2H NMR results from 2D exchange, solid echo, and wide-line absorption spectra as well as spin-lattice relaxation times are analyzed in terms of different reorientation models applied to the C-2H bond directions of chain-deuterated polystyrene. The dominant mechanism is rotational diffusion by small angular steps where the mean rotational correlation time agrees with relaxation times from dynamic mechanical experiments over a dynamic range of 10 decades. However, the width of the correlation time distribution extracted from the NMR results varies from about 5 decades at Tg to not more than 1 decade at T £ Tt + 40 K, whereas other relaxation techniques yield constant correlation time distributions. The results of the different methods employed for the study of chain motion are compared. It is shown that the motions of well-defined C-H bond directions which are probed by NMR are tightly coupled to the cooperative motion of the o-process. Moreover, they also monitor the separation of the fast 3-process from the slow a-process when approaching Tg by cooling down from the melt.

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Time domain 1 H multiple quantum NMR (MQ NMR) was applied to study binary guest/host systems. We investigated protonated adamantane-h 16 (A-h 16 ) molecules in deuterated crystalline adamantane-d 16 (A-d 16 ) and in glassy polystyrene-d 8 (PS) for various guest concentrations and coupling times τ/τ c . For pure A-h 16 crystals spin clusters of more than 1000 connected spins were observed. We observed the evolution of the multiple quantum connectivities as a function of the coupling time. In all cases the growth curves of the multiple quantum orders can be described by a master curve, showing the validity of a scaling law. For the diluted systems the master curve is obtained by multiplying the time axis with the square root of the dipolar line width (∆ν) 1/2 . The different local structure of the systems leads to characteristic growth curves, in particular to a quadratic function for the crystalline and to a linear function for the glassy material. For short coupling times these differences can be attributed to geometrical constraints caused by the polymer chains while for longer coupling times geometrical constraints and dynamics of the polymer chains can both be responsible for the different growth curves. The technique was applied to study slow phase separation processes in a solution of A-h 16 in PS.