A series of monotropic liquid crystal poly (ester imide)s (PEIMs) was synthesized from IV-[ 4-(chloroformyl)phenyl]-4-(chloroformyl)phthalimide and nine diols containing 4-12 methylene units (m).During cooling from their isotropic melts, all the polymers underwent a monotropic liquid crystal transition to form a smectic A phase, followed by a transition to a more ordered structure, which was examined with wide-angle X-ray diffraction, differential scanning calorimetry, and polarized light microscopy. The fact that the liquid crystal transition temperatures for some of the PEIMs were close to their glass transition temperatures provided an opportunity for the study of liquid crystal transition kinetics in temperature regions close to the glass transition temperature. It was found that when the temperature, and thus the molecular mobility decreased, the transition time increased despite the fact that this transition is close to equilibrium. The crystallization kinetics of PEIM(m)s from both the liquid crystal phase and the isotropic melt were also studied. In PEIM(m=even)s (except for m = 4), two different ordered structures can be formed. One is a crystalline phase formed directly from the isotropic melt, and the other is a highly ordered mesophase having a hexagonal-like packing develop from the liquid crystal state. Only one crystal structure in PEIM(m=odd)s is observed. Special attention has been paid to the effect of the presence of liquid crystal order on the crystallization kinetics. The pronounced acceleration of the crystallization was observed whenever this was preceded by liquid crystal formation, an effect pertaining within a wide temperature range from close to Tm down to Tg.

A series of low molecular weight poly(ethy1ene oxide) (PEO) fractions with different molecular weights (MW=3000 and7100) andendgroups (-OH,-OCH~,-OC(CH~)S, and-OC&) have beensystematically studied. The end-group effect on diffusional motion in the melt of these PEO fractions was characterized by self-diffusion coefficient measurements through nuclear magnetic resonance. Wide-angle X-ray diffraction experiments indicated that the crystal structures of the PEO fractions with different end groups were identical during and after crystallization. The existence of nonintegral folding chain (NIF) crystals in these PEO fractions in a wide undercooling region was observed by time-resolved synchrotron small-angle X-ray scattering, differential scanning calorimetry, and transmission electron microscopy experiments. The integral folding chain (IF) crystals were found to be formed through both thickening and thinning processes during and/or after the NIF crystallization. It was also found that, with increasing molecular weight and size of the end group, the thickening and thinning processes were increasingly hampered. Of additional interest, the fold length of initial NIF crystals not only increases with crystallization temperature (or decreasing undercooling) for each PEO fraction as commonly observed in polymer lamellar crystals but also changes with the size of the end group. The kinetics of transformation from NIF to IF crystals is explained through the chain sliding diffusional motion along the direction perpendicular to the lamellar surface, which is end-group size dependent. Linear crystal growth rate data measured via polarized light microscopy confirmed that the existence of bulky end groups reduces NIF crystal growth rates for PEO (MW = 3000) fractions. With increasing molecular weight, the end-group dependence gradually vanishes due to the introduction of chain entanglement.

SYNOPSISThe polymer decoration method based on the vaporization and condensation-crystallization of polyethylene (PE) upon the fold surface of polymer crystals has been widely used to study the chain folding behavior of the crystals. When this method was utilized to study solution-grown high molecular weight poly (ethylene oxide) (PEO) lamellar crystals, the highly anisotropic, low molecular weight fragment PE decorated become oriented parallel to the fold direction and form rods, which can be observed by transmission electron microscopy (TEM) and electron diffraction (ED). The growth sectors were clearly observed.From the ED patterns the { 200) planes of the orthorhombic low molecular weight P E rod crystals can be observed, and the c -axis of these crystals is aligned parallel to the { 120 } growth planes of the PEO crystals. The decoration results indicate that the major fold orientation of high molecular weight PEO single crystals grown from dilute solution is along the (120) planes. 0 1995 John Wiley & Sons, Inc.

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