Kinetically Controlled Photoinduced Phase Separation for Hybrid Radical/Cationic Systems

Abstract

Controlling phase separation in polymer systems has shown significant promise in combining properties of different components into an integrated polymer system. In this work, we investigate the effect of photoinduced phase separation on polymer morphology and properties in hybrid radical/cationic systems composed of butyl acrylate (BA) and difunctional oxetane (DOX). We show that the irradiation intensity has a significant effect on the formation of phase-separated domains. By increasing the irradiation intensity at fixed co-monomer composition, the morphology changes from one with a continuous soft BA domain to one with co-continuous BA (soft) and DOX (hard) domains. At higher irradiation intensity, the domain size of each phase is decreased because of fast photopolymerization, which significantly limits monomer/polymer diffusion. The smaller domain size enhances the flexibility and strength of the phase-separated polymers. On the other hand, the irradiation intensity has little to no effect on the polymer structure or properties for systems that do not phase-separate. Dynamic mechanical analysis demonstrates that phase separation associated with higher irradiation intensity during cure contributes to a 40-fold increase in toughness and up to fivefold higher elongation at break. This behavior is attributed to the formation of polymers with co-continuous hard/soft domains and decreased domain size. This study demonstrates that the morphology and properties of photoinduced phase-separated materials can be controlled by altering the initiation irradiation intensity for hybrid radical/cationic materials.

NIR‐Sensitized Cationic and Hybrid Radical/Cationic Polymerization and Crosslinking

“…Oxetanes have moved in the focus of photoinduced cationic crosslinking [52, 53] . Their material properties have attracted the interest of applications comprising electronic components [57, 58] .…”

Development of High-Resolution Three-Dimensional-Printed Extracellular Matrix Scaffolds and Their Compatibility with Pluripotent Stem Cells and Early Retinal Cells

“…However, the dynamic environment that occurs during photopolymerization has been known to induce phase separation and disruptions in anticipated polymer architecture. 26,27 These previous studies suggest that tuning polymerization rate could alleviate phase separation effects, but this theory should be investigated in future studies, particularly if additional components are added to the formulation. The cell viability data we collected suggest that methacrylated gelatin and gelatin/HA biopolymer formulations are appropriately biocompatible for use in in vitro retinal tissue engineering.…”

NIR‐sensibilisierte kationische und hybride radikalische/kationische Polymerisation und Vernetzung

“…Monomere mit Vinylether [51] oder Oxetanstruktur [52–56] ergänzen die Möglichkeiten der kationischen Vernetzung. Solche Untersuchungen zur kationischen Polymerisation können erweitert werden, um die Bildung interpenetrierender Polymernetzwerke zu untersuchen, was unter Verwendung von UV‐Bestrahlung durchaus fehlschlagen kann [52, 53] . Die NIR‐sensibilisierte Polymerisation von hybriden Systemen basierend auf einem radikalischen und kationischen Mechanismus kann neue Einblicke in dieses Gebiet bringen, weil diese Systeme zusätzlich Wärme zur Verfügung stellen, welche durch interne Konversion des Sensibilisators generiert wurde [11, 26] .…”

“…Oxetane sind in den Fokus der photoinduzierten kationischen Vernetzung gerückt [52, 53] . Ihre Materialeigenschaften haben das Interesse von Anwendungen geweckt, die auch elektronische Komponenten beinhalten [57, 58] .…”

“…Monomere mit Vinylether [51] oder Oxetanstruktur [52][53][54][55][56] ergänzen die Mçglichkeiten der kationischen Vernetzung. Solche Untersuchungen zur kationischen Polymerisation kçnnen erweitert werden, um die Bildung interpenetrierender Polymernetzwerke zu untersuchen, was unter Verwendung von UV-Bestrahlung durchaus fehlschlagen kann.…”