WO2022201070A1

WO2022201070A1 - Polyethylene terephthalate derived polyurethane polymers, methods of production and uses thereof

Info

Publication number: WO2022201070A1
Application number: PCT/IB2022/052667
Authority: WO
Inventors: Regina Andreia TORRES MALGUEIRO; Juliana Andreia SILVA ALVES OLIVEIRA; David João LOUREIRO RAMADA; Helena Isabel OLIVEIRA SÁ
Original assignee: Centitvc - Centro De Nanotecnologia E Materiais Técnicos Funcionais E Inteligentes
Priority date: 2021-03-24
Filing date: 2022-03-23
Publication date: 2022-09-29

Abstract

The present disclosure relates to polyurethane polymers. Specifically, bis(2‐hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers that are biodegradable and/or self-healing.

Description

D E S C R I P T I O N

POLYETHYLENE TEREPHTHALATE DERIVED POLYURETHANE POLYMERS, METHODS OF PRODUCTION AND USES THEREOF

TECHNICAL FIELD

[0001] The present disclosure relates to polyurethane polymers. Specifically, bis(2 - hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers that are biodegradable and/or self-healing.

BACKGROUND

[0002] The significant increase in waste generation and disposal in landfills made it crucial to change the linear economy model (extract, manufacture, consume and disposal) to a circular economy model (dynamic system of production and consumption in closed circuits). This paradigm shift has covered different industrial sectors, from the construction sector to the packaging sector. Several studies and developments have been conducted to recycle the polymeric materials such as the polyethylene terephthalate (PET) used in the production of water bottles. PET recycling has focused, above all, on mechanical recycling, through crushing and extrusion processes; however, there are already some developments in chemical recycling with promising yields (aminolysis, glycolysis, hydrolysis). In fact, the recycling process is a more sustainable option as it leads to the formation of the raw materials (monomers) from which the polymer is produced and, therefore, presenting greater potential for recovery. Nevertheless, there is a continuous need for increasingly sustainable processes which favour the use of more ecological and economical reagents and processes, as well as products with increased functionality that satisfy the needs of the market. Polyurethane (PU) is widely used in different economic activities, namely in packaging, textile, construction, automotive and electronic sectors due to the ease of adjusting their reactional parameters (NCO:OH ratio, the number of reactive end-groups or the aliphaticvs. aromatic, the crystalline vs. amorphous and the hydrophobic vs. hydrophilic composition, etc.) to meet the desired chemical, thermal and mechanical properties. However, during utilization, PU containing products are exposed to several degradation agents (for example solar radiation, temperature changes, mechanical abrasion, etc.) which are responsible for limiting the PU performance and lifetime. Thus, it is of utmost interest for the industry to have a solution that is not only sustainable, but also healable.

[0003] Document US8658786B2 describes self-repairing cyclic oxide-substituted chitosan polyurethane networks. The invention relates to coating and polymer compositions derived from a biodegradable natural polysaccharide compound such as chitosan, pectin, heparin, and combinations thereof reacted with a cyclic oxide compound, such as an oxetane, oxolane or oxepane. The polymers exhibit self-repairing properties upon exposure to ultraviolet (UV) light.

[0004] Document CA2219545A1 describes a biodegradable polyurethane material having a backbone including a soft segment polyol, a diisocyanate and diamine chain extender.

[0005] Document NL8703115A1 describes biodegradable polyurethanes on the basis of a polyol prepolymer and an L-lysine derivative having at least 2 isocyanate groups. The polyol prepolymer is preferably a polyester polyol prepolymer obtained by ring-opening polymerization of L-lactide, glycolide and/or lactone with a cyclic polyol.

[0006] Document US6221997B1 describes a biodegradable polyurethane material having a backbone containing at least one amino acid group. The amino acid group is in a condition rendering it recognizable by a biological agent.

[0007] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.

GENERAL DESCRIPTION

[0008] The present disclosure relates to polyurethane polymers. Specifically, bis(2 - hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers that are biodegradable and/or self-healing. [0009] The present disclosure relates to polyurethane polymers, preferably a biodegradable polymer, comprising the following formula

wherein Y and Z are independently selected from each other; wherein Y selected from a list consisting of: H or

R4)m, and Z is selected from a list consisting of H and OCH3 or

wherein n is an entire number from 2000-4000; wherein m or X are entire numbers independently selected from each from 1-BOO, more preferably 50-100; wherein Rl, R2, R3, R4, R5 and R6 are independently selected from each other; wherein Rl, R2, R3, R4, R5 or R6 is a diol or a diamine. [0010] In an embodiment, Rl, R2, R3, R4, R5 or R6 is a low molecular weight diol or diamine.

[0011] In an embodiment, Rl, R2, R3, R4, R5 or R6 is C2-C10 diol or diamine.

[0012] In an embodiment, Rl, R2, R3, R4, R5 or R6 are selected from:

[0013] In an embodiment, Rl, R2, R3, R4, R5 or R6 are selected from bis(2-hydroxyethyl) disulfide (HEDS), coumarin, diethanolamine, ethylene glycol, dimethylol butanoic acid, isophorone diamine, 2-methyl-l, 3-propylene diol, diethylene glycol, propylene glycol, dipropylene glycol.

