Polymer grafting monomers

The mechanism proposed in Reaction 3—i.e., the generation of a polymeric carbonium ion by the reaction of Et2AlCl with PVC and the addition of the carbonium ion to a double bond in cts-1,4-polybutadiene —would appear to be applicable to the polymer-polymer grafting reaction. The monomer-polymer grafting reaction may involve polymerization of butadiene on the polymeric carbonium ion site or the reaction between polybutadiene generated in situ and the polymeric carbonium ion. 

This technique of in situ interlayer polymerization is also particularly attractive due to its versatility and compatibility with reactive monomers and is begiiming to be used for commercial applications. However, there is ample evidence that nanocomposites can also be formed by melt processing in extruders. There are many reasons why melt processing may be more preferred method for producing nanocomposites for commercial use. Additionally, other approaches, such as the sol-gel proeess [44, 47] and monomer/polymer grafting to clay layers, have resulted in organie/inorganic polymer hybrids. 

Solution polymers are the second most important use for acryflc monomers, accounting for about 12% of the monomer consumption. The major end use for these polymers is in coatings, primarily industrial finishes. Other uses of acryflc monomers include graft copolymers, suspension polymers, and radiation curable inks and coatings. 

If (P ) is terminated by a chain transfer to a solvent or a monomer, a graft copolymer is formed, or, if the termination is from a combination, a crosslinked network polymer is formed. If the pre-existing polymer (B) contains an end group that itself is photosensitive (or can produce a radical by interacting with photoinitiator) and in the presence of a vinyl monomer (A), block copolymer of type AB can be produced if the photosensitive group is on one end of the polymeric chain. Type ABA block copolymer can be produced if the polymer chain (B) contains a photosensitive group on both ends. 

Two general methods of improving polymer hemocompatibility are known (1) grafting of hydrophilic chains, and (2) the chemical attachment of an antiplatelet agent. In this respect, many hydrophilic and other monomers are grafted on solid polyurethane surfaces such as... 

Polymers are classified according to their chemical structures into homopolymers, copolymers, block copolymers, and graft copolymers. In a graft copolymer, sequences of one monomer are grafted onto a backbone of the other monomer and can be represented as follows ... 

When the AAM monomer was grafted onto polymer films, the grafted films showed much higher water absorption than the original ungrafted films. This is due to... 

Monomer Iniferter C=C-R-X > -C M) R-fM X Comb-like polymer, Graft copolymer... 

After photopolymerization of a certain monomer for a given time, the polymerization mixture was poured into excess precipitant to isolate the polymer, which was then extracted with a solvent to separate the polymer grafted onto the PSG from the homopolymer. 

Figure 15.3 Various strategies leading to dendronized or hyperbranched glycopolymers. (A) grafting of dendronsto pre-formed polymers (B) polymerization of dendron monomers (C) grafting dendrimers on pre-formed polymers...

Graft polymers are produced by sonicating a mixture of a polymer and a dissimilar monomer. The graft is produced by breaking a side chain bond to produce the macroradical (Fig. 5.33) which then reacts with the monomer. 

The synthetic methods and chemical characterization data for the various polymeric materials to be discussed in this work have been reported elsewhere [6-8]. In some cases copolymerization of the unchlorinated oxazolidinone monomer with other common monomers such as acrylonitrile, vinyl chloride, styrene, and vinyl acetate, using potassium persulfate as an initiator, was performed. In other cases the unchlorinated oxazolidinone monomer was grafted onto polymers such as poly(acrylonitrile), poly(vinyl chloride), poly(styrene), poly(vinyl acetate), and poly(vinyl alcohol), again using potassium persulfate as an initiator. 

Figure 3 Novel oxazolidinone monomers that can be copolymerized with other monomers or grafted to polymers.

Bell, 1989 Rhee and Bell, 1991), random copolymers of methyl acrylate and acrylonitrile were directly polymerized onto the carbon fiber surface. Dimethyl formamide, dimethyl sulfoxide and distilled water proved to be useful as solvents for this process. Polymerization can take place on the carbon fiber electrode, with initial wetting of the fiber surface leading to better adhesion of the polymer formed. The structure and properties of the polymer can be varied by employing different vinyl and cyclic monomers in homopolymerization. Chemical bond can also be formed, such as polymer grafting to the carbon fiber surface. 

Lastly, there are graft copolymers that result when a polymer chain of one monomer is grafted on to an existing polymer backbone by creation of a free radical site along the backbone that initiates growth of a polymer chain. 

