PBS高端访谈:能让番茄酱、牙膏和胶水从容器中滑出的高科技涂料（在线收听）

Judy Woodruff: Finally tonight- Have you ever had trouble getting ketchup out of a bottle? How about stopping an oil rig from exploding? A lab in Boston has developed a slick solution for both problems. Our science producer, Nsikan Akpan, reports about this new coating in our latest episode of ScienceScope.

Nsikan Akpan: Look at this ketchup sliding, so smooth, so easy. Back in the day, using condiments tended to end with a caveman-mess, but not with these high-tech bottles. Their insides are coated with something called LiquiGlide.

Kripa Varanasi: It's a coating technology that can basically get every last bit of the product out, so you can save on billions of tons of product that's wasted. What LiquiGlide does is fundamentally changes how liquids and solids interact.

Nsikan Akpan: That's Kripa Varanasi, a mechanical engineer at the Massachusetts Institute of Technology who co-created LiquiGlide to battle the nefarious issue of interfaces. An interface is any spot or surface where two things meet. You're familiar with the physical forces creating friction and solid interfaces, like when a tire skids on a road. But a liquid sliding across a solid also experiences this friction in tension. It's part of what makes some liquid sticky, such as maple syrup.

Kripa Varanasi: It's a ubiquitous problem, whether it be in consumer products, or personal care products to chemical industry to energy industry.

Nsikan Akpan: LiquiGlide came about due to an infamous interface problem in the oil industry. Drilling oil unearths all types of crud, mucky sediment and minerals. This includes methane hydrate crystals, which can form molasses-like goop and plug a pipe.

Kripa Varanasi: If they form, it can be very catastrophic, because if you release sort of this methane hydrate plug, the methane can come out and essentially lead to an explosion.

Nsikan Akpan: Kripa was mulling how to prevent these plugs from forming when a similar problem sprouted at home.

Kripa Varanasi: And at that time, my son was about a year old. My wife was trying to get honey out of a bottle. And, you know, she said, you know, why don't you apply this technology to bottles?

Nsikan Akpan: Kripa knew a plastic surface, a glass surface, any solid surface, for that matter, isn't truly smooth. It's covered with microscopic ridges and gaps. These pockets trap liquid and cause friction at interfaces. So, Kripa and his former grad student Dave Smith chemically designed a liquid to intentionally experience so much friction, it gets stuck in these pockets. This embedded liquid acts like a lubricant. Put ketchup in the bottle and it glides against the lubricant nano-layer, never coming in physical contact with the glass. Get it? LiquiGlide.

Dave Smith: Then we thought about, how can we make this easily and sprayable?

Nsikan Akpan: Smith developed a formula that can predict and build coatings for any solid surface. Once sprayed, LiquiGlide adheres so firmly to the bottle that it can't seep into the container's contents. But, as a precaution, the coatings they use for food applications are edible and FDA-approved. They founded a start-up in 2012 and their sprayable coatings now help squeeze out the stickiest stuff, toothpaste, cream cheese, paint. Even Elmer's Glue uses LiquiGlide. LiquiGlide won't work for every pocketbook. Uniformly applying a coating becomes tricky for larger containers. And specialized coatings are more expensive than materials like plain old glass. So, right now, LiquiGlide is best suited for smaller containers or situations where you can easy respray it, like with industrial bins. Back at Kripa's lab, a new legion of grad students is conquering other interfaces. Say you're tired of flight delays due to ice-covered planes.

Henri-Louis Girard: If you have icing rain, for instance, on a wing, the time that it's going to spend on the surface will determine whether it ices or it doesn't. So we want to minimize the time that it spends on the surface. And the way we do that is that we create microscopic ridges on the surface. And if we impact a drop now on the middle of the ridge, we can see that it breaks up in two parts that will bounce off independently. And because these two parts are smaller than the initial drop, they bounce off faster. And this is because when the drop bounces, it actually acts like a spring that gets compressed when it expands and then retracts. And smaller drops act like smaller springs that are actually stiffer than the larger drop. And stiffer springs will bounce off faster.

Nsikan Akpan: If smaller drops bounce off faster, then water is less likely to stick, so covering a plane in these microscopic ridges could eliminate the toxic chemicals airlines currently use. Other students in Kripa's lab are learning how to stop clogs at desalination water facilities by observing how saltwater evaporates, or they're keeping water from condensing on steam turbines to improve energy efficiency at power plants, or they have brewed a pesticide spray that sticks to plant leafs more effectively, rather than washing away into the environment. That's all from now. I'm Nsikan Akpan, and this is ScienceScope from the PBS NewsHour.

