MOLECULAR CHARACTERISTICS AND CRYSTALLINE-STRUCTURE OF ETHYLENE-DIMETHYLAMINOETHYL-METHACRYLATE COPOLYMERS

The relationship between molecular and crystalline structural characteristics of the ethylene -dimethylaminoethylmethacrylate copolymers (EDAM) was investigated and related to melt flow index MI and average gross content of DAM comonomer, in comparison with low density polyethylene (LDPE) produced by the common high-pressure radical polymerization process. Although the average molecular weight and its distribution are influenced predominantly by the polymerization conditions, DAM-content seems not to depend significantly on molecular weight according to the GPC-FT/IR measurement. Comonomer sequence distributions were determined quantitatively with the C-13-NMR spectra entirely assigned by DEPT and H-1-C-13 COSY techniques. The result suggests the alternating copolymerization tendency and surprisingly coincides with the simulation out-puts based on the assumption of continuous complete mixing reactor model, using Mayo-Lewis equation and the same Q-e values as previously reported on different types of copolymers such as EVA and St.DAM (VA;vinylacetate, St;styrene). It was confirmed by WAXD and SAXS analyses that the crystallinity X(c) and the thickness of lamellar crystal l(c) decreased with increasing DAM-content, whereas the a-lattice and b-lattice dimensions enlarged. X(c) and l(c) can definitely be correlated to the heats of fusion and crystallization measured by DSC. The average size of spherulites measured with light scattering photometry tends to be enlarged with decreasing molecular weight (increasing MI) and DAM-content.

MICROSTRUCTURE ANALYSIS OF 3 SEGMENTED COPOLYMERS CONTAINING POLYDIMETHYLSILOXANE BY SOLID-STATE HIGH-RESOLUTION NMR

The microstructure of two bicomponent and one tricomponent segmented copolymers, based on polydimethylsiloxane, poly(p-hydroxystyrene) or/and polysulfone, were investigated using an extended Goldman-Shen pulse sequence, proton spin-spin relaxation measurements, and C-13 and Si-29 NMR spectra. The results indicate that there exist four phases with different sizes, components and morphological structure in the segmented copolymers studied in this work, i. e., a rigid-chain phase of very slow motion, a rigid-chain-rich phase of slow motion, a flexible-chain-rich phase of fast motion and a flexible-chain phase of faster motion. The sizes of different domains, calculated from the spin diffusion rates, are about 50-100 angstrom for the flexible-chain-rich phase of fast motion and 200-300 angstrom for the flexible-chain phase of faster motion. The relative quantities of polydimethylsiloxane in the flexible-chain phase of fast motion are slightly different in different kinds of segmented copolymers.

SYNTHESIS AND CRYSTAL-STRUCTURE OF [(ME4C2CP2SMCL.MGCL2.3THF)THF]2

[(Me4C2Cp2SmCl.MgCl2.3THF)THF]2 was prepared by the reaction of Me4C2Cp2MgCl2.4THF (Cp=C5H4, THF = tetrahydrofuran) with SmCl3 in THF. The crystals belong to triclinic space group P-1 with a 12.149(3), b 13.187(4), c 13.810(5) angstrom, alpha 117.23(2), beta 94.07(2), gamma 62.86(2)-degrees, V = 1723.9(1.0) angstrom3. In the molecular structure of the title compound there is a symmetrical centre and a quadrilateral formed by SM, Mg, Cl1, Cl2 atoms. Two centroids of the cyclopentadienyls, bridged by a tetramethylethano group form with three bridging chlorine atoms (Cl1, Cl2, Cl1a) a pseudo-trigonal bipyramid around Sm. Three oxygen atoms of THF and three chlorine atoMS (Cl1, Cl2, Cl3) constitute a distorted octahedron around Mg.

A HIGH-RESOLUTION SOLID-STATE NMR AND DSC STUDY OF MISCIBILITY AND CRYSTALLIZATION BEHAVIOR OF POLY(VINYL ALCOHOL)/POLY(N-VINYL-2-PYRROLIDONE) BLENDS

Blends of crystallizable poly(vinyl alcohol) (PVA) with poly(N-vinyl-2-pyrrolidone) (PVPy) were studied by C-13 cross-polarization/magic angle spinning (CP/MAS) n.m.r. and d.s.c. The C-13 CP/MAS spectra show that the blends were miscible on a molecular level over the whole composition range studied, and that the intramolecular hydrogen bonds of PVA were broken and intermolecular hydrogen bonds between PVA and PVPy formed when the two polymers were mixed. The results of a spin-lattice relaxation study indicate that blending of the two polymers reduced the average intermolecular distance and molecular motion of each component, even in the miscible amorphous phase, and that addition of PVPy into PVA has a definite effect on the crystallinity of PVA in the blends over the whole composition range, yet there is still detectable crystallinity even when the PVPy content is as high as 80 wt%. These results are consistent with those obtained from d.s.c. studies.

