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A new, ridiculously slippery toilet bowl could keep poop from sticking, scientists report
An incredibly slippery 3D-printed toilet doesn't get dirty and requires less water to flush than a typical one, scientists say. Could cleaning toilets become a chore of the past?
Right now, the concept is just a prototype, but researchers are working on ways to eventually bring this clever chemistry to market. So far, the researchers have printed only a tiny model of the toilet that stands about one-fifth the height of a typical porcelain throne, and they tested its slickness by exposing its surface to yogurt, honey, starchy gel and fake poop, not the real stuff.
The invention of the flushing toilet revolutionized the way we live, but the innovation came at a cost: namely, 37 billion gallons (141 billion liters) of water flushed per day globally, the researchers wrote in their recent paper, published Aug. 5 in the journal Advanced Engineering Materials. And often, there's another problem: Even all that flushing isn't enough to remove all of the excrement in the bowl.
Bin Su, a principal investigator at Huazhong University of Science and Technology in China, and his team of materials scientists may have found a solution to these problems.
In their study, the researchers reported that their 3D-printed abrasion-resistant super-slippery flush toilet, or ARSFT, is completely resistant to soiling with various liquids, including milk, muddy water and even synthetic feces. And unlike other slippery toilets, ARSFT maintains its slipperiness even after heavy and repeated use.
The team drew inspiration from tropical pitcher plants (Nepenthes), carnivorous plants that capture prey in vase-like leaf cups; to help channel prey into their traps, the plants secrete a slippery, lubricating substance. Similarly, the researchers coated the toilet's surface in a greasy oil that helped funnel the waste down and out of the bowl.
"When the contaminants fall on to the surface, they first encounter the lubricant film rather than the surface [itself], which can greatly reduce adhesion," the study authors wrote.
On a chemical level, this slippiness originates from a material property called "hydrophobicity," which is a measure of how well the material repels water. Human waste has a high moisture content, so a hydrophobic surface will help prevent poop from sticking.
Using a technique called selective laser sintering 3D printing, the team fused plastic grains and a type of hydrophobic sand to produce the solid shell of the toilet. Sintering is a chemical process that compacts and combines two types of solid without melting them together; importantly, this creates a porous structure with many tiny gaps between the solid particles. The researchers filled these holes using a common lubricating oil that spread throughout the entire structure to coat the whole toilet.
Because the lubricating oil is stored throughout the whole toilet, thanks to the porous structure, any oil lost from the surface is quickly replenished from deeper within the material, enabling the bowl to maintain its super-slippy properties. Even intense mechanical abrasion — like that caused by an overenthusiastic scrub with a toilet brush — doesn't diminish the slipperiness, because the material quickly self-heals by shuffling oil to the newly exposed surface. The team tested this by scrubbing their mini-toilet 1,000 times with sandpaper.
But while the slick new toilet promises to prevent unsightly skid marks on the bowl, it will be a while before you see one of these at your local hardware store.
The team's tiny toilet bowl measured just 3.1 inches (8 centimeters) high, 4.7 inches (12 cm) deep and 3.4 inches (8.8 cm) wide, so it will obviously need to be made bigger. 3D printing can also be notoriously expensive, so producing these toilets cheaply could also be a challenge.
Su's team is already working on these issues. But beyond that, manufacturers would also need to find a way to incorporate the important sintering step into the existing toilet production process. However, there could be uses for this robust nonstick surface beyond toilets, so you may someday see this clever chemistry applied outside the water closet.
注释：
prototype: n
表示" 原型；范例"，means "first or original example of sth that has been or will be copied or developed"，如：The strange mechanical device is the prototype of modern cars. 这个奇怪的机械装置是现代汽车的原型。
starchy: adj
表示" 含淀粉的；古板的"，means "consisting of or containing starch"，如：He eat too much starchy food. 他贪吃含淀粉多的食物。He's always been rather starchy. 他一向非常刻板.
