Technology: The naughty kid ruined my college entrance examination, but I turned over to nuclear fusion

Chapter 465

Lu Yu’s words are very clear.

After listening, the brows of the scholars all frowned slightly.

“If you say so…” ”

Is it really impossible to use polyvinyl alcohol as a flexible material?”

Su Xiaoxiao frowned and said slowly:

“Although it has certain problems in earthquake resistance and impact resistance.”

“But we can also strengthen its earthquake resistance and impact resistance through some special methods.”

“At least… In my previous idea, this is already the most suitable material for our exoskeleton devices.

She expressed her point of view slowly.

The problem of insufficient seismic and impact resistance of polyvinyl alcohol was discovered by Su Xiaoxiao as early as the initial stage of conception.

However, after some deliberation, she still chose polyvinyl alcohol as a flexible material for exoskeleton equipment, which is not for nothing.

The problem does exist.

But in her design, there should be a way to solve these problems, right?

“I know what you mean.”

“But I roughly thought about it, conventional solutions, should not solve the problem of polyvinyl alcohol.” Its problem is in the material itself.

Lu Yu bowed his head slightly, came to the center of the entire conference room, and explained to everyone in detail:

“I think everyone should know.” Polyvinyl alcohol (PVA) is a water-soluble polymer with good flexibility and transparency, but first of all, the glass transition temperature of polyvinyl alcohol is low, about 75~85 °C1, easy to soften and change color at high temperature, lose mechanical strength.

“Our exoskeleton equipment needs to adapt to various terrains and temperatures.”

“In an ordinary climate, it may not be so easy to reach the temperature at which it vitrified.”

“But…. Once you get to the terrain of the extreme hot climate of the desert, coupled with the heat of the exoskeleton equipment itself, the temperature exceeds 85°, which is too easy! ”

In case there is a problem with vitrification.”

“The flexible material of the entire exoskeleton device collapsed at once! This is equivalent to your bones directly blowing!

“You think, how scary is that?”

Lu Yu took a deep breath and continued to describe the experimental results he had just obtained: “But that’s it. ”

Polyvinyl alcohol contains many alcohol groups in its molecular chain that form hydrogen bonds with water, resulting in its high water solubility. When polyvinyl alcohol encounters water or moisture, it absorbs moisture, causing its structure to relax and expand, greatly reducing its impact resistance. ”

It’s another terrain factor.”

“Equivalent to once we use polyvinyl alcohol as a flexible material for exoskeleton devices in extreme climates, such as… In the hot and humid terrain, the failure rate will instantly increase countless times!

“In addition, the molecular weight and alcohololysis of polyvinyl alcohol also greatly affect its impact resistance.” In general, the larger the molecular weight, the lower the alcohololysis, and the higher the impact resistance of polyvinyl alcohol. However, too large molecular weight or too low alcohololysis will also affect the flexibility and processability of polyvinyl alcohol! ”

….,”

Lu Yu slowly told everyone about the drawbacks.

The faces of everyone instantly became extremely complicated.

In this way, the risk of using polyvinyl alcohol as the subject of flexible materials is indeed too great!

“But…”

Su Xiaoxiao hesitated for a moment and continued, ”

These problems are not impossible to solve, right?”

“For example, we can increase the dielectric constant and energy storage density of polyvinyl alcohol by adding small molecule ferroelectric materials. Using the spontaneous polarization ability of small molecule ferroelectric materials, and crystallizing in situ with polyvinyl alcohol materials to form a film to form a hydrogen bond dinode-charge accumulation model, the polarization response and electric field coupling effect of composite films can be directly enhanced! ”

As long as a transparent flexible polymer film with high dielectric constant (up to 1000) and high energy storage density (up to 20 J/cm3) can be prepared, it has good mechanical properties and processing properties.”

“The problem of impact resistance can be easily solved!”

Su Xiaoxiao directly said the thoughts in his mind.

“Half right, half wrong.”

Lu Yu shook his head and said with a smile: “What you said is indeed correct, by adding small molecule ferroelectric materials, it is indeed possible to improve the dielectric constant and energy storage density of polyvinyl alcohol to a certain extent.”

