NL2034668A

NL2034668A - Polyurethane and preparation thereof, and supramolecular polyurethane elastomer and preparation and application thereof

Info

Publication number: NL2034668A
Application number: NL2034668A
Authority: NL
Inventors: Wang Xiaoyue; Zhang Yaoming; Wang Qihua; Yang Zenghui; Xu Jing; Zhang Xinrui; Wang Tingmei
Original assignee: Lanzhou Inst Of Chemical Physics Cas
Priority date: 2022-05-06
Filing date: 2023-04-24
Publication date: 2023-11-14
Also published as: CN114752036A; CN114752036B

Abstract

The present invention provides a polyurethane (PU) and preparation thereof, and a supramolecular PU elastomer and preparation and application thereof in the technical 5 ﬁeld of PU materials. A UPy group in a polymer segment of the PU elastomer provided by the present invention can not only induce phase separation to form a soft and hard segment structure by forming a quadruple hydrogen bond through dimerization and a zinc ion coordination bond formed through metal coordination, but also form stable microcrystals at ambient temperature through n-n stacking interaction, 10 thereby further improving the mechanical strength of the PU materials. In addition, the presence of weak hydrogen bonding between carbamate groups on ﬂexible poly(oxytetramethylene)glycol segments imparts super-tough properties to the materials. Accordingly, the present invention provides the PU with high strength and high toughness.

Description

POLYURETHANE AND PREPARATION THEREOF, AND

SUPRAMOLECULAR POLYURETHANE ELASTOMER AND

PREPARATION AND APPLICATION THEREOF

TECHNICAL FIELD

[01] The present invention relates to the technical field of polyurethane (PU) materials, and in particular to a PU and preparation thereof, and a supramolecular PU elastomer and preparation and application thereof.

BACKGROUND ART

[02] With the continuous progress and development of modern science and technology, the global demand for high-performance structural and functional materials is increasing year by year. For most structural materials, strength and toughness are critical indicators for evaluating mechanical properties of the materials.

PU materials, as a new class of polymer materials, have unique structural characteristics, controllable physical and chemical properties, and great application potential. Despite the high level of development of PU materials today, there are still many opportunities and challenges in manufacturing high-performance PU materials because toughness (that 1s, resistance to destruction) and strength are often mutually exclusive. Today, there is a constant quest for increasingly stronger and tougher polymer materials, yet in most materials, these two properties (strength and toughness) are often mutually exclusive. In the development of advanced materials, mechanical properties (strength and toughness) are one of the most basic indicators for evaluating the applicability and durability of almost all engineering structural materials. In general, conventional strategies for optimizing tensile strength often come at the expense of the toughness of materials, making it difficult to meet requirements of both strength and toughness. Up to now, it is difficult to match the strength and toughness of polymer materials at the same time. The preparation of a supramolecular PU with high strength and high toughness is still faced with difficult challenges.

a 0 o

[06] € =

NH

>

SUMMARY

[03] An object of the present invention is to provide a PU and preparation thereof, and a supramolecular PU elastomer with high strength and high toughness, and preparation and application thereof.

[04] In order to achieve the above-mentioned object, the present invention provides the following technical solutions:

[05] The present invention provides a supramolecular PU based on a quadruple hydrogen bond with a structure as shown in Formula I.

[07] Formula L

[08] Wheren=8to27.

[09] The present invention provides a preparation method for the supramolecular

PU based on a quadruple hydrogen bond according to the above-mentioned technical solution, including the following steps:

[10] acquiring a prepolymer by mixing poly(oxytetramethylene)glycol (PTMG), isophorone diisocyanate (IPDI), a catalyst, and an organic solvent to perform a pre-polymerization reaction;

[11] acquiring the supramolecular PU based on a quadruple hydrogen bond by mixing the prepolymer with a T-type chain extender to perform a chain extension reaction before curing.

[12] The T-type chain extender has a structure as shown in Formula II:

SN 0 HO,

[13] oy Hoan Ns dà

HO Formula IL

[14] Preferably, the catalyst is dibutyltin dilaurate; a molar ratio of PTMG, IPDI and the catalyst is 10:20:0.1.

[15] Preferably, the pre-polymerization reaction is performed at a temperature of 80°C for 4 hours.

[16] Preferably, a molar ratio of PTMG to the T-type chain extender is 10:(5 to 10).

[17] Preferably, the chain extension reaction is performed at a temperature of 80°C for 2 hours.

[18] The present invention provides a preparation method for a supramolecular PU elastomer, including the following steps:

[19] acquiring a prepolymer by mixing PTMG, IPDI, a catalyst, and an organic solvent to perform a pre-polymerization reaction;

[20] acquiring the supramolecular PU elastomer by mixing the prepolymer with a

T-type chain extender to perform a chain extension reaction and adding a zinc salt solution to the acquired PU product to perform a coordination reaction before curing.

