CN114634641B

CN114634641B - Use of porous polymer films with regular pores for producing antiblocking films

Info

Publication number: CN114634641B
Application number: CN202210335221.9A
Authority: CN
Inventors: 罗彦凤; 杨伟; 王锡婉
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2022-03-31
Filing date: 2022-03-31
Publication date: 2023-05-23
Anticipated expiration: 2042-03-31
Also published as: CN114634641A

Abstract

The invention belongs to the technical field of polymer materials, and particularly relates to application of a porous polymer film with regular pores in preparation of an anti-blocking film. The invention provides a shape memory polyurethane which is prepared from diisocyanate, soft segment polymer and

polymerized to form; the soft segment polymer is polylactic acid, polyglycolic acid, polycaprolactone, polyol or copolymer of at least two of them. This shape memory polyurethane material, in combination with a water drop templating method, can comprise a porous polymer film of crystalline structure. The porous film material has excellent mechanical properties, can meet the performance requirements of application scenes such as artificial periosteum, anti-adhesion film and the like, and has good application prospects.

Description

Use of porous polymer films with regular pores for producing antiblocking films

Technical Field

The invention belongs to the technical field of polymer materials, and particularly relates to application of a porous polymer film with regular pores in preparation of an anti-blocking film.

Background

Shape memory polymers (Shape Memory Polymer, abbreviated as SMPs), also known as shape memory polymers, refer to polymeric materials that recover their original shape by external stimuli (e.g., heat, electricity, light, chemical induction, etc.) after the article having the original shape has changed its original condition under certain conditions and has been fixed. Shape memory polymers have wide applications in biomedical, aerospace, optical, and textile fields due to their shape recovery properties.

Shape memory polymers include thermally induced, electrically induced, photoinduced, chemically induced, and the like, according to their recovery principle. Wherein the thermotropic shape memory polymer can be used in medicine by controlling the glass transition temperature and adjusting the recovery temperature to be consistent with the body temperature. For example: the film made of thermal shape memory polymer material or the device with specific shape can be miniaturized and deformed, then implanted into the body through the microcatheter, and the original set shape can be restored after the correct position is reached.

Thermotropic shape memory polymers include polyurethane, ethylene/vinyl acetate copolymers, and crosslinked polyethylene, among others. When the materials are used for preparing membranes or devices implanted into human bodies, a series of performance requirements such as permeability, biocompatibility and mechanical properties are required to be met according to implantation positions and purposes. These existing thermotropic shape memory polymer materials do not meet these permeability and biocompatibility requirements as conventional dense membranes. To ameliorate this problem, porous polymer films with regular pores have potential as membranes for implantation into the human body due to their unique performance characteristics (e.g., permeability to molecules/ions, biocompatibility, and extensibility, etc.).

However, the existing thermotropic shape memory polymer material can cause the problem of insufficient mechanical properties in the process of introducing a large number of pores to prepare the porous membrane. For example, "CN201110224930.1 a method for forming a polyurethane porous film" provides a method for preparing a polyurethane porous film by using a water-drop template method. However, due to the limitation of mechanical properties, the porous polymer film made of the polyurethane materials is still difficult to apply to fields with high requirements on the mechanical properties of materials, such as bionic, tissue engineering and the like. The development and application of the porous polymer film are greatly limited, and the design and preparation of the polymer film with good mechanical property and regular porous structure are beneficial to expanding the application of the material. Ordered arrangement, crystal or microphase separation of polymer molecules can help to enhance mechanical properties of materials, however, the type and structure of ideal shape memory polymer materials cannot be deduced according to the prior theory, and the problem to be solved is urgent.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a shape memory polyurethane material and a self-reinforced regular pore polymer film prepared from the same, and aims to provide a porous polymer film with regular pores, which has mechanical properties, and is used for preparing an anti-blocking film.

An anti-adhesion film is prepared from porous polymer film,

the porous polymer film is prepared by taking shape memory polyurethane as a raw material and adopting a water drop template method;

the shape memory polyurethane is amorphous polymer with glass transition temperature of 37-45 ℃ or semi-crystalline polymer with melting point of 37-45 ℃ and consists of diisocyanate, soft segment polymer and

according to the mole ratio of 1.2-8:1:0.2-7 of a linear polymer polymerized to a molecular weight of 30000-150000;

the soft segment polymer is polylactic acid, polyglycolic acid, polycaprolactone, polyol or copolymer of at least two of them.

Preferably, the soft segment polymer is expressed as HO-R-OH, and the structural formula of the shape memory polyurethane is shown as formula I:

wherein x is selected from 1 to 10, y is selected from 1 to 10;

repeating units that are said soft segment polymer;

is diisocyanate (bis)Repeating units of esters, or diisocyanates with +.>

Is a copolymer of a vinyl aromatic monomer and a vinyl aromatic monomer.

Preferably, the molecular weight of the soft segment polymer is 1000-10000.

Preferably, the soft segment polymer is a polymer of lactic acid and a polyol.

Preferably, the molar ratio of the repeating units of lactic acid to the repeating units of the polyol in the soft segment polymer is 10-102:1-20.

Preferably, the structural formula of the soft segment polymer is shown as formula II:

wherein m and n are respectively and independently selected from 4-50, and r is selected from 1-20.

Preferably, the diisocyanate is selected from aliphatic diisocyanates or aromatic diisocyanates, the aliphatic diisocyanates comprise hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and the aromatic diisocyanates comprise at least one of toluene diisocyanate or diphenylmethane diisocyanate.

