thickness and the finger-like structure section. For filtration
applications, such asymmetric finger-like structures would
favor high fluxes, owing to the draining effect of the macrovoids, while keeping the sieving rejection thanks to the top
surface. Unfortunately, these membranes exhibited poor
mechanical properties, hindering their use for filtration tests.
The poor mechanical properties associated with the asymmetric structures and their macrovoids were something
already observed in the literature (Tsai et al. 2001). But, if
the asymmetric structures may partly cause the poor
mechanical properties of these membranes, the nature of the
polymer could be involved too. For the membrane
Table 7 P(3HB3HV)-based membranes made by NIPS and EIPS
Dope solution composition (wt %)
Membrane fabrication technique
Structure
Thickness ( µm)
Mechanical integrity
P(3HB3HV)/NMP (15/85)
NIPS—In water bath
Asymmetric
77
Very fragile
P(3HB3HV)/NMP (20/80)
NIPS—In water bath
Asymmetric
113
Very fragile
P(3HB3HV)/NMP (25/75)
NIPS—In water bath
Asymmetric
130
Very fragile
P(3HB3HV)/CHCl 3 (10/90)
EIPS
Symmetric
18
Good
P(3HB3HV)/PEG300/CHCl 3 (10/5/85)
EIPS
Symmetric
18
Good
P(3HB3HV)/PEG8000/CHCl 3 (10/5/85)
EIPS
Symmetric
42
Good
Fig. 5 SEM images of the
membranes prepared by NIPS
with different P(3HB3HV)
concentrations (w/w). Surface on
the left and cross section on the
right
Polyhydroxyalkanoates (PHAs) for the Fabrication …
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