I Have a Research Support System

The five-day National Day holiday passed by in a flash.

During this period, the overall framework of Xu Qiu's article has been completed.

In the text part, there are only two more important characterizations, the transmission electron microscope TEM, and the magic light source test GIWAXS.

As for other characterization tests, such as NMR spectroscopy of polymer donor materials, elemental analysis, they can only be included in the supporting information.

In addition, he received an email that the Macromolecules that was reworked before the holiday had been successfully accepted.

The impact factor of this journal is around 5. Because Xu Qiu and Chen Wanqing are the co-authors, they shared the prize for publishing the article equally, 500 yuan each.

To get the bonus, you have to invite the research team to dinner.

The whole group of five people, plus the juniors who came to have a meal, go out to eat. According to the standard of 70-100 per capita, there is not much left.

If each person added the first cup of milk tea invited by someone else in autumn, the bonus they just earned would be basically gone.

The prices in Shanghai are still quite expensive. According to the standard of 70 per capita near the university town, you can almost eat half meat and half vegetarian dishes, plus the staple food to barely eat enough.

If you go to eat hot pot and barbecue, 100 per capita may not be enough.

As for the bonus that was just obtained and then spent after changing hands, the two of them didn't care too much.

After all, we all have a bright future, don't we?

After graduation, the bonus I get now may be just the daily salary in the future.

...

After a few days.

Xu Qiu, we will test the TEM tomorrow, and we need to prepare a sample.

I remember when I tested the atomic force microscope AFM before, I just took the battery device to test it, Xu Qiu said:

Does the TEM sample need special preparation?

AFM tests the surface of the film, TEM is transmission, and electrons must pass through the film for testing, so there cannot be a glass substrate.

I see, it's just a separate film to test, right?

That's right, and the thickness of this film should not be too thick. It needs to be at the micronano level, otherwise the electron beam cannot penetrate. Chen Wanqing said:

However, our effective layer is only 100 nanometers, so we don't have to worry about the thickness of the film.

How to prepare samples for TEM?

Xu Qiu didn't rush to check the system images, or ask his senior sister for help, but started to analyze independently:

When doing synthesis in Zhangjiang before, the polymer material was dissolved in chloroform or toluene, and then dropped into the methanol solvent, but the polymer film could be formed.

However, the thickness should be on the order of millimeters, which is obviously not advisable.

There is a high probability that the method of spin coating is still used to obtain nanometer-scale films.

It’s just that spin coating must use the substrate, so the question is converted to “how to separate the film from the substrate”.

heating?

Poked with tweezers?

Soak it in water?

Ultrasound?

Xu Qiu racked his brains and thought for a long time, but he still couldn't think of any way to separate without damage.

Don't reinvent the wheel, let's see what other people's wheels look like.

Start the system image.

This method is good, it can still be like this.

However, for such an ingenious method, the senior sister probably didn't come up with it by herself.

Saying 80% should be overestimating her.

Be more precise, ninety-nine percent?

What are you thinking? Chen Wanqing waved her hand in front of his eyes and said:

Come with me to get a place to use. The test TEM needs to use a copper grid, which is used to place the sample film.

...

When finished, return to the laboratory.

A box of copper mesh is 250 yuan, 50 pieces, and an average of 5 yuan.

Xu Qiu picked up a copper net with tweezers to check.

The circular copper mesh, about 4mm in diameter, is very small and thin, and will bend with a little force.

Chen Wanqing began to introduce the operation, which was basically the same as that in the system image.

Spin-coat a thick layer of PEDOT on a clean glass slide, and then spin-coat an active layer.

PEDOT is applied thicker than usual for device fabrication.

The glass piece is then soaked in water.

PEDOT is water-soluble and will dissolve when soaked in water.

The upper effective layer is insoluble in water, and when the middle layer PEDOT is dissolved in water, the effective layer film will be separated from the underlying substrate.

Because the density of the film is less than that of water, it floats on the water.

Most of the membrane will curl up, and a small part of the membrane can be stretched out and float on the water.

Finally, the stretched film was collected with a dedicated copper grid for TEM to obtain a single-layer film sample.

Senior sister, is this the method you came up with yourself?

Of course... no, this is what I learned from the TEM test teacher.

As expected.

...

Han Jiaying didn't come today, Xu Qiu didn't have his younger brother to help, so he could only do it himself.

Spin-coat PEDOT at low speed first, and then spin-coat the effective layer normally.

Chen Wanqing took out several disposable PE cups, cut the cups halfway, leaving a shallow bottom, and then added half the volume of deionized water to each cup.

Because TEM tests the morphology of the donor/acceptor blend film, there is no need to test the samples of individual polymer films, so the number of samples is not many, only eight samples.

In order to prevent accidents, one more backup should be made for each type, so a total of sixteen samples should be prepared.

For equipment like TEM, the test fee is still relatively expensive, some are calculated according to the length of the test, and some are calculated according to the number of samples.

The unit in the Department of Chemistry is calculated according to the duration of the sample test.

The price of the internal test in the school is relatively low. If the test is carried out in a special test center outside the school, the test fee may cost several thousand yuan for three or four samples.

Therefore, the general tutor will only allow students to test TEM when they are sure that they can produce results, or other necessary tests.

Unless it is the kind of research group with a lot of research funds that can't be spent, then it's another matter.

...

Xu Qiu placed the glass substrates face up, carefully put them into the PE cup, and then marked the outside of the PE cup with a marker pen.

After the substrate entered the water, it changed quickly.

The corners of the film were the first to meet the water and rolled upwards.

After a minute, most of the film had detached from the substrate and floated on the water.

But the largest piece of membrane, curled up together.

Xu Qiu used pointed tweezers to stir up the curled film.

If the film can be flattened, then naturally everyone will be happy.

It doesn't matter if you can't pick a level.

Because film fragments are produced during the agitation process, they can also be collected if they are flat.

The area of ​​the entire film is more than 5 square centimeters, and Xu Qiu only needs to take one percent of it.

In theory, of course.

In actual operation, various accidents will inevitably occur.

For example, no matter how you pick the film, it is uneven. The copper mesh that made the sample was not clamped and fell off. After collecting the sample, it was found that it was not a layer of film.

Intermittently, it took Xu Qiu and Chen Wanqing a total of three or four hours to complete all the samples.

Finally, the pair collected the copper mesh with the samples into disposable centrifuge tubes.

Keep the lid of the centrifuge tube open and leave it overnight to allow the moisture on the copper grid to evaporate completely before it can be used for testing.

Thanks for the reward of 500 starting coins for Oolong Latte, and the reward of 100 starting coins for Haifeng Liuyu and Sean Zhe.