A method for measuring and analyzing linear rheological behavior of a nanopolymer thin film

Abstract

The present application belongs to the technical field of polymer measurement and analysis, and particularly relates to a method for measuring and analyzing the rheological behavior of a nano-polymer film. The method comprises the following steps: heating a polymer film to a temperature T and keeping the temperature; placing a liquid drop on the surface of the polymer film at the temperature T and keeping the temperature for a time t; cooling the polymer film with the liquid drop and removing the liquid drop; measuring the height h of the convex deformation of the polymer surface under the action of the liquid drop; changing the time t of placing the liquid drop on the surface of the polymer film; measuring the height h of the convex deformation of the polymer film surface formed under different placing times and temperatures; and transforming the equivalent h(t)~t relationship to obtain the change of the storage modulus and the loss modulus of the polymer film with frequency, i.e. the linear viscoelastic spectrum of the polymer film. The present application can accurately determine the frequency dependence of the storage modulus and the loss modulus of the nano-polymer film, and realize the analysis of the linear rheology and the molecular motion behavior of the film.

Description

Technical Field

[0001] This invention belongs to the field of polymer measurement and analysis technology, specifically relating to a method for measuring and analyzing the rheological behavior of nanopolymer thin films. Background Technology

[0002] Polymers, due to their unique flow properties, can be shaped and processed. The entanglement between molecular chains and the unique molecular dynamics in the glassy and rubbery states endow related materials with good mechanical properties and lead to their wide application. However, in the research and development and production of polymer nanodevices, device fabrication is a fundamental yet crucial step. When the size of materials reaches the nanoscale, the force field of the molecules changes, causing the polymer flow to deviate from its bulk, resulting in changes in material properties such as shear modulus and glass transition behavior. This presents significant challenges and difficulties for the fabrication of polymer nanomaterials.

[0003] The tensile, shear, stress yield, fatigue resistance, and viscoelasticity properties of polymer materials are closely related to their linear rheological behavior, which involves the multi-level motion of polymer chains and determines the application range and conditions of the material. For example, polystyrene with high stress yield can be used to manufacture electrical appliances, electronic products, and automotive parts; photoresists based on polymer materials are needed in the field of electronic chips; polymer nanocoatings are required for special military equipment; and thermal insulation materials are indispensable in the aerospace field. Whether it is photoresist, nanocoating, or thermal insulation material, polymers are presented in the form of thin films. However, when the thickness of polymer films is reduced to the micrometer or nanometer scale, the changes in molecular rheological behavior caused by the restriction will inevitably affect the material's performance. Therefore, measuring and developing the rheological behavior of polymer nanofilms is crucial for material performance regulation and the development of new materials.

[0004] However, due to limitations in characterization methods, conventional rheometers can only obtain macroscopic viscoelastic spectra of polymer samples and cannot be applied to the nanoscale microscopic realm. Although molecular tracing, dewetting, and nanobubbling methods have measured the molecular motion behavior of polymer films in recent years, these methods cannot obtain complete linear rheological spectra, thus missing much important information, such as storage and loss moduli and plateau moduli. Therefore, developing a new method for measuring and analyzing the rheological behavior of polymer films is not only highly beneficial for understanding the linear viscoelastic information of films, but also has important guiding significance and great value in the development of related materials and the optimization of material properties. Summary of the Invention

[0005] The purpose of this invention is to provide a method for measuring and analyzing the rheological behavior of nanopolymer thin films. The method provided by this invention can accurately obtain the linear rheological viscoelastic spectrum of polymer films by statistically analyzing the development of the height of the protrusion deformation over time.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for measuring and analyzing the rheological behavior of nanopolymer thin films, comprising the following steps:

[0008] (1) The polymer film is heated to a temperature T and then held at that temperature; the temperature T is greater than the glass transition temperature of the polymer film;

[0009] (2) Place the droplet on the surface of the polymer film that was kept warm in step (1) and keep it at temperature T for a time t; the droplet is incompatible with the polymer;

[0010] (3) After cooling the polymer film containing droplets in step (2), remove the droplets and form a bulge deformation at the polymer-droplet-air triple line on the surface of the polymer film after the droplets are removed; measure the height h of the bulge deformation.