[21] Preferably, a molar ratio of zinc ions in the zinc salt solution to the T-type chain extender is (1.67 to 5):5, and the coordination reaction is performed at a temperature of 40°C for 5 hours.

[22] The present invention provides a supramolecular PU elastomer acquired by the preparation method according to the above-mentioned technical solution.

[23] The present invention provides application of the supramolecular PU elastomer according to the above-mentioned technical solution in flexible robots, wearable electronic devices, or self-healing film electrodes.

[24] The present invention provides a PU. A UPy group in a polymer segment of the PU can not only induce phase separation to form a soft and hard segment structure by forming a quadruple hydrogen bond through dimerization and a zinc ion coordination bond formed through metal coordination, but also form stable microcrystals at ambient temperature through a-7 stacking interaction, thereby further improving the mechanical strength of the PU materials. In addition, the presence of weak hydrogen bonding between carbamate groups on the flexible PTMG segments imparts super-tough properties to the materials. Hydrogen bonds and metal coordination bonds act as sacrificial bonds that can dissociate and reconstitute under external forces, a process that requires the dissipation of energy to preserve chain integrity. Non-covalent bonds, through effective energy dissipation and inhibition of stress concentration, further promote directional crystallization of molecular chains, thereby improving strength, toughness, and even self-healing ability. Therefore, the present invention integrates the synergistic effect of two supramolecular interactions (non-covalent interactions) of hydrogen bonding (single hydrogen bonding, double hydrogen bonding, and quadruple hydrogen bonding) and metal coordination bonding (coordination of zinc ions and pyrimidinone groups) into the PU skeleton based on the synergistic effect of multiple hydrogen bonds and metal coordination bonds, and achieves the synergistic enhancement of PU strength and toughness using the non-covalent interactions, so as to acquire supramolecular PU materials with high strength and toughness.

[25] The non-covalent interactions in the supramolecular PU elastomer provided by the present invention mainly include three interactions of quadruple hydrogen bonding (UPy-UPy), single hydrogen bonding (carbamate-carbamate), and metal coordination bonding (Zn-UPy). Therefore, the synergistic enhancement mechanism based on multiple hydrogen bonds and metal coordination bonds will open up new possibilities for designing PU elastomers with high toughness and high strength, and broaden their application potential and value in flexible robots, wearable electronic devices, self-healing film electrodes, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[26] FIG. 1 is a diagram showing a network structure of a supramolecular PU elastomer provided by the present invention;

[27] FIG. 2 shows an infrared spectrum of UPy-NCO and UPy-AMPD prepared according to the present invention; 5 [28] FIG. 3 shows infrared spectra of a PU prepared in Embodiment 1 and supramolecular PU elastomers prepared in Embodiments 2 to 4;

[29] FIG. 4 shows stress-strain curves of products prepared in Embodiment 1 and

Comparative embodiments 1 to 2; and

[30] FIG. 5 shows stress-strain curves of products prepared in Embodiments 1 to 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[31] The present invention provides a supramolecular PU based on a quadruple hydrogen bond with a structure as shown in Formula I:

Doret ge Ald ei pop pram, pm ö 5 = 5 6

[32] B

Formula I.

[33] Wheren=8t027.

[34] Inthe present invention, the n is preferably 13.

[35] The present invention provides a preparation method for the supramolecular

[36] acquiring a prepolymer by mixing PTMG, IPDI, a catalyst, and an organic solvent to perform a pre-polymerization reaction;

[37] acquiring the supramolecular PU based on a quadruple hydrogen bond by mixing the prepolymer with a T-type chain extender to perform a chain extension reaction before curing.

[38] The T-type chain extender has a structure as shown in Formula II:

Ml oz AAA

H HM tu §

HG Formula II.

[40] In the present invention, unless otherwise specified, the raw materials required for preparation are commercially available commodities well known to those skilled in the art.

[41] In the present invention, the prepolymer is acquired by mixing PTMG, IPDL the catalyst, and the organic solvent to perform the pre-polymerization reaction.

[42] In the present invention, a molecular weight of PTMG is preferably 600 to 2000 g/mol, and more preferably 1000 g/mol.

[43] In the present invention, the catalyst is dibutyltin dilaurate; a molar ratio of

PTMG, IPDI and the catalyst is preferably 10:20: 0.1.

[44] In the present invention, the organic solvent is preferably N,

N-Dimethylacetamide (DMAc) or N, N-Dimethylformamide (DMF). The present invention has no special limitation on the specific amount of the organic solvent, and it is sufficient to dissolve the material sufficiently.

