CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅰ.POLY(P-PHENYLENE TEREPHTHALATE)*

The morphology and crytal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin filmmelt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electronmicroscopy, electron dimaction and molecular modeling. The unit cell is monoclinic (P2_1/a space group) with parameters a =7.89, b = 5.49, c = 12.65 A, α=γ= 90°, β=100.33°, density = 1.48 g/cm~3, the a, b and β values differing slightly from thosereported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted[001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence wasfound for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220℃ (up to 370℃) and CTFSP crystals polymerized at 300℃ consisted oflamellae 100-200 A thick.     

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS I.POLY(P-PHENYLENE TEREPHTHALATE)

The morphology and crystal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin film melt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electron microscopy, electron diffraction and molecular modeling. The unit cell is monoclinic (P21/a space group) with parameters a =7.89, b = 5.49, c =12.65 A α= γ= 90°,β= 100.33°, density = 1.48 g/cm3, the a, b andβ values differing slightly from those reported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted [001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence was found for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220°C (up to 370°C) and CTFSP crystals polymerized at 300°C consisted of lamellae 100-200 A thick.     

MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE——Ⅱ. LOW MOLECULAR WEIGHT FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES

The effect of sintering dispersed and bulk, low molecular weight (Mn = 50,000 Da), nano-emulsion polytetrafluoroethylene (PTFE) particles near their melting point is described. With the nascent particles consisting of ca.75 nm diameter, hexagonal, single crystals, sintering at, e.g., 350℃, results, initially, in merger of neighboring particles,followed by individual molecular motion on the substrate and the formation of folded chain, lamellar single crystals and spherulites, and on-edge ribbons. It is suggested these structures develop, with time, in the mesomorphic “melt”. Sintering of the bulk resin yields extended chain, band structures, as well as folded chain lamellae; end-surface to end-surface merger,possibly by end-to-end polymerization, occurs with increasing time.     

STRUCTURAL STUDIES OF SNAKE INSULIN CRYSTALS——X-RAY CRYSTALLOGRAPHIC ANALYSIS OF SINGLE CRYSTALS

On the basis of the isolation and crystallization of snake (Zaocys dhumnades dhumna-des, Cantor) insulin, single crystals suitable for X-ray analysis were obtained in citrate buf-fer by micro-method of super-saturation. Resolution of diffraction by the crystal was over4 A, X-ray crystallographic analysis showed that the crystal was cubic with α=67.31 A, itsspace group was P4_232 and each asymmetric unit contained one molecule of snake insulin.The possible packing of hexamers and the orientation of monomers in the unit cell of snakeinsulin crystal were discussed.     

PRELIMINARY CRYSTALLOGRAPHIC ANALYSIS OF DESHEXAPEPTIDE (B25—B30) INSULIN

Satisfactory single crystals of deshexapeptide(B25—B30) insulin for X-ray crystal structure analysis have been grown in citrate buffer by the method of hanging-drop gas phase diffusion. The crystal belongs to the monoclinic system with space group C2. The unit cell constants are α=42.6, b=37.9, c=27.2, β=125.4 and there is only one molecule of deshexapeptide insulin in an asymmetric unit.     

CRYSTALLOGRAPHIC STUDIES OF THE COMPLEX OF MUNG BEAN TRYPSIN INHIBITOR WITH PORCINE TRYPSIN

The Bowman-Birk family inhibitor isolated from the mung bean can combine with porcine trypsin to form a complex at a molar ratio of 1:2. The single crystals of the complex, suitable for X-ray structural study, were obtained by using the micro-still-setting method. Initial crystallographic investigation showed that the crystals diffract to 2.7 resolution and belong to the tetragonal system. Its space group is 1422 with cell dimensions a=b=122.4 (2), c=113.4(2). The density of the crystal was 1.20g/cm~3 and the solvent constant was 36%. There is one complex molecule in a crystallographic asymmetric unit.     

STRUCTURE AND TECTONIC EVOLUTION OF OKINAWA TROUGH

Okinawa Trough is a back-arc basin with some features of transitional structures-thinned crust,active tectonic movement and high value of heat flow. Seismic survey reveals that there are three strati graphic series of different environments: layer A of Pleistocene-Holocene is thin in the north and thick in the south, layer B of the Pliocene is thin in the south and thick in the north, and layer C is an "acoustic basement". The phase Ⅰof Trough movement taking place during the last Miocene to the early pliocene is a foundational episode of tectogenesis in Okinawa Trough. The phase Ⅱin the last Pliocene is the unified and spreading episode of tectogenesis. The formation of Okinawa Trough underwent the doming phase due to upwelling of material from deep earth, the rifting phase of lithosphere, and the spreading phase from overflowing of magma and pushing both sides of rocks.     

KINETICS OF SUSPENDED EMULSION POLYMERIZATION OF METHYL METHACRYLATE

The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of MMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (Rp0) and steady-state polymerization rate (Rp) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: Rp0 ∝ [I]0.73[S]0.32 and Rp ∝ [I]0.71[S]0.23. The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methyl methacrylate) decreased as the polymerization temperature, [I] and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.     

