Copolymerizations of Norbornene and Tetracyclododecene with α-Olefins by Half-Titanocene Catalysts: Efficient Synthesis of Highly Transparent, Thermal Resistance Polymers

High-Refractive-Index Cross-Linked Cyclic Olefin Polymers with Excellent Transparency via Thiol-Ene Click Reaction

High-refractive-index polymers are important optical materials in optoelectronics. Conventional cyclic olefin polymers (COPs), possessing many excellent optical properties, are a class of highly promising optical materials; however, one of the greatest obstacles is their low refractive index of n = 1.52-1.54. Here, one efficient strategy of first incorporating high molar refraction groups, including carbazolyl and indolyl moieties, into unsaturated COPs via ring-opening metathesis polymerization (ROMP) and then introducing another high molar refraction sulfur atom by a subsequent thiol-ene click reaction is presented. The obtained cross-linked COPs bearing both an aromatic group and sulfur possess significantly higher refractive indices (n = 1.611-1.684 at 589 nm) and highly optical transparency (approximately 95%) in the range of vis-NIR. This provides a way toward potential applications of new-generation optical materials.

Amorphous Elastomeric Ultra-High Molar Mass Polypropylene in High Yield by Half-Titanocene Catalysts

Propylene polymerizations with different ketimide-modified half-titanocene catalysts, Cp'TiCl2(N=CtBu2) [Cp' = C5H5 (1), C5Me5 (2), Me3SiC5H4 (3)], with MAO as a cocatalyst, were investigated. The obtained polymers were studied in detail by determining their microstructure, molar masses, thermal, and mechanical properties. The Cp*-ketimide, (C5Me5)TiCl2(N=CtBu2) (2), exhibited higher catalytic activities than Cp'TiCl2(N=CtBu2) (1,3), yielding higher molar mass polymers, Mw up to 1400 Kg/mol. All the synthesized polypropylenes (PP) are atactic and highly regioregular, with predominant rrrr pentads, especially PP prepared with catalyst 1. Differential scanning calorimetry (DSC) established that the polymers are fully amorphous aPP, and no melting endotherm events are detected. Glass transition temperatures were detected between -2 and 2 °C. These polypropylenes have been established to be high-performance thermoplastic elastomers endowed with remarkably high ductility, and a tensile strain at break higher than 2000%.

Cyclic Olefin Terpolymers with High Refractive Index and High Optical Transparency

Cyclic olefin copolymer (COC) is one of the most promising optical materials; however, the brittle COC suffers from issues including a low refractive index. In this contribution, by the introduction of high refractive index comonomers including phenoxy substituted α-olefin (C₄OAr), p-tolylthio substituted α-olefin (C₄SAr) and carbazolyl substituted α-olefins (C₄NAr, C₃NAr, and C₂NAr), the zirconocene mediated terpolymerization of ethylene (E) and tetracyclododecene (TCD) produces the preferred E-TCD-C_nNAr (n = 2, 3, and 4) cyclic olefin terpolymers (COT) with tunable compositions (TCD: 11.5- 35.8 mol %, C_nNAr: 1.2-5.0 mol %), high molecular weights and high glass transition temperatures (up to 167 °C) in high catalytic activities. Compared to the E-TCD copolymer (COC) material, these COT materials show the comparable thermal decomposition temperature (T_d,5% = 437 °C), slightly higher strain at break value (up to 7.4%) and higher tensile strength (up to 60.5 MPa). In particular, these noncrystalline optical COT materials have significantly higher refractive indices of 1.550-1.569 and are more transparent (transmittance: 93-95%), relative to the COC materials, indicative of an excellent optical material.

Effect of para-Substituents in Ethylene Copolymerizations with 1-Decene, 1-Dodecene, and with 2-Methyl-1-Pentene Using Phenoxide Modified Half-Titanocenes-MAO Catalyst Systems

Effect of para-substituents in the ethylene (E) copolymerization with 1-decene (DC), 1-dodecene (DD), and with 2-methyl-1-pentene (2M1P) using a series of Cp*TiCl2 (O-2,6-i Pr2 -4-R-C6 H2 ) [R=H (1), t Bu (2), Ph (3), CHPh2 (4), CPh3 (5), SiMe3 (6), SiEt3 (7), and newly prepared 4-t BuC6 H4 (8) and 3,5-Me2 C6 H3 (9)]-MAO catalyst systems has been studied. The activities in these copolymerization reactions were affected by the para-substituent, and the SiMe3 (6), SiEt3 (7) and 3,5-Me2 C6 H3 (9) analogues showed the higher activities at 50 °C in the E copolymerization reactions with DC (1.06-1.44×106  kg-polymer/mol-Ti⋅h), DD (1.04-1.88×106  kg-polymer/mol-Ti⋅h) than the others, whereas no significant differences were observed in the comonomer incorporations. Complexes 6 and 7 also showed the higher activities at 50 °C in the E/2M1P copolymerization, and the 2M1P incorporation was affected by the para-substituent and the polymerization temperature; complex 9 showed better 2M1P incorporation at 25 °C.

