摘要:

AbstractWe discuss the aggregation behavior of flexible‐rigidflexible triblock copolymers in a selective solvent of low molecular weight. Aggregation may lead either to plates of (R) covered by brushes of (F), or to large “needles” (as a consequence of the Skoulios effect). In the absence of anisotropic bonding between adjacent rods, the “fence” morphology is not

ISSN:0258-0322    

DOI:10.1002/masy.19920620104

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractTwo experimental evidences are discussed of the reflectance discontinuity associated with very long adsorbed polymer chains.The anomalous low reflectivity is compared to the Ramsauer‐Townsend effect in the scattering of slow electrons by rare‐gas at

ISSN:0258-0322    

DOI:10.1002/masy.19920620105

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractWe discuss the adsorption of polymer solutions on chemically heterogeneous surfaces. Two types of heterogeneities are considered, annealed and quenched. In both cases, the disorder increases the adsorption. For a same adsorption strength, the adsorbed amount of polymer is higher on an annealed surface than on a quenched surface. The adsorption on an annealed surface can induce a two‐dimensional phase transition on the surfac

ISSN:0258-0322    

DOI:10.1002/masy.19920620106

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractNonlinear kinetics of both spinodal decomposition at early stages, and the dissolution of homogeneities formed during spinodal decomposition, is studied. Variation of the scattering intensity during a complete cycle consisting of a step temperature change from T1in the one‐phase region to T2in the two‐phase region, a period of spinodal decomposition followed by a temperature drop from T2back to T1, and the subsequent relaxation to the original equilibrium state, is investigated at various wavenumbers. Step temperature changes within one‐phase region are also investi

ISSN:0258-0322    

DOI:10.1002/masy.19920620107

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractLocalization of cross‐links is an important issue in the theory of rubber elasticity. We consider freely‐hinged rigid rod networks and show that in some cases they behave like critical objects: junctions fluctuate on all length scales. Such networks exhibit anomalously low shear modulus and cannot resist shear deformations. These conclusions are very different from the classical picture and might be of some significance for gels near the critical point of volume transition. We comment on the reasons for the different behavior of gels under more usual conditions and raise questions concerning the ability of cross‐links to rearrange on scales larger than the mesh

ISSN:0258-0322    

DOI:10.1002/masy.19920620108

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractSelf‐assembled structures in solvent‐cast films of binary mixtures of poly(styrene‐block‐isoprene) (SI) and homo‐polystyrenes (HS) were studied as a function of rs, the ratio of molecular weights of HS and polystyrene block (PS) in SI and of wHS, the weight fraction of HS. For rS1 (still in the criterion of dry brush), SI and HS undergo macrophase separation, forming SI domains composed of a

ISSN:0258-0322    

DOI:10.1002/masy.19920620109

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this paper one recalls the history of the development of scattering studies after the first world war in Strasbourg.Tremendous progress has been made and some examples of this progress are discussed

ISSN:0258-0322    

DOI:10.1002/masy.19920620110

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe application of the neutron reflectivity technique to the study of polymer‐polymer interfaces is described and several examples given. The high resolution of the technique allows the details of the interface during early stages of mixing to be resolved for a partially miscible blend. The results are discussed in terms of recent theorie

ISSN:0258-0322    

DOI:10.1002/masy.19920620111

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractCritical fluctuations were studied in polymer mixtures of poly(dimethylsiloxane) and poly(ethylmethylsiloxane), which exhibit an upper critical temperature at Tc⋍ 57 °C. The measurements were performed in a broad temperature range at three compositions in the miscible region close to the coexistence line. The temperature dependence of the static structure factor S(q=0) can be described by a mean field behaviour except for temperatures in the range of 6 K above Tc. There, a turnover to an Ising behaviour is observed according to a modified Landau‐Ginzburg criterion. The mean field spinodal temperature Tswas determined by extrapolation of S(0)−1to zero. From the Ornstein‐Zernike representation of the angular dependence of S(q), the correlation length ζ of the concentration fluctuations can be determined and leads to a critical amplitude ζ0= lim ζ(T→∞) = 20.5 Å.The interdiffusion dynamics described by the mutual diffusion constant D has been measured by quasielastic light scattering. It shows for the critical composition ϕca critical slowing down as T approaches the critical temperature Tc. Furthermore, the q2scaling of the relaxation rate of the interdiffusion dynamics changes to q3behaviour close to Tcaccording to the mode coupling t

ISSN:0258-0322    

DOI:10.1002/masy.19920620112

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPlotting log[η] versus logM (Mark‐Houwink‐Sakurada equation) we observe a crossover region in which a continuous variation of the exponent of this equation takes place. This crossover region is delimited by two characteristic numbers: Nc (or Mc), the number of statistical segments (or the molecular weight) in the onset of excluded volume behavior and Nc' (or Mc') the number of statistical segments (or the molecular weight) in the onset of the complete excluded volume behavior. Relations are given in order to obtain these numbers. The Stockmayer‐Fixman‐Burchard equation is valid for the flexible and wormlike polymers in the molecular weight region which lies above the crossover region while the Dondos‐Benoit equation is valid in the medium and low‐molecular‐weight region including the cr

ISSN:0258-0322    

DOI:10.1002/masy.19920620113

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY