Monomers macromonomer

In accordance with the Smith-Ewart theory, the nucleation of particles takes place solely in the monomer-swollen micelles which are transformed into polymer particles [16]. This mechanism is applicable for hydrophobic (macro)mon-omers (see Scheme 2). The initiation of emulsion polymerization is a two-step process. It starts in water with the primary free radicals derived from the water-soluble initiator. The second step occurs in the monomer (macromonomer)-swollen micelles by entered oligomeric radicals. 

According to the aggregative and coagulative nucleation mechanisms which have been derived originally from the homogeneous nucleation theory of Fitch and Tsai [128], the most important point in the reaction is the instant at which colloidally stabilized particles form. After this point, coagulation between similar-sized particles no longer occurs, and the number of particles present in the reaction is constant. As shown in Fig. 6, the dispersion copolymerization with macromonomers is considered to proceed as follows. (1) Before polymerization, the monomer, macromonomer, and initiator dissolve completely into the... 

Table 5 Values of the exponents in R=K [Monomer] [Macromonomer] [Initiator]...

Penezek, S., Kubisa, R, and Matyiaszewski, K., Macromolecular Monomers-Macromonomers Synthesis and Applications. Adv. Polym. Sci., 35, 68/69,1985. Semiyen, J.A., Ed., Cyclic Polymers, Adv. Polym. Sci., 21,41,1976. Elsevier Applied Science Publishers London, 1986. 

Methanolysis under mild conditions has been studied mainly for structural elucidation purposes [7, 51, 60]. However, such conditions can also be considered for the preferential isolation of specific groups of components, such as the alkanoic and a,w-dicarboxylic acids generally involved in more labile structures [7,51,60]. Finally, methanolysis in the presence of calcium oxide was shown to yield oligomers [39, 40, 48-50, 59, 67], which, apart from their interest for structural elucidation, might also be considered as macromonomers for other applications. However, these mild methanolysis conditions are marred by an important drawback in terms of their use as sources of monomers/macromonomers for polymer synthesis, because they generally result in quite low yields. 

The functionality of the end group itself is important. When such groups are hifimctional (eg, vinyl groups) they can participate in polymerization reactions, 5delding graft copol5uners or networks such telechelic polymers are called macromolecular monomers, macromonomers, or macromers. 

Other studies investigated the incorporation of active molecules without a functionalization step. For example, supercritical CO2 was employed to impregnate the core of the PNBE-PEO particles with salicylic acid [35, 36]. Another variation consisted of adding a di-norbornenyl molecule 19 (Scheme 2.6) to the monomer-macromonomer mixture to obtain cross-linked nanoparticles by dispersion ROMP [37]. Reticulated polymer particles are interesting nanocarriers for the controlled release of encapsulated active substances. Raspberry-shaped nanoparticles in the size range of 300-600 nm were obtained, which arose from a double nucleation mechanism. NBE and the cross-linker were rapidly copolymerized in the first minutes of the reaction to afford a first population of highly cross-fiked particles, thereby preventing the incorporation of new active chains inside. A second population of particles was created subsequently from the... 

ROMP copolymers have been functionalized in order to introduce photosensitive groups with a view to bringing new functionalities. Biological detection with signal amplification has been explored by Sleiman et al. [74] from ROMP copolymers incorporating luminescent and electrochemiluminescent transition-metal-containing monomers, biologically compatible monomers, macromonomers... 

The initial reaction mixture of the monomer, macromonomer, initiator and additive is homogeneous, that is, all the reactants are dissolved completely in the solvent. 

Cationic polymerization has also progressed considerably in the direction of controlled living polymerization. For example, advances have been made in the polymerization of isobutylene and vinyl ethers. These include controlled initiation processes, the use of ini-fers, binifers, trinifers, the preparation of bifunctional monomers, macromonomers, functional monomers and telechelic polymers based on isobutylene and the vinyl ethers. 

