Hi8O6: 259.1181; found: 259.1176.

[0104] Step 3: Synthesis of monomer 1, isosorbide dicarbonate (ISO-DC)

[0105] ISO-DGE (11 g, 0.0318 mol) and TBAB catalyst (5 mol %) were dissolved in Acetone and poured into the 50 mL autoclave reactor. Then, 20 bars of CO2 were charged into the reactor and the reaction was conducted at 100 °C for 24 h. After completion of the reaction, the reactor was degassed and allowed to cool to room temperature. The solvent was removed by rotavapor to obtain the crude product and which was then extracted with ethyl acetate. (12.24g, yield:83%)

[0106] 'H-NMR (500 MHz, DMSOde) 6 (ppm): 3.44-3.52 (m, 1H, isosorbide ring -CH), 3.62-3.81 (m, 5H, isosorbide ring -CH, and CH2), 3.86-4.09 (dd, 4H, carbonate - CH2), 4.23-4.26 (dd, 1H, bridgehead -CH), 4.32-4.35 (m, 1H, bridgehead -CH), 4.41-4.62 (dd, 4H, carbonate -CH2), 4.92 (m, 2H, carbonate -CH).

[0107] 13C-NMR (500 MHz, DMSOde) 6 (ppm): 66.46 (-CH2-O, carbonate), 68.69-70.32 (-CH2-O, isosorbide ring), 72.83-72.94 (-CH-O, carbonate), 75.74-75.94 (-CH2-O), 80.24-80.59 (-CH-O, isosorbide ring), 84.52-85.87 (-CH-O, bridgehead), 155.36- 155.43 (C=O, carbonate).

[0108] FT-IR: 2866-2981 (aliphatic -CH stretches), 1778 (carbonate C=O stretch), 1175 (isosorbide C-0 stretches), 1044 (isosorbide C-O-C stretches).

[0109] HRMS (ESI) m / z: [M + H]+calculated for CuHisOio: 347.0978; found: 347.0973.

[0110] Example 2: Synthesis of divanillin-spiro-dicarbonate (DVS-DC) (Monomer 2) Step 1: Synthesis of divanillin-spiro-diol (DVS-DL)

[0111] Vanillin (10 g, 0.02473 mol) and pentaerythritol (8.95 g, 0.06574 mol) were dissolved in a mixture of DMF (22 ml) and pet ether (24 ml). Pet ether was used as water removing solvent. The RB flask was equipped with a Dean-Stark trap, reflux condenser, and magnetic stirrer. Then, p-toluenesulfonic acid monohydrate (pTSA.H2O, 0.38 g, 2 wt% of the total weight of vanillin and pentaerythritol) was added, and the reaction was carried out at 105°C for 15 h. The L-shaped tube of the Dean-Stark trap was charged periodically throughout the reaction (every 15 minutes) using a hot gun to increase the vapor speed towards the condenser. The crude product was precipitated with a 3 wt% aqueous solution of NaHCCh, washed with water, and finally, purified by precipitating it in pet ether.

[0112] 'H-NMR (500 MHz, CDCh) 6 (ppm): 3.59 (d, 2H, spirocyclic -CH2), 3.76 (t, 4H, spirocyclic -CH2), 3.85 (s, 6H, OCH3), 4.81 (d, 2H, spirocyclic -CH2), 5.33 (s, 2H, spirocyclic -CH). 5.59 (s, 2H, aromatic -OH), 6.85 (d, 2H, aromatic -CH), 6.90 (d, 2H, aromatic -CH), 6.96 (s, 2H, aromatic -CH).13C-NMR (500 MHz, CDCh) 8 (ppm): 32.46 (-C-(CH2)4-, spirocyclic), 55.94 (OCH3), 70.59-71.08 (-CH2)4-O, spirocyclic), 102.29 (O-CH-O, spirocyclic), 108.26-119.51 (C-H, aromatic), 130.15 (C-CH, aromatic), 146.31-146.45 (C-O, aromatic).

[0113] FT-IR (cm4): 3488 (-OH stretch), 2872-2969 (aliphatic -CH / CH2stretch), 1613 (aromatic C=C stretch), 1519 (aromatic C-C stretch), 1467 (C-H bend), 1263 (spiroacetal C-0 stretch), 1167 (spiroacetal C-O-C stretch).

[0114] HRMS (ESI) m / z: [M + H]+calculated for C2IH240S: 405.1549; found: 405.1544.

