Dear Gopi,

Surface modification can be done through various methods, which can be classified through three main groups: physical (physical adsorption, Langmuir blodgett film), chemical (oxidation by strong acids, ozone treatment, chemisorption, and flame treatment) and radiation (glow discharge, corona discharge, photo activation (UV), laser, ion beam, plasma immersion ion implantation, electron beam lithography, and γ-irradiation)

Q. F. Wei; W. D. Gao; D. Y. Hou; X. Q. Wang (2005). "Surface modification of polymer nanofibers by plasma treatment". Appl. Surf. Sci. 245: 16–20.

For a specific procedure, please read the following text:

Grafting Procedure

Grafting was carried out using eight different procedures. In the first procedure, active centers on the PET yarn were formed by treatment with 5% (wt/v) BP solution in toluene for 30 min at 50°C. Next, the excess of the BP solution was squeezed out and traces of toluene were removed by evaporation for 15 min at 85°C. The pretreated yarn sample was placed into a 1000 ml reactor. First, water and dispersing agent (Irgasol Na) were added to the reactor, and temperatures were raised to 80°C. AA was then added to the reactor. The grafting time was 60 min after which the reaction was stopped and the samples were removed and washed with boiling water for 4-5 hr to remove the traces of monomers and oligomers. But the grafting percentage was not high.Method no. 2: In this method, before grafting, the samples were impregnated with Univadin PB for swelling. The samples were boiled for 1 hr in swelling agent solution with L : R 90 : 1, and after that we followed method no. 1 for grafting. But with this method, also graft percentage was too low. No. 3: Samples were treated with NaOH (10%) with L : R 120 : 1 for 2 hr in boiling temperature, and their weight decreased. Method no. 1 was used for grafting. But grafting percentage was low in this procedure as well. No. 4: At first, samples were impregnated in AA, water and dispersing agent in reactor and temperature raised to 70°C, and benzoyl peroxide solution in benzene (5% wt/v) was added to the reactor. Grafting time was 1 hr. In this method, the grafting percentage was low. No. 5: Samples were swelled in AA solution with water (22%) for 16 hr and 24 hr at 50°C, and after that benzoyl peroxide solution in benzene (5% wt/v) was added to the reactor. The grafting time was 1 hr, but the grafting yield was low.

No. 6: Samples were treated with dichloroethane at 20°C for 60 min, and then benzoyl peroxide solution in Benzene (5% wt/v) was added to the reactor. Grafting was carried out for one hour. The grafting percentage was low in this method as well. No. 7: Samples were boiled in Univadin PB (4 g/lit, 2 g/lit) for 1 hour, and after that they were washed with water, and then benzoyl peroxide solution in Benzene (5% wt/v) was added to the reactor. The grafting time was 1 hr, but in this method the grafting percentage was low. No. 8: The PET fabrics were kept in boiling water containing Univadin. This will let the fabric swell. Then, AA which had been mixed with water (10%) was added to the reactor. The fabric was kept for another 10 minutes to swell under boiling. 0.1 g CuCl2 which was dissolved in water was added to the reactor, and immediately Irgasol NA was added too. Benzoyl peroxide was then added to the reactor (0.33 g in l0 CC of Benzene). After 2.5 hr, the reaction was stopped, and the fabrics were removed and washed 8 times with boiling water to remove the traces of monomer and oligomers. The washed fabric was then dried to a constant weight. The grafting percentage was higher than other procedures; therefore, this method was selected. The graft percentage was calculated from the following equation:𝑊−𝑊𝑜𝑊𝑜×100,(1)whereas W = weight of the rubric after grafting, Wo = weight of the fabric before grafting.

https://www.hindawi.com/journals/isrn/2011/265415/

Aother publications which may interest you are the followings:

Surface Modification of Ultra-high Molecular Weight Polyethylene Membranes Using Underwater Plasma Polymerization

http://link.springer.com/article/10.1007/s11090-013-9476-2

Surface engineerings of polyacrylonitrile-based asymmetric membranes towards biomedical applications: An overview

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.454.2341&rep=rep1&type=pdf

Hoping this will be helpful,

Rafik

Dear Gopi,

Surface modification can be done through various methods, which can be classified through three main groups: physical (physical adsorption, Langmuir blodgett film), chemical (oxidation by strong acids, ozone treatment, chemisorption, and flame treatment) and radiation (glow discharge, corona discharge, photo activation (UV), laser, ion beam, plasma immersion ion implantation, electron beam lithography, and γ-irradiation)

Q. F. Wei; W. D. Gao; D. Y. Hou; X. Q. Wang (2005). "Surface modification of polymer nanofibers by plasma treatment". Appl. Surf. Sci. 245: 16–20.

