Presuming you may not remove HEMA from the formulation, you might want to tie up the ethylhydroxy group by pairing it with a hydrophobic alcohol. Essentially all alcohols form a pair of hydrogen bonds when forming crystals, and you could investigate whether or not you could tie up pendant hydroxyls with added hydrophobic alcohol. Usually HEMA is included in order to attract water into hydrogel applications, and it would seem illogical to retain HEMA of you want to exclude water.

You would probably not want to use these exact material combinations but perhaps something based on the same principle would work for you. Here's a study on graphene oxide in epoxy:

http://www.sciencedirect.com/science/article/pii/S0141391012004739

The above was tried after we saw encouraging results with MWCNT in this study:

http://www.sciencedirect.com/science/article/pii/S0014305713002346

Please give complete formulation

dear Omkar Singh

if you mean the composition of the nanocomposite, the principal components are:

HEMA + HAP nanorods+ PMMA powder.

hema/pmma powders are in 2 different ratios (2/1 and 3/2).

You can use crosslinking agent (Glutaradehyde) to form the three dimensional stable structure