[0115] Step 2: Synthesis of divanillin-spiro-diglycidyl ether (DVS-DGE)

[0116] To synthesize DVS-DGE, a DVS-DAE (8.70g, 0.0215mol) was added to a RB flask equipped with a reflux condenser and magnetic stirrer. Epichlorohydrin (79.64g, 0.861 mol), and tetrabutylammonium bromide (TBAB, 10 wt%) were then added. The reaction was carried out at 75 °C. After 3 h, Afterwards, the reaction mixture was cooled down to room temperature and a 50 wt% of aqueous NaOH solution (5.16 g, 0.129 mol) was added dropwise. The reaction continued again for an additional 3 h while maintaining the temperature around 16 °C to promote the ringclosing. The resulting mixture was filtered, washed with DI water, and dried with anhydrous sodium sulfate. Finally, a white-colored powder was obtained by precipitating it with pet ether. (8.11g, yield: 72.86%).

[0117] 'H-NMR (500 MHz, CDCh) 8 (ppm): 2.73 (m, 2H, epoxy -Cfh), 2.88 (m, 2H, epoxy -Cfh), 3.37 (m, 2H, epoxy -CH), 3.66 (m, 2H, Cfh-OAr), 3.85 (m, 2H, Cfh- OAr), 3.85 (m, 2H, spirocyclic -CH2), 3.89 (s, 6H, OCH3), 4.04 (m, 2H, spirocyclic -Cfh), 4.22 (dd, 2H, spirocyclic -Cfh), 4.84 (d, 2H, spirocyclic -CH,2), 5.40 (s, 2H, spirocyclic -CH), 6.92 (d, 2H, aromatic -CH), 6.99 (d, 2H, aromatic -CH), 7.04 (s, 2H, aromatic -CH).

[0118] 13C-NMR (500 MHz, CDCh) 8 (ppm): 32.49 (-C-(CH2)4-, spirocyclic), 45.00 (CH2-O, epoxy), 50.14 (CH-O, epoxy), 55.94 (OCH3), 70.26 (CH2-OAr), 70.58- 71.07 (-CH2)4-O, spirocyclic), 102.09 (O-CH-O, spirocyclic), 109.51-118.70 (C-H, aromatic), 131.76 (C-CH, aromatic), 148.53-149.56 (C-O, aromatic).

[0119] FT-IR (cm4): 2872-2969 (aliphatic -CH / CH2stretch), 1613 (aromatic C=C stretch), 1519 (aromatic C-C stretch), 1467 (C-H bend), 1263 (spiroacetal C-O stretch), 1167 (spiroacetal C-O-C stretch), 908-918 (asymmetric C-0 stretch, epoxy), 809 (symmetric C-0 stretch, epoxy).

[0120] (ESI) m / z". [M + H]+calculated for C27H32O10: 517.2073; found: 517.2068.

[0121] Step 3: Synthesis of final monomer 2, divanillin-spiro-dicarbonate (DVS-DC)

[0122] The DVS-DGE compound (10 g, 0.0166 mol) and TBAB catalyst (5 mol %) were dissolved in Acetone and poured into the 100 mL autoclave reactor which was equipped with a mechanical stirrer and temperature controller. Next, 30 bars of CO2 were introduced into the reactor and the reaction was performed at 100°C for 24 h. After completion of the reaction, the reactor was degassed and cooled to room temperature. Then, the white solid was precipitated out by adding the reaction mixture to cold water. Finally, the crude product was purified in DCM-pet ether (10.30g, yield: 88 %).

[0123] 'H-NMR (500 MHz, CDCh) 8 (ppm): 3.64 (d, 2H, spirocyclic -CH2), 3.81 (dd, 4H, spirocyclic -CH2), 3.86 (s, 6H, OCH3), 4.20 (dd, 4H, carbonate -CH2). 4.60 (dd, 4H, carbonate -CH2), 4.80 (d, 2H, spirocyclic -CH2), 4.99 (m, 2H, carbonate -CH), 5.41 (s, 2H, spirocyclic -CH), 6.92 (d, 2H, aromatic -CH), 7.01 (d, 2H, aromatic - CH), 7.06 (s, 2H, aromatic -CH).

