u . s . pat . no . 6 , 232 , 354 issued may 15 , 2001 describes an environmentally friendly and commercially practicable process for the production of microcellular polymer foams from amorphous , semi - crystalline and crystalline polymers which involves consolidating the polymer , saturating the polymer with an inert gas at elevated temperature and under elevated pressure , and controllably cooling , i . e . quenching the saturated polymer under a variety of temperature and pressure conditions to produce either a closed or open celled microcellular foam or a high density microcellular foam . it has now been discovered that a process similar to that described in this patent can be used for the production of nanocomposite and molecular - composite foams that exhibit exceptional physical properties .