Peer review of: A solution-processable and ultra-permeable conjugated microporous thermoset for selective hydr (2020)

Reviewers' comments: 

Reviewer #1 (Remarks to the Author): 

This is an interesting an potentially useful method of obtaining a highly size selective membrane 
for gas permeability. I recommend publication with the following amendments. 

1. Permeability measurements for helium should be added as this will help to confirm the the size 
selectivity of the membranes. 

2. Data should added for PIM-BTrip (E&ES, 2019, 12, 2733) to the Robeson plots and S table. 

Otherwise I am happy to recommend publication of this exciting research. 


Reviewer #2 (Remarks to the Author): 

The authors describe a thermal polymerization technique to produce a conjugated microporous 
thermoset (CMT) as gas separation membrane. The authors describe the direct synthesis on 
several different substrates (Alumina and Polymers, e.g. Nylon) and with different deposition 
techniques such as filtration. The membrane exhibits extremely high permeabilities up to ~40.000 
barrer (H2) and moderate selectivity. The presented material is very interesting. 
However, the manuscript structure is a bit confusing and I see several points necessary to make 
the paper suitable for publication in Nat. Commun. 
Some minor remarks: 
Line 159 – “1D nanotubes” – since you have multilayers (thickness of at least 5nm) of your 
material your nanotubes correspond to 3D structure. I am not convinced that it is only a 
monolayer. I would simply refer to “nanotubes”, without dimensions. 
Line 196 – “concerntration” should be concentration 
Line 281 – “selevtivity” should be selectivity 
You should read the paper carefully again to ensure there are no typos anymore. 

Some major remarks: 
1) Page 8, 171 – you have such a narrow size distribution, that you should be able to see it on the 
XRD, since it must be ordered in some way. XRD data should be added to your general 
characterization methods? Compare for PIMs: https://doi.org/10.1002/adsu.201800044 

2) In Figure 1e there is a nice AFM picture of the single sheet. In Figure 2h there is another AFM 
image. The latter is not really needed to state your points, everyone would agree that your sheet 
thickness stays the same after filtration. 

3) In Figure 2e you show your membrane prepared by filtration, with the SEM top view and cross 
section in Figure 2 f/g. This membrane is 20 µm thick and was not used for any of your 
experiments, as far as I see it. Why do you not give the actual membrane, that was used for your 
experiments in the main section (which now is in SI Fig. 16). I cannot really understand your 
filtration technique to prepare a membrane, when you afterwards measure a different membrane, 
which is directly synthesized. 

4) It is completely unclear, where your data originates from. You write that you use a 1 µm thick 
membrane for H2/CO2 mixed gas in line 252-253. Then, in line 257-259 you speak of a 0.5 µm 
thick membrane, where you collected your single gas permeation data on. 
Keep it consistent and measure it all for the same sample (and add error bars from your control 
experiments). And if you measure it again, make sure to measure everything at elevated 
temperatures and in mixed gas permeation (see point 5). 

5) The next thing I find is Figure 3 – You compare the Robeson plot with your ideal permeability 
and selectivity - this is not consistent. You should easily use your “real” permeability data 
from mixed gas measurements of the binary mixtures. I think you would still be better than all the 
other points. However, there is often a strong variation between ideal and real permeation data. 
You should also check back on your data points, whereas the data points originate from real or 
ideal permeation data and if it is comparable. 

6) The same point as in my comment (5) – Line 281-282. 

7) Line 310-313. Your data seems to be inconsistent here. When heating up neat materials 
outgoing from general physical knowledge about adsorption and diffusion, even in zeolites, MOFs, 
COFs and especially in polymers (solution diffusion), your permeability ALWAYS increases, whereas 
your selectivity ALWAYS decreases. This is the general trade-off in membrane science. I can also 
not find the data set on this study in the supporting information, where you measure at different 
temperatures. 

After the manuscript is subjected to a major revision considering the points listed above, it may be 
suitable for a publication in Nat. Comm.