Small-angle neutron scattering from two-phase polymeric systems

A small-angle neutron scattering method is presented for the determination of single-chain scattering functions in heterogeneous two-phase polymeric materials such as incompatible polymer blends and microphase-separated diblock copolymers. Development of the method makes use of both the discrete and continuum approaches to scattering theory. In this fashion it is shown that extraction of the single-chain scattering function requires only two experimental observations, regardless of the compressibility of the system. These experiments consist of small-angle neutron scattering profiles from two samples: an unlabeled two-phase material and a similar two-phase material in which a portion of the molecules in one phase have been replaced by molecules which are contrast labeled by isotopic deuterium substitution. Anticipated difficulties associated with actual application of the procedure and requirements of the necessary experimental samples are discussed.