Synthesis of a Star‐Shaped Copolymer with a Hyperbranched Poly(3‐methyl‐3‐oxetanemethanol) Core and Tetrahydrofuran Arms by One‐Pot Copolymerization

A star‐shaped copolymer consisting of a hyperbranched poly(3‐methyl‐3‐oxetanemethanol) core and polytetrahydrofuran arms was obtained by a one‐step cationic copolymerization of 3‐methyl‐3‐oxetanemethanol with tetrahydrofuran initiated by BF₃·OEt₂. Tetrahydrofuran served as a solvent at the earlier stage of the polymerization. After 3‐methyl‐3‐oxetanemethanol was exhausted essentially, the resulting hyperbranched species acted as a macro‐initiator, and initiated the cationic polymerization of tetrahydrofuran. This can be attributed to the large difference in reactivities of the monomers.     

Hyperbranched polyimides prepared by ideal A2+B3 polymerization,non-ideal A2+B3 polymerization and AB2 self-polymerization

In this paper, hyperbranched polyimides having the same repeating unit were synthesized by employing ideal A₂+B₃ polymerization, non-ideal A₂+B₃ polymerization and AB₂ self-polymerization methods. The polymerization behavior, polymer properties were compared for three methods. Hyperbranched polyimides by ideal A₂+B₃ polymerization, non-ideal A₂+B₃ polymerization and AB₂ self-polymerization methods show apparent difference in many physical properties, such as inherent viscosity, glass transition temperature, and film formation behavior etc. The hyperbranched polymers by the non-ideal A₂+B₃ polymerization are suitable for smooth, flexible and self-standing film preparation, which provides useful information for hyperbranched polymers toward self-standing materials.     

Synthesis of Hyperbranched Polysaccharide by Thermally Induced Cationic Polymerization of 1,6-Anhydrohexopyranose

The thermally induced cationic polymerizations of 1,6-anhydro-β-D -glucopyranose ( 1a ), 1,6-anhydro-β-D -mannopyranose ( 1b ) and 1,6-anhydro-β-D -galactopyranose ( 1c ) as a latent cyclic AB₄-type monomer were carried out using (S-2-butenyl)tetramethylenesulfonium hexafluoroantimonate ( 2 ) as an initiator. The solution polymerization in propylene carbonate proceeded without gelation to produce the water-soluble hyperbranched polysaccharides ( 3a-c ) with controlled molecular weights and narrow polydispersities. The degree of branching (DB), estimated by the methylation analysis of 3a-c , was in the range of 0.38 – 0.49. The thermally induced cationic polymerization of 1a-c using 2 is a facile method leading to a hyperbranched polysaccharide with a high DB value.     

Supramolecular Thermotropic Liquid Crystalline Materials with Nematic Mesophase Based on Methylated Hyperbranched Polyethylenimine and Mesogenic Carboxylic Acid

Summary: Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen‐based carboxylic acid, 5‐(p‐cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phases were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X‐ray diffractometry.

Schematic illustration of the supramolecular assembly of CBPA with PEIMe backbone.