[45] In the present invention, the process of mixing PTMG, IPDI, the catalyst and the organic solvent preferably includes mixing PTMG and the organic solvent, and stirring for 1 hour under an oil bath condition of 110°C and N; atmosphere to remove water residue in the solvent and avoid excess water interference; IPDI and dibutyltin dilaurate are added under N: atmosphere in response to the mixture being cooled to 80°C.

[46] In the present invention, the pre-polymerization reaction is performed at a temperature of preferably 80°C for preferably 4 hours; the pre-polymerization reaction is preferably performed under a stirring condition; the present invention has no special limitation on the stirring process, and it is sufficient to ensure a smooth reaction according to the process known in the art.

[47] Upon acquiring the prepolymer, the present invention preferably mixes the prepolymer directly with a T-type chain extender without processing, to perform a chain extension reaction before curing to acquire the supramolecular PU based on a quadruple hydrogen bond. In the present invention, a molar ratio of PTMG to the

T-type chain extender is preferably 10:(5 to 10).

[48] In the present invention, the T-type chain extender is preferably used in the form of a solution, and a solvent used for the solution of the T-type chain extender is preferably DMAC:; the present invention has no special limitation on a concentration of the solution of the T-type chain extender, and it is sufficient to satisfy the requirement of the molar ratio; in an embodiment of the present invention, the concentration of the T-type chain extender is 0.25 mmol/mL.

[49] In the present invention, the T-type chain extender has a structure as shown in

Formula II:

Fp 9 . HO o

HO Formula II.

[51] In the present invention, the T-type chain extender is preferably prepared according to a method known in the art, and the preparation method for the T-type chain extender preferably includes:

[52] 2-Amino-4-hydroxy-6-methylpyrimidine (MIC, 5.00 g 40 mmol) is mixed with hexamethylene diisocyanate (HDI, 40.32 g, 240 mmol) in a round-bottomed flask and stirred for 24 hours at 100°C under N: atmosphere; the acquired mixture is cooled to room temperature, and excess n-pentane is added to precipitate the product and remove excess unreacted HDI; the acquired product is washed and precipitated 3 times or more with n-pentane and dried for 12 hours under vacuum at 50°C, to acquire isocyanate-terminated 2-urea-4[H]-pyrimidinone, designated as UPy-NCO.

[53] The UPy-NCO (12.60 g, 43 mmol), 2-Amino-2-methyl-1,3-propanediol (AMPD) (7.03 g, 66.9 mmol) and 450 mL of anhydrous chloroform are placed in a round-bottomed flask equipped with a condenser, and refluxed for 10 hours at 60°C under N: atmosphere until complete reaction; the acquired milky turbid solution is suctioned and filtered under vacuum and washed with a large amount of chloroform for 3 times; the acquired powder is dissolved in DMF and separated by centrifugation (9000 r/min for 10 minutes) before taking supernatant; 1000 mL ether is poured into the supernatant for precipitation, suction and filtration, and vacuum drying to acquire

UPy-AMPD, namely the T-type chain extender.

[54] In the present invention, preparation reaction processes of UPy-NCO and

UPy-AMPD are:

Step 1

Lr oan NNN Fr LIS

BEC HO GPy HCO

[55] |seet we 80°C Dg Ho,

Ld 2 Ton Lg

He! if

GPy-NCO ANFD UPy-AMPD

[56] The present invention preferably drops the solution of the T-type chain extender into the prepolymer; the present invention has no special limitation on a rate of dripping, and it is sufficient to perform according to the process well known in the 13 art.

[57] In the present invention, the chain extension reaction is performed at a temperature of preferably 80°C for preferably 2 hours; the chain extension reaction is preferably performed under a stirring condition; the present invention has no special limitation on the stirring process, and it is sufficient to ensure a smooth reaction according to the process known in the art.

[58] Upon completing the chain extension reaction, the present invention preferably cools the acquired product to room temperature, and drops polyether amine (D230) for curing to acquire a PU, designated as SPU-UPy; the curing is performed at a temperature of preferably 40°C for preferably 3 hours; the curing is preferably performed under a stirring condition; the present invention has no special limitation on the stirring process, and it is sufficient to perform according to the process well known inthe art.

[59] In embodiments of the present invention, in order to prepare a film sample, upon completing the curing, the present invention preferably pours the acquired product into a tetrafluoro mold, and places in a vacuum drying oven to dry for 48 hours at 80°C (completely volatilizing the solvent) to acquire a PU transparent film.

