Polymer surface chemistry: Structure and reactivity of surface segments and oligomeric chain distributions from model systems to novel polymer materials
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Poly (dimethylsiloxane) PDMS, produced from anionic polymerization with a narrow polydispersity, can form well ordered helically coiled monolayers using Langmuir-Blodgett methods at air-water interface, either in a hairpin configuration, if the endgroups are functional or as flat helically coiled chains. Reflection Absorption Fourier Transform Infrared (RA-FTIR) spectroscopic analysis shows the changes in bonding between flat helically coiled PDMS and cast films from dilute solvents, which produces a random coil configuration. Band shifts in the infrared spectrum show evidence of changes in bonding, producing weaker bonds along the siloxane backbone. These changes result in difference in the relative intensities of fragments formed in the repeating pattern of clusters in the high mass TOF-SIMS spectra of the monolayers versus the solution cast films. Both statistical chain break analysis and molecular mechanics simulations of structure are used to support the analysis. Surface analysis of polyimides and fluorinated polyimides were obtained using the XPS. The Si/C, Ti/C and Si/Ti ratio were compared with the different compositions of Si and Ti in the polyimide silica/titania samples. The Si/C and F/C ratio were compared with the different compositions of Si and F in the fluorinated polyimide samples.