[0014] In an embodiment, the polymer may have the following formula

wherein n is an entire number from 2000-4000; wherein m is an entire number from 1-300, more preferably (50-100). [0015] In an embodiment, the polymer may have the following formula

wherein Y and Z are independently selected from each other; wherein Y = H or

wherein R3, R4, R5 and R6 are independently selected from each other; wherein R3, R4, R5 or R6 are selected from the following list:

wherein n is an entire number from 2000-4000; wherein X and m are entire numbers from 1-300, more preferably (50-100); preferably wherein the polymer is a biodegradable polymer.

[0016] In an embodiment, the self-healing segment is chitosan or sodium 2((2- aminoethyl)amino)ethane sulfonate (AAS), bis(2-hydroxyethyl) disulfide (HEDS), coumarin derivatives or mixtures thereof.

[0017] In an embodiment, the chain extender is 1,4-buthanediol (BD), 2((2- aminoethyl)amino)ethane sulfonate, HEDS, diethanolamine, ethylene glycol, dimethylol butanoic acid, isophorone diamine, 2-methyl-l, 3-propylene diol, diethylene glycol, propylene glycol, dipropylene glycol or mixtures thereof.

[0018] In an embodiment, the isocyanate is isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), diphenyl methane diisocyanate(MDI), hydrogenated MOI (H12MDI), meta-tetramethylxylene diisocyanate (TMXDI), trimethylhexamethylene diisocyanate (TMDI) or mixtures thereof.

[0019] Another aspect of the present disclosure relates to a film comprising the polymer of the present disclosure.

[0020] In an embodiment, the film has a thickness from 30 pm - 120 pm, preferably 60 pm.

[0021] In an embodiment, the film has a thermal stability of approximately 215 °C.

[0022] In an embodiment, the film has a T_g between 76 °C and 105 °C.

[0023] In an embodiment, the film is chemically resistant to: acid, alkaline, saline media, water, ranging from 3 hours to 24 hours.

[0024] Another aspect of the present disclosure relates to a method for preparing the polymer of the present disclosure comprising the steps of: adding a depolymerization agent to polyethylene terephthalate to obtain bis(2-hydroxy ethylene) terephthalamide (BHETA); adding a polyol, a self-healing agent and/or a biodegradable agent, a catalyst, a chain extender, a reaction medium, an acid neutralizer and an isocyanate to BHETA to obtain a biodegradable and/or self-healing polyurethane polymer;

[0025] In an embodiment, the method further comprises the step of dispersion of the functional polyurethane polymer in aqueous medium, preferably an emulsion step.

[0026] In an embodiment, the method further comprises the step of thermally curing the biodegradable and/or self-healing polyurethane polymer to obtain polymeric films.

[0027] In an embodiment, the polyol is poly(ethylene glycol) (PEG), polypropylene oxide), diethylene glycol, dimethylol propionic acid (DMPA), poly(tetramethylene oxide), poly(butylene adipate), polycaprolactone, polydimethylsiloxane, polyisobutylene, polyethylene butylene), or mixture thereof.

[0028] In an embodiment, the self-healing agent is chitosan, sodium 2((2- aminoethyl)amino)ethane sulfonate (AAS), bis(2-hydroxyethyl) disulfide (HEDS), coumarin derivatives or mixtures thereof.

[0029] In an embodiment, the catalyst is dibutyltin dilaurate (DBTL), dibutyltin diacetate, methane sulfonic acid, triflic acid, l,4-diazabicyclo[2,2,2]octane, 1,8- diazabicyclo[5,4,0]undec-7-ene, l,5,7-triazabicyclo[4,4,0]dec-5-ene, N-heterocyclic carbenes, or mixture thereof.

[0030] In an embodiment, the reaction medium is dimethyl sulfoxide, ethanol, ionic liquids, or mixtures thereof.

[0031] In an embodiment, the chain extender is 1,4-butanediol (BD), 2((2- aminoethyl)amino)ethane sulfonate (AAS), bis(2-hydroxyethyl) disulfide (HEDS), diethanolamine, ethylene glycol, dimethylol butanoic acid, isophorone diamine, 2- methyl-1, 3-propylene diol, diethylene glycol, propylene glycol, dipropylene glycol or mixtures thereof.

[0032] In an embodiment, the acid neutralizer is triethylamine.

[0033] In an embodiment, the isocyanate is isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), diphenyl methane diisocyanate(MDI), hydrogenated MOI (H12MDI), meta-tetramethylxylene diisocyanate (TMXDI), trimethylhexamethylene diisocyanate (TMDI) or mixtures thereof.

[0034] In an embodiment, polyurethane polymers (PU1 to PU7) were synthesized from bis(2-hydroxy ethylene) terephthalamide (BHETA), wherein said BHETA was obtained by aminolysis of PET waste.

[0035] In an embodiment, the polyurethane polymers obtained are surprisingly biodegradable and/or self-healing.

[0036] In an embodiment, the biodegradable and/or self-healing polyurethane polymers are obtained via aqueous dispersion, wherein the polymers have novel chemical structures containing at least a recycled segment (from the aminolysis of PET bottle residues), a biodegradable segment and/or a self-healing segment.

[0037] In an embodiment, the polyurethane polymers (PU1 to PU7) obtained have a thermal stability of approximately 215 °C, thermosetting properties and T_g between 76 °C and 105 °C, which are higherthan regular polyurethanes (namely thermal stability or thermosetting), due to the presence of BHETA and other hard segments.

[0038] In an embodiment, FTIR spectra of the polyurethane polymers (PU1 to PU7) obtained showed the characteristic spectral bands of polyurethanes, the shared spectral bands of their segments (BHETA, IPDI, PEG, DMPA, BD, HEDS, chitosan and AAS), as well as the strong hydrogen bonding.