excrement: n
表示" 排泄物；粪便"，means "waste matter (as urine or sweat but especially feces) discharged from the body"，如：My main role was to analyse human excrement. 我的主要任务是分析人体排泄物。
pitcher: n
表示" 水罐；"，means "e arm"
an open vessel with a handle and a spout for pouring"，如：The pitcher contains enough water for all of us. 那水罐可容纳足够我们全体饮用的水。
funnel: n
表示" 漏斗；漏斗状物；烟囱"，means "a conical shape with a wider and a narrower opening at the two ends"，如：I need a funnel to pour petrol into the tank.我需要一个漏斗把汽油灌进油箱。
hydrophobicity: n
表示" 疏水性"，means "the property of being water-repellent; tending to repel and not absorb water"，如：The hydrophobicity is related to molecular volume and polarity. 分子的疏水性跟分子的体积和极性有关。
sinter: v
表示" 烧结"，means "cause (ores or powdery metals) to become a coherent mass by heating without melting"，如：Lower Basicity of Sinter, Increasing The Sinter Charging Ratio of BF. 降低烧结矿碱度提高烧结矿入炉比。
porous: adj
表示" 可渗透的；多孔的"，means "able to absorb fluids"，如：Most soils and rocks are porous. 大部分土壤和岩石都是多孔的。
replenish: v
表示" 补充"，means "fill something that had previously been emptied;"，如：We need to replenish our stocks of coal. 我们需要再次补充煤的储备。
diminish: v
表示" 减少；"，means " make less; decrease; reduce"，如：We should try to diminish the cost of production. 我们应尽力减少生产成本。
中文简要说明：
虽然大家都知道，吃喝拉撒是基本需求，所以厕所相当重要。但是保持整洁的厕所并不容易，需要时时清洁，否则马桶里出现一些沾黏，视觉与气味上就令人不悦了。中国华中科技大学的科学家，正在进行马桶材质的研究，想要制造出一种不会沾黏粪便的马桶， 使打扫厕所变得更为轻松。
生活科学(LiveScience)报导，中国华中科技大学首席研究员苏斌，和他的材料科学家团队用一些带黏性的材料来模仿粪便，调配酸酪奶、蜂蜜、淀粉凝胶的配方，制作出黏性不同的假粪便，经过反复研，他们发现降低认沾黏的秘诀，与疏水性材料很类似。
在8 月5 日发表在《先进工程材料》(Advanced Engineering Materials)最新论文中写道：冲水马桶的发明，彻底改变了我们的生活方式，但这项创新是有代价的：即全球每天需要冲掉370 亿加仑（1,410 亿公升）的水。而且有时候冲不干净，会沾黏，只好再多冲几次。
研究团队从热带猪笼草的表面汲取灵感，猪笼草是一种食肉植物，可以在花瓶状的叶杯中捕获猎物；为了帮助将猎物引入陷阱，植物会分泌一种光滑的润滑物质。研究人员先在马桶表面涂上了一层油，有助于降低沾黏的机率。
论文写道：「当粪便落在材料表面上时，它们首先遇到的是润滑膜(油)，而不是材料表面，这会大大降低黏附力。」
在化学层面上，这种光滑性源于一种称为「疏水性」的材料特性，人类排泄物的水分含量很高，因此疏水性表面将有助于防止粪便沾黏。
不过，油并不容易附着在马桶壁上，所以还需要新的马桶材料。团队使用一种称为选择性雷射烧结的 3D 打印技术，将塑料颗粒和一种疏水性沙子融合在一起，生产出马桶的外壳，称为耐磨超滑冲水马桶（ARSFT），他们做出了一个小尺寸，仅8公分长、12公分深，和8.8宽的迷你马桶进行实验，融合塑料颗粒与沙子的特性，形成了多孔结构，刚才提到的润滑油就能填充这些孔洞，使得整个马桶都光滑不已。
由于润滑油储存在整个马桶表面上，甚至渗透进内部材料，从表面流失的油还能从材料内部更深处得到补充，使马桶继续保持其超滑的特性。即使是强烈的机械磨损（例如用马桶刷造成的磨损）也不会降低其光滑性。团队以最极端的方式，通过用砂纸擦洗迷你1,000 次来对此进行测试，仍然效果不错。
不过，目前还只是小尺寸的，显然还需要实际马桶大小才能知道是否理论正确，而且材料且前还不够普及，如何廉价生产也是一个挑战。
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