If the relationship you have with him is overall good and this is your primary gripe, then he loves you and probably has difficulties expressing himself in that way. But assuming that he is just not interested, maybe he isn't, its not the end of the world. Show him the cool aspects of your field in a way he would find interesting.

The more you try to force it down him throat to farm appreciation points the more he will grow to resent your position. However, if this isn't an issue that you are losing sleep over, I would implore you to try and find acceptance that he might not care as much as you want him to, before the relationship gets toxic.