Polymerization behavior of N-phenylbenzoxazine in bulk was studies in detail to discover new reaction pathways: (1) formation of an intermediary polymer having N,O-acetal-type linkage in the main chain and (2) its rearrangement into Mannich-type linkage in the solid state. Efficient promotion of the main chain rearrangement was achieved by using a dual system composed of imidazole and sulfonic acid.

We report 195 Pt-NMR and 75 As-NQR measurements for the locally non-centrosymmetric superconductor SrPtAs where the As-Pt layer breaks inversion symmetry while globally the compound is centrosymmetric. The nuclear spin lattice relaxation rate 1/T 1 shows a well-defined coherence peak below T c and decreases exponentially at low temperatures. The spin susceptibility measured by the Knight shift also decreases below T c down to T < T c /6. These data together with the penetration depth obtained from the NMR spectra can be consistently explained by assuming a spin-singlet superconducting state with a full gap. Our results suggest that the spin-orbit coupling due to the local inversion-breaking is not large enough to bring about an exotic superconducting state, or the inter-layer hopping interaction is larger than the spin-orbit coupling.

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