Proton Spin Relaxation in the Rod Micelles of Type I CM Mesophases

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Abstract
The dynamics of the hydrocarbon chains in lyotropic nematic type I cylindrical micellar liquid crystals prepared with D2O has been selectively studied by Zeeman and rotating frame nuclear spin-lattice relaxation. The measurements of the proton spin-lattice relaxation time T 1 as a function of frequency and temperature demonstrate that relatively fast local fluctuations of individual amphiphilic chains relax the proton spins at high magnetic fields. This process is facilitated also by the rapid diffusive motion of the chains within the micellar units. The rotating frame Zeeman relaxation time T 1x, is associated at room temperature with a long correlation time of ~11 μs. Slow micellar orientational fluctuations have been assigned to this characteristic time.