CN113278128B

CN113278128B - Waterborne polyurethane/polyurea with fluorine-containing side chain and preparation method thereof

Info

Publication number: CN113278128B
Application number: CN202110378690.4A
Authority: CN
Inventors: 程俊; 戴宇; 赵艳青; 陈蔚清; 赵强
Original assignee: SICHUAN CARPOLY PAINT CO Ltd
Current assignee: SICHUAN CARPOLY PAINT CO Ltd
Priority date: 2021-04-08
Filing date: 2021-04-08
Publication date: 2022-11-11
Anticipated expiration: 2041-04-08
Also published as: CN113278128A

Abstract

The invention discloses waterborne polyurethane/polyurea with a fluorine-containing side chain and a preparation method thereof, and the structure of the waterborne polyurethane/polyurea is as follows

Wherein: r ₄ The general structural formula is as follows:

R ₃ the general structural formula is as follows:

R ₂ the general structural formula is as follows:

R ₁ the structure of (1) is as follows:

Description

Waterborne polyurethane/polyurea with fluorine-containing side chain and preparation method thereof

Technical Field

The invention belongs to the technical field of paint, and particularly relates to waterborne polyurethane/polyurea with a fluorine-containing side chain and a preparation method thereof.

Background

Polyurethanes are generally prepared by the synthesis of isocyanate-terminated prepolymers from diisocyanates, polyether polyols or polyester polyols and then further reaction with diols or diamine chain extenders to convert them to the final high molecular weight polymers. Polyurea is a novel high-performance polymer elastomer material and is generated by polymerization reaction of a polyisocyanate compound and an amino compound according to a certain proportion at normal temperature. From the perspective of molecular structure, the polarity of the urea bond structure is much greater than that of the carbamate structure, and the urea bond groups form a structure similar to a chelate in the whole polymer network, so that the molecular structure is more stable. The urethane groups in the polyurethane can form monodentate hydrogen bonds, while the urea groups in the polyurea structure can form bidentate hydrogen bonds, and compared with the polyurethane, the polarity, the crystallinity, the rigidity and the melting point of the polyurea material are higher. In addition, the C-N bonds in the polyurea structure are also much more stable than the C-O bonds in the polyurethane structure, and therefore, the thermal stability of the polyurea coating is higher than that of the polyurethane coating. Therefore, modification and hybridization of polyurethane with polyurea to obtain polyurethane/polyurea containing both urethane groups and urea groups is one of the ways to improve the performance of polyurethane, and the synthesis of aqueous polyurethane/polyurea dispersions is one of the important means to improve the performance of aqueous polyurethane.

The waterborne polyurethane takes water as a dispersion medium, is nontoxic, odorless and pollution-free, and has the characteristic of environmental protection. With the increasing awareness of environmental protection, aqueous polyurethane is becoming a necessary trend for the development of polyurethane industry. However, in the preparation of aqueous polyurethane, hydrophilic ionic groups or segments need to be introduced, resulting in deterioration of the hydrophobic properties of the polyurethane film. The hardness, water resistance, corrosion resistance and other properties of the waterborne polyurethane coating are also greatly limited, and the development and application of the waterborne polyurethane coating are greatly limited. Therefore, the improvement of the comprehensive performance of the waterborne polyurethane through modification has important significance.

At present, a plurality of methods for improving the water resistance of the water-based polyurethane are available, such as crosslinking modification, polyacrylate modification, epoxy resin modification, organosilicon modification, organic fluorine modification and the like. For example, the Yitao group prepared an aqueous polyurethane-polydimethylsiloxane block graft copolymer, which had significantly improved water resistance, but had a great limitation in the application of WPU modification due to the complicated synthesis of the PDMS intermediate. The organic fluorine has very low surface energy, and the water resistance of the aqueous polyurethane film can be obviously improved by introducing the organic fluorine into the aqueous polyurethane chain segment, but the physical blending of the polyurethane and the organic fluorine is often unstable due to phase separation, so that excellent performance is difficult to obtain. In general, the properties are only significantly improved by grafting organofluorine segments onto polyurethane segments by copolymerization. There are generally two ways to incorporate fluorine-containing segments into polyurethane structures: one is that a fluorine-containing chain segment is introduced into a polyurethane chain segment as a main chain, and perfluoropolyether diol is used as a chain extender by Castellano and the like, so that the fluorinated modified polyurethane is prepared by reacting the perfluoropolyether diol with diisocyanate, polyester diol, butanediol and the like; piotrKr Lou and the like take short-chain fluorine-containing dihydric alcohol as a chain extender to participate in the preparation reaction of polyurethane to prepare organic fluorine modified polyurethane; the other is that the fluorine-containing chain segment is hung on the main chain of the polyurethane in the form of a side chain, wang and the like firstly synthesize side chain fluorine-containing polyether diol, and then add the side chain fluorine-containing polyether diol into the preparation reaction of the polyurethane to prepare side chain fluorinated polyurethane; however, when the fluorine-containing segment is introduced into the polyurethane as a main chain, the movement of the fluorine-containing segment is restricted by the entire main chain, resulting in poor migration ability of the fluorine-containing segment to the surface, failing to significantly improve the hydrophobic property of the polyurethane film. When the fluorine-containing chain segment is hung on the polyurethane chain as a side chain, only one end of the fluorocarbon chain is connected to the polyurethane main chain, and the other end of the fluorocarbon chain segment can move freely.

