JP2000214086A - Method for observing gelation process or gel state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a non-ergodic sample in real time by detecting as two-dimensional scattering intensity data a scattering light obtained by irradiating a sample, extracting and analyzing the two-dimensional scattering intensity data with a constant scattering angle. SOLUTION: A two-dimensional light-scattering and measuring apparatus is used to observe a gelation process or gel state of a non-ergodic sample 8 of a polymer gel or the like. The laser light from a laser device 1 is turned to only a vertical polarization component and irradiated to the sample 8. A scattering light from which the polarization component is selected forms an image on photodetectors 18 arranged in two dimensions of a CCD camera 15 or the like through a lens 12 and the like. Two-dimensional scattering intensity data with a constant scattering angle is extracted by an azimuth angle of a predetermined range, and an ensemble average scattering luminous intensity is found. A change with time of the luminous intensity is tracked. A gelation point is specified from a time when a point of inflexion is formed. Also, a method is used whereby a scattering intensity frequency distribution is obtained by a predetermined method, a change with time of the distribution is tracked and a time point when a shape of the distribution changes large or the like is specified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for measuring a gelling process or a gel state of a non-ergodic sample by irradiating the sample with light and measuring two-dimensional scattering intensity data.

[0002]

2. Description of the Related Art Conventionally, many studies have been made on the structural analysis of polymer gels by the scattering method. One of the reasons for making this analysis difficult is that gels are difficult to analyze. Structural non-uniformity. That is, since the structure of the polymer gel has inhomogeneity due to cross-linking between molecules, the ergodic hypothesis that "the phase space average and the temporal average of physical quantities are equivalent" in statistical mechanics does not hold, At one observation point, the universal physical properties of the gel cannot be understood. Such a system is called a non-ergodic system, and includes a polymer gel and glass in its category.

[0003] In order to analyze the structure of such a non-ergodic sample and observe the gelation process and the state of the gel, in addition to the scattering behavior due to thermal fluctuation corresponding to a solution having the same concentration as that of the sample, the inter-molecular It is necessary to consider the effect of freezing thermal fluctuations due to cross-linking, and it is very important to separate the observed quantities such as scattering intensity into thermal fluctuations (dynamic fluctuations) and static fluctuations due to structural non-uniformity. Is important.

In order to specify the structure of a non-ergodic sample, it is necessary to (1) extract universal physical properties unaffected by structural heterogeneity, that is, to extract a non-crosslinked polymer solution of the same concentration. It is also important to evaluate the fluctuation and (2) to quantify the structural non-uniformity and make it possible to calculate by calculation. The fluctuation separation method of a polymer gel according to the conventional method has been performed by dynamic light scattering measurement using ensemble averaging. In other words, the light scattering is measured over a period of several minutes at a specific scattering angle over several minutes, and the measurement is repeated at different measurement positions until sufficient statistical accuracy is obtained, so that the structural analysis of the non-ergodic sample can be performed. It was done.

However, in the above-mentioned conventional method, it is impossible to separate the fluctuation components by only one measurement. In order to collect measurement data having sufficient statistical accuracy, it is necessary to rotate the sample, It is necessary to repeat the measurement while changing the measurement position. For this reason, it takes several hours to measure one sample, and it measures in real time how the ergodic system changes from ergot system to non-ergote system, such as gelation, that is, performs time-series measurement It was difficult.

Accordingly, an object of the present invention is to solve the above problems and to provide an observation method capable of measuring the gelation process or gel state of a non-ergodic sample in real time.

[0007]

Means for Solving the Problems To solve the above problems, the method of observing the gelation process or gel state of the present invention comprises:
The scattered light obtained by irradiating the non-ergodic sample with light is
Detected as two-dimensional scattering intensity data through the imaging means,
Two-dimensional scattering intensity data at a fixed scattering angle is extracted and analyzed from the detected data (claim 1).

According to the gelation process or the method of observing a gel state of the present invention, the scattering intensity data can be extracted at one time as two-dimensional data at a fixed scattering angle through the imaging means. The gelation process or gel state of the non-ergodic sample at the time of collecting the data can be observed as universal physical properties that are not affected by the structural heterogeneity of the sample.

