Increasing temperature has been widely considered as a primary and effective way to improve the segmental mobility of polymer chains and subsequently cause polymer chains to flow. Here, by confining the morphology of polymers into nanospheres and combining this process with external stress, we present an important new approach to achieve the cold flow of glassy polymers at room temperature, under which the mobility of chain segments are enhanced significantly. The interparticle fusion and the flow of polymer chains under pressure were monitored by utilizing a non-radiative energy transfer (NRET) method. Additionally, we showed that low-temperature processing based on cold flow retains the biological activity of bio-additives. (C) 2017 Elsevier Ltd. All rights reserved.