Disclosure of Invention

Aiming at the problem of poor water resistance after hydrophilic groups are introduced into waterborne polyurethane, the invention provides waterborne polyurethane/polyurea modified by fluorine-containing side chains.

The technical scheme of the invention is as follows: the structure of the waterborne polyurethane/polyurea with the fluorine-containing side chain is shown as the general formula (I)

Wherein: r ₄ Has a general structural formula as follows:

R ₃ the general structural formula is as follows:

R ₂ the general structural formula is as follows:

R ₁ the structure of (1) is as follows:

n is the degree of polymerization, and R is polyaspartate.

The invention has the beneficial effects that:

the fluorine-containing chain extender PFAD has a double-hydroxyl structure, so that end capping does not occur in the polymerization process, and a fluorocarbon chain is introduced as a side chain. The introduction of the fluorine-containing side chain into the WPU/PUA can increase the interaction of hydrogen bonds in a system, increase the microphase separation degree of a soft section and a hard section in the WPU/PUA, and the fluorine atoms in the side chain can freely migrate to the surface of a coating film to reduce the free energy, thereby improving the water resistance, the thermal stability and the mechanical property of the WPU/PUA; and the higher the PFAD content is, the more hydrogen bond interaction in the WPU/PUA is, and the more obvious the improvement of the mechanical property of the WPU/PUA is.

The invention also provides a preparation method of the waterborne polyurethane/polyurea with the fluorine-containing side chain, which comprises the following steps:

s1: synthesizing N- (2-methyl-1,3-propanediol-2' -) -perfluorobutanesulfonamide;

s2: reacting isophorone diisocyanate and polytetrahydrofuran diol under the action of a catalyst for 2-3 hours in an inert environment at the temperature of 75-85 ℃ to synthesize an isocyanate group-terminated prepolymer;

s3: cooling to 65-74 ℃, and adding a hydrophilic chain extender;

s4: cooling to 55-65 ℃, adding N- (2-methyl-1,3-propanediol-2' -) perfluorobutyl sulfonamide and 1,4-butanediol for reaction to carry out chain extension reaction;

s5: cooling to room temperature, and adding a secondary amine chain extender for reaction;

s6: neutralizing the carboxyl group in the hydrophilic group;

s7: emulsification;

s8: and curing to form a film.

Further, the step S1 is specifically:

s1-1: mixing 2-amino-1,3-propylene glycol, triethylamine and N, N-dimethylformamide in an ice bath, anhydrous and inert environment to obtain a mixed solution;

s1-2: and (3) dropwise adding the perfluoro-1-butanesulfonyl fluoride dissolved in the ethyl acetate into the mixed solution, continuing to react for 8 to 8.7 hours after the dropwise addition is finished, and separating and purifying to obtain a white solid.

Further defined, the catalyst in step S2 is dibutyl tin dilaurate.

Further defined, the hydrophilic chain extender in step S3 is 2,2-dimethylolbutyric acid.

Further limiting, the step S5 is to cool to room temperature, add polyaspartic ester and stir for 20-31 minutes.

Further, the step S6 is specifically: adding triethylamine to neutralize and react for 28-33 minutes.

Further, the step S7 is specifically: adding isophorone diamine dissolved in water for emulsification.

Further defined, the molar ratio of the N- (2-methyl-1,3-propanediol-2' -) perfluorobutanesulfonamide to 1,4 butanediol is in the range of 1 to 5:1.

Further defined, the polyaspartic ester is prepared by the following method: refluxing 1,6-hexanediamine at 55-60 deg.C in a constant temperature anhydrous and inert environment, adding twice the molar amount of diethyl maleate to 1,6-hexanediamine, heating to 75-80 deg.C, reacting for 28-32 min, and reacting for 24-26 hr.