[60] In the present invention, reaction processes of the pre-polymerization reaction and the chain extension reaction are: woh + (Xe, co

GCN

PTMG [PDT

Dibutvitin wd BOC, 3h wa Np Ay REO 0

Prepolymer

Hs HH, > HQ Be, 61] TTA Fo ne

CHy CH; ROR Ty

Polyether amine DI30 T-type chain extender Ha . 2 ° tp Lot A pimp om [53 8 wl 3 0 hu

So

Qn . we

A

5

[62] The present invention provides a preparation method for a supramolecular PU elastomer, including the following steps:

[63] acquiring a prepolymer by mixing PTMG, IPDI, a catalyst, and an organic solvent to perform a pre-polymerization reaction;

[64] acquiring the supramolecular PU elastomer by mixing the prepolymer with a

[65] In the present invention, the process of acquiring a prepolymer by mixing

PTMG, IPDI, a catalyst and an organic solvent to perform a pre-polymerization reaction, and a raw material ratio are the same as the above-mentioned process for preparing the PU, which will not be described again.

[66] Upon acquiring the prepolymer, the present invention mixes the prepolymer with a T-type chain extender to perform a chain extension reaction, and adds a zinc salt solution to the acquired PU product to perform a coordination reaction before curing, to acquire the supramolecular PU elastomer.

[67] In the present invention, the process of mixing the prepolymer with a T-type chain extender to perform a chain extension reaction, and a raw material ratio are the same as the above-mentioned process for preparing the PU, which will not be described again.

[68] In the present invention, the zinc salt in the zinc salt solution is preferably zinc chloride; a solvent used for the zinc salt solution is preferably DMAC; a concentration of the zinc salt solution is preferably 1 mmol/mL.

[69] In the present invention, a molar ratio of the zinc salt in the zinc salt solution to the T-type chain extender is preferably (1.67 to 5):5, and more preferably 2.5:5; the coordination reaction is performed at a temperature of preferably 40°C for preferably 5 hours; the coordination reaction is preferably performed under a stirring condition; the present invention has no special limitation on a rate of stirring, and it is sufficient to ensure a smooth reaction according to the process known in the art.

[70] During the coordination reaction, zinc ions coordinate with N, O, H on a 2-urea-4[H]-pyrimidinone group.

[71] Upon completing the coordination reaction, the present invention preferably cools the acquired product to room temperature, and drops polyether amine (D230) for curing; the curing is performed at a temperature of preferably 40°C for preferably 3 hours; the curing is preferably performed under a stirring condition; the present invention has no special limitation on the stirring process, and it is sufficient to perform according to the process well known in the art.

[72] Upon completing the curing, the present invention preferably pours the acquired product into a tetrafluoro mold and dries under vacuum for 48 hours at 80°C until the solvent is completely removed before drying, to acquire a supramolecular PU elastomer, designated as SPU-UPy-Zn. The present invention has no special limitation on the drying process, and it is sufficient to perform according to the process well known in the art.

[73] The present invention provides a supramolecular PU elastomer acquired by the preparation method according to the above-mentioned technical solution, where a structural diagram of the supramolecular PU elastomer 1s shown in Formula III:

Je a

I= NH Rms

APY oo kN aanwe Tg

HN.

Formula HI.

[75] The supramolecular PU elastomer of the present invention has a quadruple hydrogen bond and a metal coordination bond, and a bonding relationship between supramolecular interactions is shown in FIG. 1. The supramolecular PU elastomer finally prepared includes a quadruple hydrogen bond and a metal coordination bond in the polymer network structure, with the two supramolecular interacting. Specifically, the presence of multiple hydrogen bonds can not only achieve rapid sequential recombination after breaking, but also effectively dissipate energy in a form of weaker non-covalent bonds, giving the elastomer better stretchability and elasticity. Metal coordination bonding: as a strong non-covalent bond, Zn-UPy coordination bond, composed of Zn?’ coordinated with UPy groups, helps to form a strong physical cross-linked network, thereby significantly enhancing the mechanical strength of elastomers. The acquired supramolecular PU elastomer, due to the synergistic effect of optimized quadruple hydrogen bonds and metal coordination bonds, exhibits high tensile strength, excellent toughness, and large Young's modulus.

[76] Compared with traditional chemical covalent bonds, the self-assembly and connection of non-covalent interactions are dynamic and reversible, which can effectively dissipate strain energy through breaking and reconstruction of non-covalent bonds, thus playing a role in hardening the network. On the one hand, non-covalent bonds act in a sacrificial and reversible manner, preferentially breaking before the structural system is destroyed, and undergo reversible bond breaking and recombination under external loads, which provides efficient energy dissipation for the enhancement of material properties. On the other hand, the polymerization and recombination of non-covalent bonds increase the cross-linking density, resulting in limited chain mobility, slow down the diffusion of self-assembled units and reduce the opportunity of seeking bond exchange at available sites, thus hindering bond rearrangement and inhibiting exchange reactions, effectively avoiding stress concentration on shorter chains, delaying breakage, and achieving higher tensile and strength. The present invention combines multiple supramolecular interactions (hydrogen bonding and metal coordination bonding, two non-covalent interactions) to synergistically enhance the mechanical properties of PU materials, and the synergistic effect of multiple hydrogen bonds and metal coordination bonds can provide great flexibility to enhance a PU and significantly improve its toughness so as to construct a supramolecular PU material integrating high strength and high toughness. Based on non-covalent interactions of hierarchical strong and weak bonds, the present invention constructs supramolecular PU materials with easy processing, stretchability, high toughness, and robustness.