Fu, Z. S., Liang, W. D., Yang, A. M., Wang, Z. G. (2002). Role and relevance of polarity and hindrance of vinyl monomers in graft copolymerization onto potato starch. Journal of Applied Polymer Science, 85, 896-899. 

Plasma Polymerization. Plasma-induced polymerization (24) of vinyl monomer from inorganic particles is also employed for polymer grafting. The conventional reactors for liquid-phase polymerization of vinyl compounds after generation of plasma on inorganic particles or powders have been recently invented by Ikeda et al. (25). Haraguchi et al. (26) have also prepared polymer-modified silica by plasma-induced polymerization of glycidyl methaciylate. 

Polyacetals. Simionescu and coworkers (28) have extended to polyoxy-methylene the process of grafting vinyl polymers (acrylonitrile and methylmethacrylate). They performed the synthesis using a virbomill at room temperature under vacuum (10.1 Torr). The initial monomer-polymer ratio was 1 -5/1.0 and the degree of vibromill packing 0.44. Before milling the polyoxymethylene granules were dissolved in dimethyl formamide and repredpitated with the aim of stabilizer removal and for reduction of polymer particle size (from 2-2.5 mm to 0.05-0.10 mm). Full details of the reaction have been described (40). 

Instead of monomers, polymers in solution can be grafted on Nylon structures. Aqueous solution of poly(acrylic add) is used for impregnation of polyamide fabrics which is subsequently dried during 1 to 5hrs at 80-150° C after which cure is carried out for 15 to 60 min at 150-218° C (99). A copolymer of styrene-maleic anhydride is said to be grafted on polycaprolactam by heating at 230° C at a pressure of 25 kg/cm2 (100). 

Several graft copolymerizations were described by Ballantine (17, 64), Henglein (104, 105) and coworkers. Different monomer-polymer systems were examined styrene on polymethyl methacrylate, poly-2, 5-dichlorostyrene, polytetrafluoroethylene, polyethylene, polypropylene and polyisobutylene, acrylonitrile on polyethylene, rubber, polymethyl methacrylate and dimethyl polysiloxane, vinylpyrrolidone and acroleine on polymethyl methacrylate. The results agree with the preceding ones moreover they show the influence of the swelling and diffusion of the monomer into the polymer. 

The mechanical degradation and production of macroradicals can also be performed by mastication of polymers brought into a rubbery state by admixture with monomer several monomer-polymer systems were examined (10, 11). This technique was for instance studied for the cold mastication of natural rubber or butadiene copolymers in the presence of a vinyl monomer (13, 31, 52). The polymerization of methyl methacrylate or styrene during the mastication of natural rubber has yielded copolymers which remain soluble up to complete polymerization vinyl acetate, which could not produce graft copolymers by the chain transfer technique, failed also in this mastication procedure. Block and graft copolymers were also prepared by cross-addition of the macroradicals generated by the cold milling and mastication of mixtures of various elastomers and polymers, such as natural rubber/polymethyl methacrylate (74), natural rubber/butadiene-styrene rubbers (76) and even phenol-formaldehyde resin/nitrile rubber (125). 

It is known that most mixtures of elastomers and resinous copolymers are rather polydisperse, their incompatibility giving rise to poor interfacial adhesion. Preferably, a resinous monomer or monomers are grafted to the rubber, and they act as a link between the rubber and the resin phases. As Rosen (13) has pointed out, one means of predicting the affinities of polymer pairs from measurable properties is through the use of the solubility parameter, and this has proved useful in this study. The solubility parameter concept was originally derived from the thermody-... 

Janssen et al. [144] focused their work on ozonization of polyvinyl lactam, grafting with hydrophilic methacrylic monomers for applications in the field of contact lenses and other products used in the medical domain. The most studied polymer remains the poly-N-vinyl pyrrolidone which is ozonized either in solid state or in aqueous solution. This activation step leads to three hydroperoxides per chain but also to chain scissions. The resulting product is formulated with different mixtures of methacrylic and dimethacrylic monomers to graft them onto activated polymer by UV initiation. Using dimethacrylic monomers lead to perfect cross-linked polymers presenting excellent resistance to solvents. Unfortunately, the mechanisms of action of ozone onto polyvinyl lactams do not seem to have been studied in detail. 

Characterization of the poly(macromonomers) prepared by homopolymerization has proved that they provide a useful probe for discussing the structural characteristics of the star and brush polymers. Graft copolymers have been and will be a most important area of application of the macromonomer technique since a variety of multi-phased and microphase-separated systems can easily be designed just by an appropriate combination of a macromonomer and a conventional monomer. In general, however, characterization of their absolute MW, branch/backbone composition as well as their distributions remain to be studied in more detail. 

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