Preferably, the said

The method comprises the following steps: />

The invention also provides application of the porous polymer film with regular pores in preparation of an anti-blocking film.

The invention also provides a preparation method of the porous polymer film, which comprises the following steps:

step 1, dissolving the shape memory polyurethane in a volatile solvent to obtain a polyurethane solution;

and 2, coating the polyurethane solution on the surface of a substrate, and volatilizing in humid air to obtain the polyurethane.

Preferably, in step 1, the volatile solvent is at least one selected from chloroform, dichloromethane, tetrahydrofuran or carbon disulfide;

and/or the concentration of the polyurethane solution is 5-200mg/mL;

and/or, in the step 2, the substrate coated with the polyurethane solution is dried under the conditions of the ambient temperature of 4-50 ℃ and the humidity of 25-80%, and the volatilization rate of the solvent is 5-50 mu L/min.

The invention designs a novel shape memory polyurethane material, and after the shape memory polyurethane material is prepared into a porous polymer film with regular pores by a water drop template method, the microstructure of the film material shows a certain crystal characteristic. This shows that the molecular chains in the porous polymer film are arranged more orderly, and the hard segment assembly is better, so that the prepared porous polymer film has good mechanical properties. Compared with the similar porous polymer films, the porous polymer film with high mechanical properties has good application prospect in the fields of artificial periosteum, anti-adhesion films and the like with higher requirements on the mechanical properties of the films.

It should be apparent that, in light of the foregoing, various modifications, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

The above-described aspects of the present invention will be described in further detail below with reference to specific embodiments in the form of examples. It should not be understood that the scope of the above subject matter of the present invention is limited to the following examples only. All techniques implemented based on the above description of the invention are within the scope of the invention.

Drawings

FIG. 1 shows two coupling agents according to example 1 ¹ H NMR spectrum;

FIG. 2is the FT-IR spectra of two coupling agents in example 1;

FIG. 3 is a FT-IR spectrum of PDLLA-PEG400-PDLLA macrodiol and ISO-PUs in example 1 (right spectrum is an enlargement of rectangular label portion of left spectrum);

FIG. 4 is a diagram of PDLLA-PEG400-PDLLA and ISO-PUs of example 1 ¹ H NMR spectrum;

FIG. 5 is a GPC curve of ISO-PUs in example 1;

FIG. 6 is a macroscopic morphology (thickness = 0.032.+ -. 0.011 mm) of ISO-PUs porous film (a) and non-porous control film (b);

FIG. 7 is an optical microscope image of water droplets coalescing at the surface of an ISO-PUs solution during porous film formation;

FIG. 8 is an SEM image of a dried ISO-PUs porous film, (b) is an enlargement of the red phase region in (a);

FIG. 9 is an optical microscope image (a) of an ISO-PUs porous film and an optical microscope image (b-d) under a crossed polarizer, where (c) and (d) are the magnification of the red region in (b);

FIG. 10 is an optical microscope image of an ISO-PUs porous film prepared at rates of 10. Mu.l/min ((a) and (b)) and 40. Mu.l/min ((d) and (e)), and a microscope image under crossed polarizers ((c) and (f) are magnified views of red areas in (b) and (e), respectively);

FIG. 11 is the microscopic morphology under PPZ-PU (a and b), upy-PU (c and d) and PDLLA (e and f) porous film optical microscope and cross-polarizer;

FIG. 12 shows DSC curves of ISO-PUs nonporous control films and ISO-PUs porous films ((a) first heat cycle curve, (b) cool down and second heat curve);

FIG. 13 is a graph showing the 2D-WAXD diffraction patterns of ISO-PUs non-porous control film (a) and ISO-PUs porous film (b), and the 1D-WAXD curves of ISO-PUs non-porous control film (c) and ISO-PUs porous film (D);

FIG. 14 FT-IR spectrum (a) and 3260-3460cm of ISO-PUs control film and porous film ^-1 A fitted peak-splitting curve (b) of the region;

FIG. 15 shows the tensile stress-strain curve (a) and mechanical properties (b) at 25℃for ISO-PUs porous films and nonporous transparent control films;

FIG. 16 is a view showing the results of cell compatibility test morphology observation performed on ISO-PUs porous anti-blocking films and non-porous control films;

FIG. 17 shows absorbance values of NIH 3T3 cells at different culture times as measured by CCK-8 method (p <0.05 and p < 0.01) in a cell compatibility experiment of ISO-PUs porous anti-adhesion film and non-porous control film.

Detailed Description

The reagents and materials not specifically described in the following examples and experimental examples are commercially available.

Example 1 shape memory polyurethane

The present embodiment provides a shape memory polyurethane material. The preparation method comprises the following steps:

1. synthesis and purification of PDLLA-PEG400-PDLLA macrodiol

D, L-Lactide (D, L-Lactide, melting point: 118 ℃, purity: 99.9%), PEG400 (Allatin, CAS number: 25322-68-3, cat number: P103723), sn (Oct) ₂ (Sigma-Aldrich, CAS number: 301-10-0, cat number: S3252) in a molar ratio of 5000:100:1, vacuum pumping for 30min, and sealing; placing the single-mouth bottle into an oil bath pot at 140 ℃, starting magnetic stirring after the mixture is completely melted, uniformly stirring a reaction system, and continuously reacting for 24 hours; after the reaction is finished, repeatedly purifying the product for three times by adopting a methylene dichloride/ice absolute ethyl alcohol (-15 ℃) coprecipitation system, and purifying the product once by adopting a methylene dichloride/ice normal hexane (-15 ℃) coprecipitation system; vacuum drying at room temperature for 72h to obtain target product PDLLA-PEG400-PDLLA macromolecular diol (m=46, n=46 and r=10 in the structural formula) for standby.

