Styrene, graft copolymers with acrylate

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

M.K. Laughner, Molding compositions with methyl (meth)acrylate-butadiene-styrene graft copolymers, US Patent 5 087 663, assigned to The Dow Chemical Company (Midland, MI), February 11,1992. 

It is well known that primary amines are efficient initiators for the polymerization of Leuch s anhydrides (oxazolidinediones) and that initiation proceeds by the addition of the amine to the monomer. This pathway has been utilized recently to synthesize polypeptide macromonomers bearing a terminal p-vinylbenzyl group 88). Copolymerization of these macromonomers with a vinylic or acrylic comonomer yields graft copolymers with polypeptide grafts. Alternately, the monomer adduct (IV) was copolymerized with styrene, and the primary amine functions of this polymer were used to initiate the polymerization of an oxazolidinedione whereby polypeptide grafts are formed 89). Such graft copolymers may be of interest for biomedical applications. 

The macromonomers thus obtained exhibit molecular weights as low as 1000. They were copolymerized with monomers such as styrene and butyl acrylate whereby graft copolymers with poly(vinyl chloride) grafts were obtained. 

Interesting blends, having a broad range of properties, were prepared in two steps 1. BR was grafted and crosslinked with either styrene or methylmethacrylate to produce a core-shell copolymer. 2. Next, it was blended with PO for improved processability, impact resistance, rigidity, etc. [Aoyama et al., 1993, 1994]. Structural blends of styrene-grafted PP with either SBR, SBS, or an acrylic elastomer were developed [DeNicola andConboy, 1994]. 

PI with pendant ftmctional groups was successfully synthesized by thiol-ene addition reaction (Figure 11) and was further modified to serve as macroinitiator for the ATRP of styrene or tert-butyl acrylate (tBA) to give graft copolymers with V -shaped side chains (Pl-g-PSi and PI- -PtBA2 or PI- -PAA2 (by hydrolysis of PI-g-PtBA2)). ... 

The use of macromonomers in controlled living polymerization techniques, such as ionic or CRP, is at present the preferred synthesis strategy for the preparation of relatively well-defined graft copolymers. Macromonomers are oligomers fitted with polymerizable end-groups, mainly styrenic or (meth)acrylic, that can copolymerize with monomers to form comb-type graft copolymers with pendent preformed polymer chains. 

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

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. 

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. 

Finally, the ASA graft copolymer is prepared. To the alkyl acrylate rubber polymer obtained as described just above, styrene and acrylonitrile are added in the desired quantities. Dodecylmercaptan and potassium persulfate are added as chain transfer agent and radical initiator, respectively. An ASA copolymer with a mean diameter of 550 nm is obtained. 

H.P. Siebel and H.-W. Otto, Styrene- acrylonitrile copolymers blended with graft copolymers of styrene onto butadiene-alkyl acrylate-vinyl alkyl ether terpolymers, US Patent 3280219, assigned to BASF AG, October 18,1966. 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acrylic (52). The acrylic—vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aliphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, solid epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

Free radical polymerization of styrene, of acrylate and of methacrylate monomers in solutions at 60° C in the presence of this preformed polymer produced graft copolymers in high efficiency, the chain transfer constants for these mercapto groups with styrene and methyl methacrylate being similar to those found with simple mercaptans (80, 85). 

Elastomeric graft copolymers of methyl methacrylate upon diene and acrylic rubbers were prepared by R. G. Bauer and co-workers. These elastomers are compatible with rigid methyl methacrylate-styrene copolymers of identical refractive index, yielding transparent polyblends. 

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