A disposable bottle that stays chilled for 6 hours

Looking for: Designer, Engineer
You are one of 1.6 billion people living in India. Its 120 degrees outside (not joking). You want to go out in this heat but with access to a bottle of chilled beverage.
It can either be bought overpriced from a shop or pack a thermos flask. There are options like a thermal sleeve etc or an ice bucket. There are also threats like fake Aquafinas.
Or, you could just take one out of your fridge, pop the 'Chillock' on and keep it chilled for 6 hours. Throw it in a bin when you are done.
We are developing the concept here at the Uni incubator. The business plan and market research is ready. The physics equations are proven on paper. The thermodynamics is basic but the advangate is a design adaptation for a regular PET bottle. We also have few initial design ideas. The local bottlers seem interested in the concept if it can be made into a reality. The people involved currently are getting busy with their PhDs therefore need a mechanical engineer to join and talk ''Rocket Science'' to the investors!

Additional Info

  • Time commitment: part time (10h/week)
  • Idea stage: prototype development