Controlled-release cinnamon oil in flexible poly(lactic acid) films via mesoporous SBA-15 encapsulation

Poly(lactic acid) (PLA) has critical limitations in food packaging applications because of its inherent brittleness and lack of active functionality. To address these limitations, we developed flexible PLA films with sustained-release antimicrobial activity via mesoporous Santa Barbara Amorphous-15 (SBA-15) encapsulation of cinnamon oil (MAO). SBA-15 (Brunauer–Emmett–Teller surface area: 568.9 m<sup>2</sup>/g; pore diameter: 7.5 nm) demonstrated exceptional MAO loading capacity (801.5 mg/g). MAO@SBA-15 was incorporated into the polyethylene glycol-plasticized PLA via solution casting. The 3 wt% MAO@SBA-15 composite exhibited the highest tensile strength (16.0 MPa) and crystallinity (32.4%) owing to the uniform filler dispersion and nucleation effects. At 7 wt% loading, films achieved superior barrier properties [water vapor permeability: 2.6 × 10<sup>-13</sup> g·cm/(cm<sup>2</sup>·s·Pa); oxygen transmission rate: 4.5 × 10<sup>-13</sup> cm<sup>3</sup>·cm/(cm<sup>2</sup>·s·Pa)], antioxidant activity (1,1-diphenyl-2-trinitrophenylhydrazine scavenging: 34.4%), and preservation efficacy for mulberries (weight loss rate: 3.6%; hardness: 0.82 N) over seven days. The MAO release followed Higuchi model (R<sup>2</sup> = 0.9738), confirming controlled diffusion. This study established a potentially scalable strategy for fabricating multifunctional PLA packaging with enhanced flexibility, barrier performance, and sustained bioactive delivery.