A comparative study of intrachain cyclization and solution properties of long-subchain hyperbranched polymers prepared via Y-type and V-type macromonomer approaches

V-type (B∼∼A∼∼B) and Y-type (A∼∼∼∼B₂) macromonomer approaches are two of the most widely adopted synthetic methodologies for the preparation of long-subchain hyperbranched polymers (LHPs) with a controlled subchain length.

The Synergy of Double Cross-linking Agents on the Properties of Styrene Butadiene Rubber Foams

Sulfur (S) cross-linking styrene butadiene rubber (SBR) foams show high shrinkage due to the cure reversion, leading to reduced yield and increased processing cost. In this paper, double cross-linking system by S and dicumyl peroxide (DCP) was used to decrease the shrinkage of SBR foams. Most importantly, the synergy of double cross-linking agents was reported for the first time to our knowledge. The cell size and its distribution of SBR foams were investigated by FESEM images, which show the effect of DCP content on the cell structure of the SBR foams. The relationships between shrinkage and crystalline of SBR foams were analyzed by the synergy of double cross-linking agents, which were demonstrated by FTIR, Raman spectra, XRD, DSC and TGA. When the DCP content was 0.6 phr, the SBR foams exhibit excellent physical and mechanical properties such as low density (0.223 g/cm³), reduced shrinkage (2.25%) and compression set (10.96%), as well as elevated elongation at break (1.78 × 10³%) and tear strength (54.63 N/mm). The results show that these properties are related to the double cross-linking system of SBR foams. Moreover, the double cross-linking SBR foams present high electromagnetic interference (EMI) shielding properties compared with the S cross-linking SBR foams.

Quantitative Analysis of Step-Growth Polymers by Size Exclusion Chromatography

We report an advanced analysis protocol that allows to quantitatively study the course of step-growth reactions by size exclusion chromatography on the example of the depolymerization of a Diels-Alder polymer based on a furane/maleimide couple at elevated temperatures. Frequently occurring issues of molar mass calibrations and overlap of monomer with solvent signals are addressed for determining reliable molar masses. Thereby, even kinetic parameters (e.g., rate coefficients) can be derived that otherwise would require performing additional spectroscopic experiments. Our results confirm first-order behavior of the rDA reaction with an activation energy of 33 kJ mol^-1.

Non-covalent dispersion of multi-walled carbon nanotubes in aqueous solution with hyperbranched polyethylene-g-poly(methacrylic acid)

Amphiphilic hyperbranched polyethylene-g-poly(methacrylic acid) was synthesized and found to be an efficient dispersant for dispersing MWCNTs in water.

Hyperbranched polymers from A2 + B3 strategy: recent advances in description and control of fine topology

Recent advances in the fine topology regulation of hyperbranched polymers from an A₂ + B₃ strategy were presented from the perspectives of topology description and architecture control.

100% hyperbranched polymers via the acid-catalyzed Friedel–Crafts aromatic substitution reaction

A highly efficient and benign strategy to synthesize hyperbranched polymers with a degree of branching of 100% was presented via the Friedel–Crafts reaction.

Intramolecular cyclization of long-chain hyperbranched polymers (HyperMacs) from A2 + Bn step-wise polymerization

We presented a precise topological analysis on intramolecular cyclization for long-chain hyperbranched polymers via the new parameter of the macro-cyclic index (m-CI).