Copolymer static structure factor

Fig. 6.6 Variation of the static structure factor S(Q) measured on hPE-dPEE diblock copolymer chains (sample IV) as a function of the wave number Q. Temperature closed star 393 K, closed circles 403 K, closed square 413 K, inverted triangle 423 K, closed star 433 K, open triangle 433 K, open circle 453 K, open square 463 K. Solid lines represent the fit with a two-component static RPA approach (Eq. 6.12). (Reprinted with permission from [44]. Copyright 1999 American Institute of Physics)...

Olvera de la Cruz and Sanchez [76] were first to report theoretical calculations concerning the phase stability of graft and miktoarm AnBn star copolymers with equal numbers of A and B branches. The static structure factor S(q) was calculated for the disordered phase (melt) by expanding the free energy, in terms of the Fourier transform of the order parameter. They applied path integral methods which are equivalent to the random phase approximation method used by Leibler. For the copolymers considered S(q) had the functional form S(q) 1 = (Q(q)/N)-2% where N is the total number of units of the copolymer chain, % the Flory interaction parameter and Q a function that depends specifically on the copolymer type. S(q) has a maximum at q which is determined by the equation dQ/dQ=0. 

In pRISM theory, the MIST process is directly reflected in the normalized static structure factor, S(copolymer system is cooled and microdomains are forming, the peak scattering intensity grows in a mean-field maimer corresponding to the linear portion of the S(< ) curve in the coordinates Extrapolation of this linear portion to divergent intensity defines an apparent mean-field spinodal temperature. ... 

De la Cruz and Sanchez [3] have calculated, using a mean-field theory, the phase stability criteria and static structure factors for n-arm star diblock copolymers [(AB) star]. According to their calculations, as n becomes large, the (AB) star begins to develop a core-and-shell structure. The core is rich in A monomer and the shell is rich in B monomer even in the disordered state. 

Relatively few theoretical studies have been devoted to the conformational characteristics of nonlinear block copolymers in different solvent environments. Burchard and coworkers [284] studied theoretically the behavior of the static and dynamic structure factors for regular star-block copolymers in dilute solutions. They considered different cases where the refractive index (n)s of the solvent takes certain values with respect to the corresponding refractive indices of the inner and outer blocks. A different dependence of the ratios... 

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