Macromolecular Chemistry and Physics

Cover: Weak polyampholytes made of N,N′-diallyl-N,N′-dimethylammoniumchloride and N-substituted maleamic acid derivatives show a transition from an extended conformation of a polycation at pH≪IEP to one of a polyanion or to a compact polyampholyte coil at pH≫IEP. The acidity of the carboxylic groups depends on the degree of dissociation and the ionic strength. Further details can be found in the article by M. Fechner and J. Koetz* on page 2691.

The P-stereogenic optically active polymer is synthesized using P-chiral bisphosphine as a key monomer. Bisphosphine moieties can coordinate to transition metals such as palladium and platinum, leading to a change in the conformation.

Orthogonally reactive, heterobifunctional polyesters are obtained by Baylis–Hillman polymerization of 1,3-butanediol diacrylate with iso- and terephthaldehyde. The influence of a variety of catalysts and additives on the polymerization of these two pairs of monomers and the molecular weight of the resulting polymers has been investigated. The obtained polymers may be interesting precursors, e.g., for the development of dual-cure coatings.

Branched and network polysilanes [Et₂Si(CH₂)₃Si]_n and [(PhMeSi)_0.8-co-(Et₃Si(CH₂)₂Si)_0.2]_n are proposed as sources of silyl radicals. The direct cleavage of the Si—Si bonds in these oligomers ensures the formation of reactive silyl radicals. The examples shown outline the interest of poly(silane)s as macrophotoinitiators in FRP or FRPCP processes. The specific behavior of PSs under air is worthwhile for practical applications.

The series of P[M(E)_mMO-alt-SA] alternating copolymers are a new class of thermoresponsive polymers with a degradable polyester backbone and oligo(ethylene glycol) side chain. They possess many excellent properties for biomedical applications, such as wide-range thermoresponsivity, unusual degradation modes and appropriate degradation periods, and no acute toxicities.

The synthesis of polyelectrolytes by regioselective modification of cellulose with three different ionic liquids via click chemistry is described. The rheological behavior in 1-ethyl-3-methyl-imidazolium acetate is studied with respect to the influence of the different substituents.

A new type of conductive polymer based on sodium sulfosuccinate coupled poly(ethylene glycol) is synthesized and characterized. PEGs of different molar masses are used to produce a family of conductive polymer materials. All products exhibit a low viscosity, where the viscosity decreases as the molar mass of the PEG chains increases.

The detection of products derived from thermo-oxidation of poly(bisphenol A carbonate) is performed by direct electrospray mass spectrometry. The formation of bisphenol A oligomers as well as several new species containing biphenyl units, phenols, acetophenones, alcohols, acids, and xanthones molecules is evident.

The shear modulus of nematic side-chain liquid-crystal elastomers swollen with a nematic solvent is studied. Elasticity is Gaussian for systems oriented before crosslinking and non-Gaussian for systems oriented by stretching the network formed during its synthesis. For systems oriented before crosslinking, a crossover between Gaussian and non-Gaussian behavior is observed at a particular solvent concentration.

Composite hollow microspheres consisting of polyaniline (PANI) and indomethacin (IND) are prepared through a self-assembly process in a mixed methanol/water solution. Different volume fractions of methanol to water and different aniline concentrations are investigated to obtain the optimal conditions for the formation of PANI/IND composite hollow microspheres. The morphologies are characterized, showing the inner hollow center of the microspheres. A controlled release of IND is achieved by adjusting the pH value of the buffer solution.

For decades, the viscosity (η)–molecular weight (M) relationship of linear polymer melts has been successfully described by the Debye–Bueche model when M is lower than critical molecular weight (Mc). Experimental results show that the Debye–Bueche model does not hold for some polymers with polar endgroups and a modified molecular-level model is proposed.

Weak polyampholytes composed of N,N′-diallyl-N,N′-dimethylammoniumchloride and different N-substituted maleamic acid derivatives show a transition from an extended chain to a coil conformation by reaching the isoelectric point. Potentiometric titration curves show that the acidity of the carboxylic groups strongly depends on the degree of dissociation and the ionic strength.

An easily modifiable propargyl acrylate-based monolithic stationary phase is developed for capillary electrochromatography. The functionalization is obtained by alkyne-azide 1,3-dipolar cycloaddition. Two azides are synthesized: cinnamyl azide increases the retention of PAHs and the separation of flavonols, and the 6-azido-6-deoxy-β-cyclodextrin allows the chiral separation of warfarin.