I'd say your problems is that you are using triphenylphosphine ligands on the copper, if one of these dissociates they you will get a staudinger reaction occurring which may cause problems.Not sure about the second case though, may have something to do with the azide structure, any more information?

Thank you Luke for your response. The substrate carrying the azide moiety is a polyester with 25% repeat units of alkyl side chains terminated with the azide. I thought about the possibility of the staudinger reduction of the azide by the PPh3 ligand. i expected that if that happens then the release of the two nitrogens from the azide should leave one nitrogen on the side chain which finally forms an amine. However the nmr shows no evidence of the presence of amines on the chain. 

Which solvents u used

Hello Rajendra, THF was the solvent used.

Only use 2mol% CuSO4.5H2O and 5~10mol% sodium ascorbate instead of using  CuBr(PPh3)3/ DIPEA.

Hey Sam,

                  What are the other functional groups present in your polymer. Have you tried screening other solvent systems?

Hey Bhuwan, thanks for your response. One substrate is the polyester with the terminal azido functional group on its alkyl side chains and the other substrate is the cyclopentylacetylene with the terminal alkyne functional group. I have screened THF, DMF and DMSO so far. 

Hello Nadeem, thanks for your response. I have tried the CuSO4/Na Asc catalyst system only, however, I lose half of the azide in this case. 

Thank you Erkan. Yes the reactions were heated at 45oC. As I mentioned earlier, the azide is lost from the polymer, however, there are no conversions to the triazole product. Screening more solvent systems currently to see if this problem can be circumvented. 

Thanks guys, I am also currently facing a similar challenge, But mostly on how I can verify that my click has worked. Im actually biology major and getting to understand this things now. I would appreciate a response on how I can confirm that my click between polymer and ssDNA has worked. 

Thanks in advance

Hello Jay, you could try doing a proton NMR on your click product to find the characteristic triazoline proton which typically appears between 7.4ppm- 7.8ppm (note that it may be shifted a bit upfield or downfield from the typical range). This should give you confirmation of a triazole linkage between your polymer and the ssDNA. Best wishes

Thanks Nkrumah. I will talk with my collaborators in the polymer science department. I have no experience in using NMR. Thanks again.