[0039] In an embodiment, the polyurethane polymers (PU1 to PU7) obtained showed high uniformity to the naked eye and under optical microscopy.

[0040] In an embodiment, the polyurethane polymer PU2 presented self-healing properties after being submitted to temperatures of 60 °C and 70 °C, and polyurethane polymers PU3 to PU7 presented self-healing properties after being submitted to temperatures of 70 °C.

[0041] In an embodiment, the polyurethane polymers PU2, PU3, PU6 and PU7 present biodegradability due to the chitosan backbone in their chemical structure.

[0042] In an embodiment, the polyurethane polymers (PU1, PU2 and PU3) obtained showed good chemical resistance. The chemical resistance of the three polymers to acid, alkaline, saline media and water after 3 hours and 24 hours of contact was assessed. PU1 presented good resistance to all media up to 3 hours, and poor resistance to HCI and water after 24 hours. PU2 presented good chemical resistance to the alkaline and saline media and water up to 3 hours. PU3 presented good chemical resistance to saline medium up to 24 hours, good chemical resistance to acid, alkaline, saline media and water up to 3 hours. This can be explained by the increase in the polar groups in the chemical structure of PU2 and PU3 polymers as compared to PU1. The increase in polar groups allowed the permeation of water molecules into the polymeric matrices, encapsulating them and facilitating reactions such as hydrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

[0044] Figure 1 shows the synthesis mechanism for PU1.

[0045] Figure 2 shows the synthesis mechanism for PU2.

[0046] Figure 3 shows the synthesis mechanism for PU3.

[0047] Figure 4 shows the synthesis mechanism for PU4.

[0048] Figure 5 shows the synthesis mechanism for PU5.

[0049] Figure 6 shows the synthesis mechanism for PU6.

[0050] Figure 7 shows the synthesis mechanism for PU7.

[0051] Figure 8 is an image of the result of the biodegradability exploratory studies of PU1, PU2 and PU3 films.

[0052] Figure 9 is an image of the PU films before the chemical resistance study.

[0053] Figure 10 are images of the PU films after chemical resistance study.

[0054] Figure 11 is an image of the PU1, PU2 and PU3 films deposited on PET sheets and cured at 100 °C.

[0055] Figure 12 shows the TGA thermograms for PU1, PU2 and PU3 films.

[0056] Figure 13 shows the DSC thermograms of PU1, PU2 and PU3 films.

[0057] Figure 14 shows the FTIR-ATR spectra for the BHETA powder and the PU1, PU2 and PU3 films.

[0058] Figure 15 are images of Optical Microscopy of the PU1, PU2 and PU3 films at a magnification of 200x.

[0059] Figure 16 are photographs of the PU1 to PU7 films before being damaged, after being damaged and after induced self-healing. DETAILED DESCRIPTION

[0060] The present disclosure relates to polyurethane polymers. Specifically, bis(2 - hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers that are biodegradable and/or self-healing.

[0061] In an embodiment, the method of obtaining bis(2 - hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers comprises the following steps: Depolymerization of PET waste by aminolysis to obtain BHETA;

Synthesis of the pre-polymer containing the recycled segment;

Neutralization of the acidic groups of the DMPA segment;

Addition of the biodegradable segment (chitosan);

Chain extension with 1,4-buthanediol (BD), bis(2-hydroxyethyl) disulfide (HEDS) and sodium 2((2-aminoethyl)amino)ethane sulfonate (AAS);

[0062] In an embodiment, the method of obtaining bis(2-hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers further comprise the step of aqueous dispersion of the functional polyurethane via emulsion.

[0063] In an embodiment, the bis(2 - hydroxy ethylene) terephthalamide (BHETA) based polyurethane polymers obtained from the method described are biodegradable and/or self-healing.

[0064] In an embodiment, the sources of PET/PES used in depolymerization (aminolysis) to obtain the recycled segment inserted in the chemical structure of the synthesized biodegradable and/or self-healing polyurethane polymers disclosed herein are from PET and PES based residues and mixtures thereof

[0065] In an embodiment, the aminolysis catalyst is sodium acetate.

[0066] In an embodiment, the depolymerization agent is ethanolamine (ETA).

[0067] In an embodiment, the rigid segment and anionic group donor in the polyurethane polymer is dimethylol propionic acid (DMPA). DMPA helps to improve polyurethane dispersion in water. [0068] In an embodiment, the soft segment in the polyurethane polymer is polyethylene glycol (PEG) 2000 and 4000.

[0069] In an embodiment, the acid neutralizer is triethylamine (TEA), for neutralizing the acidic group of the DMPA.

[0070] In an embodiment, the polymeric chain extender is 1,4-buthanediol (BD), sodium 2((2-aminoethyl)amino)ethane sulfonate (AAS) and/or bis(2-hydroxyethyl) disulfide (HEDS).

[0071] In an embodiment, the catalyst is dibutyltin dilaurate (DBTDL).

[0072] In an embodiment, the reaction medium is dimethyl sulfoxide (DMSO).

[0073] In an embodiment, the isocyanate is isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HDI).

[0074] In an embodiment, the self-healing and biodegradable agent is chitosan.

[0075] In an embodiment, the chain extender and self-healing agent is sodium 2((2- aminoethyl)amino)ethane sulfonate (AAS) and/or bis(2-hydroxyethyl) disulfide (HEDS).