Drawings

FIG. 1 is a synthetic route for N- (2-methyl-1,3-propanediol-2' -) -perfluorobutanesulfonamide;

FIG. 2 is a synthetic route for an aqueous polyurethane/polyurea having fluorine-containing side chains;

FIG. 3 is an infrared spectrum of PFAD;

FIG. 4 is a nuclear magnetic resonance hydrogen spectrum of PFAD;

FIG. 5 is an XPS spectrum of PFAD;

FIG. 6 is a PFAD ¹⁹ F nuclear magnetic resonance spectrogram;

figure 7 is a mass spectrum of PFAD;

FIG. 8 is an infrared spectrum of F-WPU/PUA;

FIG. 9 is an XPS plot of WPU/PUA and F-WPU/PUA;

FIG. 10 is an XRD plot of WPU/PUA and F-WPU/PUA;

FIG. 11 is a TGA plot of WPU/PUA and F-WPU/PUA;

FIG. 12 is a DTG graph of WPU/PUA and F-WPU/PUA;

FIG. 13 is a graph of the energy dissipation modulus of WPU/PUA and F-WPU/PUA as a function of temperature;

FIG. 14 is a graph of storage modulus versus temperature for WPU/PUA and F-WPU/PUA;

FIG. 15 is a graph of tan delta versus temperature for WPU/PUA and F-WPU/PUA;

FIG. 16 is a stress-strain graph of WPU/PUA and F-WPU/PUA;

FIG. 17 is the contact angle of water molecules with WPU/PUA, 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PUA film surfaces;

FIG. 18 is a graph showing the tendency of water absorption of F-WPU/PUA with time.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention are described in detail and completely, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The English abbreviation, purity and source of part of the material are as follows: isophorone diisocyanate (IPDI, 99%), polytetrahydrofuran diol (PTMEG, mn =1000 g/mol) was synthesized after dehydration at 110 ℃ under high vacuum (0.5 mmHg) for 12 h; 2,2-dimethylolbutyric acid (DMBA, 98%), isophoronediamine (IPDA, 99%), perfluoro-1-butanesulfonyl fluoride (PBF, 96%), diethyl maleate dibutyl tin dilaurate (DBTDL, 98%) and 2-amino-2-methyl-1,3-propanediol (AMPD, 99%) were all purchased from Aladdin Biotech, inc. (Shanghai, china), 1,4-butanediol (BDO, 98%), triethylamine (TEA, 99%), N-dimethylformamide (DMF, 99%) and Acetone (AR) were all purchased from Corlon Chemicals, inc. (Chengdu, china); the structural formula of the N- (2-methyl-1,3-propanediol-2' -) perfluorobutyl sulfonamide is shown in the specification

English is abbreviated as PFAD; the English abbreviation of the aqueous polyurethane/polyurea with fluorine-containing side chain is as follows: F-WPU/PUA, wherein 1F-WPU/PUA represents PFAD accounting for 1% of the total molar amount of F-WPU/PUA; 2F-WPU/PUA means PFAD 2% of the total molar amount of F-WPU/PUA; 5F-WPU/PUA means that PFAD represents 5% of the total molar amount of F-WPU/PUA.

Synthesis of PAE

A three-neck flask is erected in a constant-temperature oil bath kettle, and is provided with a stirrer, a dropping funnel, a thermometer and a nitrogen inlet; adding 1,6-hexanediamine into a three-neck flask filled with nitrogen, heating to 55 ℃, stirring, and controlling the reaction temperature to reflux below 60 ℃;2 times of metered diethyl maleate is dripped into the three-neck flask at the speed of one drop per two seconds, the reaction is continued for 30min after the dripping is finished, the temperature is raised to 75 ℃, and the reaction is carried out for 25h.

Synthesis of PFAD

In a device provided with a dropping funnel and a reflux condenser pipe (provided with anhydrous CaCl) ₂ Drying tube) is added with 1.09g (0.012 mol) of AMPD, 1.02g of TEA and 10mL of DMF (as solvent), 3.02g (0.010 mol) of PBF is dissolved in 15mL of ethyl acetate and then is dropwise added into the three-neck flask, the temperature is reduced to 0 ℃ in an ice bath, nitrogen gas is filled for protection, and after the dropwise addition is finished, the stirring reaction is continued for 8 hours. Filtering to obtain white solid, separating and purifying; the reaction process is shown in figure 1.

The synthetic schemes of 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PUA are the same as those in FIG. 2.