2. Synthesis and purification of novel diisocyanate of HDI-terminated ISO

HDI (Allatin, CAS number 822-06-0, cargo number H106723) and ISO #

Sigma-Aldrich, CAS number: 652-67-5, cat No.: i157515 Respectively adding different round-bottom single-neck flasks in a molar ratio of 4:1, and simultaneously putting a magnetic stirrer into the round-bottom single-neck flasks, wherein m (ISO, g): v (DMF, mL) =1:6 ratio was added to two single-port flasks in anhydrous grade DMF, magnetic stirring to completely dissolve ISO; and then ISO and Sn (Oct) ₂ Sn (Oct) is added in a molar ratio of 500:1 ₂ After nitrogen is replaced for three times, the mixture is reacted for 1h at 75 ℃ under the protection of nitrogen; after the reaction is finished, cooling to room temperature, pouring the mixture into n-hexane dried by a molecular sieve for precipitation, obtaining white powder, and drying the white powder to constant weight to obtain the novel diisocyanate coupling agent of the HDI end-capped ISO (the value of z in the structural formula is z=0 in the embodiment) for standby.

3. Synthesis and purification of ISO-PUs

Wherein OCN-DI' -NCO is the novel diisocyanate synthesized in the step 2. Wherein, the value of y is y=5.

OCN-DI' -NCO and PDLLA-PEG400-PDLLA (macrodiol) were added in a molar ratio of 1.5:1.0 to a round bottom four-necked flask equipped with mechanical stirring and thermometer, with m (macrodiol, g): v (DMF, mL) =1.0:0.8, anhydrous DMF was added, and mechanical stirring was performed to completely dissolve the macrodiol; then macromolecular diol and Sn (Oct) ₂ Sn (Oct) is added in a molar ratio of 500:1 ₂ Reacting for 6h at 75 ℃ under the protection of nitrogen (anhydrous grade DMF accounting for 20vol% of the initial volume is added into the reaction system every 2h so as to reduce the viscosity of the system); the ISO was then added in a molar ratio of ISO to macrodiol of 0.5:1.0, and the reaction was continued at 75℃for 12 hours under nitrogen protection (20 vol% of anhydrous DMF was added to the reaction system every 4 hours to reduce the viscosity of the system). Cooling to room temperature after the reaction is finished, pouring the reaction system into normal-temperature absolute ethyl alcohol for precipitation, and precipitating whiteThe solid is ISO-PUs. And finally, purifying the ISO-PUs twice by using a methylene dichloride/absolute ethyl alcohol coprecipitation system, and drying for later use. The glass transition temperature of ISO-Pus was determined to be 42 ℃.

4. Structural characterization

4.1 structural characterization of coupling agent

FIGS. 1 (a) and (b) are respectively the nuclear magnetic hydrogen spectra of novel diisocyanates of the sample HDI-terminated ISO obtained by the reactions of HDI and ISO at 4:1 and 2:1 [ ] ¹ H NMR) spectra, the proton absorption peak positions on the two lines are identical, but the intensities are greatly different. Wherein peaks at σ=3.98 to 4.29 (H-1, H-6), σ=4.78 (H-3), σ=5.12 (H-4) and σ=5.28 to 5.32 (H-2, H-5) are proton absorption peaks in ISO; peaks at σ=1.30 to 1.48 (H-c ', H-c), σ=1.58 to 1.72 (H-b ', H-b) and σ=3.14 to 3.29 (H-a ', H-a) belong to methylene proton absorption peaks in HDI; of two products ¹ No proton absorption peak on the unreacted ISO ring appeared in the H NMR spectrum, indicating that ISO was fully end capped with HDI. According to the theoretical formula (HDI-ISO (-HDI-ISO) _z HDI) it can be seen that the molar ratio of HDI to ISO in both coupling agents can be calculated from the integrated area of H-a', a and peak H-3, as shown in formula (4-1):

HDI/ISO＝I _H-a′+a /(I _H-3 ×4) (4-1)

for FIG. 1 (a), the HDI/ISO is close to 2 (7.74/(1.00X 4) ≡2), indicating that HDI and ISO react in a 4:1 reaction to give HDI-ISO-HDI. Whereas the HDI/ISO in FIG. 1 (b) is approximately 1.5 (6.37/(1.00X 4) ≡1.5), indicating that HDI and ISO react in a 2:1 reaction to give HDI-ISO-HDI-ISO-HDI.

Furthermore, in the FT-IR spectra of the two coupling agents (FIG. 2), it was clearly observed that the reaction time was 2273cm ^-1 The absorption peak of the-NCO group appears and is at 1698cm ^-1 An absorption peak of the-c=o group in the urethane bond occurs. And 1698cm in the HDI-ISO-HDI-ISO-HDI spectrum ^-1 And 2273cm ^-1 The peak area at the position is obviously larger than the peak area ratio of two positions in the HDI-ISO-HDI spectrogram. These further demonstrate the successful synthesis of the novel diisocyanates HDI-ISO-HDI and HDI-ISO-HDI-ISO-HDI.

