Ethylene oxide/methyl methacrylate block

A detailed study on the possibility of carrying out block copolymerizations by high-speed stirring was performed by Minoura and co-workers [145, 147] on the system poly(ethylene oxide)-methyl methacrylate. The polymer was dissolved in the monomer at 45 °C and stirred in a high-speed homomixer in a nitrogen atmosphere. The polymer molecular weight was in the range... 

Several other di- and triblock copolymers have been synthesized, although these are of limited commercial availability. Typical examples are diblocks of polystyrene-block-polyvinyl alcohol, triblocks of poly(methyl methacrylate)-block poly(ethylene oxide)-block poly(methyl methacrylate), diblocks of polystyrene block-polyethylene oxide, and triblocks of polyethylene oxide-block polystyrene-polyethylene oxide [4]. 

Qiao XG, Fansalot M, Bourgeat-Lami E, Charleux B (2013) Nitroxide-mediated polymerization-induced self-assembly of poly(poly(ethylene oxide) methyl ether methacrylate-co-styrene)-h-poly(n-butyl methacrylate-co-styrene) amphiphilic block copolymers. Macromolecules 46 4285 295... 

In a similar manner polyisoprene-polyethylene oxide block copolymers can prepared301. It is surprising that the poly(methyl methacrylate) anion can be successfully used for the polymerization of ethylene oxide without chain transfer302. Graft copolymers are also prepared by successive addition of ethylene oxide to the poly-... 

The range of monomers that can be incorporated into block copolymers by the living anionic route includes not only the carbon-carbon double-bond monomers susceptible to anionic polymerization but also certain cyclic monomers, such as ethylene oxide, propylene sulfide, lactams, lactones, and cyclic siloxanes (Chap. 7). Thus one can synthesize block copolymers involving each of the two types of monomers. Some of these combinations require an appropriate adjustment of the propagating center prior to the addition of the cyclic monomer. For example, carbanions from monomers such as styrene or methyl methacrylate are not sufficiently nucleophilic to polymerize lactones. The block copolymer with a lactone can be synthesized if one adds a small amount of ethylene oxide to the living polystyryl system to convert propagating centers to alkoxide ions prior to adding the lactone monomer. 

The formation of block polymers is not limited to hydrocarbon monomers only. For example, "living polystyrene initiates polymerization of methyl methacrylate and a block polymer of polystyrene and of polymethyl methacrylate results (0). Ethylene oxide and its analogues or cyclic silicons such as... 

Further studies were directed to examine different SCBs and the effect of different counterions. Potassium counterions provide improved efficiency as compared to lithium or sodium counterions. The most efficient system in terms of formation of carbanions was achieved with diphenylsilacyclobutane in combination with potassium tert-butoxide and diphenylethylene <2004MI856>. Di-block copolymers from ethylene oxide and methyl methacrylate (or styrene) were synthesized by this method with 85% efficiency (Scheme 14) <2004MI856>. 

The carbanion pump method has been successfully applied for the preparation of different block copolymers including poly(ethylene oxide)-block-polystyrene, poly(ethylene oxide)-block-polystyrene-block-poly(ethylene oxide), poly(ethylene oxide)-block-poly(methyl methacrylate), poly(ethylene oxide)-block-poly(methylmethacry-late)-block-poly(ethylene oxide) (shown in Scheme 14), and poly(ferrocenyldimethylsilane)-block-(methyl methacrylate) <2004MI856, 2004MM1720, 2006MI(928)292>. 

Th-FFF can be applied to almost all kinds of synthetic polymers, like polystyrene, polyolefins, polybutadiene, poly(methyl methacrylate), polyisoprene, polysulfone, polycarbonate, nitrocelluloses and even block copolymers [114,194,220]. For some polymers like polyolefins, with a small thermal diffusion coefficient, high temperature Th-FFF has to be applied [221]. Similarly, hydrophilic polymers in water are rarely characterized by Th-FFF, due to the lack of a significant thermal diffusion (exceptions so far poly(ethylene oxide), poly(vi-nyl pyrrolidone) and poly(styrene sulfonate)) [222]. Thus Th-FFF has evolved as a technique for separating synthetic polymers in organic solvents [194]. More recently, both aqueous and non-aqueous particle suspensions, along with mixtures of polymers and particles, have been shown to be separable [215]. 

