Polymerization with a
monomer dropwise-feeding method was adapted. Specifically, 0.8 wt %
CNF suspension in water was charged into a 250 mL three-necked
round-bottom flask connected with a nitrogen gas inlet, a refluxcondenser,
and a mechanical stirrer, and mounted in an oil
temperature-controlled bath. Nitrogen was bubbled through the
suspension under 350 rpm stirring for at least 45 min at 80 °C to
remove dissolved and vapor space oxygen. KPS was added as an
initiator, and the mixture was stirred for 15 min. A 1 mL portion of
monomer mixture containing n-butyl acrylate, styrene, and ethylene
dimethacrylate was introduced dropwise over a period of 35 min.