Effect Of Inorganic Additives On Polymorphism Of Glycine In Microdroplets

Salt-dependent polymorphic control of glycine was investigated by using microdroplets technique in this work.Sodium chloride(NaCl)was chosen as the additive to probe the influence of inorganic ion on polymorphic nucleation of glycine.The thermodynamics and nucleation kinetics of glycine polymorphs in microdroplets were systematically analyzed based on microdroplets technique.The crystal structures of polymorphs were confirmed by powder X-ray diffraction(PXRD).The results illustrate that the critical concentration of NaCl inducing pure ?-form in microdroplets is lower than that in the conventional method,which means that microdroplets technique is more sensitive in polymorphs nucleation control.The polymorphic nucleation selectivity of glycine was then discussed in the view of classical nucleation theory.Results demonstrate that NaCl reduces the nucleation energy barrier of ?-form glycine and as for the same form glycine,crystallization in conventional method has a higher interfacial tension than in microdroplets.