When I was doing my master's degree, I got in a bit of trouble for saying that "materiality", a topic I had chosen to write a paper on, was not really a theory so much as a buzzword. It turns out "buzzword" is a rude term in academic circles. What I meant at the time was that when people refer to "materiality", they are pointing towards a topic of concern, rather than any particular way of thinking about that topic. I still basically think that's true. Instead of "materiality", it makes more sense to refer to "new materialism", as this is actually a movement with specific thinkers who think in specific ways.
New materialism aims to critically examine "how matter comes to matter". The work of Judith Butler, Donna Haraway, Karen Barad and Bruno Latour has contributed a great deal to New Materialism. There tends to be a focus on verbs and doing, rather than nouns and being - things are enacted rather than existing objectively.
Elsewhere: New Materialism 