A foamable poly carbonate composition comprising 5 to 95 wt % of a poly(siloxane) block copolymer comprising a poly(carbonate-siloxane) comprising 50 to 99 wt % of bisphenol A carbonate units and 1 to 50 wt % of dimethylsiloxane units, each based on the weight of the poly(carbonate-siloxane), a poly(ester-carbonate-siloxane) comprising bisphenol A carbonate units, isophthalate-terephthalate-bisphenol A ester units, and 5 to 200 dimethyl siloxane units, or a combination thereof; 5 to 95 wt % of an auxiliary component comprising a poly(alkylene ester), a poly(ester-carbonate), or a combination thereof, and optionally, a homopolycarbonate; optionally, up to 10 wt % of an additive composition, wherein the composition has a glass transition temperature of 140° C. and below measured using differential scanning calorimetry, and wherein a foamed sample of the composition has an average cell size of 10 nanometers to 20 micrometers.