朱蒂·伍德瑞夫：今晚的最后——你有没有遇到过这样的麻烦，番茄酱黏在瓶子里不出来？那么石油钻塔防爆又如何呢？波士顿的一个实验室已为这两个问题找到了解决之道。我们的科学制片人，尼斯坎·阿克潘将在最新一集的ScienceScope中为您报道这种新型涂层（材料）。

尼斯坎·阿克潘：看这番茄酱滑动得如此平顺，如此容易。以前，使用调味品时总不免会出点乱子，因为那时没有这些高科技的瓶子。如今瓶子的内部覆有名为LiquiGlide的涂层。

克利潘·威瓦纳斯：这是一种涂层技术，应用这种技术，基本可以把产品一点不剩地挤出来，这样可以使数十亿吨的产品免于浪费。而LiquiGlide技术所做的就是从根本上改变液体和固体之间的相互作用关系。

尼斯坎·阿克潘：这是麻省理工学院的机械工程师克利潘·威瓦纳斯，为攻克接触面难题，威瓦纳斯与人合伙创立了LiquiGlide。 两个物体相遇的任何点面即是接触面。大家对物理力产生摩擦和固体界面比较熟悉，比如像轮胎在路上打滑。但液体在固体上滑动时，也会产生这种张力摩擦。这也是为什么像枫糖浆这样的液体具有粘性的部分原因。

克利潘·威瓦纳斯：这个问题普遍存在，无论是消费品，还是个护产品，再到化工产业，能源产业都会用到。

尼斯坎·阿克潘：石油行业中有个讨厌棘手的接触面问题，LiquiGlide的成立正是为了解决这一问题。石油钻探挖掘各类杂质、淤泥质沉积物和矿物。这其中包括甲烷水合晶体，这种晶体可形成糖浆一样的黏糊，堵塞管道。

克利潘·威瓦纳斯：如果这种黏糊形成，后果可能是灾难性的，因为如果除掉这种甲烷水合物黏糊，甲烷就会冒出来，势必会引发爆炸。

尼斯坎·阿克潘：正当克利潘思考如何防止这些黏糊形成时，发现类似的问题也会出现在家里。

克利潘·威瓦纳斯：那时，我儿子大约一岁。我妻子正尝试从瓶子里把蜂蜜挤出来。而且，你知道，她说，你知道，你为什么不把这项技术应用到瓶子上呢？

尼斯坎·阿克潘：克利潘知道就这点而言，塑料表面，玻璃表面，任何固体表面，都并非完全平滑。上面布满了微小的凸脊和缝隙。这些缝隙捕捉住液体，引起了界面间的摩擦。于是，克利潘和他以前的研究生戴夫·史密斯有意设计了一种可以产生大量摩擦化学液体，它就粘在了这些缝隙里。这种嵌入液体就像润滑剂。把番茄酱放在瓶子里，它滑到润滑剂纳米层上，不会与玻璃发生物理接触。明白了吗？LiquiGlide。

戴夫·史密斯：然后，我们思考，怎么才能让它容易实行还易于喷涂？

尼斯坎·阿克潘：史密斯构建了一个公式，它可以预测和建立任何固体表面的涂层。一次喷涂，LiquiGlide便牢牢黏在了瓶子上，并且不会渗入容器内的承载物。但是，预防起见，他们在食品应用中使用的涂料是可食用的，已经过FDA批准。2012年他们创办了一家公司，如今使用他们的涂层可以挤出最粘稠的物质，牙膏、奶油、奶酪、油漆。连埃尔默胶水，也使用了LiquiGlide。LiquiGlide也并非处处适用。对较大容器进行均匀喷涂还是会很棘手。这种特殊涂料比普通的旧玻璃昂贵得多。所以，现在，LiquiGlide是最适合于较小的容器或你很容易重新喷涂的场合，比如像工业垃圾箱。在克利潘的实验室，另外一批研究生正在努力攻克其他界面。比如说你对飞机结冰，造成航班延误感到厌倦。

亨利-路易斯吉拉德：如果你遇到冻雨，例如，在机翼上，水停留在上面的时间将决定它是否会结冰，所以我们想尽量减少水停留在上面的时间。我们的做法是在机翼表面上形成微小的脊线。如果现在我们让一滴水落在脊线中央，我们可以看到它分裂成两部分，独立地弹开。因为这两个部分比原来的那滴水小，所以它们反弹得更快。这是因为当下落弹起，它就像一个弹簧被压缩时，膨胀然后缩回。较小的水滴就像更小的弹簧，比大的更硬。而较硬的弹簧会弹跳得更快。

尼斯坎·阿克潘：如果较小的水滴反弹得更快，那么水就不太可能粘住（机翼），所以在机翼上覆盖一层这样的微脊，飞机就可以减少使用当下应用的有毒化学物质。在克利潘的实验室里，其他学生正在通过观察海水蒸发，学习如何解决海水淡化设施中的问题。他们（研究如何）保证水不在蒸汽涡轮机上冷凝，从而提高发电厂的能源效率。他们也在研究如何才能让农药喷雾高效附着在植物叶表，而不会冲刷到环境中去。一切就从现在开始。我是尼斯坎·阿克潘，这里是PBS NewsHour ScienceScope。