Polymorphic transformation of 1,3‐distearoyl‐<i>sn</i>‐2‐linoleoyl‐glycerol

Abstract

Abstract Polymorphic transformation behavior of sub‐α 1 , sub‐α 2 , α, and γ in 1,3‐distearoyl‐ sn ‐2‐linoleoyl‐glycerol (SLS) has been studied with X‐ray diffraction, differential scanning caloremetry, and Fourier‐transform infrared spectroscopy. Synchrotron radiation X‐ray beam was employed to observe rapid transformation processes from the sub‐α and α forms to the γ form. The chain length structures were double in sub‐α 1 , sub‐α 2 , and α, whereas γ was of triple chain‐length structure. The subcell packing was pseudohexagonal for the two sub‐α forms, hexagonal for the α form, and parallel type for the γ form. In comparison with 1,3‐distearoyl‐ sn ‐2‐oleoyl‐glycerol (SOS), the occurrence behavior of sub‐α, α, and γ of SLS was the same as that of SOS. However, the absence of β′ and β was unique for SLS. The chain‐chain interactions between the linoleoyl moieties may stabilize the γ form, prohibiting the transformation into β′ and β forms. The presence of two cis double bonds may cause this stabilization, revealing the disordered chain conformation of the unsaturated chains.