4.2ISO-PUs structural characterization

The samples synthesized from HDI as coupling agent were designated ISO1-PU, while the samples synthesized from HDI-ISO-HDI and HDI-ISO-HDI-ISO-HDI as coupling agent were designated ISO2-PU and ISO3-PU, respectively. FT-IR spectra of PDLLA-PEG400-PDLLA and ISO-PUs are shown in FIG. 3. 1751cm in PDLLA-PEG400-PDLLA curve ^-1 The absorption peak at this point is the ester-c=o absorption peak in PDLLA-PEG 400-PDLLA. No observation at 2273cm was made in all ISO-PUs spectra ^-1 the-NCO absorption peak appears at this point, and some new peaks appear compared to the spectrum of PDLLA-PEG 400-PDLLA. I.e. 3300-3400cm ^-1 、～1621cm ^-1 And-1529 cm ^-1 The stretching vibration absorption peaks respectively belong to-NH, an amide I band (-C=O) and an amide II band (-NH) in the urethane bond. In summary, the occurrence of these absorption peaks demonstrates that ISO-PUs have been successfully synthesized.

To further explore the molecular structure of ISO-PUs, PDLLA-PEG400-PDLLA and ISO-PUs were also subjected to ¹ H NMR test, the obtained spectrum is shown in fig. 4. In PDLLA-PEG400-PDLLA ¹ H NMR spectrum, peaks at σ=1.57 ppm (H-B) and σ=1.48 ppm (H-B'), respectively, belong to the-CH of the macrodiol lactoyl unit ₃ and-CH in the terminal lactic acid residue of macromolecular alcohols ₃ Proton absorption peak; the peak at σ=3.64 ppm (H-D) comes from-CH within PEG400 ₂ Proton absorption peak; peak σ=5.16 ppm (H-a) is the-CH proton absorption peak on the macrodiol lactoyl unit; the peak at σ=4.23 to 4.46ppm (H-a', H-C) is-CH on the terminal lactic acid residue of the macromolecule alcohol linked to-OH and-CH adjacent to the PDLLA block in PEG400 ₂ Proton absorption peak of (2). With peak σ=5.16 ppm (I _H-A =17.08) and σ=4.23 to 4.36ppm (I _H-A'+C Integral value of =1.00) and formula (4-2), the molecular weight (M) of the used PDLLA-PEG400-PDLLA was calculated _n ) 7700.

/>

Three ISO-Pus types ¹ H NMR spectrum sigma=4.36-4.46 ppm and sigma=1.48 ppm at the terminal lactic acid residue of PDLLA-PEG400-PDLLA linked to-OH-CH3 (H-a ', H-B ') proton absorption peaks almost completely disappeared, and proton absorption peaks belonging to H-a ', H-B ' and H-c ' of HDI appeared at σ=3.14 ppm, σ=1.38 ppm and σ=1.28 ppm. Furthermore, the proton characteristic peaks on the ISO ring (H-1 to H-6) are evident in the spectra of ISO2-PU and ISO3-PU, whereas they cannot be observed in the spectra of ISO1-PU due to the low ISO content. The proton absorption peak ascribed to H-D in PDLLA-PEG400-PDLLA at sigma=3.64 ppm was used as an internal standard (I _H-D =1.00), while taking the integrated area of the H-3 peak (I _H-3 ) Or the integrated area of the H-4 peak (I _H-4 ) Represents the ISO content, expressed as the integral value of the H-a' peak (I _H-a' ) Representing the HDI content, the actual ratio of PDLLA-PEG400-PDLLA/ISO/HDI in ISO-PUs can be calculated, and the calculation results are shown in Table 1. M of ISO-PUs derived from GPC test (FIG. 5) at the same time _w And PDI are also listed in table 1. As the molecular length of the coupling agent increases, the larger the actual ratio of PDLLA-PEG400-PDLLA/ISO/HDI is different from the theoretical ratio, and the lower the molecular weight of PU is, which is caused by the difference of the reactivity of the coupling agent.

TABLE 1 composition ratio and molecular weight data for three ISO-PUs

The above test results show that ISO-PUs have been successfully synthesized, and their molecular structure and theoretical structure have been continued.

Example 2 high mechanical porous Polymer film with regular pores

In this example, the shape memory polyurethane material of example 1 was prepared as a high mechanical porous polymer film with regular pores by the following method:

the ISO-PUs (ISO 2-PU, M) prepared in example 1 were weighed _w =61 kda, pdi=1.57), and after complete dissolution in a beaker with chloroform, the volume was fixed with a volumetric flask to prepare a 50mg/mL solution. The cover glass is washed by three times of double steaming and water, washed by absolute ethyl alcohol and then dried. The coverslips were placed on a horizontal laboratory table in a fume hood at an ambient temperature of 28℃and a humidity of 70%, and about 200. Mu.L of ISO-PU was taken with a pipetteThe solution was uniformly spread on the surface of the coverslip while the air flow rate was adjusted so that the evaporation rate was about 20. Mu.L/min. And obtaining the porous film with a regular hexagonal pore structure after the solvent is completely volatilized. The pore diameter of the porous film can be adjusted by controlling the volatilization rate, and the faster the volatilization rate of the solution is, the smaller the pore diameter is, and the larger the pore diameter is on the contrary. Porous films with different pore diameters are prepared by using the principle at 10 mu L/min and 40 mu L/min respectively.

