JP2012063319A - Atomic force microscope observation method of polymeric material at high temperature state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atomic force microscope observation method of a polymeric material at a high temperature state by a simple method since AFM measurement under high temperature environment requires an extremely expert operation technology and know-how, especially, measurement of the polymeric material which is an organic substance is difficult since crystal variation, thermal expansion, phase variation and morphology variation such as softening at the high temperature state are large, there is also the case that stable measurement can not be performed since a low molecular weight component adheres to a probe when the polymeric material is left under the high temperature environment.SOLUTION: In the atomic force microscope observation method of the polymeric material, a polymeric material sample at an equilibrium state under the high temperature environment is rapidly frozen, and the surface shape of the sample is fixed by the atomic force microscope observation method of the polymeric material at the high temperature state. In the atomic force microscope observation method of the polymeric material at the high temperature state, as means for rapid freezing, the sample is immersed in a cryogen which is selected from liquid nitrogen, liquid ethane, and liquid propane.

Description

  The present invention is a method for simply analyzing the surface shape of a polymer material in a high-temperature environment, which has been difficult in the past, using atomic force microscopy.

  A scanning probe microscope (SPM) is a broad-sense microscope that scans the surface of a sample using a probe with a sharp tip and observes the surface state by the interaction between the sample surface and the probe. Among them, a scanning tunneling electron microscope (STM) that detects a tunneling current flowing between a sample surface and a probe is used, and an atomic force microscope (AFM) that uses an atomic force is detected by using a scanning tunneling electron microscope (STM). (Atomic Force Microscope). However, although STM is limited to a sample having conductivity, AFM does not require conductivity in a sample. Therefore, AFM is used in a wide variety of fields such as metals, semiconductors, and organic substances.

  As a feature of the AFM, since the force acting on the cantilever to which the probe is attached is measured, it is possible to simultaneously measure electricity, magnetism, viscoelasticity, hardness, etc. in addition to the shape with high resolution at the atomic level. In addition, AFM can be measured in the atmosphere. Due to recent technological advances, it can be measured in a liquid or in a high-temperature and high-humidity environment.

  In particular, the AFM measurement technique in a high temperature environment, which has been difficult in the past, enables observation of the surface state of various materials at a high temperature, and is expected to be used in research and development in various fields in the future.

  However, AFM measurement in a high-temperature environment is subject to changes in the relative position (thermal drift) of the sample and probe due to thermal expansion and contraction of the detection device such as the probe and cantilever (thermal drift) and the influence of static electricity. Technology and know-how are required. In particular, high molecular weight organic materials are difficult to measure due to large crystal changes and thermal expansion due to high temperature conditions, and morphological changes such as phase change and softening, and low molecular weight components adhere to the probe when left in a high temperature environment. In some cases, stable measurement cannot be performed.

  The AFM measurement under a high-temperature environment that has been proposed so far mainly involves a device on the device as described in Patent Document 1. In other words, thermal drift is suppressed by devising the AFM device, such as improving the heat resistance of the probe, probe scanning / driving system and its circuit system in a high temperature environment, and lowering the thermal expansion coefficient of the detection instrument. Although there is still a skill and know-how required to set the position of the probe.

JP-A-6-123744

  The present invention has been made in consideration of the above technical background, and an object thereof is to provide an atomic force microscope observation method for a polymer material in a high temperature state by a simple method.

  As a means for solving the above-mentioned problem, the invention according to claim 1 is a method of observing a polymer material in an equilibrium state in a high temperature environment in an atomic force microscope observation method of the polymer material, It is an atomic force microscope observation method of a polymer material in a high temperature state characterized by fixing the shape.

  The invention described in claim 2 is characterized in that the sample is immersed in a cryogen selected from liquid nitrogen, liquid ethane, and liquid propane as the means for quick freezing. This is an atomic force microscope observation method for a polymer material.

  The invention according to claim 3 is characterized in that the generation of frost and dew condensation is suppressed by moving the sample immediately under the dry air atmosphere after the quick freezing. It is an atomic force microscope observation method of the polymer material in the described high temperature state.

  As described above, according to the atomic force microscope observation method for a polymer material in a high temperature state of the present invention, the surface state is fixed by rapidly cooling the polymer material in a high temperature state, and AFM measurement can be performed at room temperature in the atmosphere. Therefore, there is an advantage that the surface shape of the polymer material that has been in a high temperature state can be easily observed with the AFM without causing thermal drift in a high temperature environment.

It is an AFM image in a reference example of the present invention. It is an AFM image in the Example of this invention. It is an AFM image in the comparative example of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.
A method for producing a high-temperature polymer material according to the present invention is not particularly limited, but a commercially available heating stage, a hot air circulation oven, or the like is assumed as an apparatus in which the polymer material is in an equilibrium state at a uniform temperature. Since the temperature of the sample surface is particularly a place to be observed by AFM, it is desirable to confirm that the sample surface has reached a predetermined temperature with a radiation thermometer or the like other than the thermometer attached to the heating device.

