The microstructure and thermal stability of multilayer thin films of rodlike polyglutamate copolymers having flexible aliphatic side chains have been studied with X-ray and neutron reflectometry. The complementary sensitivity of X-rays and neutrons and the use of four different sequences of protonated and deuterated molecules provides an enhanced level of structural discrimination. Within bilayers formed upon deposition, the backbones are located preferentially near the center, with backbones from the two layers overlapping strongly. The side chains of molecules in adjacent layers belonging to different bilayers interdigitate substantially, and interdigitation between layers within a bilayer is seen as well. Upon annealing at 70 or 84 °C, the backbone positions within each bilayer relax. However, there is no ascertainable interlayer interdiffusion and the nature of the side chain interdigitation does not change. No evidence is found for the formation, with annealing, of a three-dimensional ordered structure.

The thermal stability of Langmuir-Blodgett multilayers of cadmium arachidate and perdeuterated cadmium arachidate layers deposited on hydrophobic silicon is investigated by neutron and X-ray reflectometry. Using this pair of techniques allows one to depth resolve changes induced by annealing and also to discriminate between the behavior of the Cd head lattice and that of the aliphatic tails. All samples initially have ill-defined interfaces between the tails of adjoining protonated and deuterated layers, and some interchange of chains among layers occurs during the deposition process itself. The form of the multilayer structure is thermally stable at 70 and 84 °C, even though aliphatic tails are lost gradually due to ablation, leading to noticeable losses when annealing for 1 week at 84 °C. These losses occur almost exclusively from the layers closest to air, suggesting that the rate of ablation is considerably higher than that of interdiffusion. There appears to be little interlayer interdiffusion of chains when annealing for several hours at 84 °C. We conjecture that the type of interaction anchoring the two layers adjoining an interface may influence the stability of that interface to molecular exchange across it.

Interlayer diffusion and interdigitation in Langmuir−Blodgett multilayers containing asymmetric interfaces between cadmium arachidate (CdA) and an octadecyl-substituted polyglutamate (PG) were studied using neutron reflectometry and X-ray reflectometry. It was found that the structure of the two-component CdA/PG multilayers is less stable to annealing than is the structure of multilayers containing only CdA or only PG. The PG side chains and CdA tails at adjoining layers appear to interdigitate significantly in unannealed multilayers, and this interdigitation becomes more marked after annealing.

Interlayer diffusion in Langmuir-Blodgett multilayers containing Cadmium Arachidate (CdA), polyglutamate (PG) copolymers, or both, was investigated using neutron and x-ray reflectometry. Measurements from multilayers comprised only of CdA or PG revealed that little interdiffusion occurred upon annealing at 70°C or 84°C. However, some relaxation of the intralayer microstructure in the PG samples was observed at both temperatures. In contrast, the neutron reflectivity of a multilayer sandwich containing a bilayer of PG between two multilayers of CdA showed gradual and progressive change with annealing at both temperatures for annealing times of up to several hours. This change is surprising as PG is expected to act as a barrier to interdiffusion of the CdA molecules at these temperatures.

The microstructure and thermal stability of Langmuir‐Blodgett‐Kuhn multilayers containing rod‐like polyglutamate copolymers having flexible aliphatic side chains have been studied with x‐ray and neutron reflectometry. Upon annealing at 84°C the multilayer structure changes in a manner which is dependent upon the degree of orientation of the rod‐like backbones and therefore upon the flow dynamics of the deposition. A sample deposited with a highly convergent flow loses the bilayer structure induced by deposition, whereas samples with less highly aligned backbones may not undergo this relaxation as readily.