JP3314648B2 - Surface functional group estimation method using atomic force microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a functional group on a surface of a polymer material such as a polymer and a coating film, and more particularly, to a method for detecting a change in polarity of a solvent component by observing an object to be measured in a liquid with an atomic force microscope. The present invention relates to a method for estimating a surface functional group by measuring and comparing the measurement result with a relation map obtained in advance.

[0002]

2. Description of the Related Art In general, the amount of water retained in a material often has various effects on the characteristics of the material itself. Especially polymers,
Moisture exists in various materials such as coating films as attached water and compounded water, and these often result in material deterioration.
For example, in the case of a coating film, it is water that physically enters the interface between the base coat and the inner coat. In the case of a polymer member, water containing falling matter due to rainfall or the like invades from the surface and causes material deterioration. In particular, in developing a coating film resistant to acid rain, etc.
Degradation analysis of coatings is important.

[0003] Since the change of the coating film due to water is on the order of nm, it is optimal to use an atomic force microscope (AFM). Conventionally, when estimating the properties, the properties of the surface part are indirectly estimated by the AFM measurement mode such as the electric / magnetic measurement mode, the viscoelasticity measurement mode, and the frictional force measurement mode. Not enough to use. For micro / nano-level shape observation of organic material surface, the use of AFM that can support non-conductive materials in the air is necessary for micro sites (nm square area).
Undulation observation on the order of nm (up to 0.01 nm) is possible and most effective. However, it is difficult to grasp the properties of the observed part only by AFM shape observation.
In the magnetic measurement mode, an electric field and a magnetic field distribution are possible, but they are not generally applicable to organic materials. In the viscoelasticity measurement mode, the viscoelasticity distribution and the like are available, but information that goes into the molecular structure cannot be obtained. Further, in the frictional force measurement mode, a frictional force distribution or the like is possible, but information for analyzing a molecular structure cannot be obtained. At present, the properties of the site are indirectly estimated using these AFM measurement modes.

FIG. 9 shows a conventional AFM, and FIG. 10 shows a surface shape observation state in the liquid. FIG. 9 shows a case in which measurement is performed in the atmosphere, and the tip of the tip of the probe 30 is made of a high-insulating material.
The scanning is performed with the interatomic force generated with the gap between them being constant. At this time, changes in characteristics including electromagnetic force, viscoelasticity, frictional force, and the like are captured. At this time,
The spot diameter can be up to about 0.1 μm, and the resolution can be up to about tens of nm. For this reason, in the measured object whose surface is controlled, observation on the order of atoms and molecules is possible. In particular, it is superior to the SEM in the resolution in the depth direction of the measured object.

[0005] FIG. 10 (c) shows a submerged observation using the AFM underwater observation unit 1, in which a probe 12 scans in a solvent fixing space 8 sealed with a rubber ring 10. As shown in FIGS. 10A and 10B, in this method, the solvent is suctioned from the solvent tank 3 to the syringe 33 via the injection needle 34 and the solvent is injected by the syringe 33, so that the surface state of the sample and the image are disturbed. And it is impossible to compare before and after solvent injection. For this reason, solvent injection by the syringe 33 is not suitable for obtaining highly accurate information such as molecular information. As described above, in the conventional measurement mode alone, information in the molecular structure of the organic material cannot be obtained from the AFM image, and thus cannot be linked to molecular design for the development of the organic material. Therefore, development of a technique for estimating surface functional groups while utilizing the above-mentioned atomic force microscope has been desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to examine a method of utilizing an atomic force microscope for analyzing the molecular structure of an organic material, and to continuously change the polarity of a solvent to obtain an image on the surface of an object to be measured. It is an object of the present invention to provide a method for estimating a surface functional group by measuring a surface change at a site similar to the polarity. Another object of the present invention is to use an atomic force microscope to analyze the molecular structure of the organic material, as described above. It is an object of the present invention to provide a method for estimating a surface functional group by measuring a surface change at a portion approximate to the polarity and comparing the measurement result with a result obtained by identifying an adsorbed substance by liquid chromatography.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for estimating a surface functional group from a change in a specific surface portion of an object to be measured by observation in liquid with an atomic force microscope. Mixing and supplying while continuously changing the ratio, a step of observing a surface change of the object to be measured in a liquid comprising the solvent with an atomic force microscope, and a step of observing the observation result in advance with a specific solvent and a specific solvent. Estimating a functional group on the surface of the measured object by comparing the relationship with the surface change of the measured object.

