Tuneable phase behaviour and glass transition via polymerization-induced phase separation in crosslinked step-growth polymers. Issue 23 (6th June 2022)

• Record Type: Journal Article
• Authors: Leguizamon, Samuel C.; Ahn, Juhong; Lee, Sangwoo; Jones, Brad H.
• Is Part Of: Soft matter. Volume 18:Issue 23(2022)
• Page Start: 4455
• Page End: 4463
• Publication Date: 2022-06-06
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/d2sm00485b
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : A universal approach to tune polymerization-induced phase separation is expanded and studied by X-ray scattering and dynamic mechanical analysis. Abstract : Once limited to chain-growth polymerizations, fine control over polymerization-induced phase separation (PIPS) has recently been demonstrated in rubber-toughened thermoset materials formed through step-growth polymerizations. The domain length scales of these thermoset materials can be elegantly tuned by utilizing a binary mixture of curing agents (CAs) that individually yield disparate morphologies. Importantly, varying the composition of the binary mixture affects characteristics of the materials such as glass transition temperature and tensile behavior. Here, we establish a full phase diagram of PIPS in a rubber-toughened epoxy system tuned by a binary CA mixture to provide a robust framework of phase behaviour. X-Ray scattering in situ and post-PIPS is employed to elucidate the PIPS mechanism whereby an initial polymerization-induced compositional fluctuation causes nanoscale phase separation of rubber and epoxy components prior to local chain crosslinking and potential macrophase separation. We further demonstrate the universality of this approach by alternatively employing binary epoxy or binary rubber mixtures to achieve broad variations in morphology and glass transitions.