Example 1

Synthesis of 1F-WPU/PUA

IPDI and PTMEG1000 were added to a 250mL three-necked round bottom flask with nitrogen protection, condenser and mechanical stirrer, 3 drops of DBTDL were added dropwise as catalyst, and reacted at 80 ℃ for 2.5h to form an isocyanate-terminated prepolymer. Cooling to 60 ℃, adding DMBA (dissolved in acetone) to introduce hydrophilic groups, and heating to 70 ℃ for reaction for 2 hours. Then cooling to 60 ℃, adding PFAD and BDO to continue the chain extension reaction for 1h. After cooling to room temperature, PAE (dissolved in acetone) was added as a secondary amine chain extender and stirred for 30min. TEA (DMBA: TEA =1:1 (molar ratio)) was then added to neutralize the carboxyl groups in the hydrophilic groups. And adding ultrapure water dissolved with IPDA after 30min, and performing high-speed shearing emulsification to form the fluorine-containing side chain waterborne polyurethane/polyurea emulsion. The 1F-WPU/PUA film is prepared by pouring the emulsion on a clean polytetrafluoroethylene plate, then naturally drying to form a film at room temperature, and then vacuum drying at 65 ℃ for 24 hours to remove all water; wherein: the mole ratio of IPDI, PTMEG, DMBA, PFAD, BDO, PAE and IPDA is 9:2:2:0.2:0.8:1:2.

example 2

Synthesis of 2F-WPU/PUA

IPDI and PTMG1000 were added to a 250mL three-necked round bottom flask with nitrogen protection, condenser and mechanical stirrer, 3 drops of DBTDL were added dropwise as catalyst, and reacted at 80 ℃ for 2.5h to form an isocyanate group-terminated prepolymer. Cooling to 60 ℃, adding DMBA (dissolved in acetone) to introduce hydrophilic groups, and heating to 70 ℃ to react for 2h. Then the temperature is reduced to 60 ℃, PFAD and BDO are added to continue the chain extension reaction for 1 hour. After cooling to room temperature, PAE (dissolved in acetone) was added as a secondary amine chain extender and stirred for 30min. TEA (DMBA: TEA =1:1 (molar ratio)) was then added to neutralize the carboxyl groups in the hydrophilic groups. And adding ultrapure water dissolved with IPDA after 30min, and performing high-speed shearing emulsification to form the fluorine-containing side chain waterborne polyurethane/polyurea emulsion. The 2F-WPU/PUA film was made by pouring the emulsion onto a clean Teflon sheet, then naturally drying to form a film at room temperature, followed by vacuum drying at 65 ℃ for 24 hours to remove all water, wherein the molar ratio of IPDI, PTMEG, DMBA, PFAD, BDO, PAE and IPDA was 9:2:2:0.4:0.6:1:2.

example 3

Synthesis of 5F-WPU/PUA

IPDI and PTMG1000 are added into a 250mL three-neck round bottom flask with a nitrogen protection, a condenser tube and a mechanical stirrer, 3 drops of DBTDL are dripped to be used as a catalyst, and the reaction is carried out for 2.5h at 80 ℃ to form the prepolymer with the end capped by isocyanate groups. Cooling to 60 ℃, adding DMBA (dissolved in acetone) to introduce hydrophilic groups, and heating to 70 ℃ for reaction for 2 hours. Then the temperature is reduced to 60 ℃, PFAD is added to continue the chain extension reaction for 1 hour. After cooling to room temperature, PAE (dissolved in acetone) was added as a secondary amine chain extender and stirred for 30min. TEA (DMBA: TEA = 1:1) was then added to neutralize the carboxyl groups in the hydrophilic groups. And adding ultrapure water dissolved with IPDA after 30min, and performing high-speed shearing emulsification to form the fluorine-containing side chain waterborne polyurethane/polyurea emulsion. The 5F-WPU/PUA film was made by pouring the emulsion onto a clean Teflon sheet, then naturally drying to form a film at room temperature, and then vacuum drying at 65 ℃ for 24 hours to remove all water, wherein the molar ratio of IPDI, PTMEG, DMBA, PFAD, PAE and IPDA was 9:2:2:1:1:2.

comparative example 1

Pure WPU/PUA (free of fluorine) was prepared directly, and compared with the preparation method for synthesizing 1F-WPU/PUA, PFAD therein was replaced by equimolar BDO.

The WPU/PUA, 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PUA prepared in examples 1 to 3 and comparative example 1 were verified or tested for their related properties.

The apparatus used therein was as follows: fourier transform-induced spectroscopy (FTIR): the infrared spectrum of the samples was measured using an Invenior (Bruker) Fourier Infrared spectrometer. Each sample is 400-4000 cm ^-1 Internal scanning 16 times with 4cm resolution ^-1 。

¹ H-NMR: on a Bruker AV-400NMR (400 MHz) spectrometer, tetramethylsilane (TMS) is taken as an internal standard, deuterated dimethyl sulfoxide (DMSO-d 6) is taken as a solvent, and the product is obtained at 25 DEG C ¹ H NMR spectrum.

