Controlling the morphology of polymer blends using periodic irradiation

Abstract

Morphology is the decisive factor controlling practical properties such as impact strength or transparency in multiphase polymeric materials. The co-continuous structure formed by polymers has been of great interest to material scientists because of their superiority over those with random morphology. Although a number of efforts--including forcibly freezing the spinodal structure of polymer blends--have been made to produce materials with co-continuous structures, an efficient method for controlling their regularity is still lacking. Here, we demonstrate a novel method using periodic photo-crosslinking to control the length-scale distribution of the spinodal structure in binary polymer blends. It was found that the period distribution of the resulting co-continuous structure became significantly narrow under this periodic forcing. Also, there exists a particular irradiation frequency at which the periodic structure exhibits a minimum, indicating the existence of an ordering process driven by the external modulation frequency. Our findings reveal an easy way to produce polymer materials that is not only useful for optical applications, but also promising for biological separation, such as hemodialysis.

Colloquium: Phase transitions in polymers and liquids in electric fields

“…In addition, photochemical reaction was induced in anthracene-labeled polystyrene-PVME blends irradiated by periodic UV light. The distribution of length scales in the resulting spinodal decomposition depends sensitively on the applied frequency (Tran-Cong-Miyata et al, 2004).…”

Imaging with Chemical Analysis: Adsorbed Structures Formed during Surface Chemical Reactions

“…[39,40] This concept has already been applied to non-equilibrium chemical reactions interconverting two separating polymer species by photoisomerisation, leading to the creation of polymer blends with desired morphologies. [41,42] The most important feature of the adsorbed microstructures formed by "chemically frozen" phase separation is that they are "adaptive"; that is, they develop and remain stable on the surface only under certain reaction conditions; they can be dissolved and again formed; and their wavelength can be controlled by changing the reaction rate. This would not be possible for any lithographic technique or growth-based fabrication of nanostructures.…”

Modeling the Self‐Assembly of Ternary Blends that Encompass Photosensitive Chemical Reactions: Creating Defect‐Free, Hierarchically Ordered Materials

“…There are several examples of reaction-induced phase separation in photosen sitive systems. Blends of -stilbene labeled polystyrene and poly(vinyl methyl ether) (PSS/PVME) constitute one well-known example [16][17][18][19][20][21]. Upon irradiation, the stilbene moieties on the PSS chains undergo a reversible trans-cis photo isomerization.…”

“…Thus, a reversible chemical reaction and phase separation taking place simultaneously within this binary blend. Other photosensitive pendent groups can also be used to yield a similar behavior [16][17][18][19][20][21].…”