[0076] In an embodiment, depolymerization of PET waste was performed to obtain BHETA. The depolymerization of PET bottle waste followed the procedure of Shukla and Harad. Before the depolymerization reaction, the PET bottles were grinded using a PULVERISETT 19 cutting mill (FRITSCH) until a particle size equal or less than 500 pm was achieved. Thereafter, in a 3 neck round bottom flask under reflux, grinded PET and ETA were added in a mass ratio of 1:6 (PET:ETA). Sodium acetate (1% by weight of polymer) was also added as catalyst. The mixture was left to react for 8 hours at 160 °C under stirring. At the end of the reaction, excess distilled water was added to promote the precipitation of the BHETA monomer. The resulting dispersion was filtered and subsequently dissolved in boiling water for 30 min for purification to take place. The filtration and crystallization processes were repeated, and the white crystalline powder was then dried in an oven at 80 °C.

[0077] In an embodiment, functional polyurethane was obtained via aqueous dispersions. The procedure was based on the work reported by Shamri et al. The procedure consists of a single shot reaction where the BHETA, polyol, catalyst, chain extender, solvent and diisocyanate were added to a 3-neck round bottom flask under reflux and stirring. The reaction occurred for 6 hours at 90 °C.

[0078] In an embodiment, the polyol is selected from the list: polyethylene glycol), polypropylene oxide), diethylene glycol, dimethylol propionic acid, poly(tetramethylene oxide), poly(butylene adipate), polycaprolactone, polydimethylsiloxane, polyisobutylene, poly(ethylene butylene).

[0079] In an embodiment, the catalyst is selected from the list: dibutyltin dilaurate, dibutyltin diacetate, methane sulfonic acid, triflic acid, l,4-diazabicyclo[2,2,2]octane, l,8-diazabicyclo[5,4,0]undec-7-ene, l,5,7-triazabicyclo[4,4,0]dec-5-ene, N-heterocyclic carbenes.

[0080] In an embodiment, the chain extender, a low molecular weight diol or diamine, that reacts with diisocyanates to build polyurethane molecular weight, is selected from the list: 1,4-butanediol, diethanolamine, ethylene glycol, dimethylol butanoic acid, isophorone diamine, 2-methyl-l, 3-propylene diol, diethylene glycol, propylene glycol, dipropylene glycol, sodium 2((2-aminoethyl)amino)ethane sulfonate (AAS), bis(2- hydroxyethyl) disulfide (HEDS).

[0081] In an embodiment, the reaction medium is selected from the list: dimethyl sulfoxide, ethanol, ionic liquids, or mixtures thereof.

[0082] In an embodiment, PU1 was obtained via aqueous dispersion of BHETA-based PU. BHETA, PEG 2000, DMPA, DBTDL, BD and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Then, the IPDI was added to the flask and the mixture was left to react for about 4 to 6 hours. The reaction temperature was lowered to 45 °C to add the TEA for the neutralization of the acid groups on DMPA, which occurred for 30 min under stirring. The reaction mixture was added drop-wise to water pre-heated to 100 °C (15:150 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicator and was cured in an oven at temperature between 60 °C - 100 °C. Figure 1 shows the synthesis mechanism of PU1. [0083] In an embodiment, PU2 was obtained via aqueous dispersion. BHETA, PEG 2000, DMPA, DBTDL and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Then, the IPDI was added to the flask and the mixture was let to react for about 4 to 6 hours. The reaction temperature was lowered to 45 °C to add the TEA for the neutralization of the acid groups on DMPA, which occurred for 30 min under stirring. The reactional mixture was heated to 90 °C to add chitosan, and was left to react for about 1 to 2 hours. Thereafter, BD was added and the mixture was allowed to react for 1 to 2 hours. The reaction mixture was added drop- wise to water pre-heated to 100 °C (15:150 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicator and was cured in an oven at temperature between 60 °C - 100 °C. Figure 2 shows the synthesis mechanism of PU2.

[0084] In an embodiment, PU3 was obtained via aqueous dispersion. BHETA, PEG 2000, DMPA, DBTDL and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Then, the IPDI was added to the flask and the mixture was let to react for about 4 to 6 hours. The reaction temperature was lowered to 45 °C to add the TEA for the neutralization of the acid groups on DMPA, which occurred for 30 min under stirring. The reactional mixture was heated to 90 °C to add chitosan and was left to react for about 1 to 2 hours. Thereafter, BD and AAS were added, and the mixture was allowed to react for 1 to 2 hours. The reaction mixture was added drop-wise to water pre-heated to 100 °C (15:150 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicator and was cured in an oven at temperature between 60 °C - 100 °C. Figure 3 shows the synthesis mechanism of PU3.

[0085] In an embodiment, PU4 was obtained via aqueous dispersion. BHETA, PEG 2000, DMPA, DBTDL and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Thereafter, IPDI was added to the flask and the mixture was left to react for 4 hours. The reaction temperature was lowered to 50 °C to add HEDS, and it was left to react for 1 hour. After lowering the temperature to room temperature, TEA was added for neutralization of the acid groups on DMPA, which

IB occurred for BO min under stirring. The reaction mixture was added drop-wise to water at room temperature (15:50 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicatorand was cured at 50 °C- 100 °C in an oven. Figure 4 shows the synthesis mechanism of PU4.

