# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DcXPL46AZqz
- **Gondola URL:** https://gondola.cc/posts/69422653-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/b030277a7a.jpg
- **Posted:** 2026-08-23T00:49:56.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Seaweed needs no farmland, no freshwater and no fertiliser. That single fact underpins Notpla — short for “not plastic” — founded in 2014 by two Imperial College London and Royal College of Art students who wanted packaging that vanishes.

The chemistry begins with alginate, a polysaccharide that can account for up to 40% of the dry mass of brown seaweed. In living kelp it is a structural gel, letting fronds flex in surf without tearing. Extracted as sodium alginate, it dissolves into a viscous solution. Introduce calcium and the transformation is immediate.

Alginate is a linear copolymer of two sugar acids: mannuronic (M) and guluronic (G). Only the G-blocks have the buckled geometry needed to cradle a divalent calcium ion between two adjacent chains. Materials scientists named it the egg-box model in 1973.

- Sodium alginate solution meets a calcium bath
- Ca2+ displaces Na+ and bridges neighbouring chains
- The network crosslinks from the outside inwards
- A coherent, watertight membrane forms in seconds

That membrane became Ooho, the edible liquid pod. More than 30,000 were handed to runners at mile 23 of the 2019 London Marathon, each holding 30 ml of sports drink. Bite, swallow, done. Discarded instead, the film biodegrades in four to six weeks.

The larger prize is the takeaway box. Giant kelp can extend by half a metre in a day, drawing carbon and nutrients straight from seawater, so the feedstock competes with nothing on land. Conventional food board carries a thin polyethylene or fluorochemical liner for grease resistance — a few microns of plastic that renders the entire container unrecyclable. Notpla’s seaweed coating delivers the same barrier and still breaks down in home compost. The work won the 2022 Earthshot Prize for building a waste-free world.

Nature solved waterproofing long ago. It simply never invented waste.

#stemantics #materialsscience #sustainability #biomaterials #engineering

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## Tags

engineering, biomaterials, materialsscience, stemantics, sustainability

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