F-NMR: testing samples with Bruker AV-400NMR spectrometer using heavy water (Deuterium oxide) as solvent and TMS as internal standard ¹⁹ F Nuclear Magnetic Resonance (NMR) spectrum. Mass spectrometer, mass Spectrometry (MS): the samples were dissolved in methanol and tested for molecular weight using a Finnigan TSQ-Quantu type mass spectrometer, electrospray ionization (ESI) source.

X-ray photoelectron spectroscopy, X-ray photoelectron spectroscopy (XPS): x-ray photoelectron spectroscopy was performed using AXIS Supra DLD (Kratos) spectrometer. An Al-K-alpha anode is used as an X-ray source (1486.6 eV), and the range of the binding energy is 0-1200 eV. XPS survey spectra were scaled using C1s (285 eV). Setting power: full spectrum: 10KV,7mA;

X-Ray diffractometer, X-Ray Diffraction (XRD): the crystallinity of the film was measured by X' Pert Pro MPD DY 129X-ray diffractometer. The incident light source is CuK alpha (lambda =0.154 nm), the test voltage is 40kV, the current is 40mA, the scanning range is 5-50 degrees, and the thickness of the emulsion film is about 0.50mm.

Thermogravimetric analyzer, thermovirometric analysis (TGA): the sample (5-8 mg) was heated from room temperature to 600 ℃ at a rate of 10 ℃/min under a nitrogen atmosphere.

Contact angle, contact angle analysis: the emulsion is formed into a film on a clean glass slide, naturally dried and then dried for 6 to 8 hours at the temperature of 120 ℃. The latex film was tested for static contact angle using a DSA-25S contact angle tester while being placed in a desiccator for 1 day. The contact angle at 25s of contact of the drop with the membrane was taken as the stable contact angle, and 5 measurements were made for each sample, with the average being taken as the final contact angle.

Mechanical Properties, tensile Properties: the mechanical properties (tensile strength and elongation at break) of the polymer films were tested using an INSTRON (usa) universal materials tester. The tensile rate was 50mm/min and the test temperature was 25 ℃. The test specimen was dumbbell-shaped, and the middle extension was 33.0mm long, 6.0mm wide and 0.5mm thick. Each sample was tested 5 times and the average was taken as the final result.

Dynamic mechanical analysis, dynamic Mechanical Analysis (DMA): the dynamic mechanical analysis was carried out on a dynamic mechanical spectrometer (model Q850) in a tensile mode with a frequency of 1Hz and an amplitude of 5 μm, a temperature range of-100 to 50 ℃, a temperature rise rate of 3 ℃/min, a strain amplitude of 0.2%, and a specimen size of 20mm × 5mm × 0.2mm (L × W × H).

Water absorption: the water absorption of the polyurethane in water characterizes the water resistance of the F-WPU/WPUA film. The film was cut into 30X 30mm sheets, dried in a vacuum oven for 24h and the dry weight M was determined ₀ . The water absorption M of the sample can be measured by wiping off the surface water with clean filter paper. The swelling degree calculation formula is as follows: water absorption (%) = [ (M-M) ₀ )/M ₀ ]X 100%. Each sample was repeated five times and the mean was calculated.

1. Verification of successful Synthesis of PFAD

Systematic infrared spectroscopy (IR), NMR, and hydrogen spectroscopy (for PFAD) for its chemical structure and composition ¹ H NMR), nuclear magnetic resonance fluorine spectrum ( ¹⁹ F NMR), mass Spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). FTIR of PFAD As shown in FIG. 3, 3279cm as seen in FIG. 3 ^-1 The absorption peak at (b) is the stretching vibration of-OH, 3145cm ^-1 、1544cm ^-1 The absorption peak at (A) belongs to the stretching vibration and the bending vibration of-NH. 1365cm ^-1 、1166cm ^-1 The absorption peak should be due to-SO ₂ Asymmetric stretching vibration peak and symmetric stretching vibration peak, 1301cm ^-1 And 684cm ^-1 The absorption peak at (a) is due to the stretching vibration of C-F.

Of PFAD ¹ The H NMR spectrum is shown in FIG. 4, and the quintuple weight peak at 2.50ppm is DMSO-d ₆ The solvent peak of (1) was broad at 5.71ppm and the lower peak was an active hydrogen peak, and the methylene peak at 3.26ppm was a peak connecting hydroxyl groups.