[0011] (4) Under the same temperature T, change the placement time t of the droplet on the polymer film surface, and measure the height h of the wetting ridge formed on the polymer film surface under different placement time conditions; statistically analyze the relationship between h(t) and t.

[0012] (5) Change the heating temperature T of the polymer film and perform steps (1) to (4) to obtain the h(t) ~ t relationship under different temperature conditions; according to the time-temperature equivalence principle, obtain the equivalent bulge deformation height h as a function of time t, which is denoted as the equivalent h(t) ~ t relationship; perform B-strain fitting on the equivalent h(t) ~ t relationship to obtain the equivalent h(t) ~ t master curve;

[0013] (6) Based on the complex modulus of the polymer film G ( oh The functional relationship between h(t) and the equivalent h(t) ~ t principal curve; after performing a one-sided Fourier transform on the equivalent h(t) ~ t principal curve, the energy storage modulus is obtained. G '( oh and loss modulus G ''( oh The linear viscoelastic spectrum of the polymer film was obtained by plotting the functional relationship between the polymer film and 1 / t.

[0014] Preferably, the complex modulus G ( oh The functional relationship between h(t) and the equivalent h(t) ~ t principal curve is shown in Equation 1:

[0015] Formula 1;

[0016] In Equation 1, G (ω) represents the complex modulus. This represents a one-sided Fourier transform, where i represents the imaginary unit in the complex number. , oh =1 / t, k The constant, which is independent of the polymer film sample, is 0.33. c The surface tension of ionic liquids i To balance the contact angle;

[0017] The energy storage modulus G '( oh The functional relationship between 1 / t and t is shown in Equation 2:

[0018] Formula 2;

[0019] The loss modulus G ''( oh The functional relationship between 1 / t and t is shown in Equation 3:

[0020] Formula 3;

[0021] In equations 2 and 3, G '( oh () represents the energy storage modulus. G ''( oh () represents the loss modulus. k The constant, which is independent of the polymer film sample, is 0.33. Represents the Gamma function. , oh =1 / t, α ( oh ) represents log h For log1 / t The first derivative, c The surface tension of ionic liquids i To balance the contact angle.

[0022] Preferably, in step (6), the energy storage modulus is obtained. G '( oh and loss modulus G ''( oh After plotting the data for 1 / t, the method also includes using the BSW model to plot the energy storage modulus. G '( oh and loss modulus G ''( oh The storage modulus was tested by verifying its functional relationship with 1 / t, and the tested values ​​were obtained. G '( oh and loss modulus G ''( oh The linear viscoelastic spectrum of the polymer film was obtained by plotting 1 / t.

[0023] Preferably, the verification formula for the BSW model is shown in Equation 4:

[0024] Equation 4;

[0025] The tested energy storage modulus G '( oh The functional relationship between 1 / t and t is shown in Equation 5:

[0026] Formula 5;

[0027] The tested loss modulus G ( oh The functional relationship between 1 / t and t is shown in Equation 6:

[0028] Formula 6;

[0029] In equations 4, 5, and 6, τ represents time. Represents the relaxation time spectrum. n represents the plateau modulus of polymer rubber. e and n g This indicates that the two fixed parameters are 0.23 and 0.67, τ e and τ rep τ represents the relaxation time of the polymer network and the integral network, respectively. e and τ rep The formulas derived from Equations 2 and 3 G '( oh )and G ''( oh It is determined at the intersection of the high-frequency and low-frequency frequencies. G ' ( oh () represents the energy storage modulus. G ''( oh () represents the loss modulus. Indicates frequency, oh =1 / t.

[0030] Preferably, the temperature T ranges from T0. g +5℃~T g +35℃, the Tg is the glass transition temperature of the polymer.

[0031] Preferably, the polymer film is a linear polymer film; the droplet is an ionic liquid droplet with a diameter of 2-3 mm.

[0032] Preferably, the thickness of the polymer film is 100~500nm.

[0033] Preferably, the time t ranges from 7 to 21600 s.

[0034] Preferably, the linear polymer is polystyrene, and the weight-average molecular weight of the linear polymer is 168~780 kg / mol; the ionic liquid droplets are 1-ethyl-3-methylimidazolium tetrafluoroborate droplets.

