Gels Based on Cyclic Polymers

Abstract

Cyclic poly(5-hydroxy-1-cyclooctene) (PACOE) was synthesized by ring-expansion metathesis polymerization (REMP), and thiol-ene chemistry was used to cross-link the internal double bonds in the PACOE backbone. This created a novel network material (gels formed from cyclic polymers) with unique structural units, where the cyclic PACOE main chains, which serve as secondary topological cross-linkages, were connected by primary intermolecular chemical cross-linkages. The resulting properties were notably different from those of traditional chemically cross-linked linear PACOE gels, whose gel fraction (GF) and modulus (G) increased while the swelling ratio (Q) decreased with increasing initial polymer concentration in the gel precursor solution (C(0)). For the gels formed from cyclic polymers, however, the GF, Q, and G all simultaneously increased as C(0) increased at the higher range. Furthermore, at the same preparation state (same C(0)), the swelling ability and the maximum strain at break of the gels formed from cyclic polymers were always greater than those of the gels formed from linear polymers, and these differences became more pronounced as C(0) increased.

Synthesis of amino acid based covalently cross-linked polymeric gels using tetrakis(hydroxymethyl) phosphonium chloride as a cross-linker

“…10 Thiol-ene chemistry was used to cross-link the internal double bonds in the cyclic poly(5-hydroxy-1-cyclooctene) backbone. 11 Free radical cross-linking copolymerization (RCC) of a vinyl monomer with a divinyl monomer (cross-linker) is another important and popular strategy to prepare chemical gels. 12 However, in case of RCC method intra-molecular cross-linking predominates at the early stages polymerization and generates highly heterogeneous gels with irregularly distributed branching points.…”

Novel Developed Systems and Techniques Based on Double-Network Principle

“…In recent years, there have been many efforts toward improving the strength of hydrogels, 19,20 in which several methods, i.e., slide-ring gels, 21,22 nanocomposite gels, 23,24 double-network gels, 25,26 click gel, 27,28 and tetra-PEG gels, 29 have shown good achievements. Among these hydrogels, the double-network gels (DN gels) developed by our group obtain the highest fracture stress and toughness.…”

Depolymerization of 1,4-polybutadiene by metathesis: high yield of large macrocyclic oligo(butadiene)s by ligand selectivity control

“…[16][17][18][19][20][21][22][23] Other methodologies such as ring-expansion metathesis polymerization of cycloolefins with cyclic Ru catalysts have also been explored. [24][25][26][27] The particular synthesis of macrocycles from 1,4-PB is only scarcely described, mainly in the context of PB degradation. Though old generation tungsten and molybdenum-based alkylidene complexes have been tested in the cyclodepolymerization of 1,4-PB, [28][29][30][31][32] novel Ru-based catalysts have been unexplored, likely because the so far reported catalysts predominantly produced CDT, which is not competitive with the established butadiene tricyclization process.…”