Abd Rayes

13 Questions 11 Answers 0 Followers

Questions related from Abd Rayes

Why is my GO/polymer ultra-thin film showing poor gas selectivity?

Hello, I am creating a GO/polymer scaffold using a 2/100 ratio in a THF suspension (the polymer is soluble). I would then spin coat it onto a porous support. The membranes show reasonable...

01 January 2020 9,019 4 View

What is the procedure for spin coating multiple layers of monomer onto a porous support?

Hello, I am trying to spin coat a few layers of monomer solution in THF onto a porous support. What would be the best procedure to do so? Intuitively, it seems that every new coating would...

11 November 2019 3,716 4 View

What is the reason I cannot separate my siloxane material properly using column chromatography?

hello, I am trying to separate a star shaped siloxane polymer from starting material using column with some luck. Using 70/30 hexane/EA, I can get my product but with a few problems: 1- The...

07 July 2019 9,004 3 View

What side products can you expect from hydrosilylation reaction with styrenes?

Hello, I am trying to purify a reaction product of hydrosilylation with a styrene compound using Karstedt's catalyst. However, it seems to be cumbersome for the following reason. After...

04 April 2019 2,574 1 View

Why am I getting uneven coating/Marangoni effect when spin coating PDMS onto LDPE?

Hello, I have been trying to spin coat a layer of PDMS (Slygard 184) onto LDPE. My problem is that with Toluene, I get the Marangoni effect, where I get small circular spots of PDMS onto LDPE...

11 November 2018 9,524 4 View

How can I make a poly (ethylene-co-vinyl alcohol), EVOH, membrane flexible?

Hello, I am using phase inversion to make EVOH membranes, using DMSO as a solvent and ethanol as a non-solvent. When the membrane is wet it is flexible and stretchable. However, once I dry it in...

11 November 2018 1,696 0 View

Why am I getting a hole in the middle of film during spin coating onto PDMS?

Hello, I am spin coating a non-polar monomer onto a PDMS layer, with the coating solution made up of chloroform. The concentration is very low. However, I keep getting a hole in the middle of the...

11 November 2018 4,850 0 View

Is it possible to create LDPE membranes by phase inversion?

Hello, I have tried to create LDPE membranes using phase inversion but the result was a get-like, nonuniform membrane. The problem I think, is that LDPE can only dissolve in xylene at high...

10 October 2018 5,689 0 View

Why is my PDMS layer giving a low air permeability?

Hello, I am using Sylgard 184 crosslinked PDMS for composite membranes to test for air permeability. when I thermally crosslink it to test the permeability I get a value that is 50x less than...

10 October 2018 1,530 0 View

Can you spin coat a polymer using a solvent that swells the substrate?

Hello, I have been looking for references regarding this matter. I am trying to spin coat a polymer onto a PDMS substrate. The best solvent I can use is chloroform. However, it strongly swells...

10 October 2018 1,192 0 View

What is a simple way to fabricate a PDMS gutter layer?

Hello, I would like to spin coat PDMS onto a porous membrane to use as a gutter layer. However, I cannot seem to find any references on how to do so. I need to know what kind of PDMS to buy and...

10 October 2018 4,292 0 View

How can I avoid film cracking during solution casting of LDPE?

Hello, I have been successful in solution casting LDPE with p-xylene but only for a very thin film (1-2 wt.% LDPE casting solution). However, I need a thicker film (4% LDPE). WHen I try...

08 August 2018 9,256 14 View

During spin coating, what causes the film to be thinner in the middle and thicker on the edges?

Trying to spin coat a monomer onto a polymer substrate. The two materials have good wettability. I tried different concentrations and seem to get the same problem. I also tried doing the spin...

07 July 2018 7,663 6 View