For a specific procedure, please read the following text:

Grafting Procedure

Grafting was carried out using eight different procedures. In the first procedure, active centers on the PET yarn were formed by treatment with 5% (wt/v) BP solution in toluene for 30 min at 50°C. Next, the excess of the BP solution was squeezed out and traces of toluene were removed by evaporation for 15 min at 85°C. The pretreated yarn sample was placed into a 1000 ml reactor. First, water and dispersing agent (Irgasol Na) were added to the reactor, and temperatures were raised to 80°C. AA was then added to the reactor. The grafting time was 60 min after which the reaction was stopped and the samples were removed and washed with boiling water for 4-5 hr to remove the traces of monomers and oligomers. But the grafting percentage was not high.Method no. 2: In this method, before grafting, the samples were impregnated with Univadin PB for swelling. The samples were boiled for 1 hr in swelling agent solution with L : R 90 : 1, and after that we followed method no. 1 for grafting. But with this method, also graft percentage was too low. No. 3: Samples were treated with NaOH (10%) with L : R 120 : 1 for 2 hr in boiling temperature, and their weight decreased. Method no. 1 was used for grafting. But grafting percentage was low in this procedure as well. No. 4: At first, samples were impregnated in AA, water and dispersing agent in reactor and temperature raised to 70°C, and benzoyl peroxide solution in benzene (5% wt/v) was added to the reactor. Grafting time was 1 hr. In this method, the grafting percentage was low. No. 5: Samples were swelled in AA solution with water (22%) for 16 hr and 24 hr at 50°C, and after that benzoyl peroxide solution in benzene (5% wt/v) was added to the reactor. The grafting time was 1 hr, but the grafting yield was low.

No. 6: Samples were treated with dichloroethane at 20°C for 60 min, and then benzoyl peroxide solution in Benzene (5% wt/v) was added to the reactor. Grafting was carried out for one hour. The grafting percentage was low in this method as well. No. 7: Samples were boiled in Univadin PB (4 g/lit, 2 g/lit) for 1 hour, and after that they were washed with water, and then benzoyl peroxide solution in Benzene (5% wt/v) was added to the reactor. The grafting time was 1 hr, but in this method the grafting percentage was low. No. 8: The PET fabrics were kept in boiling water containing Univadin. This will let the fabric swell. Then, AA which had been mixed with water (10%) was added to the reactor. The fabric was kept for another 10 minutes to swell under boiling. 0.1 g CuCl2 which was dissolved in water was added to the reactor, and immediately Irgasol NA was added too. Benzoyl peroxide was then added to the reactor (0.33 g in l0 CC of Benzene). After 2.5 hr, the reaction was stopped, and the fabrics were removed and washed 8 times with boiling water to remove the traces of monomer and oligomers. The washed fabric was then dried to a constant weight. The grafting percentage was higher than other procedures; therefore, this method was selected. The graft percentage was calculated from the following equation:𝑊−𝑊𝑜𝑊𝑜×100,(1)whereas W = weight of the rubric after grafting, Wo = weight of the fabric before grafting.

https://www.hindawi.com/journals/isrn/2011/265415/

Aother publications which may interest you are the followings:

Surface Modification of Ultra-high Molecular Weight Polyethylene Membranes Using Underwater Plasma Polymerization

http://link.springer.com/article/10.1007/s11090-013-9476-2

Surface engineerings of polyacrylonitrile-based asymmetric membranes towards biomedical applications: An overview

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.454.2341&rep=rep1&type=pdf

Hoping this will be helpful,

Rafik

Hi Gopi,

Yes, you can create a smooth surface for the membrane. However, this could have an adverse effect on the pores of the membrane is done through surface machining / peening. This smoothing could be done as part of the membrane material synthesis.

Hope this answer your question.

Professor Yehia Khalil

Yale University

USA

Hi,

If you prepare your membrane by non-solvent induced phase separation then you can add some PEG to the casting solution. Although this will alter the properties of your membrane but you can always optimse this by trying different concentration.

You can also coat thin layer of some other polymers such as PDMS, polyurethane etc. but again you have to check the membrane properties specific to the membrane feed and other parameters.

I hope this will help you.