[0035] This invention provides a method for measuring and analyzing the rheological behavior of nanopolymer films, comprising the following steps: (1) heating the polymer film to a temperature T and holding it at that temperature; the temperature T > the glass transition temperature of the polymer film; (2) placing a droplet on the surface of the polymer film held at temperature (1) and holding it at temperature T for a time t; the droplet is incompatible with the polymer; (3) cooling the polymer film with the droplet placed in step (2) and removing the droplet, forming a convex deformation at the polymer-droplet-air triple line on the surface of the polymer film after the droplet is removed; measuring the height h of the convex deformation; (4) changing the time t of the droplet on the surface of the polymer film under the same temperature T, measuring the height h of the wetting ridge formed on the surface of the polymer film under different time conditions; statistically analyzing the relationship between h(t) and t; (5) changing the heating temperature T of the polymer film and performing steps (1) to (4) to obtain h(t) and t under different temperature conditions. t relationship; based on the time-temperature equivalence principle, the equivalent bulge deformation height h is obtained as a function of time t, denoted as the equivalent h(t) ~ t relationship; the equivalent h(t) ~ t relationship is fitted with B-samples to obtain the equivalent h(t) ~ t principal curve; (6) based on the complex modulus of the polymer film G ( oh The functional relationship between h(t) and the equivalent h(t) ~ t principal curve; after performing a one-sided Fourier transform on the equivalent h(t) ~ t principal curve, the energy storage modulus is obtained. G '( oh and loss modulus G ''( oh The linear viscoelastic spectrum of the polymer film was obtained by plotting the functional relationship between the polymer film and 1 / t.

[0036] This invention employs the placement of incompatible droplets on the surface of a polymer thin film material. Under the influence of surface tension, molecules gradually accumulate at the triple line of the droplet through stress creep, forming an upward convex deformation. By statistically analyzing the height of the convex deformation over time, the relationship h(t) ~ t is obtained, and the complex modulus of the polymer thin film is then considered. G ( oh The energy storage modulus is obtained by relating the energy storage modulus to the equivalent h(t) ~ t principal curve. G '( oh and loss modulus G ''( oh The present invention, by transforming the relationship between h(t) and 1 / t, obtains the changes in the storage modulus and loss modulus of the polymer film with frequency, i.e., the linear viscoelastic spectrum of the polymer film. This invention can accurately determine the frequency dependence of the storage modulus and loss modulus of nanopolymer films, enabling the analysis of the linear rheological and molecular motion behavior of the films. The method of this invention is simple, low-cost, and widely adaptable. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a droplet placed on the surface of a polymer film in an embodiment of the present invention;

[0038] Figure 2 This is a morphological image of the PS film surface deformation caused by microdroplets in Embodiment 1 of the present invention;

[0039] Figure 3 This is the deformation profile of the outer side of the droplet near the polymer-droplet-air three-phase contact line in Embodiment 1 of the present invention;

[0040] Figure 4 This refers to the change in the surface deformation height of the polymer film over time in Example 1 of the present invention.

[0041] Figure 5 This illustrates the development of the surface deformation height of the polymer film over time in Example 1 of the present invention.

[0042] Figure 6 The linear rheological viscoelastic spectrum of the polymer film was obtained after analyzing the data in Example 1 of this invention, wherein... Figure 6 The black line in the image represents the result of the inspection using the BSW model. Detailed Implementation

[0043] This invention provides a method for measuring and analyzing the rheological behavior of nanopolymer thin films, comprising the following steps:

[0044] (1) The polymer film is heated to a temperature T and then held at that temperature; the temperature T is greater than the glass transition temperature of the polymer film;

[0045] (2) Place the droplet on the surface of the polymer film that was kept warm in step (1) and keep it at temperature T for a time t; the droplet is incompatible with the polymer;

[0046] (3) After cooling the polymer film containing droplets in step (2), remove the droplets and form a bulge deformation at the polymer-droplet-air triple line on the surface of the polymer film after the droplets are removed; measure the height h of the bulge deformation.

[0047] (4) Under the same temperature T, change the placement time t of the droplet on the polymer film surface, and measure the height h of the wetting ridge formed on the polymer film surface under different placement time conditions; statistically analyze the relationship between h(t) and t.

