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Congratulations Professor Yan on being elected a new Fellow for 2021.
A new article out of Ning Yan’s lab has been published in Carbohydrate Polymers about anisotropic cellulose nanocrystal hydrogel written by Liu Liu, Nicolas R.Tanguy, Ning Yan, Yiqiang Wu, Xiubo Liu, and Yan Qing
Conventional hydrogels with isotropic polymer networks usually lack selective response to external stimuli and that limits their applications in intelligent devices. Herein, hydrogels with distinctive anisotropic optical characteristics combined with thermosensitivity were prepared through in situ photopolymerization. Self-assembled cellulose nanocrystals (CNCs) with chiral nematic ordered structure were embedded in polyethylene glycol derivatives/polyacrylamide polymer networks. The arrangement of CNCs showed a strong dependence on the self-assembly angle and standing time, enabling the fabrication of hydrogels with customizable CNCs arrangements. Increasing the self-assembly angle from 0° to 90° changed the CNCs arrangement from chiral nematic to symmetrical nematic order which, together with CNCs dynamic arrangement from isotropic to annealed chiral nematic phase at longer standing time, provided versatile ways to produce CNCs hydrogels with tunable anisotropic properties. In addition, the obtained hydrogel displayed reversible temperature and compression response, showing excellent promise to be used as soft mechanical stress and temperature sensors or novel anti-counterfeiting materials.
A new review article out of Ning Yan’s lab has been published in ACS Sustainable Chemistry & Engineering about the progress on startch maleats and polylactic acid blends for food packaging written by Shrestha Roy Goswami, Sandeep Sudhakaran Nair, Sen Wang, and Ning Yan
For the first 12 months of publication, 50 free e-prints are available for interested colleagues. Click hereto see the article and get your free e-print.
Starch maleate/polylactic acid blends could replace polyethylene terephthalate in food packaging films. These films, however, are not acceptable for commercial use due to their poor performance, which is caused by processing polylactic acid with starch maleates having a low degree of maleic anhydride substitutions (DSNMR < 0.1 or DStitration < 1). Conventionally produced starch maleates produced via dry grinding or as aqueous and nonaqueous dispersions acquire a low DS due to the presence of inactive hydroxyl and maleic anhydride groups in each of the reaction systems. Low-DS starch maleates could barely interact with polylactic acid and plasticizers during blend processing; consequently, the resultant films perform poorly in terms of ductility and compostability. The key findings of this perspective indicate that recyclable ionic liquids like 1-allyl-3-methylimidazolium chloride could disrupt H-bonds among hydroxyls of starch and catalyze in situ maleic anhydride ring openings to provide functional groups for the synthesis of high-DS starch maleates (DSNMR ≥ 0.1 or DStitration ≥ 1). Improved interfacial chain interactions between high-DS starch maleates/polylactic acid and plasticizers like epoxidized soybean oil could facilitate stress-transfer and enzymatic activities of the resultant film, potentially improving its ductility and compostable properties. Besides these promising findings, this perspective also emphasizes the need for further research into identifying a wide range of ionic liquids and compostable plasticizers for producing high-DS starch maleates/polylactic acid blends, assessing the effect of interfacial chain interactions on properties of the resultant film, and determining specific usage of the film based on the barrier properties measured using standardized techniques.