Monomer Macromonomer Mole % Macromonomer in Feed % Conversion Product M x 10 Mole % Macromonomer in Product... 

This is the source of a long-history view that, nevertheless, still exists in some minds about oligomers as something indefinite and multiple meaning. For example, oligomers are described as unfinished polymers (forpolymers) or axelrath monomers (macromonomers). 

In the case of polymerization of monosubstituted monomers S, RA) with 66-68, copolymerization of the macromonomer to form a graft copolymer is a significant side reaction.76... 

There is a considerable body of evidence (kinetic studies, chemical and NMR analysis) indicating that transfer to VAc monomer involves largely, if not exclusively, the acetate methyl hydrogen to give radical 111 (Scheme 6.29).171,172 This radical (111) initiates polymerization to yield a reactive macromonomer (112). 

Stein166 has indicated that the reactivity of the terminal double bond of the macromonomer (112) is 80% that of VAc monomer. The kinetics of incorporation of 112 have also been considered by Wolf and Burchard175 who concluded that 112 played an important role in determining the time of gelation in VAc homopolymerization in bulk. 

In polymerization of methacrylates, the adducts formed by addition to the macromonomer radicals are relatively unreactive towards adding further monomer... 

Radical induced grafting may be carried out in solution, in the melt phase,292 29 or as a solid state process.296 This section will focus on melt phase grafting to polyolefin substrates but many of the considerations are generic. The direct grafting of monomers onto polymers, in particular polyolefins, in the melt phase by reactive extrusion has been widely studied. Most recently, the subject has been reviewed by Moad1 9 and by Russell.292 More details on reactive extrusion as a technique can be found in volumes edited by Xanthos," A1 Malaika and Baker et a 21 7 The process most often involves combining a frcc-radical initiator (most commonly a peroxide) and a monomer or macromonomer with the polyolefin as they are conveyed through the extruder. Monomers commonly used in this context include MAII (Section 7.6.4.1), maleimidc derivatives and malcate esters (Section 7.6.4.2), (meth)acrylic acid and (meth)acrylate esters (Section 7.6.43), S, AMS and derivatives (Section 7.6.4.4), vinylsilancs (Section 7.6.4.5) and vinyl oxazolines (Section 7.6.4.6). 

Polymerizations of methacrylic monomers in the presence of methacrylic macromonomers under monomer-starved conditions display many of the characteristics of living polymerization (Scheme 9.36). These systems involve RAFT (Section 9.5.2). However, RAFT with appropriate thiocarbonylthio compounds is the most well known process of this class (Section 9.5.3). It is also the most versatile having been shown to be compatible with most monomer types and a very wide range of reaction conditions.382... 

Macromonomer RAFT polymerization is most effective with methacrylate monomers (Table 9.9).With monosubstituted monomers (e.g. S, acrylates) graft copolymerization, is a significant side reaction which can be mitigated but not eliminated by the use of higher reaction temperatures. 

A novel approach to RAFT emulsion polymerization has recently been reported.461529 In a first step, a water-soluble monomer (AA) was polymerized in the aqueous phase to a low degree of polymerization to form a macro RAFT agent. A hydrophobic monomer (BA) was then added under controlled feed to give amphiphilic oligomers that form micelles. These constitute a RAFT-containing seed. Continued controlled feed of hydrophobic monomer may be used to continue the emulsion polymerization. The process appears directly analogous to the self-stabilizing lattices approach previously used in macromonomer RAFT polymerization (Section 9.5.2). Both processes allow emulsion polymerization without added surfactant. 

One of the major advantages of radical polymerization over most other forms of polymerization, (anionic, cationic, coordination) is that statistical copolymers can be prepared from a very wide range of monomer types that can contain various unprotected functionalities. Radical copolymerization and the factors that influence copolymer structure have been discussed in Chapter 7. Copolymerization of macromonomers by NMP, ATRP and RAFT is discussed in Section 9.10.1. 

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. 

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