POS9-0273
Graft architecture-controlled toughening and marine biodegradation of PHB/CNC nanocomposites
When and Where
Nov 30, -0001
12:00am - 12:00am
Presenter(s)
Sunoo Hwang (Korea Advanced Institute of Science and Technology)
Co-Author(s)
Abstract
Poly(3-hydroxybutyrate) (PHB) is a promising marine-biodegradable bioplastic, but its high crystallinity and brittleness limit practical applications. Cellulose nanocrystals (CNCs) are attractive bio-based reinforcing fillers, but their hydrophilicity causes poor compatibility with hydrophobic PHB. Grafting polycaprolactone (PCL) from CNC surfaces can improve this mismatch, but the role of graft chain architecture, particularly number-average molecular weight (Mn) and dispersity (Đ), remains insufficiently understood.
In this study, CNC-g-PCL was synthesized by ring-opening polymerization (ROP) of ε-caprolactone using tin(II) 2-ethylhexanoate as a catalyst. Graft Mn was controlled by varying the monomer-to-initiator ratio, while Đ was intentionally varied as an independent parameter at comparable Mn. To characterize graft molecular weight, benzyl alcohol was used as a co-initiator to generate free PCL chains, whose Mn and Đ were determined by gel permeation chromatography (GPC). CNC-g-PCL was dispersed in deuterated chloroform (CDCl3) and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy to verify graft composition and chain characteristics.
PHB/CNC-g-PCL nanocomposite films were prepared by solvent casting. Mechanical properties, including toughness, elongation at break, were evaluated using a universal testing machine (UTM). Marine biodegradability was assessed by the biochemical oxygen demand (BOD) method, complemented by ecotoxicity assays and chemical analysis of degradation products using Fourier-transform infrared (FTIR) spectroscopy and 1H NMR spectroscopy.
This work establishes CNC-g-PCL/PHB as a fully marine-biodegradable biocomposite system and treats Đ not as a synthetic byproduct but as a deliberate molecular design variable. By decoupling the effects of Mn and Đ, this study aims to clarify how graft architecture governs interfacial compatibility, mechanical toughening, and marine degradation in PHB-based nanocomposites.
In this study, CNC-g-PCL was synthesized by ring-opening polymerization (ROP) of ε-caprolactone using tin(II) 2-ethylhexanoate as a catalyst. Graft Mn was controlled by varying the monomer-to-initiator ratio, while Đ was intentionally varied as an independent parameter at comparable Mn. To characterize graft molecular weight, benzyl alcohol was used as a co-initiator to generate free PCL chains, whose Mn and Đ were determined by gel permeation chromatography (GPC). CNC-g-PCL was dispersed in deuterated chloroform (CDCl3) and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy to verify graft composition and chain characteristics.
PHB/CNC-g-PCL nanocomposite films were prepared by solvent casting. Mechanical properties, including toughness, elongation at break, were evaluated using a universal testing machine (UTM). Marine biodegradability was assessed by the biochemical oxygen demand (BOD) method, complemented by ecotoxicity assays and chemical analysis of degradation products using Fourier-transform infrared (FTIR) spectroscopy and 1H NMR spectroscopy.
This work establishes CNC-g-PCL/PHB as a fully marine-biodegradable biocomposite system and treats Đ not as a synthetic byproduct but as a deliberate molecular design variable. By decoupling the effects of Mn and Đ, this study aims to clarify how graft architecture governs interfacial compatibility, mechanical toughening, and marine degradation in PHB-based nanocomposites.