STRUCTURES AND PROPERTIES OF DIALKYL FUMARATES POLYMERS

Polymers of methyl-iso-propyl fumarate, di-iso-propyl fumarate, di-t-butyl fumarate, di-s-butyl fumarate, di-s-amyl fumarate and di-cyclo-hexyl fumarate were prepared by radical polymerization. The structures of the polymers were examined by H-1-NMR, C-13-NMR and WAXD. Some properties of the polymers, including thermal properties, were examined.

SYNTHESIS AND MOLECULAR-STRUCTURE OF NBU2[(MEO)3C6H2C(O)N2CHC6H4O]SN FORMED IN THE REACTION OF DI-N-BUTYLTIN(IV) OXIDE WITH 3,4,5-TRIMETHOXY-BENZOYL SALICYLAHYDRAZONE

The title complex was synthesized and characterized by H-1, C-13, Sn-119 NMR and IR spectra. A single crystal X-ray diffraction study confirmed its molecular structure and revealed that 3,4,5-trimethoxy-benzoyl salicylahydrazone was a tridentate and approximately planar ligand. The complex crystallizes in the triclinic space group P1BAR with a = 9.208(3), b = 12.536(2), c = 12.187(4) angstrom, alpha = 113.12(2), beta = 90.58(2), gamma = 81.42(2), V = 1277.5(6) angstrom, Z = 2. The structure was refined to R = 0.033 and R(w) = 0.041 for 3944 observed independent reflections. The tin atom has a distorted trigonal bipyramidal coordination. The Sn-C bond lengths are 2.129(5) and 2.113(5) angstrom (av. 2.121(5) angstrom), the C-Sn-C angle is 123.3(2); the bond length between the tin atom and the chelating nitrogen is 2.173(3) angstrom. Two chain carbon atoms and the chelating nitrogen atom occupy the basal plane. The skeleton of two erect oxygen atoms and the tin atom is bent (O-Sn-O angle = 153.5(1)). In the complex, the ligand exists in the enol-form.

SYNTHESIS AND CHARACTERIZATION OF POLY-ORTHO-METHYLANILINE WITH DIFFERENT DEGREES OF OXIDATION

Poly-ortho-methylanilines (POT) in three states fully oxidized, fully reduced and oxidized in varying degrees were synthesized by the reaction of common POT (C-POT) having nearly equal amounts of benzenediamine and quinonediimine units with iodine or phenyl-hydrazine, and the resulting polymers were characterized by IR, C-13-NMR, SEM and elemental analysis. The results showed that the quinonediimine unit in C-POT could be reduced by phenylhydrazine to the benzenediamine unit, forming the polymer with low OD (oxidation degree) or in a fully reduced state and that iodine-oxidation resulted in the increase of quinonediimine unit and decrease of benzenediamine unit. The solubility and flexibility of the formed polymers depend strongly on the amount of quinonediimine unit in it. It is necessary to reduce the content of quinonediimine structure unit in order to improve the solubility of aniline-class polymers.

A HIGH-RESOLUTION SOLID-STATE NMR-STUDY OF THE MISCIBILITY, MORPHOLOGY, AND TOUGHENING MECHANISM OF POLYSTYRENE WITH POLY(2,6-DIMETHYL-1,4-PHENYLENE OXIDE) BLENDS

An extended Goldman-Shen pulse sequence was used to observe indirectly the proton spin diffusion in the blends of polystyrene (PS) with poly(2,6-dimethyl-1,4-phenylene oxides) (PPO). The results indicate that the average distance between PS and PPO is less than 5 angstrom in the intimately mixed phase, but there are heterogeneous domains on a 100-angstrom scale. The data of spin relaxation of carbons, T1(C), for homopolymers and their blends suggest that there is a strong pi-pi electron conjugation interaction between the aromatic rings of PS and those of PPO, while the aromatic rings of PPO drive the aromatic rings of PS to move cooperatively. It is the cooperative motion that markedly improves the impact strength of PS.

STRUCTURE INVESTIGATION OF TI(OBU)4-ALET3 CATALYST BEFORE AND AFTER HEAT-TREATMENT

The catalyst structure of Ti(OBu)4-AlEt3 at different Al/Ti ratios before and after heat aging has been investigated from the data of UV, GC-MS, ESR and C-13 NMR spectra. The complex compounds formed by HTiEt2 and AlEt2(OBu) exist mainly in the catalyst solution, and no -OBu ligands linking with Ti atoms can be found at an Al/Ti ratio of four before heat aging. Many kinds of catalytic species with different size are formed after heat aging the catalyst at 110-degrees-C for 2 h. Dehydrogenation, accompanied by the valence change from Ti3+ to Ti2+, is observed during the aging process of the catalyst.