Another object of the present invention is to provide a method for estimating a surface functional group from a change in a specific surface portion of an object to be measured by observation in liquid with an atomic force microscope. The step of observing the surface change of the object to be measured in a liquid comprising the solvent with an atomic force microscope, and comparing the solvent used for observation in the liquid with the solvent in which the original adsorbed substance is mixed. Atomic force microscope characterized by comprising a step of specifying the substance adsorbed on the object by the method, and a step of estimating a functional group on the surface of the object from the relationship between the observation result and the specified adsorbed substance. This is also achieved by a surface functional group estimation method using

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, since the composition of the solvent changes continuously, the polarity of the solvent also changes continuously. As a result, the specific molecules gather and protrude at a portion near the solvent polarity on the surface of the measured object. The surface functional group can be estimated by comparing this with the relationship between the specific solvent and the surface change of the object to be measured, which has been obtained in advance. According to this method, it is possible to observe a change in a specific portion of the measured object on the spot. In addition, in the present invention, since a nearly polar adsorbing substance is adsorbed to a specific portion of the object to be measured, the situation is observed with an atomic force microscope as a protrusion of the adsorbing portion. on the other hand,
By identifying and specifying the adsorbed substance by an appropriate means such as a liquid chromatograph or the like, it becomes possible to estimate a functional group at a specific portion of the measured object.

In the observation with the atomic force microscope used in the present invention, for example, an ED in an SEM (scanning electron microscope) is used.
As a function like X (elemental analyzer), ie, S
When an electron beam is point-irradiated to a site to be analyzed on an EM image, a function is provided for identifying elements constituting the site. In the past, such a function was impossible, but the present invention has made it possible to obtain useful information on the molecular structure, even if elemental information by analysis cannot be expected. In the conventional in-liquid observation, it is possible to observe the surface shape in a specific solution, but each time, the solvent concentration is adjusted, the solvent is manually sucked by a syringe, and the observation is performed after press-fitting. At that time, the surface state of the sample and the fixed state of the probe and the like are disturbed, and the observation image is interrupted. In some cases, it may not be possible to track changes in a specific part, and observation may not be possible.

In addition, since the solvent concentration is adjusted each time using a device such as a beaker, time and labor are required. In the present invention, by connecting the solvent mixing / sending pump, the sending speed of the solvent can be set very low. Therefore, it is possible to observe a change in each part on the spot without disturbing the surface state of the sample or the fixed state of the probe or the like, that is, without interrupting the image. Of course, the concentration can also be automatically and continuously changed. Therefore, the solvent polarity can be continuously changed, and the bulge of a portion close to the solvent polarity can be accurately observed, and the polarity of the portion can be estimated.

[0012]

EXAMPLES Hereinafter, based on the examples, the electric force, magnetic force,
A method of obtaining information (= functional group information) on intermolecular force by capturing properties (polarity) other than viscoelasticity and frictional force will be described in detail. Example 1 This example relates to the atmospheric solvent polarity changing method of the first invention. FIG. 1 shows an outline of the apparatus of the present embodiment. In this method, first, the solvent mixing / sending pump 2 is connected to the AFM underwater observation unit 1. This pump has a tank 3 for holding several kinds of different solvents, and the mixing ratio can be continuously (statically) changed by the automatic mixing unit 5 and controlled by the control system 4a through a program. The solvent is slowly supplied through the liquid supply pipe 7 so that the rubber ring 10
The liquid is supplied to the solvent fixing space 8 of the sample holder sealed with. This drainage is drained by drainage pipe 13.