The observation method of the present invention has significantly improved the time efficiency of data collection as compared with the conventional method, and as a result, it is possible to perform time-series measurement of fluctuation, that is, “in-situ measurement”. . Therefore, by collecting and analyzing the above-mentioned scattering intensity data according to the change over time of the sample, it becomes possible to measure over time the process of developing the structural non-uniformity of the non-ergodic sample, and consequently the non-uniformity To elucidate the expression mechanism.

[0010] The gelation process or gel state of the present invention described above.
Observation methods were obtained by irradiating non-ergodic samples with light.
Scattered light is converted into two-dimensional scattered intensity data through the imaging means.
Scattered from this detected data
After extracting the two-dimensional scattering intensity data at the corner,
Dimensional scattering intensity data is extracted at a predetermined range of azimuth angle and
Samble mean scattering intensity <I>_EAsk for this ensemble
Average scattering intensity <I> _ETo track changes over time.
It is more preferable to have

The ensemble average scattering intensity <I>
_E increases rapidly with the progress of gelation. Therefore,
By specifying the time at which the point of inflection occurs in the ensemble average scattering intensity <I> _E over time, the point in time when gelation occurs (gelation point) can be specified easily and with high accuracy. Further, the method of observing the gelation process or gel state of the present invention detects scattered light obtained by irradiating the non-ergodic sample with light as two-dimensional scattered intensity data through the imaging means. After extracting two-dimensional scattering intensity data at a fixed scattering angle from the data, the two-dimensional scattering intensity data is extracted at a predetermined range of azimuth angles to obtain a scattering intensity frequency distribution P <I> _E. It is more preferable to track a temporal change of the frequency distribution P <I> _E (claim 3).

The frequency distribution P <I> _E of the scattering intensity changes to a wide distribution with the progress of gelation (that is, the intensity distribution becomes broad), and the peak of the distribution shifts to the higher intensity side. I do. Therefore, by specifying the distribution shape of the scattering intensity frequency distribution P <I> _E and the time at which the scattering intensity changes rapidly, the gel point can be easily and accurately specified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. [Two-Dimensional Light Scattering Measurement Apparatus] FIG. 1 is an explanatory diagram showing an outline of an optical system of the two-dimensional light scattering measurement apparatus. In the present invention, the scattered light obtained by irradiating the sample with light is detected as two-dimensional scattering intensity data by using the two-dimensional light scattering measuring device shown in FIG.

In such a two-dimensional light scattering measuring apparatus, a laser beam emitted downward from a laser device 1 is reflected by a mirror 2 and the intensity is adjusted by an ND filter 3.
Next, the light is reflected again by the mirror 4, is converted into circularly polarized light by the ４λ plate 5, and is extracted by the irradiation-side polarizing plate 6. Then, the sample 8 set in the sample holder 7 is irradiated. Is done.

Of the light applied to the sample 8, the sample 8
The light transmitted straight without being scattered in the inside is guided to the transmitted light monitor 10 by the beam trap 9. On the other hand, the light scattered by the sample 8 passes through an ND filter 13 as an intensity adjusting mechanism of the amount of scattered light after passing through a lens 12 as an imaging means after selecting a polarization component by a light receiving side polarizing plate 11. Further, an image is formed in a two-dimensionally arranged light receiving element 18, such as a CCD camera 15 having a shutter mechanism 14.

In this way, two-dimensional scattering intensity data distributed in a circle in the light receiving element is obtained at a time, and by analyzing this data, the gelation process or gel state of the sample 8 can be observed. The intensity of light incident on the sample 8 can be appropriately adjusted by detecting the intensity of light guided to the incident light amount monitor 17 via the half mirror 16.

[Two-Dimensional Scattering Intensity Data] FIG. 2 is a conceptual diagram showing scattering intensity data obtained by irradiating a sample 8 with a laser beam 20. In the observation method of the present invention, FIG.
As shown in (a), the scattering intensity data 21 at the same scattering angle θ exists concentrically around the point where the scattering angle θ is 0 °. That is, data at the same scattering angle exists in an annular shape, and scattered light data of various intensities exist depending on the difference in the azimuth angle φ. By obtaining the scattering intensity data at the same scattering angle θ by computer analysis, the ring extraction data 22 shown in FIG. 2B is obtained.

The two-dimensional scattered intensity data 21 is usually obtained at one time within a range of the scattering angle θ of about ± 20 ° according to the viewing angle characteristics of the light receiving element of the two-dimensional light scattering measuring device, the performance of the lens 12, and the like. Can be captured. In addition, in the ring extraction data 22 shown in FIG. 2B, the missing portion 23 on the left side of the figure is a shadow by the beam trap 9. When producing the ring extraction data 22, it is preferable to collect the data by setting the range of the azimuth angle φ as wide as possible except for a region where data cannot be obtained due to the shadow of the beam trap 9.

