Synthesis Of Star-shaped Polymers Research Articles

Unexpected formation of a significant amount of polymer primary hydroxyl groups in synthesis of star-shaped polymer from linear alcoholate chains and diepoxides

Abstract Following our previous paper on the course of the formation of star-polymers from oligo(oxyethylene)alcoholates as arms precursors and diglycidyl ethers as core building units [1], the nature of polymer alcoholate groups formed in this process has been studied. Primary alcoholate groups reacting with diepoxide or epoxide function in polymer give initially predominantly secondary alcoholate groups in the product. However, a small fraction of primary alcoholate groups of polymer is formed from the very beginning. When consumption of epoxide groups increases the contribution of polymer primary groups increases too, reaching eventually from 5 to 15% of total alcoholate groups, depending on reaction conditions. The increase of this proportion with the reaction progress is explained by intramolecular reaction of alcoholate groups with epoxide ones (cyclization) giving a large proportion of primary alcoholate groups. This explanation was supported by the quantum-mechanical calculations of the possible routes of cyclization.

Synthesis of star-shaped polymers by coupling reaction between multifunctional core and terminal functionalized polymers

Star-shaped polymers that consist of well-defined polystyrene (PS) arms were successfully synthesized in high yield by coupling reaction between multifunctional core molecules and hydroxyl-terminated PS in the presence of 1, 3-dicyclohexylcarbodiimide and 4-(dimethylamino) pyridine at room temperature. Several systems were investigated: (1) Pyromellitic dianhydride (PMDA) and hydroxyl-terminated PS (PS-OH) with narrow molecular weight distribution, which was prepared by atom transfer radical polymerization (ATRP) of St with 2-hydroxyethyl bromoisobutylate (HEBiB) as initiator. (2) PMDA and PS-OH prepared by conventional free radical polymerization, with 2-mercaptoethanol as chain transfer agent. (3) Narrow molecular weight distributed alternating copolymer of maleic anhydride (MA) and styrene (St), which was obtained via reversible addition fragmentation chain transfer polymerization (RAFT) process, and PS-OH obtained by ATRP. The formation of star-shaped PSs was confirmed by proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC).

Synthesis of Star-Shaped Polymers

Star-shaped polymers, consisting of a core and a number of arms radiating from the core, have attracted more and more attention because of their highly branched structures and unique rheological properties. Various synthesis methods, like reversible addition–fragmentation chain transfer polymerization (AFCTP), stable free radical polymerization (SFRP), atom transfer radical polymerization (ATRP), etc., are used to synthesize star-shaped polymers. Star-shaped polymers are formed from various different chemicals compounds, like divinyl compounds, polyisoprene, polylactides and even amphiphilic compounds. In this review various synthesis schemes and chemical compounds utilized are explained in brief to give the readers an insight in the field of star-shaped polymers.

Pearl Necklace Architecture: New Threaded Star-Shaped Copolymers

The synthesis of star-shaped polymers, which are threaded regularly along a common backbone, is described. Thus, two different approaches for preparation of so-called pearl necklace polymers (synonyms: multigraft copolymers, barbwire or centipedes polymers, multiple dumbbells or star-oligomers) are presented. Poly(ethylene oxide) (PEO) was used as a thread and poly(dimethylaminoethyl methacrylate) (PDMAEMA) stars were used as pearls. In the first approach, a polycondensation reaction of PEO macromonomers with partly protected dipentaerythritol leads first to a multiblock PEO. Afterward, the protected hydroxy groups of dipentaerythritol, which is situated at the junction points of the blocks, can be released for the anchoring of PDMAEMA chains. In the second approach, anionic polymerization of ethylene oxide leads directly to a diblock PEO with an interior dipentaerythritol unit. The chain ends can be modified with further dipentaerythritols, giving access after selective deprotection to either star dimers...

Nonionogenic star-shaped calix[8]arenes: Synthesis and ionophore properties

New approach to the synthesis of star-shaped polymers based on calix[8]arene with amphiphilic arms of nonionogenic nature is described. The ionophore properties of the resulting polymer with respect to ions of alkali metals, europium, and uranium were studied by an example of a polymer containing residues of ω-cetyloligoethylene oxide as arms.

Synthesis of Star-Shaped Polymers via Coordination of Bipyridyl-Terminated Polyoxyethylene with Metal Ions

This paper describes the synthesis of various star-shaped polymers by means of complexation of bipyridyl-terminated polyoxyethylene with Ru(II) ion. Three kinds of bipyridyl-terminated polyoxyethylenes of different molecular weights were prepared from the corresponding polyoxyethylene monomethyl ethers with narrow molecular weight distributions. Bipyridyl was found to be introduced quantitatively at the end of the polymers based on the results of UV spectra. The* formation of a star-shaped polymer was carried out by the reaction of RuCl 3 with three equivalents of bipyridyl-terminated polyoxyethylene. The UV spectrum of the star-shaped polymer obtained supported the formation of a typical Ru(II) tris(bipyridyl) complex. From the results of GPC, the star-shaped polymer obtained had a higher molecular weight than the prepolymer and showed a narrow molecular weight distribution. In the case of Ni(II) or a Co(II) complex, however, the star-shaped polymer was found to be dissociated into three linear prepolymers under the conditions of GPC measurement

Synthesis of Star-Shaped Polymers by Living Cationic Polymerization

Synthesis of Star-Shaped Polymers by Living Cationic Polymerization