Macromolecular Chemistry and Physics

Front Cover: As schematically shown in the cover, polymers in electric fields have been extensively studied during the last twenty years. While first, only the alignment of structures was investigated, order-order and order-disorder transitions (amongst others) have been found since. Cover designed by C.W. Pester. Further details can be found in the article by C. Liedel, C. W. Pester, M. Ruppel, V. S. Urban, and A. Böker* on page 259.

Back Cover: A new approach for preparation of gold nano-porous films was prepared from Au nanoparticles under-going an exchange reaction with PS-b-PBO micelles in solutions to form a block copolymer/Au composite. After the pyrolysis of the block copolymer templates at a specific temperature to avoid the collapse of the gold nanoparticles, a nanoporous gold film was formed. The materials that were fabricated by this method have potential applications as modified electrodes. Further details can be found in the article by S.-W. Kuo,* H.-Y. Yang, C.-F. Wang, and K.-U. Jeong on page 344.

Since 1991, electric fields have been shown to strongly affect block copolymer structures. Aside from alignment, morphological distortions, order–order, and order–disorder transitions have been described both in bulk and thin films. Important findings of the last two decades are summarized and perspectives for future progress in the field of block copolymers in electric fields are outlined.

Ionic liquid crystalline dendrimers and hyperbranched polymers are obtained by a proton transfer reaction between a polar carboxylic acid and the amine groups of the dendritic polymers. Both the chemical structure of the mesogenic unit and the scaffold of the dendritic polymer exert an influence on the supramolecular self-assembly of these macromolecules and they self-assemble in different mesophases.

The response from a pulsed gradient stimulated echo NMR experiment on a polymer in solution is found to be approximated by a stretched exponential function. By performing an inverse Laplace transform, the molecular weight distribution is obtained. The relationship between the molecular weight distribution and a log-normal distribution is discussed.

PDnETs have ordered layer structure and the d-spacing values of the long period increase almost linearly as the number of ethylene oxide units increases from one to four. The intensities of the (100) peak related to layer spacing for PD3ET and PD4ET are much more intense than those for PD1ET and PD2ET indicating that PD3ET and PD4ET have more ordered layer structures.

A guideline for the synthesis of poly(acrylic acid) brushes on planar silica surfaces by the “grafting-onto” approach is described. Characterization determines the best conditions to obtain extended brushes. The cleavage of chains and the formation of loops during the grafting of end-functionalized poly(tert-butyl acrylate) chains can be prevented if thermal precautions are taken.

Statistical, block and star polymers with lower critical solution temperature (LCST) close to 38 °C at pH 7 to 7.4 are prepared using RAFT copolymerization of NIPAAm with acidic comonomers. Statistical copolymers and short block copolymers show complex aggregation, whereas mid-size block copolymers and star polymers show shrinkage of aggregate dimensions. pH impacts stronlgy the LCST.

The synthesis of tunable nanometer-scale architecture of organic–inorganic hybrid materials involves direct crystallization of polymers along the long axis of carbon nanotubes (CNTs), which produces a strong polymer/CNT interface. The spacing between periodic polymer crystals is tuned by changing undercooling conditions.

Acrylates and methacrylates can be photopolymerized without photoinitiator using 172 nm radiation. Real-time FTIR-ATR spectra show that layers with ≈500 nm thickness can be polymerized rapidly. The penetration of the polymerization into the layer was found to exceed the initial penetration depth of the VUV radiation, which indicates bleaching of the acrylates during irradiation.

A well-defined multiarm star copolymer, hyperbranched poly(glycidol)-b-poly(methyl methacrylate) (PGOH-b-PMMA) is used as modifier in the curing of diglycidylether of bisphenol A (DGEBA). The addition of PGOH-b-PMMA leaves the complex viscosity unaltered. The shrinkage after gelation and the mechanical characteristics are improved compared to the neat formulation.

A new approach is developed for the preparation of nanoporous gold (Au) films using diblock copolymer (PS-b-PBO) micelles as templates. After the pyrolysis of the diblock copolymer templates at a specific temperature to avoid the collapse of the gold nanoparticles, a nanoporous Au film is prepared.

Syndiotactic polystyrene particles with significant anisotropy are prepared from a miniemulsion–solvent evaporation process. The crystallinity increases with increasing particle diameter. For PLLA, it is possible to control the crystallinity of the particles by a thermal treatment of the dispersions.