Further, in the observation method of the present invention, the time required for measuring the two-dimensional scattering intensity data is several seconds per data collection, and at most tens of seconds. Therefore, by collecting data at appropriate intervals,
It is possible to track a structural change and a state change in the gelation process of the sample over time. [First Method for Specifying Gelation Point] Among the observation methods of the present invention, the first method for specifying the gelation point of a non-ergodic sample is, as described above, two-dimensional scattering at a fixed scattering angle. which obtains an ensemble average scattering intensity <I> _E extracts the intensity data in the azimuth angle of a predetermined range, the time course of the ensemble average scattering intensity <I> _E to track, identify the time the inflection point occurs It is.

FIG. 3 shows data of a fixed scattering angle θ extracted from two-dimensional scattering intensity data of a non-ergodic sample at a certain point in time. ”. The first
In order to specify the gel point by the method described above, first, the background scattering intensity is subtracted from the scattering intensity data extracted at a constant scattering angle θ as shown in FIG. In the case of FIG. 3, φ = 0 ° to 360 °, where
The ensemble average scattering intensity <I> _E is obtained by taking the average of the scattering intensity data at (excluding the defective portion near 180 ° to 200 °). Then, the ensemble average scattering intensity <I> _E is measured sequentially over time, and the change is
"Time-ensemble average scattering intensity <I
> _E ”. The point at which the inflection point is seen in this graph is the gel point.

The data shown in FIG. 4 has a predetermined density (690 m
M) with N-isopropylacrylamide (NIPA) and a crosslinking agent N, N'-methylenebisacrylamide (BI
This is a graph showing the change with time of the average ensemble scattering intensity <I> _E (scattering angle θ = 15.6 °) when a hydrogel was formed by redox polymerization with the addition of S). In the redox polymerization, after adding BIS to NIPA, ammonium persulfate (APS) as an initiator is added, dissolved in distilled water, degassed and cooled, and N, N, N ′, N′-tetramethylethylenediamine (TEMED) was added and stirred. Further, this was injected into a dedicated cell maintained at 20 ° C. to start polymerization.

As is apparent from this figure, in the above hydrogel, the ensemble average scattering intensity <I> _E rapidly changes around 30 minutes in elapsed time, and an inflection point appears on the graph. Since this inflection point corresponds to the generation of the hydrogel, such a point can be specified as the gel point. [Second Method for Specifying Gelation Point] Among the observation methods of the present invention, the second method for specifying the gelation point of a non-ergodic sample is, as described above, two-dimensional scattering at a fixed scattering angle. The intensity data is extracted at a predetermined range of azimuth angles to obtain a scattering intensity frequency distribution P <I> _E , and this scattering intensity frequency distribution P <I
> The time-dependent change of _E is tracked, and the scattering intensity frequency distribution P <I>
_It specifies the time at which the distribution shape and scattering intensity of _E suddenly change.

After subtracting the background scattering intensity from the ring-extracted data shown in FIG. 3, the data is rearranged in the order of the scattering intensity, whereby the frequency distribution of the scattering intensity data at the same scattering angle θ (FIG. 5 (a)). See). The frequency distribution P (<I> _T ) of the scattering intensity is represented by the following equation (1).

[0024]

(Equation 1)

(Where <I> _T indicates the time average of the scattering intensity, <I _F > _T indicates the time average of the dynamic fluctuation component of the scattering intensity, and <I> _E indicates the average ensemble scattering intensity. In addition, H (x) represents a step function of Heaviside, and H (x) = 0 when x <0 and H (x) when x ≧ 0.
(x) = 1. ) By transforming the above equation (1), the following equation (2)
Is obtained.

[0026]

(Equation 2)

(Wherein <I> _T , < _IF > _T , <I> _E
And H (x) are the same as above. FIG. 5 (b)
3 is a graph in which the vertical axis of the frequency distribution of the scattering intensity shown in FIG. The slope of the data on the higher intensity side than the peak value in this graph is obtained by the least square method, and the equation (3) in the equation (2) is as follows:

[0028]

(Equation 3)

Corresponds to the portion represented by In order to specify the gel point by the above second method, first, the scattering intensity shown in FIG. 5A is used by using the scattering intensity data extracted at a constant scattering angle θ shown in FIG. Create a data frequency distribution chart. Next, the scattering intensity frequency distribution is sequentially measured over time, and the change is shown in FIG.
It can be represented in the graph. In this graph, the point at which the distribution shape significantly changes broadly or the point at which the peak value is large and moves to the high strength side is the gel point.