“However, the limitations of this method are not small at all!”

The addition of small molecule ferroelectric materials may affect the transparency and flexibility of polyvinyl alcohol, because small molecule ferroelectric materials usually have a higher refractive index and a lower modulus of elasticity! Moreover, the stability and compatibility of small molecule ferroelectric materials need to be further studied and optimized. ”

Even if stability and compatibility are confirmed, it can only solve the problem at the molecular end.”

“The first and second problems I mentioned still can’t be solved.”

“What about using freeze-drying and salting out to prepare hydrogels with high strength, toughness and fatigue resistance?”

Su Xiaoxiao frowned and asked again.

“We used freeze-drying to form a porous structure in polyvinyl alcohol hydrogels, which increased the specific surface area and porosity of the hydrogel, and improved the water absorption and elastic recovery ability of the hydrogel!”

“At the same time, the salting out method is used to introduce ion crosslinking points in polyvinyl alcohol hydrogels, which increases the crosslinking density and mechanical strength of the hydrogel, and improves the impact resistance and fatigue resistance of the hydrogel!”

“I built a preliminary model before.”

“With this method, it is highly likely that hydrogels with high strength (up to 10 MPa), high toughness (up to 10,000 J/m2) and high fatigue resistance (maintaining more than 90% strength after 10,000 cycles of loading) can be prepared, and have good transparency and biocompatibility!”

“This is always okay, right?”

Su Xiaoxiao asked with a wink.

“Not bad.”

Lu Yu’s eyes showed a hint of approval, and he nodded: ”

You even thought of the salting out method.”

“However, salting out is also flawed. The first is the cost aspect.

“It’s too complicated!

“It is not only necessary to control parameters such as freezing temperature, drying time, and salting out concentration, but also to ensure the stability and reliability of the hydrogel in different environments!”

“In a high-temperature environment, hydrogels will have the problem of thermal water loss, which will lose water due to the evaporation of water, resulting in its volume shrinkage, structural deformation, functional decline and other problems. The root cause is that the interaction between the water in the hydrogel and the polymer chain is weak and cannot resist the increase of the outside temperature.

“And in low temperature environments, there will be a freeze-thaw cycle!”

“At the end of the day, the instability of polyvinyl alcohol is still not solved, but the risk is transferred to the hydrogel formed by polyvinyl alcohol.”

“At

the end of the day…”

“The problem is still not solved!”

As soon as Lu Yu’s words came out, Su Xiaoxiao was instantly silent.

After half a ring….

“You… In such a short time, these problems were discovered?

She looked Lu Yu up and down, and asked in disbelief.

Previously, when Su Xiaoxiao was building a model in the laboratory of Huaqing University, it took a lot of time just to try out the salting out method! Not to mention finding out its problems further!

But Lu Yu discovered so many key problems in just one or two hours?

This efficiency is also a little too scary!

“Ahem, sort of.”

Lu Yu cleared his throat, turned his gaze to the other researchers, and slowly asked,

“Do you have any more questions?”

He skipped the last question asked by Su Xiaoxiao.

The reason why the efficiency of Lu Yu can be so high is naturally inseparable from the credit of the system! With the super buff of intracranial ultra-high-speed calculus, he only needs to do the most basic experimental steps first, and directly calculate the data after obtaining the data.

Can this not be efficient?

“MR. LU, I have a question.

Just then, a Germanic researcher somewhat stammered in English.

“Say.”

Lu Yu found a position, sat down, and continued to listen.

“Mr. Lu, that’s right.”

“The two methods you said earlier don’t work, so let’s change our thinking and use the physical crosslinking method?”

He stood up and asked suspiciously:

“We can use the hydrogen bond cross-linking point between polyvinyl alcohol and phytic acid to prepare polyvinyl alcohol/phytic acid composites with self-healing ability, so that the composite materials have reversible deformation and self-healing ability!”

“When a composite material is damaged, it can be restored to its original shape and function simply by connecting the fracture and applying the appropriate pressure!”

“Is this okay?”

As soon as the Germanic experts said this, the scholars of the Dragon Kingdom who had engaged in similar research showed a touch of surprise in their eyes.

