Polymerization induced phase separation PIPS

The dynamic flexibility of supramolecular polymers is exploited by Keizer et al. [34]. in polymerization-induced phase separation (PIPS) with hydrogen-bonded supramolecular polymers. In PIPS, a supramolecular polymer is dissolved in a reactive monomer, which is subsequently polymerized to cause phase separation resulting in two polymeric phases with certain morphology. PIPS is currently used to produce multiphase composite materials like high-impact polystyrene, avoiding the use of solvent and consequently resulting in the fast and clean production of polymeric materials. 

Polymerization-induced phase separation (PIPS) (Yuhong 2013). 

The phase-separation method was developed at Kent State University in the late 1980s. It consists of in sitn segregation of liqnid crystalline microdroplets from a homogeneous mixture of liquid crystal and polymer/prepolymer, indnced by a factor that gave the techniqne its name, as follows (a) polymerization-induced phase separation (PIPS) (b) solvent-induced phase separation (SIPS) and (c) thermally induced phase separation (TIPS). 

HPDLCs are fabricated by photo-polymerization induced phase separation (PIPS) method by exposing a mixture of LC(s) and photo-sensitive monomer(s) to a laser optical interference field [38 1]. The laser optical field is created by two or multiple coherent laser beams. The periodic structure in HPDLCs is composed of alternating lamellas of polymer-rich layer and phase-separated LC-rich layer, in... 

Spinodal decomposition is of fundamental importance in processes involving phase separation of polymers in near- and supercritical fluids [145]. Pressure-induced phase separation (PIPS) has recently been used [4], with a novel experimental apparatus [146] that permits the imposition of rapid and controlled multiple pressure quenches, to study spinodal decomposition of near- and off-critical mixtures of a polymer and a compressed solvent following deep quenches into the unstable region. Spinodal decomposition is also important in SAS, in situations where the mass transfer pathway leads to penetration into the unstable region [76,147,148]. It can also be important in RESS involving polymeric solutes [35]. Experimental aspects of spinodal decomposition and the kinetics of phase separation in polymer solutions in near-critical fluids are discussed in the chapter by E. Kiran in this volume. 

Figure 7 Schematic representation of PIPS using hydrogen-bonded supramolecular polymers picture on the left depicts situation before polymerization of the acrylate-monomer, picture on the right depicts situation after the polymerization of the acrylate monomer has induced phase separation.

For PIPS, polymerization of the monomer or pre-polymer component in die initial mixture of liquid crystal, monomer, or pre-polymer, and photo-initiator induces fdiase separation. The conversion of monomer to polymer with thermal or photon initiated polymerization destabilizes the homogeneous mixture and induces phase separation. Photon-initiation affords the flexibility of multi-wavelen processing that has resulted in H-PDLCs and other spatially tailored LCPD morphologies (12). The morphology depends primarily on the choice of liquid crystal and monomer/pre-polymer, the weight fraction of liquid crystal in... 

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