Synthesis and Solution Properties of Dimethylsiloxane−2-(Dimethylamino)ethyl Methacrylate Block Copolymers

Abstract

A series of novel well-defined dimethylsiloxane-2-(dimethylamino)ethyl methacrylate diblock and triblock copolymers were synthesized in various solvents at or above ambient temperature. This was achieved by the oxyanion-initiated polymerization of 2-(dimethylamino)ethyl methacrylate (DMA) using either monofunctional or bifunctional low molecular weight poly(dimethylsiloxane) (PDMS) as macroinitiators. Provided that the terminal hydroxyl groups of the PDMS macroinitiators are carefully titrated to the corresponding potassium alcoholates, reasonably good control over the DMA chain length was achieved. 1 H NMR characterization of these DMS-DMA diblock copolymers proved unexpectedly problematic since micellization generally occurred even in solvents such as CDCl3 or d8-toluene, which are good solvents for both DMS and DMA homopolymers. Electron microscopy and dynamic light scattering studies confirmed the formation of spherical, polydisperse micelles of 200 nm. Presumably micellization is driven by a demixing term: the PDMS block prefers to be less solvated in order to avoid interacting with the DMA residues. Reliable block compositions were eventually obtained by NMR analysis of dilute solutions of the diblock copolymers in 3:1 d 8-IPA-D2O mixtures. These DMS-DMA diblock copolymers were highly surface active, particularly at pH 9 where the degree of protonation of the DMA block was low. Dynamic light scattering studies indicated micellization in aqueous solution, as expected.

Polydimethylsiloxane-Based Diblock Copolymer Nano-objects Prepared in Nonpolar Media via RAFT-Mediated Polymerization-Induced Self-Assembly

“…22 Amphiphilic PDMS-based diblock copolymers have also been prepared via anionic polymerization of hydrophilic monomers such as 2-(dimethylamino)ethyl methacrylate (DMA) in THF at 25-50 o C from a monocarbinol (or bicarbinol) PDMS precursor. 23,24 PDMS homopolymer has also been used in soft lithography, offering good-quality etch contrast because of its high silicon content. 25 However, much of the current focus of microelectronics research is in the field of block copolymer lithography.…”

Monitoring pH-dependent conformational changes in aqueous solutions of poly(methacrylic acid)-b-polydimethylsiloxane copolymer based on fluorescence spectra of pyrene and 1,3-bis(1-pyrenyl)propane

“…Since PDMS chains are above the glass transition at room temperature [19], A -B copolymers can form various liquid crystalline phases in water or oil. De Paz-Banez et al [20] have synthesized dimethylsiloxane-2-(dimethylamino)ethyl methacrylate di-and tri-block copolymers, and showed micelle formation in aqueous solutions at high pH. Interestingly, the micelles were also observed in solvents of both blocks, for instance in toluene and CHCl 3 .…”

Effect of block composition on thermal properties and melt viscosity of poly[2-(dimethylamino)ethyl methacrylate], poly(ethylene oxide) and poly(propylene oxide) block co-polymers

“…Results and discussion 3.1. Synthesis and characterization of block co-polymers Oxyanionic polymerization can be carried out in two different ways, namely directly from potassium hydride (KH) or through a DMSO -K + complex [16] (DMSO = dimethyl sulfoxide). The DMSO -K + method is assumed to be more accurate since the conversion of macroinitiator into RO -K + can easily be measured with triphenyl methane as an indicator.…”

“…This alcoholate synthesis was first introduced by Nagasaki et al [11], and later it was called oxyanionic synthesis when further studies of the mechanism were done [12,13]. Since then, numerous macroinitiators containing hydroxyl groups have been studied, among them PEO [14], PPO [15], poly(dimethyl siloxane) [16], short aliphatic carbon chains [17] and different combinations of these [14][15][16][17][18][19][20]. The oxyanionic method has also been successfully applied to polymerize some other methacrylates, like 2-(trialkylsiloxyethyl) methacrylate [21].…”