[0086] In an embodiment, PU5 was obtained via aqueous dispersion. BHETA, PEG 4000, DMPA, DBTDL and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Thereafter, IPDI was added to the flask and the mixture was let to react for 4 hours. The reaction temperature was lowered to 50 °C to add HEDS, and it was left to react for 1 hour. After lowering the temperature to room temperature, TEA was added for neutralization of the acid groups on DMPA, which occurred for 30 min under stirring. The reaction mixture was added drop-wise to water at room temperature (15:50 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicator and was cured at 50 °C - 100 °C in an oven. Figure 5 shows the synthesis mechanism of PU5.

[0087] In an embodiment, PU6 was obtained via aqueous dispersion. BHETA, PEG 2000, DMPA, DBTDL and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Thereafter, IPDI was added to the flask and the mixture was let to react for 4 hours. The reaction temperature was lowered to 45 °C to add TEA for neutralization of the acid groups on DMPA, which occurred for 30 min under stirring. The reactional mixture was heated to 90 °C to add chitosan, and was left to react for 1 - 2 hours. Thereafter, the reaction was cooled to 50 °C and HEDS was added and allowed to react for 1 hour. The reaction mixture was added drop-wise to water at room temperature (15:50 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicator and was cured at 50 °C - 100 °C in an oven. Figure 6 shows the synthesis mechanism of PU6.

[0088] In an embodiment, PU7 was obtained by aqueous dispersion. BHETA, PEG 4000, DMPA, DBTDL and DMSO were added to a 3-neck round bottom flask. The flask, under stirring and reflux, was heated up to 90 °C. Thereafter, IPDI was added to the flask and the mixture was left to react for 4 hours. The reaction temperature was lowered to 45 °C to add TEA for neutralization of the acid groups on DMPA, which occurred for 30 min under stirring. The reactional mixture was heated to 90 °C to add chitosan, and was left to react for 1 - 2 hours. Thereafter, the reaction was cooled to 50 °C and HEDS was added and allowed to react for 1 hour. The reaction mixture was added drop-wise to water at room temperature (15:50 (v/v) mixture: water) under stirring (10000 rpm - 16000 rpm) using a Unidrive X 1000 D homogenizer from CAT. A 30 pm - 120 pm film was applied on a PET sheet using a film applicator and was cured at 50 °C - 100 °C in an oven. Figure 7 shows the synthesis mechanism of PU7.

[0089] Table 1 shows the example reaction parameters for the synthesis of PU1 to PU7.

[0090] In an embodiment, the thermogravimetric analysis (TGA) curves of PU1, PU2, PUB were determined at a heating rate of 20 °C/min under oxidative atmosphere at temperature ranging from 25 °C to 800 °C, using a TG 209 FI Libra from NETZSCH.

[0091] In an embodiment, differential scanning calorimetry (DSC) heating curves from 30 °C to 175 °C of PU1, PU2 and PU3 were determined by a Perkin Elmer Pyris Diamond at a heating rate of 10 °C/min under nitrogen.

[0092] In an embodiment, Fourier-transform infrared spectroscopy (FTIR) spectra of PU1, PU2 and PU3 films were obtained in transmittance mode using a Perkin Elmer Spectrum 400 spectroscope.

[0093] In an embodiment, the optical microscopy images of the different polyurethane films were captured using transmitted light and at a magnification of 200x on a Leica DM 2500M Optical Microscope.

[0094] In an embodiment, the viscosity of the PU1, PU2 and PU3 dispersions were determined at 20 °C on a Fungilab viscometer using an LCP adaptor for low viscosity liquids and a velocity of 100 rpm.

[0095] In an embodiment, the density of the PU1, PU2 and PU3 dispersions were determined by weighing the mass of 5 mL of each dispersion collected using a micropipette. The density of the dispersion was then calculated. For the solid content determination, the previously weighed volume was dried at 100 °C. The dried mass was then weighed and the solid content calculated.

[0096] In an embodiment, the self-healing studies were performed with the preparation of approximately 1 mm thick film of PU2 to PU7 dispersions. PU2 to PU7 films were obtained by pouring the respective dispersions into silicone molds and drying them in an oven at 60 °C (PU2) and 70 °C (PU2 to PU7). Once the films were dried, they were left to cool to room temperature. The cooled films were then slightly cracked and placed in an oven at curing temperature of 60 °C, for PU2 and 70 °C, for PU2 to PU7, for about 4 to 8 hours depending on the depth of the damage on the PU films.

[0097] In an embodiment, the biodegradability of PU1, PU2 and PUB were determined. The biodegradability was determined by preparing approximately 2 samples of 1 cm long film of PU1, PU2 and PU3 dispersions. The PU1, PU2 and PU3 films were prepared by pouring the respective dispersions into glass slides and curing them in an oven at 100 °C. The dried films were then introduced into goblets filled with dirt and were left to degrade exposed to environmental conditions for a month. After this period, the films were collected. Figure 8 shows an image of the result of the biodegradability of PU1, PU2 and PU3 films.

[0098] In an embodiment, the chemical resistance of the polyurethane polymer films was determined. The following solutions were prepared: 50 wt% aqueous H₂SO₄, 37 wt% aqueous HCI, 25 wt% aqueous NaOH, 23 wt% aqueous NaCI and distilled water. The chemical resistance of PU1, PU2 and PU3 films was determined by adding a 100 pL droplet of each solution, at 25 °C, onto the surfaces of 60 pm coated glass slides and they are allowed to rest for 3 hours and 24 hours. Figure 9 shows an image of the chemical resistance study and Figure 10 shows an image of the results of the PU films' chemical resistance study.

