Thermosetting polymer for dynamic nuclear polarization; Solidification of an epoxy resin mixture including TEMPO

Noda, Yohei; Kumada, Takayuki   ; Yamaguchi, Daisuke; Shamoto, Shinichi  

We investigated the dynamic nuclear polarization (DNP) of typical thermosetting polymers (two-component type epoxy resins; Araldite(R) Standard or Araldite(R) Rapid) doped with TEMPO radical. The doping process was developed by carefully considering the decomposition of TEMPO during the solidification of the epoxy resin. With the resulting TEMPO-doped epoxy-resin samples, DNP experiments at 1.2 K and 3.35 T indicated a magnitude of a proton-spin polarization up to 39%. This polarization is similar to that (35%) obtained for TEMPO-doped polystyrene (PS), which is often used as a standard sample for DNP. We discussed the detail of the solidification process with considering the chemical composition of the initial epoxy resin mixture.