X-ray photoelectron spectroscopy of PFAD As shown in FIG. 5, the peak intensity of XPS was F1S, the peak was 687.9eV, and the peaks of S2S and S2p were 230.3eV and 164.3eV, respectively.

Of PFAD ¹⁹ F NMR is shown in FIG. 6, and CF at-82 ppm ₃ Radical, remainder CF ₂ The radicals are located at-110 to-130 ppm.

Mass Spectrometry of PFAD As shown in FIG. 7, C ₈ H ₁₀ F ₉ NO ₄ Calculated M/z of S =387.23, cashback (M-H) ⁺ C ₈ H ₁₀ F ₉ NO ₄ S found =388.50.

In conclusion, PFADs were successfully synthesized.

Whether PFAD was successfully introduced into the WPU/PUA molecular chain

The infrared spectrum of 2F-WPU/PUA is shown in FIG. 8, and the stretching vibration peak and the bending vibration peak of-NH are respectively located at 3319cm ^-1 And 1535cm ^-1 At l710cm ^-1 The left and right are the stretching vibration peak of C = O, 1234cm ^-1 The absorption peaks at (A) belong to the stretching vibration of C-O in the urethane bond, and these are characteristic peaks of the urethane bond and the urea bond, indicating that the synthesis of WPU/PUA is successful. 2935cm ^-1 And 2854cm ^-1 The peaks appearing to the left and right are attributed to C-H and-CH in the polyether soft segment ₂ Peak of stretching vibration, 1103cm ^-1 The absorption peak of C-O-C of the soft segment polyether is shown on the left and the right. 2275-2240cm ^-1 No broad or shoulder appeared indicating that the-NCO had reacted to completion. In the fingerprint area of 600-700cm ^-1 About and about appear-CF ₃ The characteristic absorption peak of the combination of the vibration in plane and non-plane is absorbed. At 1305cm ^-1 A peak appears, which is attributed to the stretching vibration of C-F. Thus, it was demonstrated that the fluorine-containing chain was successfully formedThe segment is introduced into WPU/PUA molecular chain as a side chain.

3. Validating F-WPU/PUA

The elemental composition of the synthesized F-WPU/PUA was analyzed by X-ray photoelectron spectroscopy (XPS), as shown in FIG. 9, which shows five major peaks, 164.1eV, 284.6eV, 397.9eV, 531.6eV, and 684.9eV, respectively associated with S2p, C1S, N1S, O1S, and F1S. As can be seen from Table 1, fluorine was detected on the surface of all F-WPU/PUA films as compared with the WPU/PUA films.

TABLE 1

Crystallinity of WPU/PUA, F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PUA

An X-ray diffraction (XRD) experiment was performed (fig. 10). A broad diffraction peak was observed around 2 θ =19 ° for each of WPU/PUA, F-WPU/PUA, 2F-WPU/PUA, and 5F-WPU/PUA, indicating that WPU/PUA is amorphous. The crystallinity of the WPU/PUA films increases with increasing PFAD content. After PFAD is introduced, the percentage of ordered hydrogen bonded C = O in the hard segment increases with increasing content of the fluorine-containing side chain, and this ordered structure may be beneficial for the hard segment to form more microcrystalline regions. Thus, crystallinity increases with increasing fluorine-containing side chain content. As the PFAD content is increased, the percentage of the hard segment connected with the fluorine-containing side chain is gradually increased, and the migration effect of the fluorine unit can cause more hard segment to migrate and penetrate into the soft segment, so that the microphase separation degree of the WPU/PUA is improved.

6. Effect of PFAD-containing on thermal stability of polyurethane films

Thermogravimetric analysis (TGA) was used to assess the effect of PFAD on the thermal stability of polyurethane films. The TGA and DTG curves for pure PU/PUA and PU/PUA with different fluorinated side chains are shown in FIGS. 11 and 12, respectively, and each TGA curve has two distinct steps, i.e., maximum degradation temperatures. Table 2 provides corresponding detailsData, including a weight loss temperature (T) of 5% _5％ ) 10% weight loss temperature (T) _10％ ) Temperature T of respective percentage of maximum weight loss _max1 And T _max2 . The results show that T increases with temperature _5％，T _10％ And T _max1 Both increase with increasing PFAD content.

