Directional Phase Separation of Binary Polymer Blends Driven by Photo-Cross-Linking with Linearly Polarized Light

Abstract

Phase separation of anthracene-labeled polystyrene/poly(vinyl methyl ether) (PSA/PVME) blends was induced by photo-cross-linking the PSA chains with linearly polarized light in the one-phase region of the blend. The cross-linking reaction was performed by taking advantage of the polarization-selective photodimerization of anthracene labeled on the PSA chains. Under this particular irradiation condition, the spatial symmetry of concentration fluctuations was broken, resulting in anisotropic phase separation directed by the exciting polarization. By comparison of these experimental data with those obtained by using unpolarized light under the same conditions, it was found that the morphology induced by linearly polarized light reflects the interference between instabilities propagating with different rates along different directions in the reacting blends.

Spinodal decomposition of chemically reactive binary mixtures

“…On the other hand, early experimental observations of the influence of chemical reactions on phase separation include a study of pattern formation in a polymer blend with segregation coupled to a transesterification reaction, 19 or the introduction of photo-cross-linking reactions to binary and ternary phase-separating mixtures by Tran-Cong and collaborators. [20][21][22][23][24][25] In fact, a number of works indicated that chemical reactions may slow down the phase separation in polymer blends; in particular, Glotzer et al 26 studied by Monte Carlo simulation the phase separation of a binary mixture in the presence of a reversible A ⇋ B reaction, showing that, unlike the nonreacting case, phase separation proceeds only to a certain extent, until the system freezes into a lamellar morphology, due to a suppression of low wavenumber composition fluctuations. 27 Ever since a number of similar studies have been conducted to further investigate the influence of reversible reactions on binary and ternary systems undergoing phase separation, based on alternative numerical methods and model equations.…”

What Is Nonlinear Dynamics and How Does It Relate to Polymers?

“…Recently, it was found that typical structures resulting from these competing mechanisms, such as hexagonal phase with the length scales in the intermediate range (micrometers), can be also obtained by the competition between cross-link reaction and phase separation in polymer mixtures [52]. Finally, it is worth noting that by introducing some sort of anisotropy into these competing interaction processes, such as reaction anisotropy induced by linearly polarized light [53] or asymmetric interactions in phase separation of block copolymers by molecular design [54], a wide variety of ordered structures can be generated.…”

Rheological Behavior of Hydrogen Bonding Miscible Blend: High Molecular Weight Poly(2-vinyl pyridine) and Low Molecular Weight Poly(4-vinyl phenol)

“…For the latter case, the phase-separated morphologies play an essential role in determining their properties 3) . Therefore, the control of the morphologies has often been a topic in controlling their properties [4][5][6][7][8] . On the other hand, for the former case, the parameters that can control properties are only two: the pure component properties and intermolecular interactions.…”