Monodisperse polystyrene, sensitivity

We note from Table VIII a strong interest in halogenated resists, particularly those substituted with chlorine. The addition of chlorine to the aromatic structure of polystyrene has a marked effect on cross-linking efficiency. Monodisperse polystyrene, for example, has a sensitivity on the order of 50 p C/cm2, yet with as little as 20% chloromethyl groups substituted on the ring, the sensitivity is improved to 2 C/cm2 for comparable molecular weight and distribution. 

The final latices were prepared for electron microscopy by dilution with xylene to ca. 0.1% polymer followed by distillation to remove the water. The distilled latices were diluted further and dried on the specimen substrates. The electron microscope specimens could not be calibrated with monodisperse polystyrene particles because of the sensitivity of the sodium poly (p-vinylbenzene sulfonate) particles to water. Instead, the magnification was calibrated from one separate exposure of monodisperse spheres which was made on each photographic plate of five ejqjosures. 

Shown in Fig. 4.12 are the data of steady-state compliance J° of nearly monodisperse polystyrene samples obtained by different laboratories. Similar to the case with zero-shear viscosity, J° shows two regions with drastically different molecular-weight dependences, separated by a transition point M. Above M, J° is basically independent of molecular weight, and the data points fluctuate mainly because J° is very sensitive to the small variations among the molecular-weight distributions, even though all nearly monodisperse, of the studied samples. Below M, the relation of log(Jg) to log(Miu) has an apparent slope of one. The explanation for the... 

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