Synthesis and properties of block copolymers composed of norbornene/higher α-olefin gradient segments using ansa-fluorenylamidodimethyltitanium-[Ph3C][B(C6F5)4] catalyst system

A series of di- and triblock copolymers composed of gradient norbornene (NB)/α-olefin segments were synthesized by a (t-BuNSiMe₂Flu)TiMe₂-based catalyst and their physical and mechanical properties were investigated.

Synthesis of ethylene–norbornene–1-octene terpolymers with high 1-octene contents, molar masses, and tunable Tg values, in high yields using half-titanocene catalysts

Synthesis of unique poly(E-ter–N-ter–O)s using half-titanocene catalysts: 1-octene does not behave as a chain termination/transfer agent unlike ansa-metallocenes.

Solution XANES and EXAFS analysis of active species of titanium, vanadium complex catalysts in ethylene polymerisation/dimerisation and syndiospecific styrene polymerisation

Mechanistic studies in homogeneous catalysis through the solution transition metal K Edge XANES (X-ray absorption near-edge structure) and EXAFS (Extended X-ray absorption fine structure) analysis for vanadium and titanium complex catalysts for ethylene polymerisation/dimerization, and syndiospecific styrene polymerisation, including interpretation of the XANES spectra, have been introduced. The core excitation spectra of the complexes based on the time-dependent density functional theory (TD-DFT) can be used to interpret the Ti and V K-edge features and to extract information on the electronic structure from the XANES spectra. Theoretical calculations and experimental XAS analysis should have great potential for analysing the active species.

Controlled Polymerization of β-Pinadiene: Accessing Unusual Polymer Architectures with Biomass-Derived Monomers

Biomass-derived polymers are emerging as critically needed alternatives to their petrochemical counterparts. Terpenes, which are among the most abundant natural products, represent particularly fertile chemical space for monomer development (given their inherent structural complexity). Here, we present the living vinyl-addition polymerization of β-pinadiene (the cumulated congener of β-pinene) at room temperature. Employing [(π-allyl)NiOCOCF₃]₂ as a catalyst afforded the desired polymers with good control over molecular weight and dispersity. Interestingly, the bicyclic pinane core was retained in the isolated materials (which starkly contrasts prototypical pinene polymerizations). Moreover, the reported materials exhibited impressive thermal stability (T_d = 294 °C) and high glass transition temperatures (T_g = 160 °C). As the polymerization of terpene-derived cumulenes can afford scaffolds that defy current synthetic logic, we anticipate our work will unlock additional avenues for sustainable polymer development.

The synthesis of cyclic olefin copolymers (COCs) by ethylene copolymerisations with cyclooctene, cycloheptene, and with tricyclo[6.2.1.0(2,7)]undeca-4-ene: the effects of cyclic monomer structures on thermal properties

The synthesis of amorphous ethylene copolymers with cycloheptene, cis-cyclooctene, or tricyclo[6.2.1.0(2,7)]undeca-4-ene using half-titanocene catalysts and the effects of ring size and structure on the thermal properties have been demonstrated.

Vinyl-addition polymerizations of cycloallenes: synthetic access to congeners of cyclic-olefin polymers

Vinyl-addition polymerizations of cyclic allenes were investigated. Copolymers of cyclic and acyclic allenes were prepared, and the impact of cycloallene feed ratio on bulk material properties was explored.

Norbornadiene homopolymerization and norbornene/norbornadiene/1-octene terpolymerization by ansa-fluorenylamidotitanium-based catalysts

Soluble polyNBD and terpoly(NBD/NB/OC) were obtained in high conversions with ansa-fluorenylamidotitanium-based catalysts.