At this time, the state where the solvent polarity continuously changes with the continuous change of the solvent composition is determined by the control system 4b and the screen 9
Observe or record with an observation device consisting of From this result, the bulge of a part near the solvent polarity is grasped, and the polarity of the part is specified. In order to estimate the presence of the functional group, FIG.
As shown in (c), the functional group 19 changes depending on the polarity of the solvent, FIG. 3 (a) shows the case where the solvent is highly polar, and FIG. 3 (b) shows the case where the compatibility with the solvent is most polar. It is presumed that a large number of functional groups matching the polarity of the solvent were present at the observation site when the observation site was most prominent. FIG. 3C shows the case of a low-polarity solvent. The functional group 19 in FIG. 3 shows a dense state to the last. For example, in the case of a hydro-oil solvent, a bulge as a change in polarity due to the aggregation of the stitch-like functional groups of the sample is observed.

As the mixed solvent, for example, water, alcohol, and hydrocarbon are used in view of the polarity of the mixed solvent shown in FIG. 11, and at this time, only the molar ratio between the alkyl (CH portion) and OH is changed. This is to avoid changing chemical properties by mixing various kinds of functional groups and to continuously change only polarity. FIG. 8 shows the limit data of the polarity (relative permittivity) and the surface roughness due to the protrusions. In this figure, the surface roughness of water projections of the solvent is set to 1, and the relative values are shown by changing the solvent. The solvent polarity compatible with the functional group may be estimated from a chemical handbook or the like (FIG. 12), or may be actually measured using a model substance containing the functional group. For example, if the ester bond is COO, RCOOR (R is an alkyl group) is used. In this case, RCOOR is dissolved in a mixed solvent of alcohol and water. At this time, the water / alcohol mixture ratio at the time of the best dissolution may be specified as a solvent characteristic having the best compatibility with COO from the approximate linear relationship.

Example 2 This example relates to the reagent adsorption method of the second invention.
An outline of the apparatus is shown in FIG. Also in the present embodiment, the solvent mixing / sending pump 15 is connected to the AFM underwater observation unit 1. From the solution tank 14 through the liquid feed pump 15 and the liquid feed pipe 7, the liquid feed pipe 7 is bifurcated in the middle for the sample holder and the liquid chromatograph device, and the solvent is supplied to the AFM underwater observation unit 1 and the liquid chromatograph device. Supply 3 At this time, a plurality of reagents having a specific functional group, such as a surfactant, are put into the solution tank 14 and slowly sent into the sample holder. The reason for this is to make it easier to see the raised state when the polar compatibility is good due to the adsorption of the reagent. At this time, a reagent that is polar to a specific site on the sample is interfacially adsorbed, and the situation is directly related to the elevation of the adsorbed site as A
Observed by FM.

[0016] As shown in FIGS. 4 and 5, for example in four of the sodium salt of long-chain fatty acids, unlike polarity and molecular length to C ₁ and C _10, made from the long molecules of the hydrophobic groups 21 and hydrophilic groups 20 Indicates a particular polarity. This solvent is adsorbed as a molecule to a site having a close polarity and is aggregated and raised. This state is shown as a schematic diagram in FIGS. FIG. 5 (a) shows the molecular state of the solution mixing / sending pump. In FIG. 5 (b), the solution is adsorbed to a near-polar functional group site. As a result, as shown in FIG. You can observe the set. On the other hand, the analysis result of the liquid chromatograph is shown in FIG. In this chart, reference numeral 24 denotes a solvent that passed through the sample holder, and reference numeral 25 denotes a solvent that did not pass through the sample holder.
In the solvent passed through the sample holder, only the molecular states C ₁ and C ₆ existing in the chart as shown in FIG.
Than not to have been through the sample holder, as a molecular state that exists as in FIG. 6 (c), further C ₂ and C ₁₀ also appear on the chart. As described above, the functional group present can be accurately estimated from the molecular information adsorbed by the difference in polarity between the sample and the solvent. That is, the distribution of the functional groups is grasped as the distribution of the adsorption reagent (height distribution based on the molecular length).

