Polymeric microstructures and dielectric properties of polynorbornenes with 3,5-bis(trifluoromethyl)biphenyl side groups by ring-opening metathesis polymerization
Abstract:exo‐Polynorbornenes containing bis(trifluoromethyl)biphenyl side groups were synthesized by ring‐opening metathesis polymerization using different Grubbs' catalysts, the microstructures of the polymer chains were established using NMR and IR spectroscopy. The influence of monomer and catalyst structures on chain microstructure was revealed and the correlation of properties with microstructure was investigated in detail. The exo‐poly(N‐3,5‐bis(trifluoromethyl)biphenyl‐norbornene‐pyrrolidine) (exo‐PTNP) and exo‐… Show more
“…Besides, the 13 C NMR spectra (Fig. 3c, d) of block copolymers showed that the signals of methylene carbon (C c ) were observed as only one single peak at 34.5–34.0 ppm, suggesting that the backbone had high stereoregularity mostly because the size of endo -N-arylpyrrolidine NBE moiety in BNP and TNP matched well with the space requirement to control the stereoselectivity of single- and double-stranded PNBE chains during ROMP process 30–33,38,39 .Fig. 3The NMR spectra of linear and monocyclic polymers.…”
Ring-closure and ring-expansion techniques are the two routes for extensive synthesis of cyclic polymers. Here, we report an alternative blocking-cyclization technique referred to as the third route to prepare cyclic polymers with regulated ring size and ring number by ring-opening metathesis polymerization of di- and monofunctional monomers in a one-pot process, where the polymer intermediates bearing two single-stranded blocks are efficiently cyclized by the cyclizing unit of propagated ladderphane to generate corresponding mono-, bis-, and tricyclic polymers, and the well-defined ladderphane structure plays a crucial role in forming the cyclic topology. Monocyclic polymer is further modified via Alder-ene reaction and the cyclic molecular topology is clearly demonstrated. The diversity features of cyclic polymers are comprehensively revealed. This strategy has broken through the limitations of previous two cyclizing routes, and indeed opens a facile and popular way to various cyclic polymers by commercial Grubbs catalyst and conventional metathesis polymerization.
“…Besides, the 13 C NMR spectra (Fig. 3c, d) of block copolymers showed that the signals of methylene carbon (C c ) were observed as only one single peak at 34.5–34.0 ppm, suggesting that the backbone had high stereoregularity mostly because the size of endo -N-arylpyrrolidine NBE moiety in BNP and TNP matched well with the space requirement to control the stereoselectivity of single- and double-stranded PNBE chains during ROMP process 30–33,38,39 .Fig. 3The NMR spectra of linear and monocyclic polymers.…”
Ring-closure and ring-expansion techniques are the two routes for extensive synthesis of cyclic polymers. Here, we report an alternative blocking-cyclization technique referred to as the third route to prepare cyclic polymers with regulated ring size and ring number by ring-opening metathesis polymerization of di- and monofunctional monomers in a one-pot process, where the polymer intermediates bearing two single-stranded blocks are efficiently cyclized by the cyclizing unit of propagated ladderphane to generate corresponding mono-, bis-, and tricyclic polymers, and the well-defined ladderphane structure plays a crucial role in forming the cyclic topology. Monocyclic polymer is further modified via Alder-ene reaction and the cyclic molecular topology is clearly demonstrated. The diversity features of cyclic polymers are comprehensively revealed. This strategy has broken through the limitations of previous two cyclizing routes, and indeed opens a facile and popular way to various cyclic polymers by commercial Grubbs catalyst and conventional metathesis polymerization.
“…19 To improve the processing property, conductivity and hydrophilicity of the aPNB, a simple but useful measure taken was to design and prepare polynorbornene-based hybrid membranes with exible backbones or polar functional groups. ROMP-type polynorbornene (rPNB) 20 could be prepared with a high molecular weight at normal temperatures and pressures and exhibited excellent processability. In addition, a cross-linked AEM was developed by Coates and co-workers, who employed ringopening metathesis polymerization (ROMP) of a tetraalkylammonium-functionalized norbornene with dicyclopentadiene (DCPD).…”
“…With the monomers in hand, polymers with different backbones were readily prepared for comparing their self-assembly and TAD modification characteristics (Scheme ), which were then modified by 4-(3-trifluoromethylphenyl)-1,2,4-triazoline-3,5-dione (FTAD) (Figure S4). The third-generation Grubbs catalyst (Ru-III)-initiated ROMP of norbornene pyrrolidine derivatives and MCP of 1,6-heptadiyne derivatives can produce trans isotactic PNBE ,, and PA with five-membered rings, , respectively. Initially, MCP of SHD was performed by Ru-III at 30 °C in THF.…”
The efficient and versatile click chemistry based on 1,2,4-triazoline-3,5-dione (TAD) was used as one of the most potential postfunctionalizing pathways to specially design polymer nanostructure for dielectric materials. The block copolymer was synthesized by tandem ring-opening metathesis polymerization and metathesis cyclopolymerization and self-assembled into the core− shell nanostructure in the selective solvent, which could be modified by TAD in a controlled manner by tuning the TAD feeding amount, enabling the Alder−ene reaction of TAD with the double bonds to occur first on the polynorbornene backbone in the shell and then the cascade Alder−ene and Diels−Alder reactions on the polyacetylene backbone bearing five-membered rings in the core. The modified block copolymers incorporating varied amount of urazole moieties exhibited enhanced dielectric constant from 16.2 to 20.3 and lowered dielectric loss from 0.031 to 0.013 to 0.009, which provides a new idea of the selective postfunctionalization of nanostructures in solution for regulating the polymer structure and properties.
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