[0099] Figure 10 shows the images of the PU films after the chemical resistance study. The three polyurethane polymers were subjected to acid, alkaline, saline media and water for 3 hours and 24 hours of contact. PU1 showed good resistance to all media for up to 3 hours, and poor resistance to HCI and water after 24 hours. PU2 only showed good chemical resistance to alkaline and saline media and water for up to 3 hours. PU3 showed good chemical resistance to saline medium for up to 24 hours, good chemical resistance to acid, alkaline, and saline media and water for up to 3 hours. This can be explained by the increase in number of polar groups in the chemical structure of the PU2 and PU3 polymers as compared to PUl. The increase in number of polargroups allowed permeation of water molecules into the polymeric matrices, encapsulating them and facilitating reactions such as hydrolysis.

[00100] In an embodiment, the polyurethane polymer obtained showed good film forming properties, as it can be seen in Figurell. The cured films are homogeneous, translucid and without visible defects. Moreover, after application and curing of these polymeric formulations on PET sheets, Teflon sheets glass and silicone, it was impossible to peel the films off without damaging them, with the exception of the Teflon coated sheets. This shows that the polyurethane polymer films obtained have good adhesion properties. Figure 11 shows an image of 60 pm PU1, PU2 and PU3 films deposited on PET sheets and cured at 100 °C.

[00101] In an embodiment, Figure 12 shows the TGA results for PU1, PU2 and PU3 films. The TGA curves show that, despite the differences in the chemical structure of the three polyurethane polymers, their TGA thermograms are very similar due to the presence of similar chemical bonds and interactions. The thermal stability and degradation behaviour of the three polymers are summarized in Table 2.

[00102] Table 2 shows the thermal stability and degradation stages of the PU1, PU2 and PU3 films.

[00103] The first and second degradation stages of the polyurethane polymers are mostly related to chain scission of urethane linkages, polyol (PEG and DMPA) and BHETA, and isocyanurate and carbodiimide. It is also possible to conclude that the presence of the BHETA segment in the polyurethane polymers contribute to the increase in hydrogen bonding in polyurethane chains. The presence of the BHETA aromatic ring causes retardation of degradation, thus shifting the thermal stability to approximately 215 °C as compared to regular polyurethane polymers which have a thermal stability of approximately 140 °C.

[00104] In an embodiment, Figure 13 shows the DSC results for PU1, PU2 and PU3 films. The results, which show an absence of melting/crystallization points for the three polyurethane polymers obtained, illustrates their thermosetting nature. In addition, the results show that PU1, PU2 and PU3 possess a glass transition temperature (Tg) at 76.80 °C, 104.48 °C and 100.95 °C, respectively. The higher Tg values in PU2 and PU3 are related to an increase in mass fraction of hard segments which is due to the addition of chitosan and AAS in the reaction process in addition to DMPA, IPDI and DB.

[00105] In an embodiment, Figure 14 shows the FTIR-ATR transmittance spectra for BHETA powder and for PU1, PU2 and PU3 films. The BHETA spectrum shows the occurrence of its characteristic N-H spectral bands at 1304 cm^-1, 1568 cm^-1 and 3364 cm^-1, referring to the secondary amide stretching, and the O-H spectral bands at 1053 cm^-1 and 3285 cm^-1, referring to the primary alcohol groups. This FTIR spectrum is similar to reported BHETA spectra such as the one in the work of Shamri et al. The PU films spectra show that, despite the differences in the chemical structure of each polyurethane polymer, the three spectra obtained were identical. This can be explained by the fact that the different segments present in each PU chemical structure share identical chemical bonds and interactions, which in turn leads to the overlay of the spectral bands. Moreover, all the characteristic PU spectral bands are present (bands identified with a red line) in each of the 3 polymer spectra. At 3290 cm^-1, a spectral band which correlates to the N-H group in hydrogen bonds was observed. The hydrogen bonded carbonyl urethane groups (C=0) are reflected as a spectral band at 1700 cm^-1, and the C-N bond of the urethane group is reflected as a spectral band at 1600 cm^-1. The spectral bands at 1220 cm ¹ and 1060 cm ¹ correlates to the ester groups (C-O-C and CH2-O-CH2) resulting from the reaction between the alcohol groups of the polyols with the isocyanate groups. In addition, other spectral bands that are characteristic of some segments that have a strong presence in the chemical structure of the synthesized PU were also observed, for example the C-H stretching vibration spectral band present in the FTIR spectra of PEG 2000, chitosan and DMPA.

[00106] In an embodiment, Figure 15 shows optical microscopy images (with a magnification of 200x) of the PU1, PU2 and PUB films applied onto glass slides. The images in Figure 15 show that, as expected, the PU1 and PU3 films are uniform, with no morphological defects. However, the PU2 film showed some defects on the coating. The defects could be attributed to large particles or aggregates that may form in the dispersion.

[00107] Table 3 shows the viscosity values measured at 20 °C for PU1, PU2 and PU3 aqueous dispersions.

[00108] In an embodiment, the viscosity values in Table 3 show that the prepared PU aqueous dispersions' viscosities are not so different from commercially available PU dispersions (lacquers and topcoats from Lubrizol, Lamberti, among others, that have some products with viscosity values from 15 mPa.s and 50 mPa.s). The low viscosity values are a result of the reactional mediunrwater proportions selected for the emulsion stage, and if needed, can be adjusted to increase the viscosity values (at least up to 200-500 mPa.s). The low measurement reliability values are also a consequence of the reactional mediunrwater proportions selected, making the viscosity of the dispersions closer to the viscosity of water, which is under the reliable quantification limits of the viscometer. [00109] Table 4 shows the solid content and volumetric mass of the PU1, PU2 and PUB polymeric dispersions.