TABLE 2

Sample	T _5％	T _10％	T _max1	T _max2
					WPU/PUA	199.28	249.82	309.58	405.47
1F-WPU/PUA	203.68	251.41	312.63	411.61
					2F-WPU/PUA	214.06	254.93	318.62	412.55
5F-WPU/PUA	219.29	258.34	321.08	411.50

7. Dynamic Mechanical Analysis (DMA)

The internal loss (tan delta) storage modulus (E ') and loss modulus (E') of WPU/PUA films are dependent on temperature

As shown in fig. 13-15 and table 3, fig. 13 is a graph of the change in dissipation modulus with temperature; FIG. 14 is a graph of storage modulus as a function of temperature; FIG. 15 is a graph of tan δ as a function of temperature. Dynamic mechanical analysis to study PFAD vs WPU/PUA glass transition temperature (T) _g ) The influence of (c). the peak temperature corresponding to the tan delta and E' curves is the T of WPU/PUA _g (ii) a As can be seen from FIG. 13 and Table 3, the T of WPU/PUA increases with the increase of the PFAD content _g The value also increased from-63.88 ℃ to-57.39 ℃. It is understood from Table 3 that the glass transition temperatures of WPU/PUA, 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PUA are-51.12 deg.C, -49.84 deg.C, -46.44 deg.C and-45.47 deg.C, respectively. The results show that with increasing PFAD content, T of F-WPU/PUA _g The values are also gradually increased, and T of 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PUA _g T with values higher than pure WPU/PUA _g Values, indicating that an increase in PFAD results in an increase in the glass transition temperature of WPU/PUA.

As can be seen from FIG. 14 and Table 3, the storage modulus of the vitrified land area decreases with increasing PFAD content, indicating a decrease in the resilience of the F-WPU/PUA film. Further, WPU/PUA, 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PU have maximum tan δ of 0.061, 0.060, 0.059 and 0.053, respectively. It was shown that the WPU/PUA stiffness gradually increased with increasing PFAD content.

TABLE 3

Sample	T _g from E”/℃	T _g from Tanδ/℃
			WPU/PUA	-63.88	-51.12
1F-WPU/PU	-62.39	-49.84
			2F-WPU/PUA	-61.87	-46.44
5F-WPU/PUA	-57.39	-45.47

8. Stress-strain analysis

FIG. 16 shows the stress-strain curves of F-WPU/PUA synthesized with different PFAD contents, and the mechanical property data are shown in Table 4. The tensile strength of WPU/PUA, 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PU was found to be 23.51MPa, 35.09MPa, 42.91MPa and 45.33MPa respectively, and the elongation at break was found to be 546.01%, 468.08%, 454.08% and 425.04% respectively. Therefore, increasing the PFAD content can increase the tensile strength of WPU/PUA and decrease the elongation at break.

TABLE 4

9. Contact Angle analysis

Enrichment of the fluorine-containing side chains affects the surface roughness of the polyurethane film, which has a significant effect on the surface properties, particularly the hydrophobic surface, which has an effect on the film surface contact angle. The Contact Angle (CA) is mainly related to two factors: surface microstructure and surface chemistry. The rougher the surface, the larger the contact angle is for materials with the same chemical properties; the material with the same roughness has stronger hydrophobicity and larger contact angle;

as shown in fig. 17 and table 5, the contact angles of water molecules with the WPU/PUA, 1F-WPU/PUA, 2F-WPU/PUA and 5F-WPU/PU film surfaces were 61.32 °, 77.01 °, 81.53 ° and 101.11 °, respectively, and the results showed that the contact angle of WPU/PUA gradually increased with the increase of PFAD content, and thus WPU/PUA with high PFAD content exhibited a larger contact angle and stronger hydrophobicity; and the hydrophobic property of polyurethane/polyurea with fluorine-containing segment chains is greatly improved, namely the water resistance is enhanced compared with the polyurethane/polyurea without fluorine.

TABLE 5

Sample	WPU/PUA	1F-WPU/PUA	2F-WPU/PUA	5F-WPU/PUA
					Contactangle/degree	61.32±1.23	77.01±0.73	81.53±1.19	101.11±0.57

Water repellency of F-WPU/PUA films

As can be seen from FIG. 18, the water absorption of WPU/PUA membrane gradually decreases from 30.13% to 12.55% in seven days as the PFAD content increases, and the introduction of PFAD can improve the water resistance of WPU/PUA, which is attributable to the influence of migration and enrichment of the fluorine-containing side chain on the surface performance of polyurethane, consistent with the aforementioned CA analysis results.