The data shown in FIG. 6 has a predetermined density (690 m
M) with N-isopropylacrylamide (NIPA) and a crosslinking agent N, N'-methylenebisacrylamide (BI
S) is added and the scattering intensity frequency distribution (scattering angle θ = 15.6 °) when a hydrogel is formed by redox polymerization
5 shows the change with time. The means of redox polymerization is the same as described above.

As is clear from this figure, in the above hydrogel, the distribution rapidly becomes broad and the peak value shifts significantly to the high intensity side between the elapsed time of 29 minutes and 30 minutes. Since this change corresponds to the formation of a hydrogel, such a point can be specified as a gel point. The ensemble average scattering intensity <I> _E in the above equations (1) to (3) is obtained by the ensemble average of all the scattering intensity data.

<I _F > _T , which indicates the time average of the dynamic fluctuation component of the scattering intensity, is a value obtained by subtracting the ensemble average scattering intensity <I> _E from the reciprocal of the slope represented by the equation (3). Desired. Therefore, by calculating the two-dimensional scattering intensity data in the present invention by the above equation, separation and analysis of the scattering intensity data into a dynamic fluctuation component and a static fluctuation component, and the structural non-uniformity in the non-ergodic sample The quantification can be easily performed, and the gelation process or gel state can be observed with extremely high accuracy as compared with the conventional method of integrating the measured values at a single observation point.

Further, since < _IF > _T / <I> _E indicates the ratio of the dynamic scattering component to the average scattering intensity, it can be used as an index of hardness in a non-ergodic sample such as a gel. . When the measurement sample is a gel, the closer this value is to 1, the softer the gel is, the closer to the solution,
It can be said that the closer the gel is, the harder the gel is. [Modification] In the two-dimensional light scattering measuring apparatus (see FIG. 1) used in the present invention, an image may be formed using a spherical mirror instead of the lens 12.

[0034]

As described above in detail, according to the method of observing the gelling process or the gel state of the present invention, the gelation is performed in an extremely short time and with high accuracy as compared with the conventional method using the scattering method. Process or gel state can be observed. Therefore, the method of the present invention is suitable for structural analysis of gels and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of an optical system in a two-dimensional light scattering measurement device used in the present invention.

FIG. 2 (a) is a conceptual diagram showing a scattering angle θ and an azimuth angle φ, and FIG. 2 (b) is a schematic diagram showing ring extraction data obtained by extracting scattering intensity data at the same scattering angle. It is.

FIG. 3 is a graph showing two-dimensional scattering intensity data extracted at a constant scattering angle.

FIG. 4 is a graph showing the change over time in the average ensemble scattering intensity.

5A is a graph showing a frequency distribution of the data shown in FIG. 3, and FIG. 5B is a graph in which the vertical axis of FIG.

FIG. 6 is a graph showing a temporal change of a scattering intensity frequency distribution.

[Explanation of symbols]

 8 Sample θ Scattering angle φ Azimuth angle

Claims (3)

[Claims] 1. A scattered light obtained by irradiating a non-ergodic sample with light is detected as two-dimensional scattered intensity data through an imaging means, and two-dimensional scattered light at a fixed scattering angle is detected from the detected data. A method for observing a gelation process or a gel state, wherein intensity data is extracted and analyzed. 2. A two-dimensional scattering intensity data at a constant scattering angle.
Ensemble average scattering
Strength <I>_EAnd obtain the average ensemble scattering intensity <
I> _ENon-ergo by tracking the aging of the
2. The gelation according to claim 1, wherein the gelation point of the volatile sample is specified.
How to observe the process or gel state. 3. A two-dimensional scattering intensity data at a certain scattering angle is extracted at a predetermined range of azimuth angles, and a scattering intensity frequency distribution P <
Seeking I> _E, by tracking the time course of the scattering intensity frequency distribution P <I> _E, to identify the gelation point of the non-ergodicity sample, observation of the gelling process or gel state according to claim 1, wherein Method.