[0048] (5) Change the heating temperature T of the polymer film and perform steps (1) to (4) to obtain the h(t) ~ t relationship under different temperature conditions; according to the time-temperature equivalence principle, obtain the equivalent bulge deformation height h as a function of time t, which is denoted as the equivalent h(t) ~ t relationship; perform B-strain fitting on the equivalent h(t) ~ t relationship to obtain the equivalent h(t) ~ t master curve;

[0049] (6) Based on the complex modulus of the polymer film G ( oh The functional relationship between h(t) and the equivalent h(t) ~ t principal curve; after performing a one-sided Fourier transform on the equivalent h(t) ~ t principal curve, the energy storage modulus is obtained. G '( oh and loss modulus G ''( oh The linear viscoelastic spectrum of the polymer film was obtained by plotting the functional relationship between the polymer film and 1 / t.

[0050] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0051] In this invention, a polymer film is heated to a temperature T and then held at that temperature; the temperature T is greater than the glass transition temperature of the polymer film.

[0052] In this invention, the polymer film is a linear polymer film.

[0053] In this invention, the linear polymer preferably includes one or more of polystyrene and its derivatives, methacrylate polymers, polyvinyl tert-butyl ether, polyacrylonitrile, polymethacrylonitrile, polyvinyl acetate, polyphenylene ether, polyvinyl chloride, polyvinylidene chloride, fluorinated vinyl polymers, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polylactic acid, nylon, polybutadiene, polyisoprene, polysulfone, and polyether.

[0054] As one or more specific embodiments of the present invention, the linear polymer is polystyrene.

[0055] In this invention, the thickness of the polymer film is in the nanometer range.

[0056] In this invention, when the linear polymer is polystyrene, the weight-average molecular weight of the linear polymer is preferably 168~780 kg / mol.

[0057] In this invention, the thickness of the polymer film is preferably 100~500nm, more preferably 400nm.

[0058] In this invention, the method for preparing the polymer film preferably includes the following steps:

[0059] The polymer is dissolved in a solvent to form a polymer solution;

[0060] The polymer solution is coated into a film to obtain a wet polymer film;

[0061] The polymer wet film is dried to obtain the polymer film.

[0062] The present invention does not have any special requirements on the type of solvent, as long as it can dissolve the polymer. The present invention also does not have any special requirements on the amount of solvent used, as long as it can ensure that the polymer solution formed can form a film.

[0063] In this invention, the coating is preferably spin-coated, and there are no special requirements for the specific implementation of the spin-coating method.

[0064] In this invention, the drying is preferably vacuum drying, the drying temperature is preferably 120°C, and the drying holding time is preferably 24 hours. This invention preferably removes the solvent from the wet film through drying to obtain the polymer film.

[0065] In this invention, the heating is preferably performed on a precision constant temperature heating stage.

[0066] Preferably, after heating the polymer film to the specified temperature T, the holding time is preferably 5 minutes. This invention preferably uses heat preservation to ensure that the polymer film is sufficiently heated, so that the polymer molecules in the polymer film are in an equilibrium state at temperature T.

[0067] In this invention, the range of the temperature T is preferably T. g +5℃~T g +35℃, the T g is the glass transition temperature of the polymer.

[0068] In one or more embodiments of the present invention, the temperature T is preferably T0. g +5℃, T g +10℃, T g +15℃, T g +25℃ or T g +35℃.

[0069] After heat preservation, the present invention places the droplet on the surface of the heat-preserving polymer film and maintains the temperature T for a time t; the droplet is incompatible with the polymer.

[0070] In this invention, the droplet is preferably an ionic liquid droplet.

[0071] As one or more embodiments of the present invention, the ionic liquid droplet is a 1-ethyl-3-methylimidazolium tetrafluoroborate ([EIm]BF4) droplet.

[0072] In this invention, the diameter of the droplet is 2-3 mm.

[0073] The present invention preferably uses a pipette to draw up the liquid and place the droplet on the surface of the polymer film at a temperature T obtained by heat preservation.

[0074] In this invention, the preferred range of time t is 7~21600s.

[0075] In this invention, the time t is preferably 7s, 15s, 30s, 60s, 120s, 300s, 600s, 1200s, 2400s, 5400s, 10800s, or 21600s.