Comparative example 1 PPZ-PU, upy-PU and PDLLA cellular porous film

Comparative example PPZ-PU (M _w ＝80kDa,PDI＝1.66)、Upy-PU(M _w =25 kda, pdi=2.12) and PDLLA (M _w =75 kda, pdi=1.35) was made into honeycomb porous membranes. The synthetic process of the PPZ-PU and the Upy-PU is as follows:

wherein, the R group of PPZ-PU is:

the R group of Upy-PU is:

HDI and PDLLA-PEG400-PDLLA (macrodiol) were added in a molar ratio of 1.5:1.0 to a round bottom four-necked flask equipped with mechanical stirring and thermometer, with m (macrodiol, g): v (DMF, mL) =1.0:4.0, anhydrous toluene (Tol) was added, and mechanical stirring was performed to completely dissolve the macrodiol; then macromolecular diol and Sn (Oct) ₂ Sn (Oct) is added in a molar ratio of 500:1 ₂ Reacting for 3 hours at 75 ℃ under the protection of nitrogen; then PPZ or Upy is added according to the mol ratio of PPZ or Upy to macromolecular diol of 0.5:1.0, and the reaction is continued for 6 hours at 75 ℃ under the protection of nitrogen. And after the reaction is finished, cooling to room temperature, pouring the reaction system into normal-temperature absolute ethyl alcohol for precipitation, and separating out white solid, namely PPZ-PU or Upy-PU. Finally, with dichloromethane/anhydrousThe PPZ-PU or Upy-PU is purified twice by an ethanol coprecipitation system and dried for standby.

The synthesis process of PDLLA is as follows:

d, L-Lactide (D, L-Lactide, melting point: 118 ℃ C., purity: 99.9%) Sn (Oct) ₂ (Sigma-Aldrich, CAS number: 301-10-0, cat number: S3252) in a molar ratio of 5000:1, vacuum-pumping for 30min, and sealing; placing the single-mouth bottle into an oil bath pot at 140 ℃, starting magnetic stirring after the mixture is completely melted, uniformly stirring a reaction system, and continuously reacting for 14 hours; and after the reaction is finished, repeatedly purifying the product for three times by adopting a methylene dichloride/normal-temperature absolute ethyl alcohol coprecipitation system, and drying the product in vacuum at room temperature for 72 hours to obtain the target product PDLLA for later use.

Comparative example 2ISO-PUs nonporous control film

This comparative example was prepared in a similar manner to example 2 to produce an ISO-PUs nonporous control film, the comparative example differing from example 2 in that: humidity was set at 30% and the air flow rate was adjusted to give a volatilization rate of 20. Mu.L/min.

The beneficial effects of the invention are further illustrated by experiments below.

Experimental example 1 structural characterization

The samples used in this experimental example were the ISO-PUs porous polymer film prepared in example 2, the PPZ-PU, upy-PU and PDLLA honeycomb porous film prepared in comparative example 1, and the ISO-PUs non-porous control film prepared in comparative example 2.

1. Experimental method

(1) Polarizing microscope test: after the porous film on the cover glass is completely dried, the glass is placed on an MP41 type polarized light microscope (Mingmei photoelectric) object stage, the appearance of the porous film under the normal transmitted light and the orthogonal polarized light at the corresponding position is respectively observed under the transmission mode of a high-power lens (20-50 times), and the appearance is recorded by a digital camera.

(2) Scanning Electron Microscope (SEM) test: the completely dried porous film sample was removed from the cover glass, and the film surface was subjected to SEM test using a JSM-7800F scanning electron microscope (japan electronics corporation). Before testing, the sample needs to be sprayed with gold, the thickness is about 0.5nm, and the testing voltage is 8KV. While the C, O and N elements of the sample were imaged using x-ray electron spectroscopy (EDS).

(3) One-dimensional wide angle X-ray diffraction (1D-WAXD) test: the thin film samples were subjected to 1D-WAXD testing using a Panalytic-Empyrean high resolution X-ray diffractometer (malverpa, the netherlands), cu targets, scan rates 2θ=1°/min, scan ranges from 5 ° -35 °.

(4) Two-dimensional wide angle X-ray diffraction (2D-WAXD) test: two-dimensional wide angle x-ray diffraction (2D-WAXD) analysis was performed on the film at the BL16B1 beam line station of the open sea synchrotron radiation device (SSRF). The sample was 30mm from the detector and the diffraction pattern was collected by a Pilatus300K detector with a resolution of 487 x 619 pixels for a test time of 45s.

(5) FT-IR test: fourier transform infrared (FT-IR) spectra were collected for the film samples using an IRTracer-100 attenuated reflectance FT-IR spectrometer (Shimadzu, japan). Each sample was scanned 16 times at a resolution of 4cm ^-1 Recording the sample at 4000-700 cm ^-1 Spectrum in range. Spectra were peaked and integrated using the OriginPro 9.0 software after the test was completed.

(6) DSC test: differential Scanning Calorimeter (DSC) of DSC 200F3 type (Netzsch, germany) in N ₂ The test was performed under an atmosphere at a rate of 10 ℃/min for temperature rise (temperature reduction). The sample was first heated from-10 ℃ to 150 ℃, then cooled to-10 ℃, and finally heated again to 150 ℃. The first warming, the second warming cycle data are recorded.

