Poly(ethylene-co-propylene macromonomer)s:  Synthesis and Evidence for Starlike Conformations in Dilute Solution

Abstract

By use of two sequential coordination−insertion polymerizations, a series of ethylene-co-propylene-based comb polymers was synthesized. First, poly(ethylene-co-propylene) macromonomers featuring one unsaturated chain end were synthesized using a titanium bis(phenoxyimine) catalyst. The macromonomers were then homopolymerized using a living nickel α-diimine catalyst. The molecular weights and corresponding number of arms for each poly(macromonomer) were determined using size-exclusion chromatography with viscometry detection and universal calibration. Viscosity−molecular weight conformation plots for the poly(macromonomer)s revealed compact solution structures. Furthermore, viscometric radii for each poly(macromonomer) (R v) and corresponding linear macromonomer (R v)a were determined and the ratio (R v)/(R v)a for each pair was compared to those of a variety of polyisoprene-based star polymers with similar functionality. The comparison revealed that despite the obvious comb topology of the poly(macromonomer)s their dilute solution conformations correspond reasonably well to the bona fide polyisoprene stars.

Recent developments in the coordination chemistry of bis(imino)acenaphthene (BIAN) ligands with s- and p-block elements

“…transition metal centers. The development of the d-block chemistry of 4 was pioneered by the groups of Brookhart, 4 Elsevier 5 and Coates, 6 and a broad range of transition metal-BIAN complexes has now been described. 7-10 A focal point of this activity has been the generation of robust, versatile catalysts for olefin polymerization 11 and other important organic transformations.…”

Defects and defect engineering in Soft Matter

“…193,195 The chain-walking polymerization method has been widely used to adjust the thermal, rheological, and mechanical properties of polymers, specifically for macromolecules formed from a-olefin monomers. [196][197][198][199] In addition, Alamo and coworkers showed that chain-walking polymerization can be utilized to synthesize isotactic polypropylene with regional defects caused by irregularity in distribution or density of methyl groups along polymer chains. 200 They illustrated that at comparable defect density, polypropylenes with such chain-walking defects have lower melting points and much lower degrees of crystallinity than isotactic polypropylenes with regional defects induced by copolymerization with other 1-alkene comonomers.…”

A Comprehensive Review on Controlled Synthesis of Long-Chain-Branched Polyolefins: Part 2, Multiple Catalyst Systems and Prepolymer Modification

“…were synthesized using “living” olefin polymerization techniques . Coates and co‐workers reported the synthesis of comb POs ( M n = 74–209 kg mol −1 , PDI = 1.51–1.90) via the ‘living” polymerization of poly(ethylene‐co‐propylene) macromonomers catalyzed by a nickel/α‐diimine catalyst. The macromonomers with unsaturated chain ends ( M n = 4.8–23.3 kg mol −1 , PDI = 1.62–1.81) were synthesized by a titanium bis(phenoxyimine) catalyst .…”

“…Coates and co‐workers reported the synthesis of comb POs ( M n = 74–209 kg mol −1 , PDI = 1.51–1.90) via the ‘living” polymerization of poly(ethylene‐co‐propylene) macromonomers catalyzed by a nickel/α‐diimine catalyst. The macromonomers with unsaturated chain ends ( M n = 4.8–23.3 kg mol −1 , PDI = 1.62–1.81) were synthesized by a titanium bis(phenoxyimine) catalyst . Latter, the same group reported controlled synthesis of syndiotactic PP bottlebrush polymers ( M n = 46–172 kg mol −1 , PDI = 1.21–1.89) via the ring‐opening metathesis polymerization (ROMP) of norbornene‐terminated syndiotactic PP .…”