Synthesis of Ultrahigh Molecular Weight Polymers Containing Reactive Functionality with Low PDIs by Polymerizations of Long-Chain α-Olefins in the Presence of Their Nonconjugated Dienes by Cp*TiMe2(O-2,6-iPr2C6H3)-Borate Catalyst

Copolymerizations of 1-decene (DC) with 1,9-decadiene (DCD), 1-dodecene (DD) with 1,11-dodecadiene (DDD), and 1-tetradecene (TD) with 1,13-tetradecadiene (TDD), using Cp*TiMe₂(O-2,6-ⁱPr₂C₆H₃) (1)–[Ph₃C][B(C₆F₅)₄] (borate) catalyst in the presence of AlⁱBu₃/Al(n-C₈H₁₇)₃ proceeded in a quasi-living manner in n-hexane at −30 to −50 °C, affording ultrahigh molecular weight (UHMW) copolymers containing terminal olefinic double bonds in the side chain with rather low PDI (M_w/M_n) values. In the DC/DCD copolymerization, the resultant copolymer prepared at −40 °C possessed UHMW (M_n = 1.40 × 10⁶ after 45 min) with low PDI (M_w/M_n = 1.39); both the activity and the PDI value decreased at low polymerization temperature (M_n = 5.38 × 10⁵, M_w/M_n = 1.18, after 120 min at −50 °C). UHMW poly(TD-co-TDD) was also obtained in the copolymerization at −30 °C (M_n = 9.12 × 10⁵, M_w/M_n = 1.51, after 120 min), using this catalyst.

Copolymerization of Norbornene and Styrene with Anilinonaphthoquinone-Ligated Nickel Complexes

Poly(norbornene-co-styrene)s were synthesized by the use of anilinonaphthoquinone-ligated nickel complexes [Ni(C₁₀H₅O₂NAr)(Ph)(PPh₃): 1a, Ar = C₆H₃-2,6-ⁱPr; 1b, Ar = C₆H₂-2,4,6-Me; 1c, Ar = C₆H₅] activated with modified methylaluminoxane (MMAO) or B(C₆F₅)₃ in toluene. The effects of the cocatalysts were more significant than those of the nickel complexes, and MMAO gave higher activity than B(C₆F₅)₃. The structural characterizations of the products indicated the formation of statistical norbornene copolymers. An increase of the styrene ratio in feed led to an increase in the incorporated styrene (S) content of the resulting copolymer. The molecular weight of the copolymer decreased with increasing the S ratio in feed at 70 °C. The copolymerization activity, using MMAO as a cocatalyst, decreased with lowering of the temperature from 70 to 0 °C, accompanied by an increase in the molecular weight of the copolymer. The S incorporation up to 59% with M_n of 78,000 was achieved by the 1b-B(C₆F₅)₃ catalytic system. The glass transition temperatures of the norbornene (N)/S copolymers determined by differential scanning calorimetry, decreased from 329 to 128 °C according to the S content.

Optically Transparent Functional Polyolefin Elastomer with Excellent Mechanical and Thermal Properties

Synthesis of a variety of optically transparent polyolefin elastomers consisting of hard segment of polynorbornene and several kinds of soft segments such as atactic polypropylene, poly(ethylene-co-propylene), and poly(ethylene-co-1-hexene) was achieved. The block copolymers exhibited excellent toughness and thermal property with efficient elastic recovery. Most importantly, the introduction of hydroxyl group into polynorbornene segment not only modulated surface property of block copolymers, but also improved their mechanical properties.

Facile functionalization of isotactic polypropylene via click chemistry

Alkynyl functionalized iPP, with 1–4 mol% comonomer incorporation, can be efficiently synthesized and conveniently converted into various functional iPPs and graft copolymers via alkynyl/N₃ reaction.

Bis(oxazoline)-derived N-heterocyclic carbene ligated rare-earth metal complexes: synthesis, structure, and polymerization performance

Bis(oxazoline)-derived NHC supported rare-earth complexes have been synthesized for the first time and showed good activity for 1-hexene (co)polymerization.

Enhancing the emission of hexa-peri-hexabenzocoronene-containing polynorbornene via electron donating, unsymmetric constitution and solvent effects

Hexa-peri-hexabenzocoronene-containing hydrogenated polynorbornene dispersion showed an intensive emission of the 0–0 transition (465 nm) and excellent dispersibility.

Efficient copolymerization of ethylene with norbornene or its derivatives using half-metallocene zirconium(iv) catalysts

Four [O,P]ZrCpCl₂ were synthesized, and showed good performance on regioselective ethylene/cyclic dienes copolymerizations. Comonomer incorporations up to 76% (ENB) and 40.6% (VNB), respectively, with activities above 10³ kg per mol_Zr per h can be achieved.

Synthesis of ultrahigh molecular weight polymers by homopolymerisation of higher α-olefins catalysed by aryloxo-modified half-titanocenes

Polymerisations of 1-dodecene, 1-hexadecene, 1-octadecene by Cp*TiX₂(O-2,6-ⁱPr₂C₆H₃) – cocatalysts afforded (ultra)high molecular weight polymers with unimodal molecular weight distributions.