Monomers with Different Functional Groups

Epoxides readily undergo anionic copolymerization with lactones and cyclic anhydrides because the propagating centers are similar—alkoxide and carboxylate [Aida et al., 1985 Cherdron and Ohse, 1966 Inoue and Aida, 1989 Luston and Vass, 1984]. Most of the polymerizations show alternating behavior, with the formation of polyester, but the mechanism for alternation is unclear. There are few reports of cationic copolymerizations of lactones and cyclic ethers other than the copolymerizations of [5-propiolactone with tetrahydrofuran and 

3-bis(chloromethyl)oxetane, probably indicative of the difference in propagating centers (dioxocarbocation and oxonium ion, respectively) [Yamashita et al., 1966]. The copolymerizations tend toward ideal behavior with the product containing large amounts of the cyclic ether. 

Anionic copolymerization of an episulfide and epoxide shows extreme ideal behavior with only small amounts of epoxide incorporated into the copolymer, since episulfides are much more reactive than epoxides. Cationic copolymerization does not occur to any extent because sulfonium ion centers do not add epoxide, although oxonium ion centers do add episulfide. 

There are very few reported copolymerizations between cyclic monomers and carbon-carbon double-bond monomers. Such copolymerizations would require a careful selection of the monomers and reaction conditions to closely match the reactivities of the different monomers and propagating centers. The almost complete absence of successes indicates that the required balancing of reactivities is nearly impossible to achieve. There are a few reports of copolymerizations between carbon-carbon double-bond monomers and cyclic ethers or acetals [Higashimura et al., 1967 Inoue and Aida, 1984 Yamashita et al., 1966], 

Some copolymerizations have been studied where one of the reactants is a compound not usually considered as a monomer. These include copolymerizations of epoxides and higher cyclic ethers with carbon dioxide, episulhdes with carbon dioxide and carbon disulhde, and epoxides with sulfur dioxide [Aida et al., 1986 Baran et al., 1984 Chisholm et al., 2002 Inoue and Aida, 1989 Soga et al., 1977]. The copolymers are reported to be either 1 1 alternating copolymers or contain 1 1 alternating sequences together with blocks of the cyclic monomer. 

The sequential addition method also allows the synthesis of many different block copo-l3fmers in which the two monomers have different functional groups, such as epoxide with lactone, lactide or cycbc anhydride, cycbc ether with 2-methyl-2-oxazobne, intine or episul-bde, lactone with lactide or cycbc carbonate, cycloalkene with acetylene, and ferrocenophane with cyclosiloxane [Aida et al., 1985 Barakat et al., 2001 Dreyfuss and Dreyfuss, 1989 Farren et al., 1989 Inoue and Aida, 1989 Keul et al., 1988 Kobayashi et al., 1990a,b,c Massey et al., 1998 Yasuda et al., 1984]. 

Although not extensively studied, various architectures such as star and comb polymers have also been synthesized [Bielawski et al., 2000 Goethals et al., 2000]. 

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The composition of the copolymers depends upon the reaction conditions, the counterions, the solvents, and the reaction temperatures. The initiator system can be very important when cyclic monomers with different functional groups are copolymerized. Also, if different propagating centers are involved in the propagation process, copolymerizations can be very difficult to achieve. 

The second type of step-growth polymerization involves the use of monomers with different functional groups in the same molecule, A-B type monomers. An example of this reaction is the production of nylon 11 from 11-aminoundecanoic acid. 

Figure 8.24 I In condensation polymerization, a molecule of water is eliminated as each monomer is added to the chain. Here we show the first steps in the formation of Nylon (a) and Dacron (b). Both are copolymers, with two different monomer molecules combining to form the polymer. Because each monomer contributes its own functional group to the condensation step, regular alternation of monomers is ensured. Other condensation polymerizations can involve a single monomer with different functional groups on each end.

Generally, two different procedures have been adopted for preparation of MIPs. They involve either covalent or non-covalent complex formation of a template and complementary monomers with apt functional groups. [19]. Co-polymerization of this complex with a cross-linking monomer in a porogenic solvent solution, followed by removal of the template, results in formation of the porous polymer material with recognition sites complementary in size and shape to molecules of the target compound that can next be determined as an analyte. 

In such cases also, all linking steps are reactions of the same groups, so that the rate coefficient can once again be assumed to have approximately the same value for all. However, the two types of functional groups now are on different monomers and therefore are not necessarily present in stoichiometric amounts. For stoichiometric mixtures of monomers with different functionalities, the rate equation 10.8 and eqns 10.9 and 10.10 for fractional conversion remain valid. For nonstoichiometric mixtures, eqn 10.8 must be replaced by... 

Monomers with Different Functionalities Introduction of other functionalities into monomer structure is a versatile approach to increase the reactivity, provide wavelength tunability, and improve the properties of the networks formed. Monomers attached to preformed polymers [2] or equipped with photosentizers [119], hydroxyl groups [108-110], and groups polymerizable by other modes [2,120,121] were readily prepared. For example, epoxy end functionalized poly (e-caprolactone)... 

Many copolymers have been prepared from cyclic monomers. These can form through ringopening copolymerizations of monomers with similar functional groups as well as with different ones. Some cyclic monomers can also copolymerize with some linear monomers. Only a few copolymers of cyclic monomers, however, are currently used industrially. 

Results of investigations the stationary and non-stationary kinetics of monomers with one functional group showed that at conversions P > 0.5 two polymeric phases are coexisted, namely first is a monomer-polymeric solution with conversion Pb 0.5 saturated by a polymer, and the second one is solid solution of a monomer in the polymer with the conversion P = 0.8. That is why two films which are polymerized under UV-illumination on different surfaces, even at high general conversion, are easily conjuncted when compressed and after that the layer formed via the postpolymerization process becomes stronger. 

A polymer obtained through a polycondensation reaction of two kinds of monomers containing different functional groups cannot be named with this... 

Metallocene-based catalysts have broadened the scope of synthesizing polyolefins with different functional groups. The polar monomers could now be polymerized with metallocene catalysts of cationic nature. 

One of successfully applied polymerization technique in grafting-from approach is atom transfer radical polymerization ATRP [5]. ATRP can be used for controlled polymerization of many vinyl monomers i.e. acrylates, acrylonitrile or monomers containing different functional groups. Most of them can be polymerized by a traditional radical polymerization, however ATRP allows to obtain polymers with precise value of molecular weight (M ) and polydispersity index (PDI). 

A monomer is a reactive molecule that has at least one functional group (e.g. -OH, -COOH, -NH2, -C=C-). Monomers may add to themselves as in the case of ethylene or may react with other monomers having different functionalities. A monomer initiated or catalyzed with a specific catalyst polymerizes and forms a macromolecule—a polymer. For example, ethylene polymerized in presence of a coordination catalyst produces a linear homopolymer (linear polyethylene) ... 

A reaction between two different monomers. Each monomer possesses at least two similar functional groups that can react with the functional groups of the other monomer. For example, a reaction of a diacid and a dialcohol (diol) can produce polyesters ... 

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