[0017]

According to the present invention, the composition of the solvent is continuously changed, a specific solvent having a similar polarity to the functional group present on the surface is detected, and accurate estimation can be made by comparing the detected solvent with a predetermined relationship. Further, in the present invention, by connecting the liquid feed pump, the liquid feed rate of the solvent can be set very low, and observation can be performed with the surface state of the sample and the fixed state of the probe or the like being fixed. Further, in the case of the solution mixing and feeding pump, the concentration can be automatically changed, so that the solution preparation time can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus configuration of an atmospheric solvent polarity change method according to the present invention.

FIG. 2 is a diagram showing an apparatus configuration of a reagent adsorption method according to the present invention.

FIG. 3 is a schematic diagram showing an aggregation state of existing functional groups according to the present invention according to the polarity, showing (a) a highly polar solvent, (b) a most compatible solvent, and (c) a low polar solvent.

FIG. 4 is a schematic diagram showing a surfactant as a reagent to be supplied to a solvent according to the present invention, showing (a) a long-chain molecule, and (b) a polarity difference.

FIG. 5 is a schematic diagram showing an aggregation state according to the polarity of an existing functional group in the reagent adsorption method of the present invention, showing (a) a solution mixed solvent, (b) an observation state in water, and (c) an observation image.

FIG. 6 shows a chromatogram of the reagent adsorption method of the present invention,
It is a schematic diagram showing (a) a chromatographic chart, (b) a solvent passing through a sample holder, and (c) a solvent not passing through a sample holder.

FIG. 7 is a schematic diagram of an atomic force microscope.

FIG. 8 is a diagram showing the relationship between the surface roughness and polarity due to the solvent according to the present invention.

FIG. 9 is a schematic diagram showing a site where an atomic force is generated between a probe of an atomic force microscope and a sample.

FIG. 10 (a) of observation in liquid by a conventional atomic force microscope.
It is a figure which shows a solvent beaker, (b) suction by a syringe, and (c) underwater observation unit.

FIG. 11 is a table showing the polarity of the mixed solvent according to the present invention.

FIG. 12 is a chart showing polar and affinity functional groups according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... AFM underwater observation unit 2 ... Solvent mixing liquid sending pump 3 ... Solvent tank 4a, 4b ... Control system 5 ... Automatic mixing part 6 ... Liquid sending part 7 ... Liquid sending pipe 8 ... Solvent fixed pump 9 ... Screen 10 ... Rubber ring DESCRIPTION OF SYMBOLS 11 ... Sample 12 ... Probe 13 ... Drain pipe 14 ... Solution tank 15 ... Liquid sending pump 16 ... Liquid chromatograph apparatus 17 ... Column 18 ... Detection part 19 ... Functional group 20 ... Hydrophilic group 21 ... Hydrophobic group 22 ... Ester 23 ... hydrocarbons 26 ... laser oscillator 27 ... reflector 28 ... detector 29 ... cantilever 30 ... probe 31 ... sample 32 ... xyz fine movement element 33 ... syringe 34 ... injection needle

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 13/10-13/24 G01N 33/00-33/98 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A method for estimating a surface functional group of an object to be measured by observation in a liquid using an atomic force microscope, wherein a step of mixing and supplying the solvent while continuously changing a mixing ratio of a plurality of solvents having different polarities. Step of observing the surface change of the object to be measured in a liquid composed of the solvent with an atomic force microscope, by comparing the relationship between the specific solvent and the surface change of the object to be measured, the observation result of which is determined in advance. A method for estimating a surface functional group using an atomic force microscope, comprising a step of estimating a functional group on a surface of an object to be measured. 2. A method for estimating a surface functional group of an object to be measured by observation in a liquid using an atomic force microscope, wherein a step of supplying a solvent in which a plurality of known adsorbing substances are mixed is performed. In the step of observing the surface change of the measured object with an atomic force microscope, it was adsorbed on the measured object by comparing the solvent used for observation in the liquid with the solvent in a state where the original adsorbed substance was mixed A method for estimating a surface functional group using an atomic force microscope, comprising: a step of specifying a substance; and a step of estimating a functional group on a surface of an object to be measured from a relationship between the observation result and the specified adsorbed substance.