Synthetic polymer-propellant compositions are provided that are capable of forming foamed structures having a temperature at least 30.degree. C. below ambient temperature and containing open and/or closed cells, which may optionally contain a material which is deposited in the pores and/or walls of the structure as the structure is formed, and comprising:(a) a film-forming synthetic polymer is an amount within the range from about 2% to about 30% by weight of the composition;(b) at least one liquefied propellant boiling below -10.degree. C;(c) the total propellant being in an amount within the range from about 50% to about 90% by weight of the composition; and having a heat of vaporization of at least 55 calories per gram; the propellant being capable of dissolving the synthetic polymer at least in the presence of a co-solvent that is soluble in the propellant and in solutions of the synthetic polymer in the propellant at ambient temperature; and(d) at least one nonsolvent that is soluble in the propellant solution but in which the synthetic polymer is insoluble in an amount within the range from about 1% to about 85% by weight of the composition; the composition forming upon volatilization of propellant at ambient temperature and pressure a foamed structure containing open and/or closed cells and having a temperature at least 30.degree. C. below ambient temperature.