In everyday life, you’ve probably used quite a few products that come with “built-in benefits”: the refreshing, non-sticky feel after applying hand cream; the water-repellent coating on car windows that leaves them streak-free and crystal-clear after a rain shower; the gentle, non-irritating ingredients in baby skincare products... Behind these experiences that greatly enhance our好感 (positive feelings), there often lies the same unsung hero—silicone.

Thanks to its three core characteristics—“non-sticky, non-staining, and non-irritating”—silicone has permeated numerous fields, including cosmetics, home furnishings, healthcare, and industry. But have you ever wondered where these remarkable “three no’s” actually come from? The answer is surprisingly simple: it all starts with its unique molecular structure.

1. Non-stick: Stemming from a molecular backbone that is both flexible and hydrophobic.

When you touch products containing silicone—such as silicone-based hand creams or silicone sealants—the smooth, non-sticky sensation you feel stems from the molecular backbone of silicone: a chain composed of alternating silicon and oxygen atoms (Si-O-Si). This structure differs dramatically from the carbon-chain organic compounds we’re more familiar with, such as oils and plastics.

On the one hand, the silicon-oxygen bond has a relatively large bond angle, giving the molecular chains exceptional flexibility—much like a series of supple “springs.” When our skin comes into contact with these molecules, the “springs” quickly adjust their shape, reducing friction between the molecules and the skin’s surface and thus providing a smooth, silky feel. On the other hand, the side chains of organosilicon molecules are mostly methyl groups (-CH3). The methyl group is a typical hydrophobic moiety that doesn’t readily bind with water molecules. The “sticky” sensation we often feel on our skin’s surface is largely caused by water molecules lingering there. Thanks to organosilicon’s hydrophobic properties, it can minimize the adsorption of water molecules, naturally preventing that sticky, clingy feeling.

For example, in makeup products like “primer,” many formulations include dimethicone—a substance that leverages its non-sticky properties to form a lightweight, thin film on the skin’s surface. This not only makes the skin feel smooth and easy to apply makeup onto, but also prevents the primer from sticking to subsequent foundation layers.

2. Non-stick: A low surface makes it “impossible for stains to adhere.”

The reason why non-stick coatings on household cookware, water- and stain-resistant films on bathroom glass, and hydrophobic car paints can easily remove stains with just a wipe lies in the “low surface energy” property of silicone—a property that also forms the core principle behind “non-stick” functionality.

Surface energy is the ability of a material's surface to attract other molecules. The lower the surface energy, the more difficult it is for other substances to adhere to the surface. Due to the relatively weak polarity of the silicon-oxygen backbone in organosilicon molecules, combined with the steric hindrance effect of the methyl side chains, these molecules can arrange themselves on a material's surface to form an ultra-low-energy "protective layer."

Whether it’s oil stains, dust, or water marks, the surface energy of these stain molecules is significantly higher than that of silicone. When they come into contact with a silicone coating, they can’t adhere due to an “energy mismatch,” and instead remain in spherical droplets that simply roll off or can be easily wiped away. For example, silicone waterproof and oil-resistant mats used in kitchens—no matter how much soy sauce or cooking oil they get stained with, a single swipe with a damp cloth will leave them spotless, eliminating the need for any strenuous scrubbing.

3. Non-irritating: Stable structure + maximum biocompatibility

Silicones can be widely used in the medical field (such as medical catheters and coatings for artificial joints) and in infant and toddler products (such as baby massage oils and pacifier materials). The core reason is that silicones are “non-irritating” and exhibit extremely high biocompatibility with the human body.

First, the molecular structure of silicone is highly stable. The silicon-oxygen bond has a very high bond energy, so it does not easily break down at room temperature and does not chemically react with biological molecules such as proteins and nucleic acids found in human tissues and body fluids, nor does it produce toxic or harmful substances. Second, silicone materials themselves are nonpolar, so they do not compromise the skin’s barrier function or trigger allergic reactions.

More importantly, specially modified silicones can also mimic certain properties of human tissues—for example, catheters made from medical-grade silicone rubber, once inserted into the body, do not irritate the mucous membranes nor trigger inflammatory responses. This is precisely why they are indispensable in the medical field.

In summary: Structure determines characteristics, and characteristics empower life.

Ultimately, the “three non-characteristics” of silicone all stem from its unique molecular structure—“siloxane backbone plus methyl side chains.” The flexible siloxane backbone provides a smooth, non-sticky feel; the low surface-energy molecular arrangement ensures that it doesn’t attract dirt or stains; and its stable structure and hydrophobic properties guarantee low irritation.

From everyday beauty and skincare routines to home cleaning, and even to high-end aerospace and biomedical applications, silicone—with its “hardcore strength”—is transforming our lives.