Nature is an excellent design that inspires scientists to develop smart systems. In the
realm of separation technology, biological membranes have been an ideal model for
synthetic membranes due to their ultrahigh permeability, sharp selectivity, and stimuliresponse.
In this research, fabrications of bioinspired membranes from block copolymers
were studied. Membranes with isoporous morphology were mainly prepared using selfassembly
and non-solvent induced phase separation (SNIPS).
An effective method that can dramatically shorten the path for designing new isoporous
membranes from block copolymers via SNIPS was first proposed by predetermining a
trend line computed from the solvent properties, interactions and copolymer block sizes
of previously-obtained successful systems. Application of the method to new copolymer
systems 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 smallangle
X-ray scattering (SAXS) and time-resolved grazing-Incidence SAXS. The PS-b-
PHS-b-PS membranes showed preferential transport for proteins, presumably due to the
hydrogen bond interactions within the channels, electrostatic attraction, and suitable pore
dimension. 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 bioinspired
channels due to the modifiable butadiene blocks. Photolytic addition of thioglycolic acid
was demonstrated without sacrificing the self-assembled morphology, which led to a
five-fold increase in water permeance compared to that of the unmodified. Membranes
with a unique feather-like structure and a lamellar morphology for dialysis and
nanofiltration applications were obtained from PS-b-PBLG copolymers, which exhibited
a hierarchical self-assembled morphology with confined α-helical polypeptide domains.
Our results suggest that bioinspired nanochannels can be designed via block copolymer
self-assembly using classical methods of membrane preparation. Investigation of the
membrane formation mechanism leads us to a better understanding of the design
strategies for the development of self-assembled nanochannels from block copolymers. In
further outlook, our research could give a contribution to the discovery of future
generation materials for water purification and desalination, as well as biological
separation.
Date of Award | Apr 2018 |
---|
Original language | English (US) |
---|
Awarding Institution | - Physical Sciences and Engineering
|
---|
Supervisor | Suzana Nunes (Supervisor) |
---|
- Block copolymer
- Membrane
- Bioinspired channels
- Self-assembly
- Water Purification
- Protein seperation