A Q2000 Differential Scanning Calorimeter (TA Instruments, New Castle, DE, USA) was used to determine the calorimetric glass transition temperature (T g,DSC , defined by the onset temperature) for each material. 2-3 mg of sample material were placed in hermetically sealed aluminium pans under a constant flow of nitrogen atmosphere (flow rate of 50 ml min -1 ) and heated at a rate of 10 K min -1 to 358 K, and subsequently cooled down to 293 K at 40 K min -1 . Finally the samples were heated from 293 K through T g to 358 K again at a rate of 10 K min -1 . The temperature and heat flow of the instrument were calibrated using indium (T m = 430 K, ∆H fus = 29 J g -1 ).