Solubility rates

The ratio Mn/Mn can be expressed as a ratio of solubility rates before and after irradiation according to the relationship given by Greeneich (b). 

Radiation Degradation and Film Solubility Rates of Poly(butene-l-sulfone)... 

The purpose of this paper was to establish a relationship between unirradiated PBS film solubility rates and molecular weight and then compare irradiated PBS film solubility rates to the solubility rates predicted by this relationship. Contributions to the solubility rate of irradiated PBS films from radiation-induced changes other than molecular weight decrease were assessed from such a comparison. Radiation G-values for PBS were determined as a first step in the comparison process. 

Solubility Rate Measurements. Solubility rates, Sr, were determined by measuring PBS film thickness as a function of development time. PBS films coated on silicon wafers were broken into several pieces. Each piece was dipped into n-butyl acetate, BuAc, and the development time measured. The film was rinsed in isopropanol and baked at 120 C for 30 minutes to remove residual solvents. Film thickness was measured by interferometry. The temperature of the developer, BuAc, was controlled at 2S C O.OS C and the developer was not stirred or agitated during the deydopment process. Plot of film thickness vs. development time were linear for low Mw films. Films having M, greater than 400,000 g/mole did not completely dissolve in BuAc. 

Table III lists the contribution to the overall irradiated film solubility rate from the enhanced solvent penetration resulting from radiation exposure. The values for Sr(IF) and Sr(IP) in Table III were calculated using the equations shown in Figure 2. The % contribution to the overall solubility rate, 100 [Sr(IF)—Sr(IP)]/Sr(IF), shown in Table III increased as the radiation dose increased. This behavior is expected since the number and possibly the size of the voids created in the film would be expected to increase as the radiation dose increased.

More evidence for enhanced porosity in irradiated PBS films is provided by postexposure annealing experiments. The solubility rate of an irradiated MP20 film which was annealed for 30 minutes at 120 C before dissolution was lower than the solubility rate of the unannealed film. Table IV shows the measured solubility rate loss and the expected solubility rate loss, Sr(IF) — Sr(IP), if all the porosity created during irradiation were removed by annealing. The soluMity rate of the annealed IF-type films are somewhat higher than IP-films of similar M . Thus, the annealing process removes most but not all of the porosity created during irradiation. 

The chemical structure of PBS also may be altered by exposure to radiation and such changes may contribute to the solubility rate difference between an exposed and an unexposed PBS film. U-type films were prepared from unirradiated powders while IP-type films were prepared from irradiated powders. Inspection of Table II or Figure 2 shows that the three U-type films have slightly larger solubility rates than IP-type films of comparable M. The solubility rate differences between IP and U-type films are small relative to the differences between IP and IF type films. The solubility rate difference between a U and an IP film of comparable M must arise from chemical structural differences between irradiated and unirradiated powders. These radiation-induced changes may also be responsible for differences observed in the elution behavior between irradiated and unirradiated PBS samples in gel permeation chromatography experiments. Irradiated PBS samples yield abnormally broad elution curves while unirradiated samples elute normally I3.8I. 

Another measure of sensitivity can be obtained from the rate of dissolution of exposed versus unexposed film at various doses. The amount of energy needed to obtain some arbitrary ratio of rates or the exponent of the dissolution rate ratio versus dose at high doses may be used. In the present study, both a contrast curve and a solubility rate ratio versus dose data are reported for the copolymer of maleic anhydride with alphamethylstyrene. However, these tests are burdensome when many materials are to be screened... 

Measures of change Viscosity measurements Intrinsic viscosity Viscosity-average molecular weight Molecular weight distribution, GPC Solubility Rates Thickness changes on development... 

The higher sensitivity indicated by the increased GCr) value can also be tested by measuring the solubility rate ratio, S/S0 where... 

The solubility rate ratio of a resist depends not only on G(s), but also on the initial molecular weight of the polymer and several constants, the relation being the following (25) ... 

For the solubility rate studies, thin films of polymer were spun on silicon wafers as described previously for the G(s) measurement. The wafers were then immersed in the developing solvent at a controlled temperature. The dissolution rate was monitored with a laser-interferometer device (28). In order to compare the dissolution rate ratios of PMMA and p(MMA-MA) (Figure 5) it is important to compare polymers of the same initial molecular weights. The... 

Bulky AlkyllAryl Substituted Phenol-Formaldehyde Novolak Resins. Low molecular weight cresol-formaldehyde Novolak resins tend to have high solubility rates in alkaline developers. To increase developer resistance, Novolak resins containing a hydrophobic chain incorporated on a portion of the phenol group were synthesized, as shown below (17). As the number of alkyl... 

The design of crystallizers is based on knowledge of phase equilibria, solubilities, rates and amounts of nuclei generation, and rates of crystal growth. Each system is... 

The main drawback in the use of fumaric acid is its slow solubility rate in compar ison with citric acid, and special methods need to be employed in its dissolution. It has been claimed that fumaric acid and its salts have a tendency to stabilise the suspended matter in both flash-pasteurised and frozen fruit concentrates (McColloch Gentile, 1958). 

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