Interfacial Contributions in Nanodiamond-Reinforced Polymeric Fibers

Abstract

We study the interfacial energy parameters that explain the reinforcement of polymers with nanodiamond (ND) and the development of mechanical strength of electrospun ND-reinforced composites. Thermodynamic parameters such as the wettability ratio, work of spreading and dispersion/aggregation transition are used to derive a criterion to predict the dispersibility of carboxylated ND (cND) in polymeric matrices. Such a criterion for dispersion (D c ) is applied to electrospun cND-containing poly­(vinyl alcohol) (PVA), polyacrylonitrile (PAN), and polystyrene (PS) fiber composites. The shifts in glass transition temperature (ΔT g ), used as a measure of polymer/cND interfacial interactions and hence the reinforcement capability of cNDs, reveal a direct correlation with the thermodynamic parameter D c in the order of PAN < PS < PVA. Contrary to expectation, however, the tensile strength of the electrospun fibers correlates with the D c and ΔT g only for semicrystalline polymers (PAN < PVA) while the amorphous PS displays a maximum reinforcement with cND. Such conflicting results reveal a synergy that is not captured by thermodynamic considerations alone but also factor in the contributions of polymer/cND interface stress transfer efficiency. Our findings open the possibility for tailoring the interfacial interactions in polymer–ND fiber composites to achieve maximum mechanical reinforcement.

Natural products from plants targeting key enzymes for the future development of antidiabetic agents

“…Among the alkaloids (Table 4), 110–112 ephedrine derivatives ( 185–190 ) exhibited IC 50 values between 124 μM to 28 mM; these relatively high values show their lack of selectivity towards other DPP isoforms, such as DPP-8 and DPP-9. On the other hand, the most active are berberine ( 191 ) and palmitine ( 192 ); docking studies predicted that they bind to the catalytic triad of DPP-IV.…”