[00110] In an embodiment, the low solid content values presented in Table 4 are a result of the reactional mediunrwater proportions selected for the emulsion stage, and can be adjusted to increase the solid content values if needed (at least up to 50%). Despite the low solid content of the polymeric dispersions, their volumetric mass is in accordance with the values of commercial products, as it can be consulted in Lubrizol's brochure.

[00111] In an embodiment, Figure 16 shows the results of the self-healing studies. Figure 16 shows photographs of the PU1 to PU7 films before damage, after damage and after inducing self-healing. The results show that apart from PU1 which did not have self-healing segments, all damage (cracks)in PU2 to PU7 films disappeared completely after exposure to a heated atmosphere. Some deeper cracks in PU2 to PU7 polymeric films repaired themselves after exposure to a heated atmosphere, leaving a vestige of their existence ("scar"). The results are a validation of the intrinsic heat induced self- healing capacity of the polyurethane polymers (PU2 to PU7) to regenerate by restabilising their intermolecular interactions (hydrogen bonds and ionic interactions). The chemical structure of PU2 to PU7 contain several reactive functional groups (COOH, NH2, OH, C=0) that are responsible for the re-association of the groups and chains. This reversible bonding enables the PU chain to move and fill the damaged area, re-bond and mechanically restore the damage. In this case, the presence of heat in the process supplies the required energy for the mobility of the polymer chains and the re-bonding process. Moreover, at the supramolecular level, the hydrogen-bonds, dissulfide bonds and the ionic interactions provided by the chitosan, HEDS and AAS segments are huge contributors for the self-healing properties of the synthesized polymers. The hydrogen- bonds strength varies between 2 kcal/mol and 40 kcal/mol, depending on the nature of the donor and receptor, and are responsible for the interaction between PU polymeric chains, contributing for the supramolecular arrangement of the polymeric matrix. When damage occurs in the polymer, these bonds can re-associate in the presence of a trigger (heat). In a similar way, the sulfonate groups and dissulfide bonds added to the chemical structure of the polyurethane polymers contribute to the self-healing characteristics of the supramolecular structure of polymer by means of ionic interactions between the PU chains, forming electrostatic clusters. In the presence of damage, these electrostatic clusters dissociate, but can be re-associated in the presence of a trigger (heat).

[00112] In an embodiment, the results of the biodegradability studies show that the 3 PU films sustained visible morphological changes within the 1-month duration of this study. As for PU1, it is visible that the films lost their transparency and became more brittle, as a result of the interaction with water molecules resultant from exposure to rain and the activity of microorganisms. The increase in number of polar groups in the structure of the polymer, allows the permeation of water molecules into the polymeric matrices, encapsulating them and facilitating reactions such as hydrolysis. This behaviour is even more evident in the PU2 and PU3 samples, where the presence of chitosan and AAS increases even more the polarity of the chemical structure of the synthesized polymers. In addition, regarding these last two polymeric dispersions, due to the presence of the biodegradable segment (chitosan) it is possible to observe a significant rarefaction of the films (loss of thickness and even small areas without film), that can be attributed to the degrading action of microorganisms.

[00113] Table 5 shows the chemical resistance results of PU1, PU2 and PU3 films, where "+" means resistant, means non-resistant, "++" means very resistant and - " means very non-resistant.

[00114] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[00115] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof.

[00116] The embodiments described above are combinable.

Reference

1. Ramin Shamsi; Majid Abdouss; Gity Mir Mohamad Sadeghia; Faramarz AfsharTaromi. Polym Int2009; 58: 22-30

2. Bertrand Willocq; Jeremy Odent; Philippe Dubois; Jean-Marie Raquez. RSC Adv., 2020, 10, 13766- 13782

3. Shukla SR and Harad AM, Polym Degrad Stab 91:1850 (2006).

4. Shamri et al., Polym Int 2009, 58: 22-30

5. Semsarzadeh MA and Navarchian AH, J Appl Polym Sci 90:963 (2003)

6. Kathalewar, Mukesh & Dhopatkar, Nishad & Pacharane, Bajirao & Sabnis, Anagha & Raut, Parag & Bhave, Vijay. (2013). Progress in Organic Coatings. 76. 147-156

7. Khairiah Badri; Wong Sien; Maisara Shahrom; Liow Hao; Norhafiza Baderuliksan; Nor Norzali. Sol. State Sci. & Tec. 2010. 18, pp. 1-8

8. Bo Feng; Zhenshan Hou; Xiangrui Wang; Yu Hu; Huan Li; Yunxiang Qiao. Green Chem., 2009, 11, 1446- 1452

9. Felippe Pavinatto; Luciano Caseli; Adriana Pavinatto; David Santos; Thatyane Nobre; Maria Zaniquelli; Heurison Silva; Paulo Miranda; Osvaldo Oliveira. Langmuir. 2007, 23, pp 7666-7671

10. https://www.lubrizol.com/-/media/Lubrizol/Coatings/Documents/Literature/Textile-Coatings- Product-Guide — 20-226950.pdf