[77] The present invention provides application of the supramolecular PU elastomer according to the above-mentioned technical solution or the supramolecular

PU elastomer acquired by the preparation method according to the above-mentioned technical solution in flexible robots, wearable electronic devices, or self-healing film electrodes. The present invention has no special limitation on the method of application, and it is sufficient to apply according to the method well known in the art.

[78] The technical solutions in the present invention will be described clearly and completely below in combination with the embodiments in the present invention.

Clearly, the described embodiments are not all but only part of embodiments of the present invention. All other embodiments obtained by those ordinanly skilled in the art based on the embodiments in the present invention without creative work shall fall within the scope of protection of the present invention.

[79] In the following embodiments, a preparation method of the T-type chain extender (UPy-AMPD) is:

[80] 2-Amino-4-hydroxy-6-methylpyrimidine (MIC, 5.00 g, 40 mmol) is mixed with hexamethylene diisocyanate (HDI, 40.32 g, 240 mmol) in a round-bottomed flask and stirred for 24 hours at 100°C under N: atmosphere; the acquired mixture is cooled to room temperature, and excess n-pentane is added to precipitate the product and remove excess unreacted HDI, the acquired product is washed and precipitated 3 times or more with n-pentane and dried for 12 hours under vacuum at 50°C, to acquire 1socyanate-terminated 2-urea-4[H]-pyrimidinone, designated as UPy-NCO;

[81] the UPy-NCO (12.60 g, 43 mmol), 2-Amino-2-methyl-1,3-propanediol (AMPD) (7.03 g, 66.9 mmol) and 450 mL of anhydrous chloroform are placed in a round-bottomed flask equipped with a condenser, and refluxed for 10 hours at 60°C under N2 until complete reaction; the acquired milky turbid solution is suctioned and filtered under vacuum and washed with a large amount of chloroform for 3 times; the acquired powder is dissolved in DMF and separated by centrifugation (9000 r/min for 10 minutes) before taking supernatant; 1000 mL ether is poured into the supernatant for precipitation, suction and filtration, and vacuum drying to acquire UPy-AMPD, namely the T-type chain extender.

[82] Embodiment 1

[83] (1) 10.00 g of PTMG-1000 (10 mmol) with a molecular weight of 1000 g/mol were weighed, and then 15 mL of DMAC were weighed; the two were mixed before placing in a three-neck flask, and stirred for 1 hour under an oil bath condition of 110°C and N: atmosphere, to acquire a mixture.

[84] (2) IPDI (4.45 g, 20 mmol) and 0.1 mmol (0.063 g) of DBTDL catalysts were added under N: atmosphere in response to the temperature of the above-mentioned mixture being cooled to 80°C, and stirred for 4 hours, to acquire a prepolymer.

[85] (3) A UPy-AMPD product (1.99 g, 5 mmol) and 20 mL of DMAC solvents were weighed, UPy-AMPD was dissolved in DMAC to perform ultrasonic dissolution before dropping the UPy-AMPD solution to the prepolymer, and stirred for 2 hours at 80°C until the chain extension reaction was completed.

[86] (4) The acquired product was cooled to room temperature, and D230 (1.15 g, 5 mmol) was dropped to stir for 3 hours at 40°C under N: atmosphere; the acquired product was poured into a tetrafluoro mold, and placed in a vacuum drying oven to dry for 48 hours at 80°C to completely volatilize the solvent, to acquire a PU transparent film sample, designated as SPU-UPy and represented by Formula I, where n = 13.

[87] Embodiment 2

[88] (1) PTMG-1000 (10.00 g, 10 mmol) and 15 mL of DMAC were weighed, the two were mixed before placing in a three-necked flask, and stirred for 1 hour under an oil bath condition of 110°C and N: atmosphere, to acquire a mixture.

[89] (2) IPDI (4.45 g, 20 mmol) and 0.1 mmol (0.063 g) of DBTDL catalysts were added under N, atmosphere in response to the temperature of the above-mentioned mixture being cooled to 80°C, and stirred for 4 hours, to acquire a prepolymer.

