Solid-state NMR has become a powerful tool for studies of structural and physical properties of polymers. This thesis investigates a technically produced block copolymer . by means of solid-state NMR. The properties which are of principal interest are the heterogeneity on various scales ranging from molecular (unit cell) to macroscopic (morphology), and molecular motion in solids. The important question of cross polarisation is addressed. Quantification of depolarisation experiments will bring some more insight into the origins of the polarisation transfer. Basically a model by Muller, Kumar and Ernst has been used to describe the polarisation transfer. Novel results are reported in this area spin-lattice relaxation measurements, both in the laboratory and on-resonance rotating frames of resonance are applied to the block copolymer. An attempt is made to address the relation of the observed relaxation times and the macroscopic properties. The behaviour of the observed and the intrinsic properties of the various regions of the heterogeneous system in the presence of spin diffusion is investigated. The system is simulated by a computer model, which allows quantification of the dimensions of the different regions. Comparison with small-angle X-ray diffraction measurements illustrates the accuracy of this new powerful technique.