摘要:

AbstractA study on aqueous solutions of an alternating copolymer maleic anhydride‐2,4,4,‐trimethylpentene‐1 is reported. The main feature of the hydrolysis product (PTMLA) is the remarkable interaction between nearest neighbor carboxyl groups. The interaction between neighbor dipoles is favored by the presence of hydrophobic side chains, which cause the lowering of the “local” dielectric constant. As a result, the PTMLA behaves like a polydi‐basic acid. From viscosimetric trends and other properties, it is possible to deduce that this copolymer undergoes a transition to a highly coiled form at low pH's and then to an intermolecular aggregation. It maintains an expanded conformation in a wide range of alkaline pH's. It is possible to correlate this behavior with its capacity as dispersant as well as the structural characteristics of the side chain for this and other

ISSN:0360-8905    

DOI:10.1002/polc.5070440103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractProton NMR spin‐lattice relaxation times are reported for the solvent in the two component lyotropic liquid crystal, dichloromethane plus poly(γ‐benzyl‐L‐glutamate). The relaxation times become Larmor frequency dependent on passing from the isotropic solution to the liquid crystal. A simple model based on thesupramolecular structure in the liquid crystal exhibits orientational fluctuations in the radio frequency region suggesting that spin‐lattice relaxation of the polypeptide protons should also show frequency

ISSN:0360-8905    

DOI:10.1002/polc.5070440104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

ISSN:0360-8905    

DOI:10.1002/polc.5070440105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

ISSN:0360-8905    

DOI:10.1002/polc.5070440106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe crystallization of polymers with long side chains proceeds in the form of hexagonal crystal lattice, regardless of the configuration of the backbone chain. For these polymers the ordered structure in the crystalline state as well as in the melt is typical. The tendency to form an ordered structure takes place in the solutions of branched polymers. At polymer critical concentration about 0.5 wt % the gelation process occurred.The structure and properties of gels of acrylic polymers (i.e., polycetylacrylate) inn‐aliphatic alcohols (C7H15OH–C12H25OH) and hydrocarbons (C10H22–C16H34) were studied. The x‐ray patterns show that all the gels have the same interplanar spacings at the wide angles which correspond to the hexagonal cell. The phase transitions and thermodynamic parameters of gel‐solution transition were studied by means of x‐ray and differential thermal analysis. The structure of gels in alcohols and hydrocarbons was found to be different. This difference was explained in terms of specific polymer‐solvent interactions.The kinetics of supermolecular structure formation in gels was investigated using small‐angle light scattering (SMAL) method. Rather good correlation between SMAL and electron microscopic data was found.Some conclusions about the character of the supermolecular structure‐forming process were made and the model of gel struc

ISSN:0360-8905    

DOI:10.1002/polc.5070440107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractStarting from the theory of formation of liquid crystalline mesophases in solutions of rod‐like rigid chain macromolecules, developed by Flory and DiMarzio, the situation is analyzed where the flexibility parameter,f, which is essential in this theory, is variable and concentration dependent. It is shown that energetic factors of physical‐chemical origin expressed by the polymer‐solvent interaction parameter, χ1, and connected with the selectivity of these interactions may influence substantiallyf, changing its value from the supercritical (>0.63), when self‐organization in an ordered mesophase is impossible, to the subcritical, i.e., values down tof→ 0, when a spontaneous formation of a liquid crystalline phase occurs. In quite a similar manner (the analogy encompassing even the corresponding formulae)fis affected by external fields, as a result, in a stationary orienting field a system of flexible chain macromolecules may become equivalent to a unperturbed system of rigid chain macromolecules. The external field can also decrease the critical concentration of the formation of the liquid crystalline phase in rigid chain systems and liquidate the domain structure, thus transforming such a system into a unique “liquid single crystal”. This is shown to be true for the behavior of a rigid chain polymer polyparabenzamide in strong magnetic fields.The analysis leads to the conclusion that a purely entropic formalism for the description of the formation of extended chain liquid crystals is neither necessary nor sufficient, and purely energetic factors most certainly must be taken into account. However, following incorporation of these data, it becomes possible to reduce the formation of the ordered phase to the “entropic” mechanism

ISSN:0360-8905    

DOI:10.1002/polc.5070440108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractRate of the diffusion front displacement, rate of sorption and rate of turbidity for the system of bisphenol A polycarbonate foil‐methylisobutylketone were determinated. The influence of the temperature on the observed phenomena was investigated. An attempt at apreliminary interpretation was don