[0076] The present invention involves cooling a polymer film containing droplets and then removing the droplets, thereby forming a convex deformation at the polymer-droplet-air triple line on the surface of the polymer film with the droplets removed; the height h of the convex deformation is measured.

[0077] In this invention, the cooling is preferably quenching. Specifically, the quenching is preferably performed by rapidly transferring the polymer film containing the liquid droplets onto a steel plate at 20°C for cooling.

[0078] After cooling, the present invention preferably uses secondary deionized water to wash away the droplets on the surface of the polymer film.

[0079] The present invention preferably uses an atomic force microscope (AFM) to measure the surface deformation caused by the droplet, and the AFM model is preferably Multimode-8.

[0080] In this invention, a deformation profile exists outside the droplet placement position near the polymer-droplet-air three-phase contact line on the surface of the polymer film for removing droplets. The distance between the highest point of deformation and the horizontal line of the film surface is called the deformation height, which is the height h of the convex deformation.

[0081] The present invention preferably uses an atomic force microscope (AFM) to measure the height h of the bulge deformation, and the AFM model is preferably Multimode-8.

[0082] Under the same temperature T, the placement time t of the droplet on the polymer film surface is changed, and the height h of the wetting ridge formed on the polymer film surface under different placement time conditions is measured; the relationship between h(t) and t is statistically analyzed.

[0083] In this invention, the time t is preferably 7s, 15s, 30s, 60s, 120s, 300s, 600s, 1200s, 2400s, 5400s, 10800s, or 21600s.

[0084] This invention uses different placement times t as independent variables and the convex deformation height h as dependent variable to obtain the functional relationship between the convex deformation height h and time t, which is statistically represented as h(t) ~ t relationship.

[0085] In this invention, after obtaining the functional relationship between the bulge deformation height h and time t under temperature T, denoted as h(t) ~ t relationship, the present invention changes the heating temperature T of the polymer film, and obtains the h(t) ~ t relationship under different temperature conditions according to the above-mentioned method for obtaining the h(t) ~ t relationship under the same temperature but different time t conditions; based on the time-temperature equivalence principle superposition, the equivalent functional relationship between the bulge deformation height h and time t is obtained, denoted as the equivalent h(t) ~ t relationship; the equivalent h(t) ~ t relationship is fitted with a B-spline to obtain the equivalent h(t) ~ t master curve.

[0086] In this invention, the temperature T is preferably T0. g +5℃, T g +10℃, T g +15℃, T g +25℃ or T g +35℃.

[0087] In this invention, the same mechanical relaxation phenomenon can be observed at a higher temperature for a shorter time, or at a lower temperature for a longer time. Therefore, increasing the temperature and extending the observation time have the same effect on molecular motion. The equivalent effect of high temperature and extended observation time on molecular motion is achieved by using a conversion factor. With the help of the conversion factor, mechanical data measured at a certain temperature can be transformed into mechanical data at another temperature but in a different time range.

[0088] After obtaining the equivalent h(t) ~ t principal curve, this invention is based on the complex modulus of the polymer film. G ( oh The functional relationship between h(t) and the equivalent h(t) ~ t principal curve; after performing a one-sided Fourier transform on the equivalent h(t) ~ t principal curve, the energy storage modulus is obtained. G '( oh and loss modulus G ''( oh The linear viscoelastic spectrum of the polymer film was obtained by plotting the functional relationship between the polymer film and 1 / t.

[0089] In this invention, the complex modulus G ( oh The functional relationship between h(t) and the equivalent h(t) ~ t principal curve is shown in Equation 1:

[0090] Formula 1;

[0091] In Equation 1, G (ω) represents the complex modulus. This represents a one-sided Fourier transform, where i represents the imaginary unit in the complex number. , oh =1 / t, k The constant, which is independent of the polymer film sample, is 0.33. c The surface tension of ionic liquids i To balance the contact angle.

[0092] In this invention, the energy storage modulus G '( oh The functional relationship between 1 / t and t is shown in Equation 2:

[0093] Formula 2;

[0094] In this invention, the loss modulus G ''( oh The functional relationship between 1 / t and t is shown in Equation 3:

[0095] Formula 3;

[0096] In equations 2 and 3, G '( oh () represents the energy storage modulus. G ''( oh () represents the loss modulus. k This represents a constant independent of the polymer film sample, approximately 0.33. Represents the Gamma function. , oh =1 / t, α ( oh ) represents log h For log1 / t The first derivative, c The surface tension of ionic liquids i To balance the contact angle.

