Well... that material just might be here in the form of a brand new kind of plastic.

這樣的材料或許已經問世了，就是一種全新形態的塑膠！

Recycling plastic is actually trickier than it sounds.

「塑膠回收」其實比聽起來還要複雜許多。

First of all, plastic is super diverse, so you can't use the same recycling process on all the different plastic things we make.

首先，塑膠有很多種，所以你沒辦法用單一種流程回收所有不同的塑膠。

Looking at these horrific displays of plastics polluting the environment, whether that was in our oceans or on land and in landfills, and it was pretty clear that plastics needed a redo in terms of how we design them, specifically addressing the eventuality that their end of life needed to be revisited a little bit.

看看這些駭人的塑膠污染景象，不論是在海洋、陸地還是掩埋場，很顯然是時候重新設計塑膠了，尤其是在最末處理的部分。

The "end life" is why plastic products have to be separated into different streams to be recycled in different ways.

正是在末端處理的部分，塑膠製品必須被分到不同的回收管道。

The polymers will respond different to heat during the recycling process.

「聚合體」在回收過程中對於熱度的反應不同。

Hence the various numbers you see on the bottom of the containers—and even then, not all plastics with the same number can be recycled together.

因此你才會在容器底部看到不同的數字，但即使如此，同數字的塑膠也不見得可以用同樣方式回收。

Most commercial plastics contain lots of extras, or additives, like dyes and ingredients to make them stronger or more heat-resistant.

大多塑膠產品含有大量添加劑，像是染劑或是添加來增添硬度和耐熱度的材料。

These additives are very difficult to remove from the plastic, making it hard to recycle just the plastic.

這些添加劑很難從塑膠中移除，使得回收更不容易。

Or the monomer building blocks, and the presence of the additives can also make the resulting recycled plastic product unreliable and unpredictable.

或是「單體結構塊」，添加劑的存在也使得回收過程不易維持且難以預測。

All of those additives end up becoming associated with the plastic.

所有的添加劑到頭來和塑膠合而為一。

That heterogeneity essentially makes it very, very, very difficult to think about what to do with the plastic outside of grinding it up into little pieces and trying to pelletize it with a bunch of other different plastics that all have their own additives.

異質性基本上使得塑膠的重複使用格外困難，多半只能將它們磨成微粒，但各自都還含有不同的添加劑。

But luckily, new innovations are leading to plastics that could be infinitely recycled.

但幸運的是，創新科技正領向一種可以永續回收的塑膠。

The team at Lawrence Berkeley National Lab has turned to a new kind of plastic called poly (diketoenamine) or PDK for short.

勞倫斯伯克利國家實驗室的團隊將目光轉向一種新型塑膠，稱為 poly (diketoenamine)，或簡稱 PDK。

PDKs are an interesting type of plastic that differ from conventional plastics in that we completely replaced the static covalent bonds that typically comprise... that make up the polymer backbone and we replaced them with dynamic covalent bonds that allow you to do a number of new things.

PDK 塑膠很有趣，和傳統塑膠的不同在於，將原本用來組成聚合體主結構的靜態共價鍵替換成動態共價鍵，就能達成許多新用途。

Picture the bonds of a polymer in a traditional plastic like a metal chain.

可以把傳統塑膠中的聚合體結構想成是一條鐵鏈。

To break down the plastic, you have to break the links of the chain and then spend time and energy trying to re-form them, with the addition of a lot of glue and maybe even some new metal.

為了分結塑膠，就要先打斷這些鐵鏈，然後花費精力重組，可能要加上許多黏著劑和新的金屬。

With a material like PDK, the links between atoms in the polymer chain are actually reversible.

但是像 PDK 這種物質，聚合體中原子間的連結就有了可逆性。

Because they use dynamic bonds between monomers called diketoenamines, which is a triketone and amine stuck together.

因為單體之間是用一種叫做二酮胺的動態價，也就是組合三酮和胺。

You can just open them up by dunking them in an acid bath and separate them from their additives, ready to use the plastic again.