2. Experimental results

1. Macroscopic morphology of ISO-PUs porous film

FIG. 1 is a comparative photograph of macroscopic morphology of ISO-PUs porous films and nonporous control films. The porous film (fig. 6 (a)) was translucent except visually that the edge region was translucent due to the too fast evaporation of the solution, and the entire porous structure was not formed, most of the region being white and opaque. All subsequent porous film tests were performed for visually white opaque areas. Whereas the ISO-PUs non-porous film (fig. 6 (b)) as a control exhibited colorless transparency, indicating that no phase separation structure was present or that the phase separation structure did not exceed the nanoscale in the non-porous control film.

2. Microcosmic morphology of ISO-PUs porous film

FIG. 7 is a photograph showing condensed water droplets collecting on the surface of a solution during the preparation of various ISO-PUs films (solvent evaporation rate of about 20. Mu.L/min). It can be observed that the coalesced water droplets (like white particles) are regularly arranged in most areas, the water droplets are regular hexagons and there are distinct boundaries between individual water droplets. This region appears as a monolayer of regular hexagonal pore regions in SEM testing (fig. 8 (a)) after complete evaporation of solvent and water. Whereas in a small part of the area, the droplets are connected to each other and overlap, and finally the solvent and water are completely evaporated to appear as a multi-layered pore area (fig. 8 (a)). Fig. 3 is a graphic image of the morphology obtained by SEM testing of the cellular porous membrane after complete drying, the size of the pores being very uniform, each regular hexagonal pore diameter being about 4.0 μm (fig. 8 (b)).

When the porous film was observed in the transmission mode using a microscope, the single-layer pores were visually white and the multi-layer pores were visually red due to the difference in light transmittance (fig. 9 (a)). When further observed under crossed polarizers (fig. 9 (b)), a peculiar image was observed in the monolayer region, four edges symmetrically distributed on both sides of the hexagon showed a crystal-like character, while the remaining two edges located between the four edges showed no crystal character, i.e. visually complete darkness. At the same time, the edges with the crystal features have regional orientation, and the boundaries of the differently oriented regions are precisely the multilayer pore regions. Further enlargement of these regions revealed that each edge with a crystalline character had a "Z" shape, and that two adjacent crystalline edges in the same alignment region were not closely connected, with a spacing of about 0.3-0.5 μm between them (FIGS. 9 (c) and (d)).

In addition, example 2 an ISO-PUs porous film having pore diameters of-1.5 μm and-7.0 μm was obtained by adjusting the air flow rate so that the solvent volatilization rates were 10. Mu.l/min and 40. Mu.l/min, respectively, and the optical microscopic morphology of the two films and the microscopic morphology under the crossed polarizers are shown in FIG. 10. When the optical microscopy morphology in fig. 10 (a) and (d) is compared with the morphology of the porous film of fig. 9 (a) with a pore size of about 4.0 μm, it can be seen that the pore size is proportional to the size of the multi-layered pore forming region, i.e., the film with a larger pore size exhibits a larger multi-layered pore region area. The hexagonal holes of the two diameters-1.5 μm and-7.0 μm (fig. 10 (b) and (e)) under the crossed polarizers showed similar crystal morphology to that of the hexagonal holes in fig. 9 (b). However, due to the resolution of the optical microscope, the "Z" shaped crystal morphology on the hexagonal hole edge having a diameter of-1.5 μm became less pronounced (FIG. 10 (c)), while the "Z" shaped crystal morphology on the hexagonal hole edge having a diameter of-7.0 μm became more pronounced (FIG. 10 (f)).

Comparative example 1 PPZ-PU, upy-PU and PDLLA porous films were also prepared by BF method, respectively, wherein PPZ-PU and Upy-PU have the same PDLLA-PEG400-PDLLA soft segment molecular chain as ISO-PUs. FIG. 11 shows the microscopic morphology of these porous films under an optical microscope and cross-polarizers, and the porous films PPZ-PU (FIG. 11 (a)) and UPy-PU (FIG. 11 (c)) are also honeycomb-shaped, i.e., the pores on the surface are regular hexagons, and the diameters of the pores are similar to those of the ISO-PUs porous film in FIG. 9 (a). The pores on the surface of the PDLLA porous membrane are irregular, and the pore diameter is obviously smaller than that of PPZ-PU and Upy-PU. Importantly, the porous films of these three materials did not show crystalline characteristics when viewed under a polarizer (fig. 11 (b), (d) and (f)), i.e., were completely dark in the field of view. Since ISO-PUs differ from PPZ-PU (as well as Upy-PU) only in the presence of repeat units of the bicyclic ISO small molecules, it is speculated that the bicyclic ISO small molecules play a crucial role in the formation of similar crystal structures in FIGS. 9 and 10.

3. Thermal Properties of ISO-PUs porous films

To further confirm the presence of crystals at the edges of the ISO-PUs porous film, DSC tests were performed on ISO-PUs porous films and ISO-PUs nonporous control films having a diameter of 4.0 μm. The first thermal scan is shown in FIG. 12 (a) where there is a typical crystalline melting peak on the DSC curve of the porous film, with a melting range of 46.5-55.7deg.C, a melting point of 51.7deg.C, and a melting enthalpy of 9.97J/g, whereas there is no similar melting peak on the DSC curve of the control film. In addition, the glass transition temperature of the porous film was 43.1 ℃ which is much higher than 31.4 ℃ of the control film, probably due to the restriction of the amorphous region molecular chains by the crystals, indicating that there was a difference in the degree and structure of phase separation of the soft and hard segments in the two films.