[0124] 13C-NMR (500 MHz, CDCh) 8 (ppm): 32.49 (-C-(CH2)4-, spirocyclic), 55.93 (OCH3), 66.37 (CH2-O, carbonate), 69.34 (CH-O, carbonate), 70.54-71.03 (-CH2)4- O, spirocyclic), 74.34 (CH2-OAr), 101.83 (O-CH-O, spirocyclic), 110.09-118.82 (C-H, aromatic), 133.28 (C-CH, aromatic), 147.92-150.26 (C-O, aromatic), 154.71 (C=O, carbonate).

[0125] FT-IR (cm'1): 2878-2941 (aliphatic -CH / CH2 stretch), 1789 (carbonate C=O stretch), 1601 (aromatic C=C stretch), 1518 (aromatic C-C stretch), 1465 (C-H bend), 1269 (spiroacetal C-0 stretch), 1167 (spiroacetal C-O-C stretch).

[0126] HRMS (ESI) m / z: [M + H]+calculated for C29H32OU: 605.1870; found: 605.1865.

[0127] Example 3: Synthesis of non-isocyanate polyurethanes (NIPUs) polymer

[0128] ISO-DC (1g, 2.88 mmol, 1 eq.) and Priamine 1074 (1.54g, 2.88 mmol, 1 eq.) were added to a 50 mL RB flask under an inert atmosphere. Followed by the addition of 1,5,7-Triazabicyclo- [4.4.0]-dec-5-ene (10 mol%). Next, the freshly distilled N- methyl-2-pyrrolidinone (2ml / lg) was added. The resulting solution was polymerized under continuous stirring at 80 °C for 24 h. After cooling, the polymer was precipitated in cold water, and further purified in DCM-pet ether.

[0129] To incorporate DVS-DC, the NIPUs were prepared by weighing ISO-DC, DVS- DC, and Priamine 1074 in a 50 mL RB flask according to the compositions shown in Table 1, entries 2-6. The conditions and time were the same as for the preparation of the 100 / 0 ISO-DC / DVS-DC ratio. In all cases, Priamine 1074 was kept at 1 equivalent with respect to 1 equivalent of carbonate.

[0130] Table 1: Molar compositions of precursors. e.g. in NIPU1, the ISO-DC is present in 100 mole % and DVS-DC is present of about 0 mole %;; in NIPU2, the ISO-DC is present of about 80 mole % and DVS- DC is present of about 20 mole %; in NIPU3, the ISO-DC is present of about 60 mole % and DVS-DC is present of about 40 mole %; in NIPU4, the ISO-DC is present of about 40 mole % and DVS-DC is present of about 60 mole %; in NIPU5, the ISO-DC is present of about 20 mole % and DVS-DC is present of about 80 mole %; and in NIPU6, the ISO-DC is present of about 0 mole % and DVS-DC is present of about 100 mole %.

[0131] Table 2: Experimental data from GPC, DSC, TGA, and Adhesive test.

[0132] NIPU1: 0.87-2.52 (Hl), 3.13 (H2), 3.56-4.16 (H3, H4, H6, H6’, H8), 4.51 (H5), 4.66 (H5’), 4.82 (H6, H6’), 5.07 (H7), 6.79-6.88 (H9, H9’).

[0133] NIPU2: 0.87-2.80 (Hl), 3.14 (H2), 3.59-4.17 (H3, H4, H5, H9, H10), 4.51-4.65 (H3), 4.86-5.05 (H6, H6’, H7, H7’, H9’, H10’), 5.41 (H4), 6.92 (H8), 7.00-7.05 (Hl l).

[0134] NIPU3: 0.87-2.80 (Hl), 3.15 (H2), 3.59-4.20 (H3, H4, H5, H9, H10), 4.83 (H3), 4.86 (H6, H6’, H7, H7’, H9’, H10’), 5.41 (H4), 6.79-6.90 (H8), 7.92-7.05 (Hl l).

[0135] NIPU4: 0.87-2.80 (Hl), 3.15 (H2), 3.62-4.27 (H3, H4, H5, H9, H10), 4.83 (H3),

[0136] 4.86-4.93 (H6, H6’, H7, H7’, H9’, H10’), 5.40 (H4), 6.72-6.80 (H8), 7.92-7.04 (Hl l).

[0137] NIPU5: 0.88-2.80 (Hl), 3.14 (H2), 3.62-4.43 (H3, H4, H5,H9,H10), 4.83 (H3),

[0138] 4.86-5.05 (H6, H6’,H7, H7’,H9’,H10’), 5.40 (H4), 6.80-6.91 (H8), 7.00-7.04 (Hl l).