Don’t say, this method is quite good!

“Maybe it works… If the physical crosslinking method can be used, isn’t it equivalent to the flexible material can be automatically repaired?

“Isn’t that similar to memory metal?” Even if there is damage, it can recover on its own. ”

Several scholars pondered it, and they all felt that this method… Sounds doable!

However.

Lu Yu didn’t think about it, so he said directly:

“I thought about this method at the beginning. Unfortunately, it still doesn’t work!

“For… Why?

Everyone asked suspiciously.

“It’s simple. Physical crosslinking is, in the final analysis, a method of connecting polymer chains using non-covalent bonds formed by hydrogen bonds, tangled chains, hydrophobic interactions, crystal interactions, and host-guest mechanisms. ”

This method, used in our flexible materials, may be able to prepare flexible materials with self-healing ability, good mechanical properties, high temperature stability, low cost and other characteristics.”

“It is also biodegradable and biocompatible.”

“But…” Lu

Yu slowly stood up, took out a pen, and drew on the whiteboard.

“One of the most likely situations is this, the distribution of physical cross-linking points is uneven!”

“Once the partial uniformity of the physical crosslinking cannot be ensured, it will lead to uneven mechanical properties of the hydrogel, and it is extremely easy to have problems such as stress concentration and fracture!”

He drew a rough sketch to make it easier for everyone to understand.

Although the sketch looks rough, everyone here is a Kochi scholar, and they can barely grasp the meaning.

“This phenomenon is called physical non-uniformity. The root cause is that the formation of physical cross-linking points is affected by factors such as the structure and movement of polymer chains, and it is impossible to achieve uniform distribution in space!

“Once you can’t resist changes in the external environment, you become unstable again!”

“When the hydrogel is stimulated by external force or temperature, the physical crosslinking point will break or recombine, resulting in a rapid change in the shape and function of the hydrogel!”

“For example, when a hydrogel is stretched, the physical cross-linking points are aligned along the stretch direction, resulting in enhanced anisotropy of the hydrogel; When the hydrogel is compressed, the physical crosslinking points are randomly distributed, resulting in an isotropic enhancement of the hydrogel….

“These changes will affect the elastic modulus, fracture strain, toughness and other mechanical properties of the hydrogel…,”

listened to Lu Yu’s in-depth explanation.

Everyone’s eyes gradually showed a touch of understanding!

Even the expert of that Germanic country showed admiration in his eyes.

He secretly sighed in Germanic Chinese:

“It is worthy of being a scientist who can study artificial kidneys!” This idea really makes me wait! ”

But.

After Lu Yu finished speaking, some scholars also showed a deflated look on their faces.

The clearer Lu Yu’s thinking, the lower the possibility that polyvinyl alcohol can serve as a flexible material, because all ways to make up for it have loopholes!

Since polyvinyl alcohol cannot be used as a flexible material…. So what should be used well?

Su Xiaoxiao’s face showed a look of hesitation:

“Then if you change to my alternative, polyurethane.” This one… Does it work? Polyurethane

was the alternative she considered.

In many properties, there is a gap with polyvinyl alcohol.

“No, I’ve thought about this too.”

Sure enough, Lu Yu shook his head directly and said,

“The biological safety of polyurethane hydrogels is too low!”

“Improper use is very likely to cause immune reactions or toxic side effects in humans or animals! It may contain isocyanates or other toxic substances left behind, or interact badly with human or animal tissues or cells! Once clotting or hemolysis occurs with blood; The consequences are unimaginable!

“Even if the problem of hemolysis is not considered, it may still adsorb or breed with bacteria…” Along

with Lu Yu’s narration, Su Xiaoxiao also sighed helplessly:

“Is it really not possible?”

“Actually, I wondered, can we abandon flexible materials and directly use a suitable material to arrange neuronal sensors on a large scale?”

“As long as the material can meet the characteristics we need, it does not necessarily need flexible materials.”

Lu Yu said.

“The question is, what is that material?”

One scholar smiled and said jokingly:

“It’s really not good, let’s get a graphene.”

“The paper will be easy to write then, hahaha.”

“….”