11. http://www.lamberti.com/products/TDS.cfm?nav=021500&CatTDS=49 S. Billiet, X. K. D. Hillewaere, R. F. A. Teixeira and F. E. Du Prez, Macromol. Rapid Commun., 2013, 34, 290 -309 J. W. Larson and T. B. McMahon, Inorg. Chem., 1984, 23, 2029 —2033 J. Emsley Chem. Soc. Rev., 1980, 9, 91 —124 Y. J. Kim, P. H. Huh and B. K. Kim, J. Polym. Sci., Part B: Polym. Phys., 2015, 53, 468 -474 Y. Xiao, H. Huang and X. Peng, RSC Adv., 2017, 7, 20093 -20100 S. Chen, F. Mo, Y. Yang, F. J. Stadler, S. Chen, H. Yang and Z. Ge, J. Mater. Chem. A, 2015, 3, 2924 — 2933

Claims

C L A I M S

1. A polyurethane polymer comprising the following formula

wherein Y and Z are independently selected from each other; wherein Y is selected from a list consisting of H or

R4)m, and Z is selected from a list consisting of H, OCH3,

wherein n is an entire number from 2000-4000; wherein m or X are entire numbers independently selected from each from 1-300, more preferably 50-100; wherein Rl, R2, R3, R4, R5 and R6 are independently selected from each other; wherein Rl, R2, R3, R4, R5 or R6 is a diol or a diamine.

2. The polymer according to claim 1 wherein Rl, R2, R3, R4, R5 or R6 is C2-C10 diol or C2-C10 diamine.

3. The polymer according to any of the previous claims, wherein Rl, R2, R3, R4, R5 or

4. The polymer according to any of the previous claims comprising the following formula

wherein n is an entire number from 2000-4000; wherein m is an entire number from 1-300, more preferably 50-100.

5. The polymer according to any of the previous claims comprising the following formula

wherein Y and Z are independently selected from each other; wherein Y is selected from H or

R4)m, and Z is selected from H or OCH3 or

wherein R3, R4, R5 and R6 are independently selected from each other; wherein R3, R4, R5 or R6 are selected from the following list: ^H0

6. The polymer according to any of the previous claims comprising the following formula

or

wherein the pre-polymer comprises the following formula:

wherein n is an entire number from 2000-4000.

7. A film comprising the polymer according to any of the previous claims 1 - 6.

8. The film according to the previous claim wherein the film has a thickness from 30 pm - 120 pm, preferably 60 pm.

9. The film according to any of the previous claims 7-8 wherein the film has a thermal stability of approximately 215 °C.

10. The film according to any of the previous claims 7-9 wherein the film's T_g ranges from 76 °C to 105 °C.

11. The film according to any of the previous claims 7-10 wherein the film is chemically resistant to: acid, alkaline, saline media, or water, ranging from 3 hours to 24 hours.

12. A method of preparing the polymer described in any of the previous claims 1 - 6 comprising the steps of: adding a depolymerization agent to polyethylene terephthalate to obtain bis(2 - hydroxy ethylene) terephthalamide; adding a polyol, a self-healing agent and/or a biodegradable agent, a catalyst, a chain extender, a reaction medium, an acid neutralizer and an isocyanate to the bis(2-hydroxy ethylene) terephthalamide, isolated from the previous mixture, to obtain a biodegradable and/or self-healing polyurethane polymer.

13. The method according to the previous claim further comprising the step of the aqueous dispersion of the functional polyurethane polymer to obtain an emulsion.

14. The method according to any of the previous claims 12-13 further comprising the step of thermally curing the biodegradable and self-healing polyurethane polymer to obtain polymeric films.

15. The method according to any of the previous claims 12-14 wherein the polyol is polyethylene glycol), polypropylene oxide), diethylene glycol, dimethylol propionic acid, poly(tetramethylene oxide), poly(butylene adipate), polycaprolactone, polydimethylsiloxane, polyisobutylene, poly(ethylene butylene), or mixture thereof.

16. The method according to any of the previous claims 12-15 wherein the self-healing agent is chitosan, bis(2-hydroxyethyl) disulfide or sodium 2((2- aminoethyl)amino)ethane sulfonate (AAS), bis(2-hydroxyethyl) disulfide (HEDS), coumarin derivatives or mixtures thereof.

17. The method according to any of the previous claims 12-16 wherein the catalyst is dibutyltin dilaurate, dibutyltin diacetate, methane sulfonic acid, triflic acid, 1,4- diazabicyclo[2,2,2]octane, l,8-diazabicyclo[5,4,0]undec-7-ene, 1,5,7 - triazabicyclo[4,4,0]dec-5-ene, N-heterocyclic carbenes, or mixture thereof.

18. The method according to any of the previous claims 12-17 wherein the reaction medium is dimethyl sulfoxide, ethanol, ionic liquids, or mixtures thereof.

BO

19. The method according to any of the previous claims 12-18 wherein the chain extender is 1,4-butanediol, bis(2-hydroxyethyl) disulfide, sodium 2((2- aminoethyl)amino)ethane sulfonate (AAS), bis(2-hydroxyethyl) disulfide (HEDS), diethanolamine, ethylene glycol, dimethylol butanoic acid, Isophorone diamine, 2- methyl-1, 3-propylene diol, diethylene glycol, propylene glycol, dipropylene glycol or mixtures thereof.

20. The method according to any of the previous claims 12-19 wherein the acid neutralizer is triethylamine.

21. The method according to any of the previous claims 12-20 wherein the isocyanate is isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate, hydrogenated MOI, meta-tetramethylxylene diisocyanate, trimethylhexamethylene diisocyanate or mixtures thereof.