Macromonomers styrene

Macromonomers Styrene derivatives, esters of (meth) acrylic acid, derivatives of maleimide... 

Interestingly, the first example of a macromonomer, long before the names Macro-mer or macromonomer have been coined 94), is a styrene terminated polydimethyl-siloxane synthesized by the reaction of a Grignard derivative of p-ch loro styrene and an co-chlorodimethylsiloxane oligomer 90) as shown in Reaction Scheme IX. Later, these macromonomers have been reacted with different vinyl monomers such as styrene and acrylates, and relatively well defined graft copolymers have been synthesized. 

Surprisingly, after this very first example, there was a 20 year delay in the literature in the appearance of the second report on siloxane macromonomers. However, during this period there have been numerous studies and developments in the vinyl and diene based macromonomers91 -94). The recent approach to the synthesis of siloxane macromonomers involves the lithiumtrimethylsilanolate initiated anionic polymerization of hexamethyltrisiloxane in THF 95,123). The living chain ends were then terminated by using styrene or methacrylate functional chlorosilanes as shown in Reaction Scheme X. 

Yamashita and co-workers have also determined the reactivity ratios of styryl terminated PDMS macromonomers (M,) with styrene (M2) and methyl methacrylate (M2)123>. They have determined (r2) and (r2) as 1.1 and 0.60 respectively. These values... 

MA and St denotes methacrylate and styrene terminated PDMS Macromonomers respectively ... 

Recently it has been shown that anionic functionalization techniques can be applied to the synthesis of macromonomers — macromolecular monomers — i.e. linear polymers fitted at chain end with a polymerizable unsaturation, most commonly styrene or methacrylic ester 69 71). These species in turn provide easy access to graft copolymers upon radical copolymerization with vinylic or acrylic monomers. 

In our own research, the functional termination of the living siloxanolate with a chlorosilane functional methacrylate leading to siloxane macromonomers with number average molecular weights from 1000 to 20,000 g/mole has been emphasized. Methacrylic and styrenic monomers were then copolymerized with these macromonomers to produce graft copolymers where the styrenic or acrylic monomers comprise the backbone, and the siloxane chains are pendant as grafts as depicted in Scheme 1. Copolymers were prepared with siloxane contents from 5 to 50 weight percent. 

Polystyrene-g-poly(ethylene oxide) was synthesized by the copolymerization of styrene and styrenic PEO with CpTiCb/MAO catalyst [190]. In this case the macromonomer was prepared by first reacting the sodium salt of PEO-OH with NaH and then with a 5-fold amount of p-chloromethyl styrene. 

An alternative route for the preparation of styrenic macromonomers is the reaction of living chains with 4-(chlorodimethylsilyl)styrene (CDMSS) [192]. The key parameter for the successful synthesis of the macromonomers is the faster reaction of the living anionic chain with the chlorosilane group rather than with the double bond of the CDMSS. Anionic in situ copolymerization of the above macromonomers (without isolation) with conventional monomers leads, under appropriate conditions, to well-defined comb-like chains with a variety of structures. 

These were obtained by copolymerization of styrenic macromonomers containing dendritic pendant groups with styrene [16a] with a later extension to methacrylate-type copolymers [16b]. As these studies were carried out with... 

It is also possible to introduce polymerizable groups at the focal point of dendritic macromolecules and a number of authors have demonstrated the synthesis of novel hybrid dendritic-linear block copolymers by this methodology [69-73]. Initial experiments in the use of the dendritic macromonomers involved the preparation of a series of polyether dendrimers, such as the third generation derivative, 37, which contains a single styrene at its focal point [74]. Copolymerization of 37 with styrene then affords a hybrid block copolymer, 38, in which... 

Statistical, gradient, and block copolymers as well as other polymer architectures (graft, star, comb, hyperbranched) can be synthesized by NMP following the approaches described for ATRP (Secs. 3-15b-4, 3-15b-5) [Hawker et al., 2001]. Block copolymers can be synthesized via NMP using the one-pot sequential or isolated macromonomer methods. The order of addition of monomer is often important, such as styrene first for styrene-isoprene, acrylate first for acrylate-styrene and acrylate-isoprene [Benoit et al., 2000a,b Tang et al., 2003]. Different methods are available to produce block copolymers in which the two blocks are formed by different polymerization mechanisms ... 

The grafting-through method has also been studied for ATRP. Vinyl chloroacetate is used as the initiator in ATRP of a monomer such as styrene to produce a macromonomer. Vinyl chloroacetate does not significantly copolymerize with styrene, and the result is a polystyrene vinyl macromonomer, which is then polymerized to a brush polymer [Davis and Matyjaszewski, 2002],... 

A telechelic polystyrene containing two carboxyl groups at one end of a polymer can be used as a macromonomer in a step polymerization with a diol or diamine to yield a polyester or polyamide containing graft chains of polystyrene. The required telechelic polymer is obtained by radical polymerization of styrene in the presence of 2-mercaptosuccinic acid. 

Thus in the emulsifier-free emulsion copolymerization the emulsifier (graft copolymer, etc.) is formed by copolymerization of hydrophobic with hydrophilic monomers in the aqueous phase. The ffee-emulsifier emulsion polymerization and copolymerization of hydrophilic (amphiphilic) macromonomer and hydro-phobic comonomer (such as styrene) proceeds by the homogeneous nucleation mechanism (see Scheme 1). Here the primary particles are formed by precipitation of oligomer radicals above a certain critical chain length. Such primary particles are colloidally unstable, undergoing coagulation with other primary polymer particles or, later, with premature polymer particles and polymerize very slowly. 

The rate of dispersion copolymerization of PEO-MA macromonomer and styrene was found to increase with increasing initiator concentration VA - water soluble, DBP (dibenzoyl peroxide) - oil soluble, [PEO-MA] =0.06 mol dnr3, [styrene] =2.13 mol dm-3, in ethanol/water, v/v4/l) [65,66] ... 

The dispersion copolymerization of PEO-MA macromonomer and styrene is presented in Figs. 1 and 2 [70]. The rate-conversion plot is curved with a maximum at very low conversion. In all runs, neither the gel effect nor the stationary interval were observed. The strong decrease of the rate of polymerization with increasing conversion results from a decrease in the monomer concentration at the reaction loci (mainly in the polymer particles). The low monomer concentration in particles is a reason why the gel effect may be operative only at very low conversion. 

In copolymerization of styrene, more monodisperse and smaller-size particles were obtained with the PEO-MA macromonomer with a longer alkylene spacer group, thus indicating their effectiveness as reactive surfactant increases in the series [71]... 

The rate of the dispersion copolymerization of PEO-MA with styrene increased with increasing temperature [72], which was attributed to the increased rate of initiation and particle formation. The overall observed activation energy (E0) for the dispersion copolymerization of PEO-MA or PEO-VB macromonomer and styrene was found to be 48 or 53 kj mol-1. These values are much lower than those (ca. 90-100 kj mol-1 [73]) obtained in the solution polymerization of low molecular weight monomers. 

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