Homopolymerization and copolymerization of tert‐butyl methacrylate and norbornene with nickel‐based methylaluminoxane catalysts

Abstract

ABSTRACT:The homopolymerization and copolymerization of tert-butyl methacrylate (tBMA) and norbornene (NB) with nickel(II) acetylacetonate in combination with methylaluminoxane were systematically investigated. This catalytic system showed high activity toward the homopolymerization of both NB and tBMA. For these copolymerizations, activity was gradually lost with an addition of tBMA to NB or of NB to tBMA. This result was qualitatively explained with the trigger coordination mechanism. Furthermore, the determination of the reactivity ratios indicated a significantly higher reactivity for NB than for tBMA (r NB ϭ 4.14 and r tBMA ϭ 0.097), and this was interpreted by the coordination mechanism. The synthesized acrylate/NB copolymers exhibited glass-transition temperatures of 100 -250°C. The absence of crystallinity and the homogeneous repartition of the monomer units along the main chain yielded products with high transparency and high stability

Geometry Constrained N-(5,6,7-Trihydroquinolin-8-ylidene)arylaminopalladium Dichloride Complexes: Catalytic Behavior toward Methyl Acrylate (MA), Methyl Acrylate-co-Norbornene (MA-co-NB) Polymerization and Heck Coupling

“…Such a shifting of peaks would not possible in a physic mixture of both polymers because no specific interaction between MA and NB monomers is possible. Moreover, some additional peaks was observed at 25.1 ppm, 30.2 ppm and 48.3 ppm which was assigned to the MA and NB sequence and the appearance of the peak intensity indicated a random sequence of co-monomers; such a sequence of MA and NB in polymer chains mostly occurs by a radical polymerization mechanism in agreement with the literature [34,[39][40][41][42][43]59]. Though, a precise mechanism is unknown, like MA homopolymerization, MA free radicals are produced from the palladium intermediates, followed by propagation of MA-co-NB polymer chain by reacting with MA as well as NB monomers.…”

“…However, it remains a great challenge to design suitable catalyst systems for efficient copolymerization of MA with NB [34,[39][40][41][42][43]59]. In this essence, we employed the Pd3/(C 6 F 5 ) 4 BC 6 H 5 NH(CH 3 ) 2 catalytic system for copolymerization of MA with NB under the aforementioned optimum conditions for homopolymerization of MA (Run 2, Table 1).…”

“…For instance, the copolymerization of polar monomers, particularly methyl acrylate (MA), with olefins confers novel properties on the resulting polymers: improved thermal stability, superior etch resistance, good adhesion due to the ester groups and a hydrophobic character derived from the C-C backbone [31][32][33]. Although recent progress in polymerization based on palladium catalysts allows the efficient copolymerization of polar and nonpolar monomers, the catalyst activity and second monomer insertion ratio remain quite low [34][35][36][37]. Subsequently, the design of suitable catalyst systems for efficient copolymerization of polar and non-polar monomers viz.…”

Palladium Catalysts for Norbornene Polymerization. A Study by NMR and Calorimetric Methods

“…Nickel and palladium complexes are very efficient catalysts for the vinyl polymerization of norbornene, for the copolymerization of functionalized norbornenes, and also for the copolymerization of norbornene with ethylene and with other functionalized norbornenes. ,– Usually the polymerization requires a nickel(II) catalyst and an organometallic cocatalyst (typically methylaluminoxane or B(C 6 F 5 ) 3 ), ,,,, but some nickel , and palladium organometallics are very efficient without cocatalyst. Many of these catalysts are based on chelating ligands, while phosphines are the most often used monodentate ligands. , The use of very bulky monodentate phosphines has proved to be advantageous for controlling the polymerization of functionalized NB …”

Bis(β-ketoimino)nickel(II) Complexes for Random Copolymerization of Norbornene and Methyl 5-Norbornene-2-carboxylate with Controlled Ester Group Incorporation

“…The ester group itself helps to improve the compatibility of polyolefins. , In addition, this group can be altered to other chemical functionalities by participating in post-polymerization modification, such as hydrolysis, , transesterification, − and amidation. , Therefore, a COC functionalized with ester groups is expected to have a role as a versatile platform that can be transformed to functional materials suitable for desired applications. Late transition metal complexes with low oxophilicity, mostly Ni­(II) and Pd­(II) complexes, have been used as catalysts for the vinyl addition copolymerization of NB and polar monomer with ester functionality and have shown promising catalytic performance. − Several previous studies have confirmed that Ni­(II) catalysts achieve higher catalytic activity than Pd­(II) catalysts. ,, Numerous ligands have been investigated for Ni­(II)-based catalyst systems. In particular, Ni­(II) complexes bearing N,O-chelating β-ketoimine ligands that form bis­(β-ketoimino)­nickel­(II) complexes have been reported to exhibit moderate catalytic activity. − …”