  In the present invention, rapid freezing refers to quick freezing generally known in the electron microscope technique. A commercially available rapid cooling apparatus may be used as the rapid freezing method, but generally there is a problem that crystal growth occurs in a molten polymer or the like unless the cooling rate is 1000 K / s or more ( (Refer to the Japanese Society for Microscopy, Introductory Guide to Electron Microscope, Society Publishing Center, 2004) Therefore, in the present invention, in order to rapidly freeze at a cooling rate of 1000 K / s or more, the movement of the polymer is selected by selecting a simple and preferable method of directly immersing the sample in liquid nitrogen, liquid ethane, or liquid propane. Was physically stopped.

  Furthermore, if a sample of the polymer material that has been rapidly cooled is taken out and left as it is at room temperature in the atmosphere, frost and condensation may occur on the sample surface, which may affect the surface state. Move to an air atmosphere and let stand until it reaches room temperature. The dry air atmosphere is not particularly limited as long as it is in a dry air stream or in a filled container, and a dry desiccator is simply assumed.

  In general, there is concern about the shape damage caused by crystallization of water existing inside or the occurrence of stress strain as an effect on the material when rapidly cooled, but in the case of polymer materials, Since the amount of is small, there is almost no effect, and the generated stress strain is mitigated by moving it to the dry air atmosphere and allowing it to stand until it reaches room temperature.

  As a similar observation method, there is a method called cryo-SEM (Cryo-Scanning Electron Microscope). This method is an apparatus for observing a water-containing sample such as a biological tissue in a state where the sample is cooled using a cryogen such as liquid nitrogen as in the present invention and frozen on a low-temperature stage attached to the apparatus. The rapid cooling apparatus using the cryogen used in this method can be used because it has the same mechanism as that of the present invention. The major difference between the cryo SEM and the method of the present invention is that the present invention uses an AFM instead of an SEM and a high-molecular material with little moisture rather than a water-containing sample such as a living tissue.

  The difference between SEM and AFM is well-known and has excellent points. From the viewpoint of the superiority of AFM, SEM requires a certain degree of conductivity on the sample surface in a vacuum and can analyze a two-dimensional shape. It can be measured with an insulating material in the atmosphere and can analyze a three-dimensional shape (height, step, roughness, etc.), and the resolution is said to be equal to or higher than that of SEM. Moreover, since the object of the present invention is not a water-containing sample, there is no influence of moisture even when the temperature is returned to room temperature after rapid cooling.

  Next, the present invention will be described below with specific examples, but the present invention is not limited thereto.

  The AFM observation apparatus that performed surface observation in the following examples was measured under the following conditions.

<Measurement conditions>
(AFM device) MFP-3D-SA (manufactured by Asylum Technology)
(Measurement conditions) Scan area: 500 nm × 1 μm ²
Scan speed: 1.0 Hz, measurement method: AC mode

<Reference example>
A commercially available PET film was observed with an AFM in a high temperature environment of 200 ° C. using a temperature control stage (product name: polyheater) attached to the AFM apparatus.

<Example>
The PET film used in the above reference example was placed in a hot air circulation oven in a high temperature environment of 200 ° C., and after confirming that the sample surface temperature was 200 ° C. with a radiation thermometer, it was immersed in liquid nitrogen and about The product was taken out after 10 seconds and then left in a dry desiccator. Thereafter, a sample was taken out from the dry desiccator, and AFM observation was performed at room temperature.

<Comparative example>
After the AFM observation in the reference example, the temperature control stage was set to room temperature and rapidly cooled (set cooling rate: −50 degrees / minute). After about 30 minutes, the measured temperature reached the set temperature (room temperature), and AFM observation was performed.

  Next, Table 1 shows the results of analyzing the AFM observation images (FIGS. 1 to 3) obtained in the reference examples, examples, and comparative examples.

  From the results of Table 1 above, it was confirmed that the analysis result of the surface shape by AFM observation of the example according to the present invention was the same as the reference example observed by AFM in a normal high temperature environment. Moreover, the comparative example which was rapidly cooled to room temperature by the temperature control stage attached to the AFM apparatus gave different results from the reference example and the example. When each AFM image was viewed, the reference example (FIG. 1) and the example (FIG. 2) were almost the same, but in the comparative example, it was found that PET spherulites had grown greatly.

  From the above, it was confirmed that the surface shape was fixed when the high-temperature polymer material was subjected to pretreatment such as rapid freezing according to the method of the present invention, and could be easily observed at room temperature. Moreover, in the rapid cooling by the temperature control stage attached to the apparatus, the growth of spherulites was confirmed because the cooling rate was slow.

  The atomic force microscope observation method of the present invention can be used in the field of application of conventional AFM observation, but the surface shape in a high temperature state of a polymer material used in various industrial fields in particular by simple pretreatment, This is an effective method that allows easy AFM observation below.

Claims (3)

In an atomic force microscope observation method for a polymer material, the polymer material sample in an equilibrium state is rapidly frozen in a high temperature environment, and the surface shape of the sample is fixed between the atoms of the polymer material in a high temperature state. Force microscope observation method. 2. The atomic force microscope observation method for a polymer material in a high temperature state according to claim 1, wherein the sample is immersed in a cryogen selected from liquid nitrogen, liquid ethane, and liquid propane as the means for rapid freezing. 3. The interatomic atoms of the polymer material in a high temperature state according to claim 1, wherein generation of frost or condensation is suppressed by moving the sample immediately under a dry air atmosphere after the rapid freezing. Force microscope observation method.