[0139] NIPU6: 0.89-2.80 (Hl), 3.14 (H2), 3.63-4.27 (H3,H4,H4’,H5,H6), 4.83-4.92 (H3,H6’), 5.40 (H3), 6.77-6.80 (H8, H8’), 6.91-7.05 (H7,H7’).

[0140] 13C-NMR (500 MHz, CDCh) 8 (ppm):

[0141] NIPU1: 14.13-37.10 (C1-C4), 41.16 (C5), 65.93-73.17 (C6,C6’,C9), 80.75 (C7), 84.67 (C8), 86.00 (C8’), 156.77 (CIO, CIO’).

[0142] NIPU2: 14.14-33.70 (C1-C4), 41.19 (C5), 55.90 (C6,C6’), 65.83-73.17 (C7,C7’,C8,C9,C9’,C10), 80.77-86.04 (CIO), 102.01 (Cl l), 109.60 (C12), 118.88 (C13), 131.76 (C14), 148.56 (C15,C16), 156.76 (C17,C17’).

[0143] NIPU3: 14.14-32.46 (C1-C4), 41.05 (C5), 55.89 (C6,C6’), 65.80-73.15 (C7,C7’,C8,C9,C9’,C10), 80.78-86.07 (CIO), 102.01 (Cl l), 109.60 (C12), 118.89 (C13), 132.06 (C14), 148.56 (C15,C16), 156.75 (C17,C17’).

[0144] NIPU4: 14.14-32.46 (C1-C4), 41.19 (C5), 55.89 (C6,C6’), 65.84-73.15 (C7,C7’,C8,C9,C9’,C10), 80.77-84.74 (CIO), 102.01 (Cl l), 109.61 (C12), 118.88 (C13), 132.06 (C14), 148.57 (C15), 149.76 (C16), 156.76 (C17,C17’). NIPU5: 14.14-32.46 (C1-C4), 41.19 (C5), 55.89 (C6,C6’), 62.69-71.05 (C7,C7’,C8,C9,C9’,C10), 80.76-86.10 (CIO), 102.01 (Cl l), 109.61 (C12), 118.89 (C13), 132.04 (14), 148.56 (C15), 149.73 (C16), 156.76 (C17,C17’).

[0145] NIPU6: 14.15-32.48 (C1-C4), 41.19 (C5), 55.89 (C6,C6’), 63.84-71.05 (C7,C7’,C8), 102.01 (C9), 109.60 (Cl l), 118.86 (CIO), 132.06 (C14), 148.56 (C12), 149.63 (C13), 156.77 (C15,C15’).

[0146] FTIR (cm'1) (NIPU1 to NIPU6): 3150-3600 (OH, NH), 2856-2934 (CH stretches), 1706 (O-CO-NH), 1592-1638 (C=C stretch), 1466 (NH bend), 1036, 1080, 1142 (C-O-C), 1210-1260 (C-O).

[0147] It can be seen from the above examples that bio-based hot melt adhesives have been prepared based on non-isocyanate polyurethane (NIPUs). Precursors such as biorenewable vanillin and isosorbide-based dicarbonates, as well as fatty acid-derived diamine, were utilized. The chemical structure of the resulting NIPUs was confirmed through FTIR and NMR spectroscopy. However, the molecular weights of NIPUs varied from 4,410 to 6,530 g / mol with a polydispersity between 1.58 and 1.90. The thermal properties of the NIPUs were evaluated using DSC and TGA. The results indicated that the Tgvalues of the NIPUs increased with the content of rigid divanillin-spiro-dicarbonate and ranged from 6 to 44°C. NIPU1 had lower Tgvalues, whereas NIPU6 had higher Tgvalues. Additionally, the thermal stability of NIPUs was found to be increased with an increase in aromatic content, and it remained stable up to 290 °C (Tdl0%). The synthesized NIPUs have the potential as an alternative adhesive to traditional petroleum-based adhesives. Lap shear measurements showed that the adhesive strengths ranged from 0.09 to 6.39 MPa, and the NIPU3 exhibited high shear strength (Figure 4). To elucidate the effect of molecular composition on the viscoelastic behaviour of NIPUs, rheological experiments were performed. Strain (2.5%) with in the LVR region was further applied for the frequency sweep and temperature ramp measurements. The NIPU3 showed highest loss modulus or G" value as a function of frequency for all NIPUs indicating higher viscosity compared to other samples. This enhanced viscosity could be attributed to the synergetic effect of high density of non-covalent interactions (hydrogen bonds and 7t-7t interactions), as well as the ordered arrangement of the cycloaliphatic and spiro-aromatic segments present in NIPU3.