In conclusion, PBF and AMPD are combined into a novel long-chain-segment side-chain fluorinated bishydroxy chain extender PFAD by a simple method, the chemical structure and components of which pass through FTIR, ¹ H NMR、 ¹⁹ F NMR, MS and XPS were confirmed and incorporated into polyurethanes to successfully synthesize a series of waterborne polyurethanes/polyureas with varying content of fluorine-containing side chains. FTIR and XPS analysis showed that the introduction of fluorine containing side chains in WPU/PUA increases hydrogen bonding interactions and that the higher the PFAD content, the more hydrogen bonding interactions in WPU/PUA. XRD shows that due to the interaction of hydrogen bonds, the fluorine-containing side chain extender is more beneficial to the microphase separation of WPU/PUA, so that the performance of the WPU/PUA is improved; TGA shows that the thermal performance of WPU/PUA increases with increasing PFAD content, the maximum degradation temperature increases from 309.58 ℃ to 321.08 ℃ and the Tg increases from-63.88 ℃ to-57.39 ℃. Mechanical property analysis shows that with the increase of PFAD content, the tensile strength is increased from 23.51MPa to 45.33MPa, and the Young modulus is increased from 1.38MPa to 4.31MPa, thus showing excellent comprehensive properties. Furthermore, as PFAD content increased, WPU/PUA hydrophobicity increased; the water absorption rate is reduced from 30.13% to 12.55% in seven days, and the water resistance of the WPU/PUA can be improved by introducing PFAD, which can be attributed to the fact that the migration and enrichment of the fluorine-containing side chain have certain influence on the surface performance of polyurethane, and is consistent with the result of the CA analysis mentioned above.

The invention is not limited to the above alternative embodiments, and any other various forms of products can be obtained by anyone in the light of the present invention, but any changes in shape or structure thereof, which fall within the scope of the present invention as defined in the claims, fall within the scope of the present invention.

Claims

1. A preparation method of waterborne polyurethane/polyurea with a fluorine-containing side chain is characterized by comprising the following steps:

s1: synthesizing N- (2-methyl-1,3-propylene glycol-2-) -perfluorobutyl sulfonamide;

s2: under the inert environment with the temperature of 75-85 ℃, isophorone diisocyanate and polytetrahydrofuran glycol react for 2-3 hours under the action of a catalyst to synthesize a prepolymer with an isocyanate group end capping;

s3: cooling to 65-74 ℃, and adding a hydrophilic chain extender;

s4: cooling to 55-65 ℃, adding N- (2-methyl-1,3-propylene glycol-2-) -perfluorobutyl sulfonamide and 1,4-butanediol for reaction to carry out chain extension reaction;

s6: neutralizing the carboxyl group in the hydrophilic group;

s7: emulsification;

s8: and curing to form a film.

2. The method for preparing the waterborne polyurethane/polyurea with the fluorine-containing side chain according to claim 1, wherein the step S1 is specifically as follows:

s1-1: mixing 2-amino-2-methyl-1,3-propanediol, triethylamine and N, N-dimethylformamide in an ice bath in an anhydrous and inert environment to obtain a mixed solution;

s1-2: and (3) dropwise adding the perfluoro-1-butanesulfonyl fluoride dissolved in ethyl acetate into the mixed solution, continuing to react for 8-8.7 hours after the dropwise addition is finished, and separating and purifying to obtain a white solid.

3. The method for preparing the aqueous polyurethane/polyurea having the fluorine-containing side chain according to claim 1, wherein the catalyst in the step S2 is dibutyl tin dilaurate.

4. The method for preparing the waterborne polyurethane/polyurea with the fluorine-containing side chain according to claim 1, wherein the hydrophilic chain extender in the step S3 is 2,2-dimethylolbutyric acid.

5. The method for preparing the waterborne polyurethane/polyurea with the fluorine-containing side chain according to claim 1, wherein the step S5 is to cool the temperature to room temperature, add the aspartic ester and stir the mixture for 20 to 31 minutes.

6. The method for preparing the waterborne polyurethane/polyurea with the fluorine-containing side chain according to claim 1, wherein the step S6 is specifically as follows: adding triethylamine to neutralize and react for 28-33 minutes.

7. The method for preparing the aqueous polyurethane/polyurea having the fluorine-containing side chain according to claim 1, wherein the step S7 is specifically: adding isophorone diamine dissolved in water for emulsification.

8. The method for preparing the aqueous polyurethane/polyurea with fluorine-containing side chains according to claim 1, wherein the molar ratio of the N- (2-methyl-1,3-propanediol-2-) -perfluorobutanesulfonamide to 1,4-butanediol is 1-5:1.

9. The method for preparing the waterborne polyurethane/polyurea with fluorine-containing side chain according to claim 5, wherein the aspartic ester is prepared by the following method: refluxing 1,6-hexanediamine at 55-60 deg.C in a constant temperature anhydrous and inert environment, adding twice the molar amount of diethyl maleate to 1,6-hexanediamine, heating to 75-80 deg.C, reacting for 28-32 min, and reacting for 24-26 hr.