writer：Jiaying Zhu, Yuxiang Chen, Hou-Yong Yu, Ying Guanb, Ying Zhou, Xiaogang Yang
keywords：Cellulose nanocrystals, PHBV, Nanocomposites, Thermal properties, In vitro degradation
source：期刊
Issue time：2019年

Cellulose nanoparticles (CNPs) have been widely reported to improve the crystallization rate, mechanical and thermal properties as well as degradation behavior of poly (3 hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Unfortunately, few studies have focused on the relationship between surface functional groups of CNPs and hydrogen bond interactions on the degradation rate and the mechanistic understanding of PHBV nanocomposites. To demonstrate degradation pathways, three types of CNPs with different amounts of surface hydroxyl groups were designed and then incorporated into PHBV to control the thermal stability, mechanical properties, and especially various degradation behavior by modulating the hydrogen bonding interactions with PHBV, achieving modulated degradation rate of nanocomposites. Furthermore, possible mechanisms describing the thermal, in vitro hydrolytic, and soil degradation of PHBV nanocomposites with various CNPs were proposed. In particular, PHBV nanocomposites reinforced by cellulose nanocrystal citrates (CN-C) with more hydroxyl groups exhibited better properties and degradation behavior than cellulose nanocrystal formates (CN-F) and cellulose nanocrystals (CN). For the possible thermal degradation mechanisms, interfacial hydrogen bond interactions hindered the formation of the six-membered ester ring on PHBV, which improved the thermal stability of the nanocomposites during the degradation process. The rigid hydrogen-bonded networks between the highly crystalline CNPs and PHBV acted as barrier layers, protecting the ester groups on PHBV from being attacked by hydronium ion from the phosphate buffer saline (PBS) solution. The microorganisms in the soil degrade and digest amorphous domains during the soil degradation process. With modulated degradation rates, high-performance and green nanocomposites could be suitable for biomedical and packaging materials.