There are glycidyl ether terminated PEGs available.  Introduce a minor amount of cationic photoinitiator along with the PEGylated epoxy and you are set to go.

There are glycidyl ether terminated PEGs available.  Introduce a minor amount of cationic photoinitiator along with the PEGylated epoxy and you are set to go.

Yeah, that should work. Diphenyliodonium hexafluorophosphate sensitized with anthracene works for epoxy and should work for glycidyl PEG as well. If you are planning to use it for Li ion batteries, the terminal hydroxyl groups of the product might be an issue though.

Article Initial step of anthracene‐sensitized photoacid generation f...

I would like to avoid using Pegylated epoxy since my substrate is PDMS based and hence might create problems during the diffusion pre-process.I did find a reference that crosslinks PEG-diacrylate using the photoinitiator HCPK or Irgacure 2959 which might be what I'm looking for. Do you think this would work?

Yes, but you will have to work under an oxygen free atmosphere as the free radical reaction is inhibited by it.

Yeah I think that will work, you can probably even get away with doing it in air. Increase the concentration of curing agent if it becomes a problem.

Dear Pranav,

PEG 200 will not polymerize  with benzophenone or any other photo initiator because it does not have functional group which can initiate polymerization.

You may add some adsorbent polymers material with PEG which will hold it inside the pores of substrate. 

or else you can instead mix some acrylic monomer (meta acrylic acid, metha acrylic anyhride) with PEG to initiate the polymerization. You may also use PEGDA which is available in various MW grades. 

Undermentioned photo initiator worked well with the PEGDA. 

2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (HHEMP) (IRGACURE 2959)

2-Hydroxy-2-methylpropiophenone

for your reference 

http://link.springer.com/article/10.1007%2Fs11095-016-1991-4

http://link.springer.com/article/10.1007/s13346-015-0245-z  

https://www.jove.com/video/52914/polymeric-microneedle-array-fabrication-by-photolithography

You could speed up infusion by vacuum/release cycles (use inert gas to vent if needed; see Kirk and Eric's answers). If your substrate is thick and you have problems with insufficient UV penetration/crosslinking in the centre, you might consider using the PEG-DA with a temperature (in stead of UV) sensitive radial initiator (e.g. a peroxide or persulphate) and heating the sample through after infiltration.

Hi same goes to me. How can i use PEG polymer to mix with photoinitiator? is it compulsory to go through functionalized process?

You can make a functionalized PEG in situ by pre-reacting it with the unsaturated isocyanate TMI, O=C=N-C(CH3)2-Ph-C(CH3)=CH2 (m-position). It is not neccessary to isolate the urethane. The molecular weight of TMI is 201 so that you need a nearly 1:1 mixture to have in average one TMI at one PEG 200. The double bond of TMI is accessible to normal photoinitiators and to cationic. I think that radical formation with unmodified PEG is not efficient enough in crosslinking. Perhaps it works if you bind the photoinitiator directly to the PEG. For this purpose you must prereact the PEG 200 with benzophenone tetracarboxylicacid dianhydride in doing so the anhydride ring opens under formation of an acidic ester. The benzophenone is active as photoinitiator and bound to the PEG from which the H. is abstacted.

Hi Burkhard.

Thanks for the answer. If let say i just used PEGDA as an alternative, is it work if the PEGDA can be used directly with photoinitiator without go through the functionalized PEG step?

Thanks in advance

Yes, it should work.

Thanks Dr for your kind explanation.

So it could be possible if i mixed the PEGDA polymer together with photoinitiator Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO)? or the PEGDA will only directly have an reaction of photocrosslink with several photoinitiator under UV ligh such as:

2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (HHEMP) (IRGACURE 2959)

2-Hydroxy-2-methylpropiophenone

BAPO works also with blue light but perhaps it needs additional a hydrogen donating reagent like a thiol or a N,N-dialkylaniline, e.g. ethyl dimethylaminobenzoate, but perhaps the polyether itself is enough as hydrogen donating reagent.

Iragacure 2959 is the only commercially available photoinitiator which is water soluble up to 1% and compatible with water containing systems. It needs no H donating reagent as well as the last initiator but they need near UV.

Noted. So means the most photoinitiator Irgacure 2959 ( 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone) really works with PEGDA under uv light?

Thanks.

You'll need to keep the reaction inerted (really limit oxygen as much as possible with a nitrogen or argon purge) to obtain good cure. Irgacure 2959 or Irgacure 651 are good photoinitiators to use in UV-cure operations. You may also consider VASO 67 in thermal cure operation.

hi

anybody can advice me what the best solvent used to dissolved PEGDA (250, 700 Mw) for certain % concentration? Can i used the distilled water?

Thanks

Pegda oligomer is very common in UV-crosslinked polymers. It can be used with Irgacure d2959, which is soluble in Pegda, and you'll get a polymer structure in seconds.

I used 0,5%-2%w/w photoinitiator into Pegda and in higher volume fractions you get an elastomeric structure instead of a more brittle in lower ratios.

A thin film of ~100μm can be obtained in less than 5sec. Or solid structures ~1cm thick in less than 20sec.

I use Pegda 575