PEE/PDMS

Schwahn et al. 1995, ginzburg criterion for the mean-field to 3-dimensional ising crossover in polymer blends, Phys. Rev. E, Vol. 52, No. 2, PP. 1288-1291 19%, Temperature and pressure dependence of the order parameter fluctuations, conformational compressibility, and the phase diagram of the PEP-PDMS diblock copolymer. Physical Reuieiv Letters, Vol. 77, No. 15, PP. 3153-3156 2001, Abnormal pressure dependence of the phase boimdaiies in PEE-PDMS and PEP-PDMS binary homopolymer blends and diblock copwlymers. Macromolecules, Vol. 34, No. 6, PP. 1694-1706... 

Fig. 24 Structure factor in Zimm representation for the PEE PDMS blend with different diblock concentrations. The contribution of the term decreases with diblock content because of the reduced strength of the surface energy. Instead the next higher expansion term becomes relevant and dominates...

Figure 25 displays the effects of thermal composition fluctuations on the inverse susceptibility S(0) for a (PEE PDMS) mixture (sample 10 in Table 2) versus 1/T for different diblock concentrations below the Lifshitz line [48]. The critical temperatures determined from S Ho) = 0 decrease with increasing diblock content in a similar way as shown for the (PB PS) blend (Fig. 23). The = 4.3% sample behaves as a pure blend At high temperatures S (0)...

Fig. 25 Susceptibility versus inverse temperature of the PEE PDMS blend at different diblock content. The increase of the curvatiue is clearly visible at higher diblock content...

The SANS data from the (PEE PDMS) mixtine between 9 and 11% diblock concentration (not shown here) [49] and the (PB PS) mixture between 6 and 8% [52] exhibit at low and high temperatmes the characteristics of diblock copolymers, i.e. S(Q) shows a maximum at the finite Q, while at intermediate... 

In the (PB PS) mixture a crossover from Ising to isotropic critical Lifshitz behavior was observed at about 4.8% diblock concentration as indicated by the dashed area in the phase diagram of Fig. 23. On the other hand, a crossover to a renormalized Lifshitz critical behavior was not observed in this system. The susceptibility critical exponent y of both systems has been depicted in Fig. 26 versus diblock concentration. A crossover of the exponent y at about 4.8% and 6.2% from the Ising 1.24 to larger values is visible for the (PB PS) and (PEE PDMS), respectively. A constant y = (1.62 0.01) and... 

Fig. 26 Critical exponent of the susceptibility y versus diblock content of two homopolymer blend-diblock copolymer melts. The crossover to the renormalized Lifshitz critical behavior with y = 1.62 is clearly visible. Differences of the two blends are remarkable In PEE PDMS a plateau of y = 1.62 and a further crossover to a renormalized Lifshitz behavior is found. In PB PS, on the other hand a double critical point with the Lifshitz critical exponent y = 1.62 is observed...

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