[0097] In this invention, the energy storage modulus is obtained. G '( oh and loss modulus G ''( oh After determining the functional relationship with 1 / t, the present invention preferably further includes using the BSW model to determine the energy storage modulus. G '( oh and loss modulus G ''( oh The storage modulus was tested by verifying its functional relationship with 1 / t, and the tested values ​​were obtained. G '( oh and loss modulus G ''( oh The linear viscoelastic spectrum of the polymer film was obtained by plotting the relationship between the polymer film and 1 / t.

[0098] In this invention, the verification formula for the BSW model is shown in Equation 4:

[0099] Equation 4;

[0100] In this invention, the verified energy storage modulus G '( oh The functional relationship between 1 / t and t is shown in Equation 5:

[0101] Formula 5;

[0102] In this invention, the tested loss modulus G ( oh The functional relationship between 1 / t and t is shown in Equation 6:

[0103] Formula 6;

[0104] In equations 4, 5, and 6, τ represents time. Represents the relaxation time spectrum. n represents the plateau modulus of polymer rubber. e and n g This indicates that the two fixed parameters are 0.23 and 0.67, τ e and τ rep τ represents the relaxation time of the polymer network and the integral network, respectively. e and τ rep The formulas derived from Equations 2 and 3 G '( oh )and G ''( oh It is determined at the intersection of the high-frequency and low-frequency frequencies. G '( oh () represents the energy storage modulus. G ''( oh () represents the loss modulus. , oh =1 / t.

[0105] This invention provides a method for measuring and analyzing the rheological behavior of polymer thin films. The method involves placing incompatible droplets on the surface of a polymer thin film material. Under the influence of surface tension, molecules gradually accumulate at the triple line of the droplet through stress creep, forming an upward-protruding deformation. By statistically analyzing the development of the height of this deformation over time, the rheological behavior information of the polymer thin film material is obtained.

[0106] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0107] Example 1

[0108] (1) Polystyrene (PS) with a weight average molecular weight of 168 kg / mol was selected as the sample to be tested. After dissolving the polystyrene, a polystyrene film with a thickness of 400 nm was prepared by spin coating and then vacuum dried at 120 °C for 24 h to remove the solvent.

[0109] (2) Place the polystyrene film obtained in step (1) on a precision constant temperature hot plate with the temperature pre-set to 115℃ for full preheating. Use a pipette to take 3 μL of 1-ethyl-3-methylimidazolium tetrafluoroborate ([EIm]BF4) and drop it onto the sample surface, such as... Figure 1 As shown;

[0110] (3) After being kept at a constant temperature for t (150 s), the sample was quickly transferred to a steel plate at 20 ℃ for quenching, and the surface [EIm]BF4 droplets were washed away with deionized water. The surface deformation caused by the droplets was measured using a Multimode-8 atomic force microscope (AFM). Figure 2 The image shows the morphology of the surface deformation of the polystyrene film sample after 150 seconds. Figure 3 The deformation profile of the droplet outside the three-phase contact line is called the deformation height h (the height of the bulge deformation h).

[0111] (4) By changing the placement time t (7s, 15s, 30s, 60s, 120s, 300s, 600s, 1200s, 2400s, 5400s, 10800s or 21600s respectively), the development process of the surface deformation height induced by the ionic liquid over time was monitored using AFM (see Figure 4 );

[0112] (5) Change the experimental temperature T (105℃, 110℃, 115℃, 125℃, 135℃), statistically analyze the relationship between h and t at different experimental temperatures, and obtain a master curve through time-temperature equivalent superposition, which is the functional relationship between the convex deformation height h and time t: wet ridge height h(t); see [link to relevant documentation]. Figure 5 In this context, 168 k, 280 k, and 780 k represent polystyrene with different molecular weights, specifically polystyrene with a molecular weight of 168 kg / mol, 280 kg / mol, and 780 kg / mol, respectively. Figure 5 T in ref =105℃, which means the reference temperature for the experiment is 105℃. Figure 5 The master curves for polystyrene of each molecular weight were obtained by plotting curves at five experimental temperatures: 105℃, 110℃, 115℃, 125℃, and 135℃, and then superimposing the time-temperature equivalent curves with 105℃ as the reference temperature.

[0113] (6) Due to the surface tension of the ionic liquid, protrusions are formed and grow, thus creating conditions for a creep experiment, wherein the complex modulus G The functional relationship between (ω) and h(t) and the functional relationship between the wet ridge height h(t) are shown in Equation 1: where c The surface tension of ionic liquids i To balance the contact angle.

[0114] Formula 1;

[0115] In Equation 1, G (ω) represents the complex modulus. This represents a one-sided Fourier transform, where i represents the imaginary unit in the complex number. , oh =1 / t, k The constant, which is independent of the polymer film sample, is 0.33. c The surface tension of ionic liquids i To balance the contact angle;

[0116] The energy storage modulus G '( oh The functional relationship between 1 / t and t is shown in Equation 2:

[0117] Formula 2;

[0118] The loss modulus G ''( oh The functional relationship between 1 / t and t is shown in Equation 3:

[0119] Formula 3;

[0120] In equations 2 and 3, G '( oh () represents the energy storage modulus. G ''( oh () represents the loss modulus. k This represents a constant independent of the polymer film sample, approximately 0.33. Represents the Gamma function. , oh =1 / t, α ( oh ) represents log h For log1 / t The first derivative, c The surface tension of ionic liquids i To balance the contact angle;

[0121] To ensure the accuracy of the experimental data, the BSW model needs to be used for further verification. The verification formula for the BSW model is shown in Equation 4.

[0122] Equation 4;

[0123] The tested energy storage modulus G '( oh The functional relationship between 1 / t and t is shown in Equation 5:

[0124] Formula 5;

[0125] The tested loss modulus G ( ohThe functional relationship between 1 / t and t is shown in Equation 6:

[0126] Formula 6;

[0127] In equations 4, 5, and 6, τ represents time. Represents the relaxation time spectrum. n represents the plateau modulus of polymer rubber. e and n g This indicates that the two fixed parameters are 0.23 and 0.67, τ e and τ rep τ represents the relaxation time of the polymer network and the integral network, respectively. e and τ rep The formulas derived from Equations 2 and 3 G '( oh )and G ''( oh It is determined at the intersection of the high-frequency and low-frequency frequencies. G '( oh () represents the energy storage modulus. G ( oh () represents the loss modulus. , oh =1 / t;

[0128] Storage modulus after verification as shown in Equation 5 G '( oh The functional relationship with 1 / t and the loss modulus after verification as shown in Equation 6 G ( oh Plotting the relationship between the polymer film and 1 / t yields the linear viscoelastic spectrum of the polymer film, as shown below. Figure 6 As shown, Figure 6 The black line represents the result of the inspection using the BSW model. Figure 6 T in ref =105℃ means that the reference temperature for the experiment is 105℃.

[0129] Example 2

[0130] The method is basically the same as in Example 1, except that PS with a weight-average molecular weight of 280 kg / mol was selected as the sample to be tested, a film with a thickness of 400 nm was prepared, the experimental reference temperature was 105 °C, and the linear viscoelastic spectrum of the polymer film was obtained.

[0131] Example 3

[0132] The method is basically the same as in Example 1, except that PS with a weight-average molecular weight of 780 kg / mol was selected as the sample to be tested, a film with a thickness of 400 nm was prepared, the experimental reference temperature was 105 °C, and the linear viscoelastic spectrum of the polymer film was obtained.

[0133] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for measuring and analyzing the rheological behavior of nanopolymer thin films, characterized in that, Includes the following steps: (1) The polymer film is heated to a temperature T and then held at that temperature; the temperature T is greater than the glass transition temperature of the polymer film; (2) Place the droplet on the surface of the polymer film that was kept warm in step (1) and keep it at temperature T for a time t; the droplet is incompatible with the polymer; (3) After cooling the polymer film containing droplets in step (2), remove the droplets and form a bulge deformation at the polymer-droplet-air triple line on the surface of the polymer film after the droplets are removed; measure the height h of the bulge deformation. (4) Under the same temperature T, change the placement time t of the droplet on the polymer film surface, and measure the height h of the wetting ridge formed on the polymer film surface under different placement time conditions; statistically analyze the relationship between h(t) and t. (5) Change the heating temperature T of the polymer film and perform steps (1) to (4) to obtain the h(t) ~ t relationship under different temperature conditions; according to the time-temperature equivalence principle, obtain the equivalent bulge deformation height h as a function of time t, which is denoted as the equivalent h(t) ~ t relationship; perform B-strain fitting on the equivalent h(t) ~ t relationship to obtain the equivalent h(t) ~ t master curve; (6) Based on the complex modulus of the polymer film G ( ω The functional relationship between h(t) and the equivalent h(t) ~ t principal curve; the equivalent h(t) ~ t principal curve is expanded after undergoing a one-sided Fourier transform to obtain the storage modulus. G '( ω and loss modulus G ''( ω Plotting the complex modulus against 1 / t yields the linear viscoelastic spectrum of the polymer film; G ( ω The functional relationship between h(t) and the equivalent h(t) ~ t principal curve is shown in Equation 1: Formula 1; In Equation 1, G (ω) represents the complex modulus. This represents a one-sided Fourier transform, where i represents the imaginary unit in the complex number. , ω =1 / t, k The constant, which is independent of the polymer film sample, is 0.

33. γ The surface tension of ionic liquids θ To balance the contact angle; The energy storage modulus G '( ω The functional relationship between 1 / t and t is shown in Equation 2: Formula 2; The loss modulus G ''( ω The functional relationship between 1 / t and t is shown in Equation 3: Formula 3; In equations 2 and 3, G '( ω () represents the energy storage modulus. G ''( ω () represents the loss modulus. k The constant, which is independent of the polymer film sample, is 0.

33. Represents the Gamma function. , ω =1 / t, α ( ω ) represents log h For log1 / t The first derivative, γ The surface tension of ionic liquids θ To balance the contact angle.

2. The measurement and analysis method according to claim 1, characterized in that, In step (6), the energy storage modulus is obtained. G '( ω and loss modulus G ''( ω After plotting the data for 1 / t, the method also includes using the BSW model to plot the energy storage modulus. G '( ω and loss modulus G ''( ω The storage modulus was tested by verifying its functional relationship with 1 / t, and the tested values ​​were obtained. G '( ω and loss modulus G ''( ω The linear viscoelastic spectrum of the polymer film was obtained by plotting 1 / t.

3. The measurement and analysis method according to claim 2, characterized in that, The verification formula for the BSW model is shown in Equation 4: Equation 4; The tested energy storage modulus G '( ω The functional relationship between 1 / t and t is shown in Equation 5: Formula 5; The tested loss modulus G ( ω The functional relationship between 1 / t and t is shown in Equation 6: Formula 6; In equations 4, 5, and 6, τ represents time. Represents the relaxation time spectrum. n represents the plateau modulus of polymer rubber. e and n g This indicates that the two fixed parameters are 0.23 and 0.67, τ e and τ rep τ represents the relaxation time of the polymer network and the integral network, respectively. e and τ rep The formulas derived from Equations 2 and 3 G '( ω )and G ''( ω It is determined at the intersection of the high-frequency and low-frequency frequencies. G ' ( ω () represents the energy storage modulus. G ''( ω () represents the loss modulus. Indicates frequency, ω =1 / t.

4. The measurement and analysis method according to claim 1, characterized in that, The temperature T range is T g +5℃~T g +35℃, the T g is the glass transition temperature of the polymer.

5. The measurement and analysis method according to claim 1, characterized in that, The polymer film is a linear polymer film; the droplet is an ionic liquid droplet with a diameter of 2-3 mm.

6. The measurement and analysis method according to claim 1 or 5, characterized in that, The thickness of the polymer film is 100~500nm.

7. The measurement and analysis method according to claim 1, characterized in that, The time t ranges from 7 to 21600 s.

8. The measurement and analysis method according to claim 5, characterized in that, The linear polymer is polystyrene, and the weight-average molecular weight of the linear polymer is 168~780 kg / mol; the ionic liquid droplets are 1-ethyl-3-methylimidazolium tetrafluoroborate droplets.

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