What ingredient is in fabric softeners that makes cloths softer?

Question

And, while we're at it, is it the same thing that helps eliminate the static electricity too?

Answer 1

The earliest fabric softeners, developed during early 20th century, were typically based on water emulsion of soap and olive oil, corn oil, or tallow oil.

Contemporary fabric softeners tend to be based on quaternary ammonium salts with one or two long alkyl chains, a typical compound being dipalmitoylethyl hydroxyethylmonium methosulfate.

Anionic softeners and antistatic agents can be eg. salts of monoesters and diesters of phosphoric acid and fatty alcohols.

The softening compounds differ in affinity to different materials. Some are better for cellulose-based fibers, others have higher affinity to hydrophobic materials like nylon, polyethylene terephthalate, polyacrylonitrile, etc.

Silicone based compounds are one of the new softeners that work by lubricating the fibers. Silicone derivates are used as well; they bind better to the fabrics and have much improved feel. They have essentially the same role as oils had in the early formulations.

Other compounds are included to provide additional functions; acids or bases for maintaining the optimal pH for adsorption to the fabric, electrolytes, carriers (usually water, sometimes water-alcohol mixture), and others, eg. silicone-based anti-foaming agents, emulsion stabilizers, fragrances, and colors. A relatively recent form on the market are the ultra-concentrates, where the amount of carriers and some other chemicals is substantially lower and much smaller volumes are used.