SYNTHESIS OF POLY(VINYLIDENE FLUORIDE) WITH LOW CONTENTS OF HEAD-TO-HEAD CHAIN

The relations between polymerization conditions of vinylidene fluoride and contents of head-tohead chain in the polymer have been studied. It shows that the contents of head-to-head chain of the polymer are related to its polymerization temperature, but are not related with the kinds of initiators used. Therefore, poly(vinylidene fluoride) with low contents of head-to-head chain (ca. 3%) can be prepared under lower polymerization temperature. Plot of the contents of A chains against melting points of the polymer is linear, which can be expressed by an equation: A=24.8 + 0.362 T_m(%).     

THE GROWTH OF SINGLE CRYSTALS OF (L-ARGININE)~(B_0) BOVINE INSULIN AND THEIR PRELIMINARY X-RAY CRYSTALLOGRAPHIC ANALYSIS

The crystals of (L-Arg)~(B_0) bovine insulin large enough for X-ray structure analysis havebeen grown by vapour diffusion in a buffer containing citrate, acetone and zinc chloride.The X-ray diffraction of the crystals extends to 3.0 A spacing. The crystals belong tothe trigonal system with unit cell dimension of a=b=81.82A, c=35.05A, α=β=90°, γ=120°,space group R3. There are two insulin molecules in the crystallographic asymmetric unit.     

THE CRYSTALLIZATION BEHAVIOR OF URETHANE SUBSTITUTED POLYDIACETYLENE

The crystalline behavior of urethane substitute polydiacetylene was studied by using pohrized light and electron microscopy. The lamellar morphological structure was observed in the crystallized films. The thickness of lamellae is about 300A, being independent of the crystalline temperature. But the size and density of lamellae were dependent on the crystallization temperature. If the molten film was sheared during the crystallzation process the oriented lamellae grew with their long axes perpendicular to the direction of shear and the chain direction was normal to the lamellar surface.     

THE GROWTH OF SINGLE CRYSTAL AND THE DETERMINATION OF CRYSTALLOGRAPHIC PA RAMETERS OF (L-TRYPTOPHAN)~(A1)-INSULIN AND (D-TRYPTOPHAN)~(A1)-INSULIN

The crystal-growing conditions and the results of preliminary X-ray crystallographic analysis of (L-Try)~(A1)-insulin and (D-Try)~(A1)-insulin are reported. The single crystals of this pair of insulin analogue suitable for X-ray diffraction analysis have been grown in the citrate buffer system by still-setting method. They both belong to the trigonal system with space group R3. The parameters of the unit cell (L-Trp)~(A1)-insulin are αH= 80.31, cH= 37.45 and those of (D-Trp)~(A1)-insulin αH = 79.48, cH = 43.81. There are two molecules in an asymmetric unit. The obtained results are discussed.     

Thickness-dependent Orientation Structure in Poly（ethylene oxide） Multi-layer Crystals

Poly(ethylene oxide) multi-layer crystals were obtained and the re-crystallization behavior was studied to give insight into how melt thickness and temperature affect the lamellar orientation. For a special re-crystallization temperature, there exists a critical transition thickness range for the occurrence of edge-on lamellar orientation. Below the critical thickness, only flat-on lamellae were observed. While above the critical thickness, both flat-on and edge-on lamellae were found and the proportion of the edge-on lamellae increases with thickness. At low re-crystallization temperatures(below 30 °C), the critical transition thickness gradually increases from about 15 nm to 35 nm when the re-crystallization temperature was increased from 20 °C to 30 °C. However, when the re-crystallization temperature is above 30 °C, the critical transition thickness becomes constant. Our results demonstrated that the lamellar orientation could be specially modified by changing the melt thickness and re-crystallization temperature.     

SYNTHESIS AND POLYMERIZATION OF BISPHENYLENE ORTHOCARBONATE

Bisphenylene orthocarbonate (Ⅱ) was synthesized by the reaction of dicopper catecholate with carbon tetrachloride, and underwent cationic ring-opening polymerization with the introduction of phenyl group into the main chain. The obtained polymer with ester and ether group was verified by IR and ~1H NMR spectra. Based on the analysis of the polymer structures, the polymerization mechanism was proposed. Its T_m and T_(?) are 254℃and 160℃respectively. No decomposition of the polymer was observed below 320℃. The volume expansion property of the monomer during polymerization was studied by measuring the density difference between Ⅰand its polymer at various temperatures.     

LAMELLAR STRUCTURE OF THERMOTROPIC LIQUID CRYSTALLINE POLYMERS

The lamellar structure of a thermotropic aromatic polyester with flexible spacer has beenstudied by using transmission electron microscopy. It was found that the lamellar structure couldbe observed in the crystalline samples of this semirigid polymer crystallized from different states.The thickness of lamellae is around 10 nm, which is similar to that of the conventional polymersof flexible chain molecules. The molecular chains in the lamellae are oriented in the thicknessdirection as determined by electron diffraction. The possibility of molecular chains folding in the lamellae has been discussed.     