There was no significant difference between the cooling curve and the secondary heating curve of the two films (FIG. 12 (b)), neither of which showed a crystallization peak nor a crystal melting peak on the secondary heating curve. In addition, the glass transition temperatures of the two films on the cooling curve and the secondary heating curve are substantially the same. It is stated that ISO-PUs are indeed amorphous polymers, the crystals in porous films being formed by the BF process.

4. WAXD analysis of ISO-PUs porous film

To further detect the crystal structure in the ISO-PUs porous film, a porous film having a pore diameter of 4.0 μm was subjected to two-dimensional wide-angle X-ray diffraction (2D-WAXD) and one-dimensional wide-angle X-ray diffraction (1D-WAXD) tests. The test was also conducted using ISO-PUs nonporous transparent film as a control sample, and the obtained 2D-WAXD diffraction pattern and 1D-WAXD curve are shown in FIG. 13. In the 2D-WAXD diffraction pattern of the ISO-PUs control film (fig. 13 (a)), a strong diffraction spot appears only on the equator, and in the corresponding 1D-WAXD diffraction pattern (fig. 13 (c)), there is a sharp diffraction peak evident at 2θ=9.8 ° in addition to the broad diffraction peak of the amorphous phase. These results indicate that the molecular chains in the ISO-PUs control film spontaneously assemble to form a structure of nano-scale and ultra-high orientation degree. However, the content of such ordered nanostructures was too small to observe a distinct melting peak in its DSC curve (fig. 12 (a)). The 2D-WAXD diffraction pattern of the ISO-PUs porous film (FIG. 13 (b)) was significantly different from that of the control film, and there were 5 typical elliptical diffraction rings in the pattern, which corresponded completely to 5 crystal diffraction peaks in the 1D-WAXD diffraction curve (FIG. 13 (D)). These phenomena further confirm that a typical crystal structure exists in the porous film, and that the crystal structure has a certain orientation.

5. FT-IR analysis of ISO-PUs porous films

Total reflection FT-IR spectra of ISO-PUs nonporous transparent control film and cellular porous film with pore diameter of 4.0 μm14 And (a). At 1528cm ^-1 The amide II band (-NH group) in the amide bond can be seen at 1590-1870 cm ^-1 The region can observe an absorption peak of the ester-c=o group in the macrodiol and the-c=o group in the amide bond. 3260-3460cm due to the partial overlap of the two groups-C=O ^-1 the-NH group at that point is more suitable for characterizing hydrogen bond formation. 3260-3460cm ^-1 The result of fitting peak-splitting of FT-IR spectrum of the region is shown in FIG. 14 (b), in which free-NH groups in both films appear at 3408cm ^-1 But they form different positions of ordered and disordered hydrogen bond-NH groups. In the spectrum of the control film, the absorption peak forming the disordered hydrogen bond-NH group appears at 3357cm ^-1 At this point, an absorption peak forming an ordered hydrogen bond-NH group appears at 3323cm ^-1 Where it is located. However, the absorption peaks of disordered and ordered hydrogen bond-NH groups formed in the porous film appear at lower wavenumbers than the corresponding-NH groups in the control film, which are shifted to 3350cm, respectively ^-1 And 3315cm ^-1 Where it is located. The peak integration areas corresponding to the different-state-NH groups in the two sample curves obtained by peak-splitting fitting are shown in Table 2, the peak integration areas corresponding to ordered and disordered hydrogen bond-NH groups in the porous membrane are far greater than those of the control film, and the peak areas corresponding to the free-NH groups are far smaller than those of the control film. This shows that the molecular chains in the ISO-PUs porous film are significantly more oriented than those of the control film.

TABLE 2 results of calculation of the fit peak separation and integration of-NH groups in ISO-PUs control films and porous films

In summary, various characterization results of the experimental example show that the shape memory polyurethane material provided by the invention can be combined with a water drop template method to prepare a porous polymer film containing an ordered crystal structure.

Experimental example 2 characterization of mechanical Properties

The samples used in this experimental example were the ISO-PUs porous polymer film prepared in example 2 and the ISO-PUs non-porous control film prepared in comparative example 2.

1. Experimental method

Mechanical Property testing of samples in an Electropuls equipped with an optical extensometer ^TM Tensile mechanical testing was performed on an E1000 test instrument (Instron, USA) at a loading rate of 5.0 mm/min. The sample was a strip of film (approximately 32 μm thick, 10mm wide, 50mm full length, 25mm gauge length). The final result is the average of 5 replicates.

2. Experimental results

The phase structure of the polymer has an important influence on its mechanical properties. Thus, this chapter evaluates the tensile mechanical properties of ISO-PUs cellular porous films having a pore size of 4.0 μm and likewise uses a nonporous transparent ISO-PUs film as a control, the thicknesses of the two films being very close. The obtained stress-strain curve and the mechanical properties calculated from the stress-strain curve are shown in fig. 15 (a) and (b), the porous film obviously has better mechanical properties than the control film, and the tensile strengths of the porous film and the control film are calculated to be 21.5+ -4.1 MPa and 16.3+ -1.8 MPa respectively; young's moduli of 942.9 + -111.7 MPa and 759.9 + -99.7 MPa, respectively; the elongation at break was 31.6.+ -. 3.2% and 11.4.+ -. 2.7%, respectively.