[90] (3) A UPy-AMPD product (1.99 g, 5 mmol) and 20 mL of DMAC solvents were weighed, UPy-AMPD was dissolved in DMAC to perform ultrasonic dissolution before dropping the UPy-AMPD solution to the prepolymer, and stirred for 2 hours at 80°C until the chain extension reaction was completed, to acquire a PU product.

[91] (4) Solid ZnCl: (0.68 g, 5 mmol) and 5 mL of DMAC solvents were weighed,

ZnCl; was dissolved in DMAC to perform ultrasonic dissolution before dropping

ZnCl: solution to the PU product, and stirred for 5 hours at 40°C for coordination.

[92] (5) The acquired coordination product was cooled to room temperature, and

D230 (1.15 g, 5 mmol) was dropped to stir for another 3 hours at 40°C under N» atmosphere; the acquired product was poured into a tetrafluoro mold, and dried for 48 hours in a vacuum oven at 80°C, to acquire a supramolecular PU elastomer sample, designated as SPU-UPy-Zn-1.

[93] Embodiment 3

[94] (1) PTMG-1000 (10.00 g, 10 mmol) and 15 mL of DMAC were weighed, the two were mixed before placing in a three-necked flask, and stirred for 1 hour under an oil bath condition of 110°C and N: atmosphere, to acquire a mixture.

[95] (2) IPDI (4.45 g, 20 mmol) and 0.1 mmol (0.063 g) of DBTDL catalysts were added under N, atmosphere in response to the temperature of the above-mentioned mixture being cooled to 80°C, and stirred for 4 hours, to acquire a prepolymer.

[96] (3) A UPy-AMPD product (1.99 g, 5 mmol) and 20 mL of DMAC solvents were weighed, UPy-AMPD was dissolved in DMAC to perform ultrasonic dissolution before dropping the UPy-AMPD mixture to the prepolymer, and stirred for another 2 hours at 80°C until the chain extension reaction was completed, to acquire a PU product.

[97] (4) Solid ZnCl; (0.34 g, 2.5 mmol) and 5 mL of DMAC solvents were weighed,

ZnCl, was dissolved in DMAC to perform ultrasonic dissolution before dropping

ZnCl solution to the PU product, and stirred for another 5 hours at 40°C for coordination.

[98] (5) The acquired coordination product was cooled to room temperature, and

D230 (1.15 g, 5 mmol) was dropped to stir for another 3 hours at 40°C under N» atmosphere; the acquired product was poured into a tetrafluoro mold, and dried for 48 hours In a vacuum oven at 80°C, to acquire a supramolecular PU elastomer sample, designated as SPU-UPy-Zn-2.

[99] Embodiment 4

[100] (1) PTMG-1000 (10.00 g, 10 mmol) and 15 mL of DMAC were weighed, the two were mixed before placing in a three-necked flask, and stirred for 1 hour under an oil bath condition of 110°C and N: atmosphere, to acquire a mixture.

[101] (2) IPDI (4.45 g, 20 mmol) and 0.1 mmol (0.063 g) of DBTDL catalysts were added under N: atmosphere in response to the temperature of the above-mentioned mixture being cooled to 80°C, and stirred for 4 hours, to acquire a prepolymer.

[102] (3) A UPy-AMPD product (1.99 g, 5 mmol) and 20 mL of DMAC solvents were weighed, UPy-AMPD was dissolved in DMAC to perform ultrasonic dissolution before dropping the UPy-AMPD solution to the prepolymer, and stirred for 2 hours at 80°C until the chain extension reaction was completed, to acquire a PU product.

[103] (4) Solid ZnCl: (0.17 g, 1.67 mmol) and 5 mL of DMAC solvents were weighed, ZnCl, was dissolved in DMAC to perform ultrasonic dissolution before dropping ZnCl: solution to the PU product, and stirred for another 5 hours at 40°C for coordination.

[104] (5) The acquired coordination product was cooled to room temperature, and

D230 (1.15 g, 5 mmol) was dropped to stir for another 3 hours at 40°C under N: atmosphere; the acquired product was poured into a tetrafluoro mold, and dried for 48 hours in a vacuum oven at 80°C, to acquire a supramolecular PU elastomer sample, designated as SPU-UPy-Zn-3.

[105] Comparative embodiment 1

[106] (1) 10.00 g of PTMG-1000 (10 mmol) with a molecular weight of 1000 g/mol were weighed, and then 15 mL of DMAC were weighed; the two were mixed before placing in a three-neck flask, and stirred for 1 hour under an oil bath condition of 110°Cand N; atmosphere, to acquire a mixture.

