Nanocomposites of Phosphonic‐Acid‐Functionalized Polyethylenes with Inorganic Quantum Dots

Abstract

Insertion of diethyl vinyl phosphonates and free vinyl phosphonic acid, respectively, into [(P^O)Pd(Me)(dmso)] ((P^O) = κ(2)-P,O-Ar2PC6H4SO2O with Ar = 2-MeOC6H4) (1-dmso) occurs in a 2,1- as well as 1,2-fashion, to form a four-and a five-membered chelate [(P^O)Pd{κ(2)-C,O-CH(P(O)(OR)2)CH2CH3}] and [(P^O)Pd{κ(2)-C,O-CH2CH(P(O)(OR)2)CH3}] (R = H, Et). No decomposition or other reactions of 1 by free phosphonic acid moieties occur. Copolymerization in a pressure reactor by 1-dmso yields linear random poly(ethylene-co-diethyl vinyl phosphonate) and poly(ethylene-co-vinyl phosphonic acid). In these copolymerizations, reversible coordination of the phosphonate moieties of free monomer as well as chelate formation by incorporated monomer retards chain growth as also evidenced by relative binding studies of diethyl phosphonate towards 1. Post-polymerization emulsification of poly(ethylene-co-vinyl phosphonic acid) together with CdSe/CdS quantum dots (QDs) yields submicron (ca. 50 nm from dynamic light scattering (DLS) and transmission electron microscopy (TEM)) polymer particles with the QDs embedded in the functionalized polyethylene in a nonaggregated fashion. This embedding benefits the fluorescence behavior in terms of continuous emission and life-time as revealed by wide-field fluorescence measurements. These composite particle dispersions are employed as a ″masterbatch" together with an aqueous high density polyethylene (HDPE) dispersion to generate thin films (by spin-coating) and bulk materials (from the melt), respectively, in which the inorganic nanoparticles remain highly disperse.

Comprehensive Picture of Functionalized Vinyl Monomers in Chain-Walking Polymerization

“…39 The less electrondeficient diethyl vinyl phosphonate (DVP) shows a less pronounced preference (2,1: 1,2 = 2: 1) for 2,1-insertion relative to MA with the phosphinesulfonato Pd(II) catalyst as expected. 40 However, treatment of DVP with Pd/NaBArF directly inverts the previous major 2,1-insertion to a clear 1,2insertion, thus producing the five-membered insertion product Pd-DVP-Five (Scheme 3).…”

Reactivity of Functionalized Vinyl Monomers in Insertion Copolymerization

“…34 However, limited data are available for the substituents of interest. It was reported, though, that the Hammett constants can be linearly correlated with the 13 C NMR chemical shift δC β of the β carbon atom in the vinyl bond as it is a measure for the polarity induced in the vinyl bond by a substituent and hence a reasonable and practicable description for relative electronic influences of various substituents. 35 A description of sterics is less straightforward as they depend on the conformation and rotational freedom of a given substituent.…”

“…Since Brookhart’s seminal findings on these long elusive reactions, they have seen significant advances. In the past few years, all fundamental monomers − (with the exception of methyl methacrylate, MMA , ) and a range of further vinyl − and related allyl − compounds have been demonstrated to be amenable to copolymerization to form linear ethylene copolymers. This applies to electron-poor monomers, like acrylates , and many others, and electron-rich monomers, like vinyl ethers alike.…”

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We report the reactivities of a comprehensive range of polar vinyl comonomers and 1-olefins in the copolymerization with ethylene by [{(o-MeOC 6 H 4 ) 2 PC 6 H 4 SO 3 }PdMe(L)] from pressure reactor studies (95 °C, 3−20 bar), as defined by r E = k ethylene /k comonomer from Markov statistics. 13 C NMR chemical shifts of the monomers' β vinyl carbon atom and Charton and Sterimol parameters were found to be appropriate descriptors for the monomers' electronic nature and steric demand, respectively. A comprehensive picture of their impact on monomer reactivity and also regioselectivity of insertion arises.

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Microstructure and Optical Properties of Composites Consisting of Nanoporous Stretched Polypropylene Doped with Liquid Crystals and Quantum Dots at a High Concentration

“…These properties of QDs make them the most promising type of fluorescent dopants for the development of nanohybrid composites based on different types of polymer matrices. Among the main lines of research in this field, noteworthy are the development of techniques for highly homogeneous aligned distribution of QDs in different organic matrices [5][6][7][8][9] , designing of light conversion devices [10][11][12] , and sensing approaches 13,14 . Significant efforts have been made to engineer hybrid nanophotonic materials from different types of liquid crystals and QDs 15,16 .…”