I Have a Research Support System

After the group meeting, Chen Wanqing said happily:

With a budget of 15,000, we can buy a lot of monomers and raw materials.

Where do we usually buy medicine? Xu Qiu asked.

Generally used reagents can be inquired from the major reagent suppliers first, such as Bailingwei, Anaiji, Aladin, Sinopharm, etc. Chen Wanqing said:

After confirming, you can place an order on the school drug warehouse website and entrust them to purchase on your behalf.

When selecting reagents, the first thing to look at is the purity. The higher the purity, the better. Generally, chemical purity is enough for synthesis, and analytical purity or above is usually used for devices.

Then look at the packaging, if it is a liquid solvent, choose 100ml, 500ml, 1 liter of packaging according to your needs.

Then see if there are any other special needs, such as whether to bring molecular sieves. Molecular sieves are mainly used to dry and remove water.

For example, if we use it in a glove box, we don’t need molecular sieves, because the water content in the use environment is extremely low, adding molecular sieves will bring impurities instead.

However, if it is used outside and there is a requirement for the water content of the reagent, it is better to choose the one with molecular sieve.

Finally, look at the price, generally you can buy it directly if it is less than 1,000 yuan, and if it exceeds 1,000 yuan...

Just lower the requirements and find a more cost-effective one? Xu Qiu said.

It's about the same. If you really need it and there is no cheap alternative, you can also ask Teacher Wei for instructions and then buy it. Chen Wanqing said:

In addition, it should also be noted that some medicines are futures rather than spot goods, and may not arrive until one or two months after the auction, which generally need to be transported from abroad.

But it's not troublesome, because we bought it directly from their domestic branch, so we don't need to declare customs by ourselves.

If you find foreign companies to buy medicines yourself, such as the PCBM materials we buy, when you pass the customs, you have to declare them in the name of carbon.

Then do we also buy our monomer materials from these reagent suppliers? I always feel that these materials are a bit niche. Xu Qiu said.

Generally, solvents are bought from the reagent dealer, Chen Wanqing said:

For example, most organic photovoltaic monomer materials cannot be purchased from reagent manufacturers, so we need to find a company that specializes in photovoltaic materials.

For example, the P3HT and PTB7-TH polymers we buy are all purchased from a photoelectric material company in Beijing. If we buy monomers, we usually go to another company in Shencheng.

I usually use QQ to contact, and they will also send me a quotation from time to time, introducing their latest products and quotations.

I feel that the only use of my QQ now is to contact them.

After finishing speaking, she pulled Xu Qiu to sit down, opened the PDF of Shencheng Optoelectronics Company's quotation on the computer, and said:

I bought the monomers from them before. Their monomers are not only of high purity, but also relatively cheap, but there are few types.

However, I have read that they have all the monomers involved in our synthesis scheme this time, so don't worry about being out of stock.

Let's determine what we want to buy first, and then send them the demand, and then we should be able to negotiate the price.

Okay. Xu Qiu nodded and began to study the quotation.

In the previous literature reading, he learned that if he wanted to link D units and A units together to synthesize D-A copolymers, he used condensation polymerization.

To put it simply, the condensation reaction is that each of the two hands of the D unit holds a key, and each of the two hands of the A unit holds a lock, there is no difference between the keys, and there is no difference between the locks.

Mix a lot of unit D with two keys and unit A with two locks in an equimolar ratio of 1:1.

Under the appropriate reaction conditions, the key can be inserted into the keyhole to open the lock, and then the key will fall off together with the lock, and the D unit and the A unit form a hand-in-hand state.

Corresponding to the synthesis reaction is:

Key-D-Key+Lock-A-Lock → Key-D-A-Lock.

The key and lock at the end can also be combined with other locks and keys to make the D-A chain longer and longer.

Finally, the structure of the obtained polymer is:

Key-D-A-D-...-A-D-A-Lock.

In the early stage of the reaction, there are many D units with keys and A units with locks, which can easily form a hand in hand state.

But in the later stage, the consumption of the key and the lock is almost the same, and after the D unit and the A unit also form a long chain, the key and the lock are difficult to touch, and the reaction almost stops.

This condensation reaction has very strict requirements on the ratio of the two monomer materials. If it is not in an equal ratio of 1:1, even if it is 1:0.9, the final molecular weight will drop significantly.

Because the number of keys is more than that of locks, the condensation reaction will be in the later stage, and there will be a lot of things like:

The structure of key-D-A-D-key, key-D-A-D-A-D-key, ... causes the reaction to stop.

As for the specific synthesis method, there are two kinds.

One is Suzuki coupling reaction and the other is Stille coupling reaction.

The key and lock of the former are boronate/boronic acid groups and bromine groups, respectively.

The latter are trimethyltin/tributyltin and bromo groups, respectively.

...

Sister, which type of condensation reaction do we usually use, Suzuki or Stille? Xu Qiu asked.

Comparatively speaking, the Stille coupling reaction is better, and the monomers are relatively complete, Chen Wanqing said, changing the subject:

However, there is a problem, that is, the monomer unit containing trimethyltin/tributyltin is highly toxic. After being absorbed by the human body, it will cause heavy metal poisoning, and in severe cases, it will cause a lot of hair loss.

Then we... Xu Qiu tentatively asked.

Let's use the Stille reaction. The dose we make is small. As long as we take protective measures and don't swallow, inhale or directly contact the skin, the danger is not great. Chen Wanqing said:

Actually, I'm not willing to do chemical synthesis, not only the tin reagent, but also other solvents such as chloroform, methylene chloride, chlorobenzene, etc. are toxic and have potential carcinogenic risks.

However, it’s okay for us to mainly do materials, but it’s miserable for us to do chemistry, basically dealing with various toxic reagents every day.

It's been rumored in circles that men don't use furan and women don't use pyridine? Xu Qiu said.

Yes, these two are common reproductive toxic solvents, and they are aimed at men and women respectively. Chen Wanqing said:

There was a postdoctoral fellow in my original group. Before planning to have a child, he took a year off from school for fear of affecting future generations.

...

Although the synthesis is dangerous, the experiment must continue.

Sister, I've already decided which monomers to buy, Xu Qiu said:

It's just that many of them start selling at 500 mg or 1 gram. Can you discuss with them about selling at 200 mg?

200 mg, isn't it gone after one reaction? Chen Wanqing saw Xu Qiu's serious expression and said:

Okay, let me try it for you, what monomers do you want?

This, this, and this. Xu Qiu pointed to the quotation and said.

Just these two?

No, buy 1 gram of each of these two, and 200 mg of each of the other monomers on this page.

Thanks for the 700 point reward of Oolong Latte.