[0148] Water Contact angle of NIPUs: The surface wettability of the NIPU films was analyzed by the water contact angle (WCA), wherein the WCA of the NIPU polymers varied in the range of 93.9 ± 1.5° to 105.9 ± 0.9° exhibiting hydrophobic nature. The hydrophobic nature of these films can be attributed to the strong water- repellence properties of the priamine architecture due to the long aliphatic backbone and two pendant alkyl chain. However, the WCA changed from 105.9 ± 0.9° to 93.9 ± 1.5° after increasing molar composition of DVS-DC in NIPUs. The enhanced wettability of films arises from the increase in concentration of the polar methoxy groups in polymer architecture, which raises the surface free energy.

[0149] Acid degradability of NIPUs: The degradation of DVS-DC monomer and NIPU polymers under acidic conditions in an HC1 / H2O solution at room temperature is investigated. For the experiment, 10 mg of DVS-DC was dissolved in a mixture of acetone and H2O (9: 1, v / v) within NMR tubes. Subsequently, varying concentrations of HC1 (0.1, 1.0, and 2.0 mol / L) were introduced, and 1H NMR spectra were recorded. Control samples consisted of DVS-DC treated solely with acetone / H2O (9: 1, v / v). Additionally, the degradation of NIPUs was assessed through exposure to acid degradation in a 1 mol / L HC1 solution. The degradation process was monitored over 1, 7, and 14 days by measuring the percentage mass loss, as well as utilizing1H NMR and FTIR spectroscopy.1H NMR analysis showed monomer DVS-DC exhibited faster degradation as HC1 concentration increased and afforded a darker solution on degradation. The acetal linkage in DVS-DC underwent complete hydrolysis after 120 hours of treatment with 0.1 mol / L HC1, whereas exposure to 1 and 2 mol / L HC1 led to complete hydrolysis of the acetal group within 5 hours. The degradation assessment of NIPU1-0, NIPU3-40, and NIPU6-100 samples was conducted by immersing them in acid solutions (1 mol / L HC1), and their decomposition process was observed over various time intervals (1, 7, 14, and 21 days) using 1H NMR and FTIR techniques. Within 24 hours, NIPU3- 40 and NIPU6-100 samples, characterized by a notable content of spiro-aromatic monomer, exhibited complete disappearance of the acetal peak at 5.40 ppm (peak ‘a’) and the emergence of a new CHO peak at 9.86 ppm (peak ‘b’) (Figure 5b and 5c). This suggests the formation of aldehyde functional oligomers and pentaerythritol as a potential degradation product, clearly illustrating the susceptibility of NIPUs containing acetal linkages to degradation in acidic environments. However, NIPU1-0, lacking acetal linkages, showed no signs of degradation even after 21 days of treatment with HC1 (Figure 5a). Furthermore, FTIR analysis revealed visible absorbance of -CHO groups at 1680 cm-1 in NIPU6- 100, but not in NIPU1-0 and NIPU3-40 due to their lower or absent spiro-aromatic content. NIPU6-100, with higher acetal linkages, exhibited a higher susceptibility to weight loss, with a percent mass loss of 13.07%, whereas NIPU6-100 with fewer acetal linkages displayed a mass loss of 8.96%. Conversely, NIPU1-0, lacking acetal linkage, showed no change in mass loss after 14 days of degradation studies (Figure 5d). These findings indicate a direct correlation between the percentage of mass loss in NIPU samples and the presence of acetal linkages within them. Thus, the rigid spirocyclic acetal molecular architecture of DVS-DC facilitated facile selective acidic hydrolysis and aided chemical degradability.

