Evaluation of Interaction Parameters

SEES triblock copolymer and MA-g-SEBS were supplied by Asahi Chemical Co., Ltd. Table 18.4 shows the characteristic properties of the copolymers. The MA-g-SEBS samples (M1911 and M1913) were received by modihcation of SEES (H1041) with MA. The number average molecular weight and the polydispersity index MJM were obtained by gel permeation chromotog-raphy (GPC) with polystyrene calibration. 

The common solvent dioctyl phthalate (DOP) was used to reduce the binary segmental interaction between S and EB so as to lower the ODT temperature Todt in the range from the room temperature to the degradation temperature of the polymer. The concentration of the polymer in the DOP solution was 60wt%. 

The samples were first brought into the disordered state by preheating at 240°C and then were cooled down to the appropriate temperature. After heating at the temperature for 5 min to ensure thermal equihbration, the SAXS measurement was started. SAXS profiles were corrected for absorption, air scattering, and thermal diffuse scattering. 

The most powerful and direct method to measure the interaction between polymers A and B is to analyze the phase transition of a mixture of A and B [7] or the ODT of a block copolymer comprising A and B connected by the covalent bond [8-10]. The segmental interaction between A and B plays an important role in these transition phenomena. 

The interaction between S and EB segments with and without the MA modification was estimated by analyzing the ODT of SEES triblock copolymer. Notice that the tacticity effect on the interaction [11] was ignored for simplicity, and it was supposed that syndiotactic S-EB and atactic S-EB interactions are the same. 

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As outlined in the previous chapters, changes of isopotential volume quantities are of special relevance for protein scientists, since most experiments in physical biochemistry and biophysics are done on solutions which have been dialyzed to equilibrium. Eor evaluation of interaction parameters by density measurements, however, both the isomolal and isopotential volumes are required. 

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