[107] (2) IPDI (4.45 g, 20 mmol) and 0.1 mmol (0.063 g) of DBTDL catalysts were added under N: atmosphere in response to the temperature of the above-mentioned mixture being cooled to 80°C, and stirred for 4 hours; the acquired product was cooled to room temperature, and D230 (10 mmol) was dropped to stir for another 3 hours at 40°C under Nz atmosphere, to acquire a PU sample, designated as SPU-UPyo.

[108] Comparative embodiment 2

[109] (1) 10.00 g of PTMG-1000 (10 mmol) with a molecular weight of 1000 g/mol were weighed, and then 15 mL of DMAC were weighed; the two were mixed before placing in a three-neck flask, and stirred for 1 hour under an oil bath condition of 110°C and N: atmosphere, to acquire a mixture.

[110] (2) IPDI (4.45 g, 20 mmol) and 0.1 mmol (0.063 g) of DBTDL catalysts were added under N: atmosphere in response to the temperature of the above-mentioned mixture being cooled to 80°C, and stirred for 4 hours, to acquire a prepolymer.

[111] (3) A UPy-AMPD product (3.98 g, 10 mmol) and 20 mL of DMAC solvents were weighed, UPy-AMPD was dissolved in DMAC to perform ultrasonic dissolution before dropping the UPy-AMPD solution to the prepolymer, and stirred for 2 hours at 80°C until the chain extension reaction was completed, to acquire a PU product, designated as SPU-UPy 0.

[112] Raw material ratios of Embodiments 1 to 4 and Comparative embodiments to 2 are shown in Table 1:

[113] Table 1 Raw material ratios of Embodiments 1 to 4 and Comparative embodiments 1 to 2

EEE ER EAS

Sample (mmol) | (mmol) | (mmol) | (mmol) | (mmol) “wm [0 ne [0 [0 “oun [0 wo [0 [0

[116] Characterization and property testing

[117] 1) Infrared tests were performed on the prepared UPy-NCO and UPy-AMPD, with the results shown in FIG. 2. It can be seen from FIG. 2 that a characteristic peak at 3333 cmt was a stretching vibration peak of the hydroxyl group (-OH-) in the

T-type chain extender (UPy-AMPD), and a characteristic peak at 2272 cm™ was a stretching vibration peak corresponding to the isocyanate group (-NCO-) of the monomer UPy-NCO, which can preliminarily prove a successful synthesis of

UPy-NCO and UPy-AMPD.

[118] 2) Infrared characterizations were performed on the PU prepared in

Embodiment 1 and the supramolecular PU elastomers prepared in Embodiments 2 to 4, with the results shown in FIG. 3, where a was an infrared spectrum of the PU prepared in Embodiment | and the supramolecular PU elastomers prepared in Embodiments 2 to 4, and b was a partially enlarged view. It can be seen from FIG. 3 that 1708 cm’! in the drawing was attributed to a stretching vibration peak of free and disordered hydrogen bond-carbamate carbonyl (-C=0-), while a characteristic peak at 1642 cmt was a stretching vibration peak of ordered hydrogen bond-allophanyl (-C=0-). Comparing the infrared spectra of SPU-UPy and SPU-UPy-Zn in FIG. 2, it can be seen that the intensity of the peak at 1642 cm™ decreased significantly with the increase of the content of zinc ions, namely, stretching vibration peaks of free and ordered hydrogen bond-allophanyl gradually disappeared, and a new stretching vibration peak appeared at 1676 cm, which indicated that allophanyl (-C=0-) in the system not only participated in the formation of hydrogen bonding, but also coordinated with Zn?" to form metal coordination bonds.

[119] In addition, a characteristic peak at 1599 cm! in FIG. 3 was a stretching vibration peak of (-CN-) in the ureido-pyrimidinone group. Due to the incorporation of the zinc ions, The position of the peak was shifted to 1620 cm™, so the new peak at 1620 cm’! was attributed to the shift of (-CN-) in ureido-pyrimidinone group, which further confirmed that (-CN-) in ureido-pyrimidinone group in a SPU-UPy-Zn elastomer also participated in the coordination of Zn?’ to form metal coordination bonds.

[120] 3) Stress-strain curve tests were performed on SPU-UPy prepared in

Embodiment 1 (Test standard: GB/T 1040-2006; Test speed: 10 mm/min; Test environment: 25°C), and compared with SPU-UPyo and SPU-UPyi¢ prepared in

Comparative embodiments 1 to 2, with results shown in FIG. 4. Stress-strain curve tests were performed on SPU-UPy prepared in Embodiment 1 and SPU-UPy-Zn-1,

SPU-UPy-Zn-2 and SPU-UPy-Zn-3 prepared in Embodiments 2 to 4, with results shown in FIG. 5 and summarized in Table 2.