[0150] ADVANTAGES OF THE INVENTION

[0151] The present disclosure provides for replacing fossil-carbon-derived polymeric materials with those derived from renewable resources. The present disclosure provides a method of utilizing Carbon dioxide (CO2) as a renewable feedstock for the development of value-added chemicals by environmentally friendly methods. The present disclosure provides a method to develop bio-derived mono and dicarbonate cyclic ring that can be a used as an alternative to isocyanate for the synthesis of polyhydroxy urethanes. The present disclosure provides polyurethanes that are sustainable from various perspectives such as environmental, health, and economic. The present disclosure provides sustainable and isocyanate-free poly(hydroxy urethane) based hot-melt adhesives. The present disclosure provides a method for replacing fossil-carbon-derived polymeric materials with those derived from renewable biomass. The present disclosure provides a facile, economical and industrially applicable method for developing PHUs from renewable resources for use in both industrial and medical applications. The present disclosure envisages different central challenges for sustainable use of raw materials, utilization of non-toxic precursors, strategies for fighting climate change, transitioning from conventional to renewable sources of materials, and their applicability as the adhesive, when compared to commercial products.

Claims

WE CLAIM1. A polymer of formula II2. The polymer as claimed in claim 1, wherein the polymer is selected from the group comprising of: i. Polymer of formula IIAFormula IIA whereinii. Polymer of formula IIBFormula IIB wherein n is in range of 2.5 to 4.5; and iii. Polymer of formula IICwherein n is in range of 2.5 to 4.5.

3. A process for synthesis of polymer of formula II as claimed in claim 1, wherein said process comprising the steps of: a) reacting a bio derived substrate with an alkylating agent, followed by an aqueous base and a phase transfer catalyst at a temperature ranging between 40°C to 100°C for a time period ranging from 2h to lOh to obtain alkenes derivative;b) reacting a bio derived substrate with pentaerythritol in the presence of an acid at a temperature ranging from 70°C to 150°C for a time period ranging from 2h to 20h to obtain diol derivative; c) contacting the alkene derivative as obtained instep (a) / diol derivative as obtained in step (b) with an oxidizing agent and a base at 0°C to obtain an epoxide; d) reacting the epoxide as obtained in step (c) with 10-30 bar of CO2 at a temperature ranging from 70°C to 150°C for a time period ranging from lOh to 30h and further contacted with a catalyst in the presence of a solvent to obtain corresponding monomer of Formula I;e) reacting at least one cyclic monomer of formula I with a diamine in a ratio ranging between 1 :4 to 4: 1 in the presence of a strong base or a solvent at a temperature range of 50°C-120°C for a time period of 15-30 hrs to obtain polymer of formula II.

4. The process as claimed in claim 3, wherein the bio derived substrates are selected from vanillin, isosorbide or combination thereof.

5. The process as claimed in claim 3, wherein oxidizing agent used is elected from ozone, epichlorohydrin or mixture thereof, and the catalyst used is Tetrabutylammonium bromide [TBAB].

6. The process as claimed in claim 3, wherein diamine is a fatty acid-derived diamine; the fatty acid derived diamine is Priamine and the strong base is 1,5,7-Triazabicyclo- [4.4.0]-dec-5-ene.

7. The process as claimed in claim 3, wherein solvent used in step (d) is selected from the group consisting of di ethyl ether, hexane, DCM, chloroform, methanol, ethyl acetate or acetone and the catalyst is selected from Tetrabutylammonium bromide or TBAB and the solvent used in step (e) is selected from the group consisting of dimethylformamide (DMF), dimethylsulfoxide (DMSO), N-Methyl Pyrrolidone (NMP), phenols or a mixture thereof.

8. A monomer of formula I9. The polymer as claimed in claim 1, wherein the monomer is a dicarbonate or a monocarbonate cyclic monomer selected from isosorbide dicarbonate (ISO-DC) or divanillin-spiro-dicarbonate (DVS-DC).

10. A process for synthesis of monomer of formula I comprising the steps of: a) reacting a bio-derived substrate with an alkylating agent, followed by an aqueous base and a phase transfer catalyst at a temperature ranging between 40°C to 100°C for a time period ranging from 2h to lOh to obtain alkenes derivative;b) reacting a bio-derived substrate with pentaerythritol in the presence of acid at a temperature ranging from 70°C to 150°C for a time period ranging from 2h to 20h to obtain a diol derivative; c) contacting the alkene derivative as obtained in step (a) / diol derivative as obtained in step (b) with an oxidizing agent and a base at 0°C to obtain an epoxide; d) reacting the epoxide as obtained in step (c) with 10-30 bar of CO2 at a temperature ranging from 70°C to 150°C for a time period ranging from lOh to 3 Oh and further contacted with a catalyst in the presence of a solvent to obtain corresponding monomer of Formula I.

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