At first - for what aplication are you doing that? What kind of nanocrystalline cellulose (NC )are you using - is it made by TEMPO, enzymatic treatment or acid hydrolysis? Will your nanocrystalline cellulose-cationic starch mixture stay in solution or you will dray it?
Depends on that:
If NC is made by TEMPO, bonding with cationic ctarch should be good due to carboxylic groups in NC.
If you will dry you suspension of NC and cationic starch there will be hidroxil bonding like in paper.
If you want stronger bonding, you have look for some other reagent to add.
looking to add a solution of cationic starch and NCC to pulp for making handsheets of paper. I have prepared NCC via acid hydrolysis using sulphuric acid. I am not going to dry the NCC it will be in solution.