화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.118, No.28, 8203-8209, 2014
Fast Crystal Growth from Organic Glasses: Comparison of o-Terphenyl with its Structural Analogs
Crystal growth kinetics and liquid dynamics of 1,2-diphenylcyclopentene (DPCP) and 1,2-diphenylcydohexene (DPCH) were characterized by optical microscopy and dielectric spectroscopy. These two molecules are structurally homologous and dynamically similar to the well-studied glassformer ortho-terphenyl (OTP). In the supercooled liquid states of DPCP and DPCH, the kinetic component of crystal growth u(kin) has a power law relationship with the primary structural relaxation time tau(omega) u(kin) tau(-xi)(alpha) (xi approximate to 0.7), similar to OTP and other fragile liquids. Near the glass transition temperature (T-g), both DPCP and DPCH develop much faster crystal growth via the so-called GC (glass to crystal) mode, again similar to the behavior of OTP. We find that the alpha-relaxation process apparently controls the onset of GC growth, with GC growth possible only at sufficiently low fluidity. These results support the view that GC crystal growth can only occur in systems where the liquid and crystal exhibit similar local packing arrangements.