The reactive end of a living polymer attacks a suitable group on a dead polymer Pji and grafts on Pjj as shown by Schreiber (15), who grafted living polystyrene on dead poly (methyl methacrylate). Such a procedure may lead to cross linking or to the formation of a loop, if both ends of the living polymer are active. Other block polymers prepared by this technique are polymers of styrene and ethylene oxide (14), polymers of styrene and dimethylsiloxanes (13), and polymers of styrene and vinylpyridine (16). 

It is claimed that styrene/butadiene diblock polymers bring about an improvement in the hardness, strength, and processability of polybutadiene elastomers (27), as well as an improvement in the ozone resistance of neoprene rubber (28). Styrene diblock polymers have also been made with isoprene, a-methyIstyrene, methyl methacrylate, vinylpyridine, and a-olefins. Block copolymers of ethylene, propylene, and other a-olefins with each other have been made as well. Heteroatom block copolymers based on styrene or other hydrocarbons and alkylene oxides, phenylene oxides, lactones, amides, imides, sulfides, or slloxanes have been prepared. 

The discovery of the anionic ring-opening polymerization of silicon-bridged[l]ferrocenophanes enabled the synthesis of well-defined, near-monodisperse poly(ferrocenylsilane) homo- and block copolymers. PFS was combined with polystyrene [38], polyisoprene [39], poly(dimethylsilox-ane) [40], poly(ethylene oxide) [41], poly(ferrocenylphenylphosphine) [42], poly(aminoalkyl methacryate) [43] and recently with poly(methyl methacrylate) [44,45] blocks. 

To improve the efficiency, 1,1-diphenylethylene was used to trap the initially formed carbanion from potassium terf-butoxide (BuOK) and dialkylsilacyclobutane. When a twofold excess of dimethylsilacyclobutane was added over 90 min, the carbanion pump efficiency reached almost 88%. Diphenylsilacyclobutane gave almost quantitative efficiency, which could be used to synthesize block copolymer from the propagating end of poly(ethylene oxide) to methyl methacrylate to give polymers with a narrow molecular weight distribution. Such a system was also used by other researchers successfully. ... 

Among these reactions, the Cu(l)-catalyzed azide-alkyne cycloaddition (CuAAC) is the most widely used. This reaction has been implemented for the preparation of segmented block copolymers from polymerizable monomers by different mechanisms. For example, Opsteen and van Hest [22] successfully prepared poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA) and PEO-b-PSt by using azide and alkyne end-functionalized homopolymers as the click reaction components (Scheme 11.2). Here, PEO, PSt, and PMMA homopolymers were obtained via living anionic ring-opening polymerization (AROP), atom transfer radical polymerization (ATRP), and postmodification reactions. Several research groups have demonstrated the combination of different polymerization techniques via CuAAC click chemistry, in the synthesis of poly(e-caprolactone)-b-poly(vinyl alcohol) (PCL-b-PVA)... 

Figure 17.23. Examples of polymerizable surfactants (a) A methacrylate ester of a methyl-capped block copolymer of ethylene oxide and butylene oxide (b) an allyl-capped block copolymer of butylene oxide and ethylene oxide with varying end-groups bottom (c) monododecylmonosulfopropylmaleate...

Similar block copolymers have also been prepared by coupling methyl methacrylate macroanions and suitably terminated poly(ethylene oxide)( )and by the initiation of methyl and ethyl methacrylate by alkali metal alkoxides of poly(ethylene oxide)( 3). styrene containing block copolymers have also been produced( ). In the former plus latter techniques the ester containing block segments were subsequently hydrolyzed to methacrylic acid thus making them water soluble. 

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