Compared with a control film with the thickness close to that of the same polymer raw material, the porous polymer film prepared by the method has obviously improved mechanical properties. According to the characterization result of the mechanical properties, the porous polymer film of the invention has reached the mechanical property requirements of artificial periosteum (tensile strength of 3-4MPa, elongation at break of 19.6-34.8%, from biomech, 2003, 18:760-764) and anti-adhesion film (Young's modulus of 131.4MPa, tensile strength of 9.5MPa, elongation at break of 630%, materials Science and Engineering:C,2020, 117:111283).

As can be seen from the above examples and experimental examples, the present invention devised a new shape memory polyurethane material, and the shape memory polyurethane material, in combination with the water droplet templating method, is capable of containing a porous polymer film of a crystalline structure. The porous film material has excellent mechanical properties, can meet the performance requirements of application scenes such as artificial periosteum, anti-adhesion film and the like, and has good application prospects.

Experimental example 3 characterization of anti-adhesion Membrane cell compatibility

The samples used in this experimental example were the ISO-PUs porous polymer film prepared in example 2 and the ISO-PUs non-porous control film prepared in comparative example 2. The cell compatibility of the ISO-PUs porous anti-adhesion film and the non-porous control film was evaluated by using mouse embryo fibroblasts (NIH 3T 3) as model cells.

1. Experimental method

Before the cell experiment, the porous film and the nonporous control film are placed in a vacuum oven for evaporating and removing the organic solvent, the temperature of the oven is set to 45 ℃, and the drying time is 72 hours until the weight content of the organic solvent is less than 0.01 percent.

Ultraviolet sterilizing the dried porous anti-adhesion film and non-porous control film, placing into 24-hole cell culture plate, adding NIH 3T3 cell suspension into 24-hole plate, and placing into plate with density of about 1, ⁴ and/or holes. Finally, the 24-well plate is put into a incubator for cell culture, and the culture solution is replaced every two days. After 1 day and 3 days of culture, the samples were taken out, and after washing, fixing, staining, sealing and the like, the cells were observed under an inverted fluorescence microscope and photographed to record the morphology. Samples were taken at 4 time points (1 day, 3 days, 5 days, 7 days) after inoculation, and absorbance values of each group were measured by CCK-8 method to evaluate proliferation activity of cells.

2. Experimental results

FIG. 16 is a morphological observation after 1 day and 3 days of seeding of NIH 3T3 cells with two films. There was no major difference in cell morphology and number on the two films after 1 day of culture. After 3 days, the number of cells on the porous membrane was significantly greater than that on the control membrane. In terms of cell morphology, more cells on the porous membrane extend out of the pseudopodium to form a contact point with the polymer surface, spreading out to form a long fusiform or triangular morphology. FIG. 17 shows absorbance values of NIH 3T3 cells on the surfaces of the porous membrane and the control membrane at different culture times, which represent the proliferation activity, as measured by the CCK-8 method. NIH 3T3 cells proliferated significantly on both groups of material from day 1 to day 7 of inoculation, during which there was a significant difference in cell proliferation activity for both groups of material at different time points, with very significant differences after 1 day, after 5 days, after 7 days (p < 0.01).

The morphological and proliferation experimental results of NIH 3T3 cells show that the surface of the porous film is more favorable for cell adhesion and spreading, thereby promoting cell proliferation. This initially demonstrates that the ISO-PUs porous membrane has good cell compatibility and is suitable for supporting tissue repair after implantation of the anti-adhesion membrane.

Claims

1. An anti-blocking film, characterized in that: it is made up by using porous polymer film as raw material,

the porous polymer film is prepared by taking shape memory polyurethane as a raw material and adopting a water drop template method; the parameters of the water drop template method are selected as follows: drying the substrate at 4-50deg.C and 25-80% humidity, wherein the solvent volatilization rate is 5-50 μL/min;

2. An antiblocking film according to claim 1, characterized in that: the soft segment polymer is expressed as HO-R-OH, and the structural formula of the shape memory polyurethane is shown as formula I:

wherein x is selected from 1 to 10, y is selected from 1 to 10;

repeating units that are said soft segment polymer;

is the repeating unit of diisocyanate, or diisocyanate and +.>

Is a copolymer of a vinyl aromatic monomer and a vinyl aromatic monomer.

3. An antiblocking film according to claim 1 or 2, characterized in that: the molecular weight of the soft segment polymer is 1000-10000.

4. An antiblocking film according to claim 1 or 2, characterized in that: the soft segment polymer is a polymer of lactic acid and a polyol.

5. An antiblocking film according to claim 4, wherein: the molar ratio of the repeating units of lactic acid to the repeating units of the polyol in the soft segment polymer is 10-102:1-20.

6. An antiblocking film according to claim 5, wherein: the structural formula of the soft segment polymer is shown as a formula II:

7. An antiblocking film according to claim 1 or 2, characterized in that: the diisocyanate is selected from aliphatic diisocyanate or aromatic diisocyanate, the aliphatic diisocyanate comprises hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate and dicyclohexylmethane diisocyanate, and the aromatic diisocyanate comprises at least one of toluene diisocyanate or diphenylmethane diisocyanate.

8. An antiblocking film according to claim 7, wherein: the said

The method comprises the following steps:

9. use of a porous polymer film with regular pores for the preparation of an anti-blocking film, characterized in that: the porous polymer film is prepared by taking shape memory polyurethane as a raw material and adopting a water drop template method; the parameters of the water drop template method are selected as follows: drying the substrate at 4-50deg.C and 25-80% humidity, wherein the solvent volatilization rate is 5-50 μL/min;