[121] It can be seen from FIG. 4 that the tensile strength of the SPU-UPy elastomer increased with the increase of the content of the quadruple hydrogen bond UPy, with the stress increasing and the strain decreasing, that is, the tensile strength significantly increased and the breaking strain decreased. The SPU-UPy10 had the highest strength of 11.09 MPa. The elongation at break of the SPU-UPy elastomer showed a decreasing trend, and the maximum value of SPU-UPyo could reach 4033.26%, while that of

SPU-UPy10 was only 131.71%. This may be due to the fact that the enhancement of hydrogen bonding in the polymer network structure has a significant effect on the mechanical properties of the polymer chain.

[122] It can be seen from FIG. 5 that the tensile strength of the SPU-UPy-Zn elastomer increased with the increase of the ratio of Zn?* to UPy, and the maximum value of SPU-UPy-Zn-1 could reach 14.15 MPa. The elongation at break of the

SPU-UPy-Zn elastomer decreased with the increase of the ratio of Zn?’ to UPy-AMPD, and the maximum value of SPU-UPy-Zn-3 was 813.53%. That is, the stress of the material increased, while the strain decreased. Thus, the coordination introduced between Zn?” and ureido-pyrimidinone can significantly improve the tensile strength and toughness of PU elastomers. In addition, the SPU-UPy-Zn-1 elastomer exhibited the highest tensile strength and toughness of 14.15 MPa and 47.57 MJ m’, respectively.

The results showed that the incorporation of the zinc ions and the content of the T-type chain extender containing a quadruple hydrogen bond had a significant effect on the mechanical properties of the polymer.

[123] Table 2 Elongation at break, ultimate tensile strength and toughness of PUs prepared in different cases me | om

Sample (MPa) break (%) m™)

[125] The results showed that non-covalent PUs exhibited significant mechanical toughening effects under external forces due to effective energy dissipation. Tensile tests showed that the strength and toughness enhancement of the material resulted from dynamic and dense hydrogen bonding interactions, which led to continuous formation of energy-dissipating rigid phases. In addition, the introduced Zn?’ coordination bond can restrict the mobility of mobile phase and enhance the crystallinity and network density of segments, which can effectively regulate the mechanical strength of PUs.

[126] The above is only the preferred embodiment of the present invention. It should be noted that for the ordinary in the technical field, a number of improvements and refinements can be further made without deviating from the principle of the present invention, which should also be considered as the protection scope of the present invention.

Claims

Conclusions

1. Supramolecular polyurethane (PU) based on a fourfold hydrogen bond, with a structure as shown in Formula I: o Qo T hi ) » YT 2 2 om ö Q {* NH o=x NH 6 Formula I, where n = 8 -27.

Preparation method for the supramolecular PU based on a quadruple hydrogen bond according to claim 1, comprising the following steps: obtaining a prepolymer by mixing poly(oxytetramethylene) glycol (PTMG), isophorone diisocyanate (IPDI), a catalyst and a organic solvent to carry out prepolymerization reaction; acquiring the supramolecular PU based on a fourfold hydrogen bond by mixing the prepolymer with a T-type chain extender to carry out a chain extension reaction before curing; the T-type chain extender with a structure as shown in formula IT: ie HG H H 1 3 : HG Formula IL

The preparation method according to claim 2, wherein the catalyst is dibutyl tin dilaurate; and a molar ratio of PTMG, IPDI and the catalyst is 10:20:0.1.

Preparation method according to claim 2, wherein the prepolymerization reaction is carried out at a temperature of 80°C for 4 hours.

The preparation method according to claim 2, wherein a molar ratio of the PTMG to the T-type chain extender is 10:(5-10).

The preparation method according to claim 2, wherein the chain extension reaction is carried out at a temperature of 80°C for 2 hours.

7. Preparation method for a supramolecular polyurethane (PU) elastomer, which consists of the following steps: obtaining a prepolymer by mixing poly(oxytetramethylene) glycol (PTMG), isophorone diisocyanate (IPDI), a catalyst and an organic solvent to carry out a prepolymerization reaction; obtaining a supramolecular PU elastomer by mixing the prepolymer with a T-type chain extender to carry out a chain extension reaction and adding a zinc salt solution to the acquired PU product to carry out a coordination reaction before curing.

The preparation method according to claim 7, wherein a molar ratio of zinc ions in the zinc salt solution to the T-type chain extender is (1.67-5):5, and the coordination reaction is carried out at a temperature of 40°C for 5 hours.

9. Supramolecular polyurethane (PU) elastomer obtained by the preparation method according to claim 7 or 8.

Application of the supramolecular PU elastomer according to claim 9 in flexible robots, wearable electronic devices or self-healing film electrodes.