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Comment by noja | Hacker News Reader

Will the replacement for PFC be something very similar that is equally dangerous?

What some of the industry has been doing is switching to shorter chain PFCs… eg C6 instead of C8 which have a shorter half-life in the environment (and presumably the body). They are toxic but less so.

As for the PFC-free DWR membranes that apparel makers have been using, I don’t know enough about them but I don’t believe them to be toxic per se.

From the article (so, the replacement is not just another equally bad chemical with an acronym that starts with "PF"):

When it comes to Gore Fabrics, it has actually telegraphed its next move, at least to an extent. Back in September, a press release went out but never got much traction. I remember it coming through my inbox at the time and the title "Introducing New Gore-Tex Products with Innovative Expanded Polyethylene (ePE) Membrane for AW22" didn't exactly catch my eye. I sent an email out to Gorewear and asked about it, but there was nothing to test and it fell off my radar.

As it turns out, that press release was a big deal. Expanded polyethylene is the future of the Gore product line. Like existing products, it's available as a three-layer fabric with a membrane-embedded between an inner and outer face fabric. It still carries the "Guaranteed To Keep You Dry" promise and it's still a microporous breathable design. What's different is that it is free of PFC [ed. Per-fluorinated compounds] and half the weight for footwear and clothing. It's currently unavailable in any cycling product, so for now, it’s a waiting game to see how it performs.

I wasn’t too clear but I kind of switched topic from the membrane to the DWR coating to give an adjacent example of how the industry has approached reducing PFCs.

ePE refers to a replacement of the ePTFE membrane (which, in a 3 layer piece, is sandwiched between the liner and outer shell). That’s not what I’m referring to.

What I’m referring to is the DWR coating on the outer shell (that keeps the membrane from “wetting out”). Traditionally it was PFCs but there are non-PFC options now

The ePE membrane sounds cool though, if it works

no, there just isn't a replacement for perfluorocarbons, that's all

perfluorocarbons themselves are among the least dangerous materials in the world, but the materials used to make them are very nasty indeed

TFA mentions Gore is putting a lot of money into R&D for PFA alternatives. They may fail, not sure if that is what you meant. But they will certainly try.

no other class of materials is anywhere close to perfluorocarbons in many properties, such as low affinity for both water and hydrocarbons (and consequently fats), and ultraviolet resistance coupled with softness

additionally such levels of resistance to biodegradation are rarely found in combination with either of the previous two qualities

no other known organic compounds, out of the currently 182 million assigned cas numbers, are as thermally stable

we are not talking about the kind of research and development that a company can carry out over a commercially viable timescale; we're talking about fundamental breakthroughs in material engineering

perfluorocarbons were discovered almost a century ago, and nothing equaling or exceeding their properties in these ways has been discovered since

moreover, there are fundamental reasons to suspect that nothing ever will be; fluorine is the most electronegative element that exists or ever will exist, if we restrict ourselves to ordinary atomic matter, and there aren't any plausible room-temperature substitutes for carbon chains in this role either

so it wouldn't be surprising if the company tries to palm off inferior polyethylene substitutes as 'gore-tex' in preference to just declaring defeat, but it's not plausible that they're going to discover an equivalent or better non-perfluorocarbon alternative within the next decade or two

this is science, not magic

some things are just impossible

There's always active materials. We already have heated jackets, why not dehumidified jackets?

Then again, I don't do activities where failure of my clothes could kill me, so I'm not sure how the market would respond.

i have been working on that for a while but my intended use is enabling autonomic thermoregulation in humid weather by condensing sweat

i hadn't thought of it as a useful adjunct to wrapping myself in essentially a garbage bag to stay dry in the rain

ok as a single layer this is the best we can do, but maybe we can combine different materials - different layers of fabris to make it work on a similar level?

or superhydrophobic metamaterials, or utility fog, or something, but it's not going to be plannable or soon

It will be something that turns out to be a carcinogen/endocrine disruptor 20 years from now.

I know you're being sardonic... but it will likely be another fluorine based chemistry that is hopefully more biocompatible (flush out of body easily), and not cause undue harm.

The perfluro- line of chemicals are quite amazing.. if it werent for them being completely obnoxious and stay in the body like lead.

What is it that makes fluorine added to carbon chains so much more versatile? I kind of get why carbon is so versatile, but what is that makes fluorine so special and why can't some other potentially less harmful halogen do the job?

Edit: Ah adding chlorine destroys the ozon layer, what's why.

Fluorocarbons have a low London dispersion (induced dipole) force due to the high polarization of the C-F bond. This is responsible for many of the unusual properties of fluorocarbon solvents, particularly high gas solubility and extreme hydrophobicity. It's also just inert, much moreso than chlorocarbons (which tend to be quite toxic).

My undergraduate research project at involved identifying poly-tert-butyl-methacrylate as a polymer with similar hydrophobicity (as measured by the wetting angle) to the fluorocarbons, but I don't think anything ever really came of it. It may be unfavorable for other reasons; I don't remember.

Fluorine forms the strongest bonds to carbon that are available (much stronger than a carbon-carbon or carbon-hydrogen bond, also stronger than carbon-chlorine). It acts like an immovable stub preventing further reactions, which is great for materials like nonstick coatings, but also prevents natural breakdown in the environment.

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