I recommend you our works related to H2O vapor sorption by polyacrylamide (V.E. Ostrovskii with B. Tsurkova and E. Kadyshevich) and by perfluorinated polymer like Nafion (V.E. Ostrovskii with B.V. Gostev). These works are available at the RG site (in my pages). This is an extended set of studies. Seek and ye shall find! 

Thanks , I will check it.

By thermogrametric analysis you can quantify the mass loss of water diffused between polymer network in the range temperature of 100 to 150°C.

If you want to measure water content in a polymer matrix, you can go for TGA method. However, I could not get right what is that you mean by interface between water and polymer. Do you mean that the diffusion of water molecules through the polymer membrane like. Otherwise, it is very difficult to understand the question.

Dear Juganta Kumar, please, take into account the following. To understand the conditions of water diffusion within the mass of a functional polymer, the full volume of data on the mechanism and kinetics of the processes within polymer/water system under different temperatures and concentrations is desirable. I hope that you can find all necessary data in the works referred by me in the previous issue; these works were performed for approximately 12-year's period.

Yours.  

If the polymer withstands heat, then there is a very simple routine procedure which we use in the chemical processes laboratory course:

Weigh a sample of your polymer on a watch glass (call it W1). Place the sample in an oven @ 110 oC for 2 hours. Get it out of the oven & wait a little until it cools down. Weigh the dried polymer (call it W2). % of water in the polymer will be (W1-W2)/W1 X100. Knowing the weights, you can find also the number of moles and thus the number of molecules will be determined.

Thank you all !

I read two papers, suggested by Victor Ostrovskii . But, actually I want to quantify from my molecular dynamics simulation trajectory in gromacs.

Juganta, 

I think that, for you, the experimental data of the papers J. Thermal Anal., v.46, 1996, 397-416 and the same journal, v. 51, 1998, 369-381, both available at my RG pages, are the most suitable.

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I think TGA (det. the mass loss) is a suitable technique. You should go around 400C to evaluate the amount of all types of water ( external or internal).