Syndioselective Coordination (Co)Polymerization of Alkyne-Substituted Styrenes Using Rare-Earth Metal Catalysts

Abstract

Developing convenient methods to introduce functional groups into syndiotactic polystyrene has gained increasing attention in recent years. Herein, we report the coordination polymerization of 4-(1-hexynyl)styrene (HES), 4-(phenylethynyl)styrene (PES), and 4-(trimethylsilyl)ethynylstyrene (TES) with half-sandwich scandium precursor C 5 Me 4 PhSc(CH 2 C 6 H 4 NMe 2 -o) 2(1) and constrained-geometry-configuration (CGC) precursors C 13 H 8 CH 2 PySc(CH 2 SiMe 3 ) 2 (2, Py = C 5 H 4 N) and 2,7-( t Bu) 2 C 13 H 8 CH 2 PyLn(CH 2 SiMe 3 ) 2 (THF) n (Ln = Sc (3a), n = 0; Y (3b), Lu (3c), n = 1). Under mild conditions, perfect syndiotactic products (rrrr > 99%) are produced by homopolymerizations of HES, PES, and TES. The random copolymerizations of TES and styrene (St) proceed smoothly with 3b, and the insertion fractions of TES are tuned in the range of 0−100 mol % via changing the TES-to-St feed ratio. The trimethylsilyl groups are facilely eliminated from the TES-based polymers by tetrabutylammonium fluoride to give terminal ethynyl-containing polystyrenes, the reactions of which with an azide compound, carbon dioxide, and anthracene-9-aldehyde afford a series of functional syndiotactic polystyrenes.

Effect of Methoxy Side Groups on the Crystal Structures of a Series of Syndiotactic Polymethoxystyrenes as Studied by the X-ray Diffraction Data Analysis

“…However, this polymer is a little weak in such a point that it consists of only C and H elements. It is natural to have a motivation for the introduction of any functional groups as the side chains, which may give us a chance to obtain a series of functionalized SPS derivatives with more excellent properties. − The present paper treats the SPS derivatives with the functional methoxy-phenyl groups as the side chains. , The electron-donating and polar methoxy groups might play an important role in the generation of some characteristic physical properties. At the same time, the methoxy-phenyl groups may induce the variation in the conformation and packing mode of the mother SPS polymer chains and affect the appearance behavior of the various types of the crystal forms.…”

Syndiospecific Polymerization of o-Methoxystyrene and Its Silyloxy or Fluorine-Substituted Derivatives by HNC-Ligated Scandium Catalysts: Synthesis of Ultrahigh-Molecular-Weight Functionalized Polymers

“…The coordination (co)­polymerization of polar olefins to prepare high functional polyolefins having superior surface properties, adhesion properties, and compatibility with other types of materials has always been a challenging and high-profile issue in academia and industry. − The most serious difficulty lies in the fact that the high oxyphilic early transition metal catalysts can be easily poisoned by polar olefins because the stronger Lewis basic heteroatom groups of polar olefins have more preferential coordination ability than the weaker Lewis basic double bond to the strong Lewis acidic metal centers. − Subsequently, the low oxyphilic late transition metal catalysts, which are more tolerant of heteroatom functionalities in the monomer and the polymer, have ascended on the history stage and gradually began to open up new areas for the coordination (co)­polymerization of polar olefins such as polar norbornene, acrylates, vinyl ethers, vinyl acetate, vinyl halides, acrylonitrile, CO, etc. − Recently, a significant breakthrough in the coordination (co)­polymerization of polar olefins has been made by the high oxyphilic rare-earth metal catalysts. − Activated by a catalytically equimolar amount of cocatalyst borate and/or an excess of AlR 3 , rare-earth metal alkyl cations [LLnR] + generated from a series of rare-earth metal dialkyl complexes LLnR 2 L' n (Ln is a rare earth metal center, L is a negative monovalent multi-dentate supporting ligand, R is a negative monovalent alkyl ligand, L' n is a neutral ligand like tetrahydrofuran (THF) solvent molecules with a number in the range of 0–2) exhibit high activities and stereoselectivities in the coordination (co)...…”