只管將它丟到酸性溶劑裡浸泡就可以打斷連結，還能將添加劑分離出，它就可以再利用了。

And the end result is the fluffy powder that's actually the exact same plastic from the beginning of the process, it didn't lose any of its integrity in the recycling process!

最後的成果是這種蓬鬆的粉狀物，和這種塑膠最一開始的樣貌一模一樣，所以它在回收過程中不會失去完整性。

And the acid isn't far from what researchers already use in the lab.

而且用到的酸性物質類似於現在實驗室中已經在使用的。

Honestly anything below a pH 1 could work, but the final call was sulfuric acid and for a couple different reasons.

只要是任何酸鹼值低於 1 的東西都有效，不過出於幾項原因最後決定用硫磺酸。

Sulfuric acid as a result, because it's a byproduct of petroleum refining, is very, very inexpensive.

之所以選硫磺酸是因為它是一種石油精煉的副產品，非常非常便宜。

So, acid is used to depolymerize PDKs and in the course of depolymerizing PDKs.

所以，酸被用在分解 PDK 的過程。

And once you go through the full cycle of recycling both the triketones and the amine monomers, you generate salty water.

過完整個回收三酮和胺單體的過程後，會得到鹽水。

And this salty water can be recovered and purified by reverse osmosis facilities.

這種鹽水可以用反滲透設施還原、淨化。

These types of facilities would be able to also recover the water and recover the commodity value of the chemicals embodied by the salt in the water as well.

這類設施也能還原水和含有這類鹽分的化學物質其商業價值。

And so, I think that that sets up a landscape for being able to do efficient resource recovery even while you're doing PDK plastic, chemical circularity.

再者，我認為這也提供了一種願景，在製作 PDK 塑膠的同時做到有效的資源還原、化學物質再利用。

The hope is that PDK could pave the way for plastic products that are infinitely recyclable in the same way that glass and metal are.

希望的是 PDK 能夠為塑膠產品永續回收鋪路，就像玻璃和金屬回收一樣。

While this material is still in its early stages, the researchers are looking at how we could incorporate PDK into existing manufacturing processes, experimenting with how it could be used in textiles, shoes, and food packaging.

這種材料還在早期階段，研究人員還在尋找將 PDK 運用進現存製造流程中，找尋將它運用至織品、鞋子和食物包裝方面。

And I think what we need to do is figure out of the sustainability challenges that we have in specific markets, where are those best solved by this particular plastic?

我認為我們需要找出在特定市場上的永續性難處，並且設想哪裡最適合用到這一類塑膠。

And in solving that, do we also identify what might be needed to advance the next design that is also circular.

做到了這點，我們就有了確切方向，知道該怎麼進展到下一個永續設計。

Which is essential, because in 2015, the U.S. actually only recycled 9% of its generated plastics.

這點至關重要，因為在 2015 年，美國才回收其所有塑膠製品的 9%。

The rest goes to landfills, is incinerated, or apparently makes its way into the ocean.

其餘的都去到掩埋場、焚化爐，或是大海。

Around 13 million metric tonnes of plastic end up in the ocean each year.

每年有近 1300 萬公噸的塑膠進到大海。

So unless we want to lose our oceans and be buried under mountains of trash à la Wall-E, something's gotta give.

所以除非我們想失去海洋然後被埋進《瓦力》的那種垃圾山，我們必須做出改變。

This new material holds great promise for modernizing our recycling world and making it more efficient, hopefully pushing toward a world where plastic products are not only much more recyclable, but don't end up in a landfill or our oceans at all.

這種新材料給了我們希望，我們或許可以現代化回收流程、提升其效率，期望能夠領向一個塑膠得以回收而非進到掩埋場或是海洋的世界。

If you're interested in how plastics are probably getting into your body through the food you're eating, check this other video here.

有興趣知道塑膠如何藉由你吃的食物進到你的身體裡嗎？看看這部影片吧！

Make sure to subscribe to Seeker to stay up-to-date with world-changing materials science discoveries, and thanks for watching.

記得訂閱 Seeker，關注最新的革命性材料和科學新發現，感謝你的收看！