Rubber Toughening as a Strategy to Co-Design the Mechanical and Transport Properties of Amphiphilic Block Copolymer Membrane

Amphiphilic block copolymers have been widely used to fabricate ultrafiltration (UF) membranes with ordered pores through self-assembly assisted nonsolvent-induced phase separation (SNIPS). However, these membranes are often brittle and incompatible with large-scale manufacturing. Designing membranes with both optimal mechanical and transport properties is critical for enabling advanced separations by UF.



In this poster, I will present a series of amphiphilic poly[styrene-­b-isoprene-b-styrene-b-4 vinyl pyridine] (SISV) block copolymers as potential candidates for such membranes. This series features polymers with similar molecular weight but varying isoprene content (0-36 wt.%). I will show that, at moderate isoprene contents of 10 wt.%, the fracture behavior transitions from brittle to ductile due to the impact of the rubbery block on the probability of craze nucleation and growth. While at high isoprene contents of 36 wt.%, (where total volume fractions of the styrene and isoprene blocks are equal) changes in block copolymer ordering result in strain hardening and rubber-like fracture. These findings extend the concept of rubber toughening in amphiphilic block copolymer SNIPS membranes, paving the way for designing advanced materials with an optimal combination of mechanical and transport properties.