NMR-STUDIES ON THE COORDINATION OF RARE-EARTHS WITH GLYCYL-DL-VALINE AND THE CONFORMATION OF THEIR COMPLEX IN AQUEOUS-SOLUTION

In this paper lanthanide-induced shifts have been measured for C-13 and H-1 nuclei of glycyl-DL-valine in the presence of three lanthanide cations (La3+, Ho3+ and Yb3+) in aqueous solution. The stability constants of the coordination compounds of rare earths (Ho, Yb) with glycyl-DL-valine have been calculated. The coordination of rare earths with the ligand has been discussed. The simulation for conformation of lanthanide coordination compounds with glycyl-DL-valine shows that the ligand is coordinated to lanthanide ion through oxygen atoms of carboxyl group and the bond length of Ln-O is 0.226 nm. In the coordination compounds glycyl-DL-valine is in extended state with minimal steric hindrance.

STRUCTURE OF CIS-DIAQUABIS(1,10-PHENANTHROLINE)ZINC SULFATE HEXAHYDRATE

[Zn(C12H8N2)2(H2O)2]SO4.6H2O, M(r) = 665.98, triclinic, P1BAR, a = 10.070 (4), b = 12.280 (3), c = 13.358 (2) angstrom, alpha = 109.12 (2), beta = 92.58 (2), gamma = 110.85 (2)-degrees, V = 1433.9 (7) angstrom 3, Z = 2, D(x) = 1.54 g cm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 10.1 cm-1, F(000) = 692, T = 293 K, R = 0.044 for 3985 observed reflections. The Zn atom is coordinated in a distorted octahedral geometry by four N atoms from two 1,10-phenanthroline (phen) ligands and two water molecules. The intermolecular ring-stacking interactions between the phen ligands occur in two forms: infinite chains and discrete dimers. Hydrogen bonds further stabilize the structure.

THE COMPOSITIONS AND STRUCTURES OF SOME COMPOUNDS IN THE SYSTEM CA-SR-CU-O

The system of Ca-Sr-Cu-O have been investigated. Two new compounds with compositions Sr3Cu5O8+alpha and CaSrCu3O5+alpha have been discovered. Both are orthorhombic with a = 6.489, b = 11.280, c = 12.240 angstrom for CaSrCu3O5+alpha and a = 3.950, b = 11.479, c = 13.420 angstrom for Sr3Cu5O8+alpha. The X-ray powder data for CaSrCu3O5+alpha, Sr3Cu5O8+alpha, Sr2CuO3 and SrCuO2 are presented. The oxidation state of Cu ion and oxygen contents are analyzed by iodometric titration. Sr0.5Ca0.5CuO2 that has a similar structure with SrCuO2 has been found and its X-ray data are presented also.

CHARACTERIZATION, MORPHOLOGY AND THERMAL-PROPERTIES OF ETHYLENE PROPYLENE BLOCK COPOLYMERS

Characterization, morphology and thermal properties of commercial ethylene-propylene block copolymers have been studied by C-13 nuclear magnetic resonance (n.m.r.) spectroscopy, differential scanning calorimetry (d.s.c.), dynamic mechanical analysis (d.m.a.) and scanning electron microscopy (SEM). The results obtained show that there exists some ethylene-propylene random copolymer in the block copolymers extractable by n-heptane. The possibility of forming PP-b-PE diblock copolymer is questionable on the basis of the effects of residual propene and the chain-transfer reaction in the sequential copolymerization. A difference in the thermal properties between commercial ethylene-propylene block copolymers and PP/PE blends was noticed, which cannot be used to identify PP-b-PE diblock copolymer. The multiphase structure has been confirmed by d.m.a. and SEM, with ethylene-propylene random copolymer and polyethylene forming the domains in the matrix of polypropylene.

取代基效应(SCS)与乙烯—α—烯烃共聚物的序列结构——Ⅱ.取代基效应方法

本文提出了一种解析乙烯-α-烯烃共聚物的~(13)C NMR谱的取代基效应方法,它揭示了存在于共聚物序列结构与~(13)C谱之间的对应关系,并对这种关系进行了系统的阐述。文章中首次按上述对应关系明显与否将共聚物~(13)C谱分成两类,并给出进行分类的三种判据:SCS参数,共单体均聚物的~(13)C谱,以及取代基的电性。文章最后比较了取代基效应方法与Grant-Paul方法的异同。

PrP_5O_(14)的晶体结构与铁弹畴

本文用X射线衍射方法研究了PrP_5O_(14)的晶体结构和铁弹相变。晶体空间群为P2_1/c,晶胞参数a=8.777(1)A,b=9.029(2)A,c=13.068(2)A,β=90.35°(1),z=4,最终R值为0.046。在130±5℃转变成正交晶系,空间群为P_(ncm),a=8.813(7)A,b=9.075(2)A,c=13.119(10)A。高温相变使晶体产生了铁弹性孪晶,室温下晶体属mmmF2/m类铁弹体。