Fabrication of cellulose-based particles/capsules using gamma radiation-initiated radical precipitation polymerization

Because fossil-based polymer particles are generally not biologically degradable, which has led to their significant accumulations as microplastic is now a serious global problem. Therefore, bio-based polymers synthesized from renewable monomers have received much attention due to their biodegradability and biocompatibility. The biopolymer in particle forms has been recently recognized as a functional material. Dispersed systems mainly synthesized them via radical polymerization. The radicals generated by gamma radiation were applied in this work to reduce chemical consumption, where cellulose acetate butyrate (CAB) was used as the main biopolymer in precipitation polymerization. The generated radical will abstract the hydrogen atom on the CAB chain, giving an active site for radical polymerization. After the comonomers, methacrylic acid and ethylene glycol dimethacrylate, were grafted to the CAB chains, the copolymer chains were self-assembly to form a particle and precipitate out from the continuous phase. Various parameters such as gamma rays dose, water content, and monomer type were studied to obtain high conversion and colloidal stability of the obtained CAB-based particles. It was found that at 10 kGy (cumulative radiation), 0.31 wt% of water and using hydrophilic monomer as hydroxyethyl methacrylate (40 wt%-CAB) was the optimal condition where the CAB-based particles with high conversion (∼≥90%), about 100 nm and high stability were obtained. Moreover, this technique encapsulated Citronella oil, an essential oil model, and found that the capsule size bit increased about 300 nm where %EE and %LE are 60 and 30%, respectively. This result indicated that radiation-initiated radical precipitation polymerization is an easy and potential technique to prepare cellulose-based particles and capsules, which may apply to other biopolymers.