Study of environmentally interactive ultrathin organic layers and novel organometallic materials

Ultrathin organic films offer a straightforward method to tailor the chemistry and properties of surfaces. Of particular interest are surfaces capable of interaction with the environment. To achieve this capability, functionalities may be introduced to well-known organic thin layers such as self-assembled monolayers (SAMs) or tethered polymer brushes, or novel materials containing unusual chemistry and properties can be directly applied to the surface. This research investigated the nanoscale structure in three different systems corresponding to these three approaches.; In the study of phenol- and o-chlorophenol-terminated SAMs, the chemisorption and subsequent in situ chemical modification were monitored. X-ray reflectometry provided detailed physical information about the SAMs after chemisorption and modification of surface-immoblized functional groups.; Novel PMMA brushes fabricated by a “grafting-from” method were also studied. An initial attempt was made to experimentally determine the deformation of the tethered PMMA molecules at the surface due to the crowding and overlapping, predicted by many theories. Small-angle neutron scattering with optimal optics was applied to investigate polymer brush thin films on flat surfaces for the very first time. While control samples gave results consistent with previous studies, data from the brushes were difficult to interpret using a Guinier analysis, indicating the need to further optimize the parameters of measurement.; Poly(ferrocenylsilanes) (PFS) are a novel class of transition metal-containing macromolecules with backbones that consist of alternating ferrocene and organosilane units. Ferrocene groups are able to interact with a variety of chemicals, thus bringing changes to the polymer. Different functionalities can be introduced as side groups. The novelty and flexibility of chemistry with the PFS molecules offers interesting sensing capabilities as well as useful electrical, optical, and chemical characteristics.; Nanofibers electrospun from poly(ferrocenyldimethylsilane) (PFS(Me) ₂), a crystalline PFS, were characterized using optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron diffraction to obtain structural information. The PFS(Me)₂ molecules adopt a monoclinic structure in the nanofibers, which is different from the triclinic structure found for single crystals of pentamer analogs. The crystal structure in the nanofibers becomes more ordered during annealing, indicating that the molecules are packed in a metastable thermodynamic state in the as-spun nanofibers. The crystals are well ordered along the fiber axis, but randomly distributed in the azimuthal direction.; In the research on equilibrium morphology of PFS-containing diblock copolymers, two issues were addressed: the influence imposed by the flexibility of the PFS blocks, and structural changes of the copolymers in response to certain external stimuli. Crystallizable PFS blocks hinder the microphase segregation and a long range ordered phase morphology is developed only upon annealing at a sufficiently high temperature. Annealing is not required to attain good ordering in a block copolymer containing an amorphous PFS block. Iodine and tetracyanoquinodimethane (TCNQ) were chosen as model stimulants as they readily oxidize ferrocene molecules in solution. Although experiments show exposure to iodine changes the crystal structure of PFS, the high electron density of iodine made it difficult to interpret the apparent morphological changes observed in small angle X-ray scattering and transmission electron micrographs. TCNQ, an electron acceptor, fails to oxidize the block copolymer in the bulk due to the bulkiness and rigidity of TCNQ.