Synthesis of cyclic polymers and topology effects on their diffusion and thermal properties

Abstract

In comparison with their linear counterparts, cyclic polymers exhibit distinctive properties due to their topology. The synthesis of cyclic polymers and the functionalities arising from their unique shapes, namely topology effects, are reviewed. The electrostatic self-assembly and covalent fixation (ESA-CF) process was used in conjunction with click chemistry and with olefin metathesis to construct selectively a variety of unprecedented polymer architectures, such as manacle-shaped and tandem multicycles, as well as doubly fused tricyclic and triply fused tetracyclic topologies. Moreover, the self-assembly of a cyclic amphiphilic block copolymer, which was prepared by intramolecular metathesis, produced micelles that exhibited an increase in thermal stability of approximately 50 1C compared with the micelles formed from the linear prepolymer. Single-molecule spectroscopic studies also revealed different diffusion modes for cyclic and linear polymers.

Cyclic Polysiloxanes with Linked Cyclotetrasiloxane Subunits

“…[1][2][3][4][5][6][7] Extensive work has been conducted to overcome the synthetic constraints due to the unfavorable entropy of cyclization. Herein we report the use of the Piers-Rubinsztajn reaction for the one-step synthesis of cyclic polysiloxanes with novel structural features.S pecifically,t he B(C 6 F 5 ) 3 -catalyzed coupling of various organic tris(dimethylsiloxy)silane and trialkoxysilane compounds generated as eries of cyclic polysiloxanes with cyclotetrasiloxane subunits.The thiolated cyclic polymers were also shown to be effective in directing the circular assembly gold nanoparticles.T he presence of constrained rings in the backbone is unprecedented and may offer opportunities for novel applications of these cyclic polymers.…”

Proton Sensing Color Changing Organoiron and Organic Macromolecules

“…The range of these properties is due to the various monomer functionalities that make up the polymers. Functional groups, such as amides, ethers, vinyls, and esters, produced materials like nylon, polyester, polyvinyl alcohol and polystyrene [1][2][3][4][5][6][7][8][9][10]. Incorporating azo dyes into polymers give materials that possess nonlinear optical properties, chirotriptic behaviour and can work as optical switches and storage media [8,9,.…”

Hydrogel formation by the ‘topological conversion’ of cyclic PLA–PEO block copolymers

“…Using PEO (Mn = 4600) as an initiator, L-lactide was heated to 130 °C and stirred in the presence of Sn(Oct)2, and HO-PLLA-PEO-PLLA-OH was obtained by ring-opening polymerisation (Mn(NMR) = 1100-4700-1100, Mp(SEC) = 8000, PDI = 1.11). The compound was analysed using 1 Obtained linear PLLA-PEO-PLLA or linear PDLA-PEO-PDLA and the firstgeneration Grubbs catalyst were dissolved in dichloromethane. In diluted conditions, they were refluxed, causing an intramolecular olefin metathesis reaction; the reaction yielded cyclic PLLA-PEO or cyclic PDLA-PEO, respectively.…”

“…1,2 For example, polyethylene, a typical general-use polymer, is used as high-density polyethylene, which has little branching in its structure, low-density polyethylene, which has a large amount of branching in its structure, linear low-density polyethylene having short-chain branching originating in the monomers. These polymers differ in physical properties such as density, crystallinity, and resistance to heat.…”