The rheological response of high molecular weight tracer chains of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA), separately blended with low molecular weight PEO/PMMA matrices of varying composition, were obtained over a 120 deg temperature window. Monomer friction factors, ζ, for each component as a function of temperature and matrix composition were extracted by various means, all of which yielded consistent results. The tracer diffusivities of low molecular weight PEO chains in some of the same blends were obtained by forced Rayleigh scattering, and the resulting friction factors agree well with those obtained using rheology. The overall results show that the mobilities of both PMMA and PEO are strongly composition-dependent in PMMA-rich blends, their monomeric friction factors dropping precipitously upon addition of small amounts of PEO. The composition dependence of the PMMA ζ is strong over a wide composition range, whereas that of PEO is only significant at high PMMA content blends. Friction factors for the PEO component are significantly larger than those inferred from segmental dynamics measurements reported in the literature. The Lodge−McLeish self-concentration model, as usually applied, is unable to predict the observed behavior of either component. However, the data can be nearly quantitatively described using a simple but empirical mixing rule. Selected experiments were repeated using a PEO matrix with methoxyl rather than hydroxyl end groups; except for the change in glass transition temperature for the PEO, no significant effects were observed.
Cationic graft polymerization lithography is a variation of top surface imaging schemes. This technique uses a spincoated, inert polymer film as a photoacid generator carrier. UV exposure is used to generate acid in the top surface of the film. A vapor-phase reaction between the generated acid and a silicon-containing monomer occurs in the exposed areas. The silicon-containing polymer formed, or grafted, on the surface is used as an oxygen etch mask for subsequent pattern transfer through the underlying film. A modular approach can be employed in material design, allowing optimization of characteristics of each component. A key criterion is introduced by the interaction between the transfer layer and the graft monomer. The solubility of the monomer into the inert polymer layer influences the growth behavior, and should be minimized to prevent background silylation and potential swelling. The solubility of the monomer in the inert polymer is characterized by measuring the equilibrium sorption of the vapor into the polymer. Solubility behavior can also be estimated from group contribution theories. These estimates guide the rational design of materials for this lithography process.Based on this analysis method, a new monomer, bis(vinyloxymethyl)dimethylsilane, has been designed and tested. Its sorption into a typical polymer layer has been characterized experimentally. Kinetic growth rate data have been obtained on a quartz crystal microbalance system, and preliminary imaging results using 248 nm exposure are presented.
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