ELECTRONIC ENERGY BAND STRUCTURE OF MOLECULAR CRYSTALS MCI·(TCNQ)_2 AND ITS RELATIONSHIP WITH THE ELECTRICAL CONDUCTION

The structure of electronic energy bands, electric charge distribution and the amount of charge transfer of molecular crystals 1-MCI·(TCNQ)_2 (Ⅰ) and 2-MCI· (TCNQ)_2 (Ⅱ) have been studied. The results are: (ⅰ) The dominant contributions to the electrical conductivities for crystals Ⅰ and Ⅱ are from TCNQ molecular columns, and the charge carriers are electrons. (ⅱ) The electrical conduction is mainly due to the hopping of charge carriers between the seats of lattice. (ⅲ) The considerable difference of the electrical conductivities between crystals Ⅰ and Ⅱ is due to the differences between (a) the concentrations of charge carriers n_(AⅠ)~C= 0.9988-|e|/cell and n_(AⅡ)~C=0.0340-|e|/cell; (b) the widths of the energy bands △E_(AⅠ)~(LU)=0.88 eV and △E_(AⅡ)~LU=0.040 eV; (c) the first derivative of E with respect to k, (dE/dk)_(K_FAⅠ)~(LU)=0.27 eV· and (dE/dk)_(K_FAⅡ)~LU=0.0048 eV·; and (d) the difference of energy barriers for the hopping of charge carriers ∈_Ⅱ-∈Ⅰ=2.5-8.8 kJ/mol.     

Lamellar liquid crystal polymerization of sodium oleate/oleic acid/octadiene/water system

In the lamellar liquid crystallization (LLC) phase of NaOL/ OLA/H2O system, the small angle X-ray diffraction measurements show that the oleic acid is solubilized in the oil layer at first and then into the amphiphile layer. The octadiene added is also located partly in the oil layer and partly in the amphiphile layer in the LLC. With the addition of octadiene as cross-Unking agent, the LLC phase of NaOL/OIA/H2O system was polymerized under the initiation of AIBN with the protection of pure nitrogen at 60℃. Most of the double bond absorption of the monomers in IR spectra disappeared after polymerization. The polymerization takes place not only in the middle of the amphiphile layer between the double bonds of NaOL or OLA and those of octadiene, but also in the oil layer of LLC between the double bonds of OLA and those of octadiene. Interlayer spacing measurements on the copolymer proved d values decreased by about 1-2 nm compared with those of the corresponding system before the polymerization, indicati     

THE CATCH MECHANISM OF MOLLUSCAN SMOOTH MUSCLES

We have examined the arrangements of the thick and thin filaments of the smooth mus-cle of the adductor of the bivalve Cristaria plicata, Leach, in the catch state induced byacetylcholine, both in ultrathin sections and in separate filaments. The thick filaments areheavily bent and entangled and the thin filaments irregularly arranged. One thin filamentmay be attached to several thick filaments. When the muscle is in the relaxed state, the twokinds of filaments are seen to be in Parallel. However, no difference could be observed in theperiodic strusture of the paramyosin core of the thick filaments in the relaxed state or in catch.Both cross-striated and checkerboard types coexist. It seems that phase transition is not di-rectly related to catch. We propose that the disordered arrangements of the thick and thinfilaments and the formation of three-dimensional anastomosed networks are the structural basisfor catch, with a consequent loss of the capability of directional sliding of the filaments andrequiri     

CRYSTAL AND MOLECULAR STRUCTURE OF DEHYDROCRYDALINE CHLORIDE

The crystals of alkaloid Dehydrocrydaline chloride (C_(22)H_(24)NO_4·HCl) belong to the orthorhombic system. The space group is D_(2k)~(14)-Pbcn with the unit cell parameters of a=8.528,b=23.317 and c=24.798, and eight molecules per unit cell. The coordinates for all the non-hydrogen atoms were found by using direct methods and Fourier syntheses. During the course of refinement of this structure (using least squares and difference Fouriers), it was discovered that there are 4.5 water molecules with different occupancies in one asymmetric volume of the unit cell. The anisotropic refinement of non-hydrogen atoms and the isotropic refinement of non-aqueous hydrogen atoms led to a final R-factor of 0.053. Water molecules formed a relatively complex network around chloride ion.In this paper the small molecule structure and the network of water molecules are described.     

WHAT ARE THE DIFFERENCES OF POLYMER SURFACE RELAXATION FROM THE BULK?

The polymer surface relaxation in thin films has been a long debating issue.We report a new method on studying surface relaxation behaviors of polymer thin films on a solid substrate.This method involved utilizing a rubbed polyimide surface with a pretilting angle in a liquid crystalline cell.Due to the surface alignment,the liquid crystals were aligned along the rubbing direction.During heating the liquid crystalline cell,we continuously monitored the change of orientation of the liquid crystals.It is u...