ISSN:0360-8905    

DOI:10.1002/polc.5070440109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe intrinsic viscosities and sedimentation constants of polymethacrylic acid‐poly‐vinylpyrrolidone (PMAA‐PVP) mixtures have been measured in water and dimethylsulf‐oxide. By conductometric method it has been shown that the composition of those complexes is stoichiometric.The value of intrinsic viscosity of the complexes in water is about 0.10 dl/g which is close to the viscosity of globular proteins. This value seems to be almost independent of the concentration and molecular weight of the macromolecular components of the complex (both PMAA and PVP have been used as an oligomer and as an matrix), and in the case of high molecular weight of both the components as well.In an organic solvent a sharp increase of intrinsic viscosity is observed. This is probably connected with the weakening of hydrophobic bonds stabilizing the compact structure of complex in water. In dimethylsulfoxide reduced viscosity depends on concentration and intrinsic viscosity on the molecular weight of the matrix (PMAA). The values of hydrodynamic‐average molecular weights of complexes establish the intermolecular association of complexes particles in water, and the degree of association depending on the molecular weight of the matrix. In dimethylsulfoxide probably not only the weakening of hydrophobic interactions but the destruction of hydrogen bonds occurs, following which the dissolution of the complexestakes places. In water‐dimethylsulfoxide mixtures a gradual destruction of the complex is observed at the transition from water to orga

ISSN:0360-8905    

DOI:10.1002/polc.5070440110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractLight scattering as a function of scattering angle, concentration, and temperature reveals that polyoxyethylene (POE) forms large aggregates in benzene and chloroform, while in methanol and dioxane almost complete molecular dispersion occurs. Although the solutions containing large aggregates contain a distribution of molecular weights, the angular envelopes ofc/R(θ) versus sin2θ/2 exhibit pronounced upward curvature, indicating that the aggregates are dense structures such as spheres or highly branched coils. In methanol, the angular envelopes exhibit moderate downward curvature, reflecting the essentially molecularly dispersed character of the solution and the breadth of the molecular weight distribution. In filtered solutions of dioxane, a tendency exists for minima to occur in the angular envelopes; this can be rationalized in terms of the anisotropy of the scattering. The polarized components of the scattered intensityVV, HV, VH, andHHwere studied in the scattering plane. For the large aggregatesHVis angular dependent, while in methanol and dioxaneHVis independent of angle. Heating or cooling a POE solution in benzene followed by a study of the angular envelope, shows that the aggregates are stable. Hydrodynamic measurements fail to detect the existence of the aggregates. Taking all the data into consideration, the large aggregates appear to be compact, extensively branched, anisotropic, and stabl

ISSN:0360-8905    

DOI:10.1002/polc.5070440111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe methods of turbidity spectrum and viscometry have been used to investigate structurization in the concentrated solutions of poly (m‐phenylene isophthalamide) (Pm‐PIPA) in dimethylacetamide (DMA). The kinetics of formation of the supermolecular order (SMO) were studied under isothermal conditions within the temperature and concentration range of 30 to 150°CC and 5 to 25 g/dl, respectively. Two stages of formation of SMO were observed, viz., a comparatively slow stage and after that a very fast increase in the SMO level. In the first stage, the average particle radius,rλ, decreases, which probably is related to the continuous formation of nuclei. In the second stage,rλ and the turbidity, τ, of solution increase steeply. In the same stage, an increase in the viscosity of solution was also observed. A diagram of the properties of the system was constructed, which is analogous to the phase diagram. The temperature limit of the stability,Tbi, fulfills the requirement ofVτ= 0, whereVτ(the rate of increasing turbidity), was determined.Tbidetermines the binodal curve depending on the polymer concentration. The temperature limit of absolute instability,Tsp, fulfilling the requirement ofVτ→∞, was determined. Depending on the concentration of solution, Tspwas identified with a spinodal curve. The property diagrams obtained are characteristic of the curves of amorphous separation with the lower critical solution temperature. With increasing molecular weight, Mζ, Tcdecreases. Additions of a third component cause a deformation of the binodal curve and shift it to higher (lithium and calcium chlorides) or lower (water) temperatures. The time,ts, of reaching a certain level of SMO during thermostabilization atT= 80°CC was taken as a measure of stability of technol

ISSN:0360-8905    

DOI:10.1002/polc.5070440112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY