Self-assembled Block Copolymer Membranes with Bioinspired Artificial Channels
Burhannudin Sutisna, Suzana Pereira
جامعة الملك عبدالله للعلوم والتقنية · السعودية
Nature is an excellent design that inspires scientists to develop smart systems. In therealm of separation technology, biological membranes have been an ideal model forsynthetic membranes due to their ultrahigh permeability, sharp selectivity, and stimuliresponse.In this research, fabrications of bioinspired membranes from block copolymerswere studied. Membranes with isoporous morphology were mainly prepared using selfassemblyand non-solvent induced phase separation (SNIPS).An effective method that can dramatically shorten the path for designing new isoporousmembranes from block copolymers via SNIPS was first proposed by predetermining atrend line computed from the solvent properties, interactions and copolymer block sizesof previously-obtained successful systems. Application of the method to new copolymersystems and fundamental studies on the block copolymer self-assembly were performed.Furthermore, the manufacture of bioinspired membranes was explored using (1)poly(styrene-b-4-hydroxystyrene-b-styrene) (PS-b-PHS-b-PS), (2) poly(styrene-bbutadiene-b-styrene) (PS-b-PB-b-PS) and (3) poly(styrene-b-γ-benzyl-L-glutamate) (PSb-PBLG) copolymers via SNIPS. The structure formation was investigated using smallangleX-ray scattering (SAXS) and time-resolved grazing-Incidence SAXS. The PS-b-PHS-b-PS membranes showed preferential transport for proteins, presumably due to thehydrogen bond interactions within the channels, electrostatic attraction, and suitable poredimension. Well-defined nanochannels with pore sizes of around 4 nm based on PS-b-PB-b-PS copolymers could serve as an excellent platform to fabricate bioinspiredchannels due to the modifiable butadiene blocks. Photolytic addition of thioglycolic acidwas demonstrated without sacrificing the self-assembled morphology, which led to afive-fold increase in water permeance compared to that of the unmodified. Membraneswith a unique feather-like structure and a lamellar morphology for dialysis andnanofiltration applications were obtained from PS-b-PBLG copolymers, which exhibiteda hierarchical self-assembled morphology with confined α-helical polypeptide domains.Our results suggest that bioinspired nanochannels can be designed via block copolymerself-assembly using classical methods of membrane preparation. Investigation of themembrane formation mechanism leads us to a better understanding of the designstrategies for the development of self-assembled nanochannels from block copolymers. Infurther outlook, our research could give a contribution to the discovery of futuregeneration materials for water purification and desalination, as well as biologicalseparation.