These cups are made from agar, an extract from reg algae, frequently used in Asian desserts and biology experiments.
According to this material data about Agar:
- It melts at 176F so holding it in your hand shouldn't be a problem.
- It is insoluble in cold water
- Is "completely resistent to the enzymes applied in the food technology area" ... which I take to mean it won't dissolve or react with things you'd want to eat or drink.
However, this material clearly has some problems with large scale use in an office:
- Agar does not fold or compress without losing it's structural integrity so it would be difficult to transport or store in large numbers.
- Agar is a nutrient so it probably needs to be refrigerated, further adding to the transportation and storage costs... unless you brew and mold your own cup on demand... which would be novel if not very efficient.
- Agar is one of the more expensive gelatines, so compared to a foldable paper cup, it would be difficult to justify the cost per unit to give away by the hundreds and thousands per months.