Side polymer synthesis

Pollino JM, Week M. Supramolecular side-chain functionalized polymers synthesis and self-assembly behavior of polynorbornenes bearing Pd SCS pincer complexes. Synthesis 2002 9 1277-1285. 

The preparation of soluble polymers containing species 1-4 was accomplished by the use of the polar trifluoroethoxy group as co-substituent. The partially substituted trifluoroethoxy polymer, prepared in the first step of the polymer synthesis (see Scheme II), provided a polar environment for the incorporation of the chromophoric side chains. However, the maximum loading of the polymers by the chromophores 1-4 was limited by the solubility of the polymeric products. Hence, the side group ratios for polymers 6-9 represent a maximum incorporation range of the chromophore side group by the use of this synthetic scheme. 

Specific feature of polymers which differentiates them from low molecular mass compounds is the existence of anomalous or defect structural units which are always a part of the chain of normal mers. The presence of the defect mers is a consequence of the polymer synthesis, where the products of side-reactions are integrated into the polymer chains as anomalous units usually without the possibility of their further separation. 

A. Miyashita, S. Nakano, M. Hirano, and H. Nohira, Negative photochromic polymers. Synthesis and photochemical properties of poly(methyl methacrylate) having spirobenzoselenazolinobenzo-pyran side groups, Chem. Lett., 1993, 501-504. 

The scope of the living cationic polymerizations and synthetic applications of these functionalized monomers will be treated in the next chapter on polymer synthesis (see Chapter 5, Section III.B). One should note that the feasibility of living processes for these polar monomers further attests to the formation of controlled and stabilized growing species. Conventional nonliving polymerizations, esters, ethers, and other nucleophiles are known to function as chain transfer agents and sometimes as terminators. In addition, the absence of other acid-catalyzed side reactions of the polar substituents, often sensitive to hydrolysis, acidolysis, etc., demonstrates that these polymerization systems are free from free protons that could arise either from incomplete initiation (via addition of protonic acids to monomer) or from chain transfer reactions (/3-proton elimination from the growing end). 

Chiral polymers have been applied in many areas of research, including chiral separation of organic molecules, asymmetric induction in organic synthesis, and wave guiding in non-linear optics [ 146,147]. Two distinct classes of polymers represent these optically active materials those with induced chirality based on the catalyst and polymerization mechanism and those produced from chiral monomers. Achiral monomers like propylene have been polymerized stereoselectively using chiral initiators or catalysts yielding isotactic, helical polymers [148-150]. On the other hand, polymerization of chiral monomers such as diepoxides, dimethacrylates, diisocyanides, and vinyl ethers yields chiral polymers by incorporation of chirality into the main chain of the polymer or as a pedant side group [151-155]. A number of chiral metathesis catalysts have been made, and they have proven useful in asymmetric ROM as well as in stereospecific polymerization of norbornene and norbornadiene [ 156-159]. This section of the review will focus on the ADMET polymerization of chiral monomers as a method of chiral polymer synthesis. 

Thereby it must be emphasized that the application of methods from organic chemistry in polymer synthesis was only possible for chain structures, that are sufficiently soluble (see section 1.3). Here again, careful consideration of the mechanistic details of the reaction and the occurrence of side reactions are important ingredients of both oligomer and polymer synthesis. Thus, the Knoevenagel eondensation is feasible for eyano-substituted precursors 71... 

A. Miyashita, H. Hirano, S. Nakano, and H. Nohira, Diode-laser susceptible photochromic polymers Synthesis and photochemical properties ofpoly(methyl methacrylate) with spiroben-zothiopyrans as side-groups, J. Mater. Chem. 3, 221-222 (1993). 

One strategy to ehminate side-reactions in NCA polymerizations is the use of transition metal complexes as active species to control addition of NCA monomers to polymer chain-ends. The use of transition metals to control reactivity has been proven in organic and polymer synthesis as a means to increase both reaction selectivity and efficiency [21]. Using this approach, substantial advances in controlled NCA polymerization have been realized in recent years. Highly effective zerovalent nickel and cobalt initiators (i.e. bpyNi(COD) [22,23] and (PMc3)4Co [24]) were developed by Deming that... 

Berlinova IV, Amzil A, Tsvetkova S, Panayotov IM. Amphiphilic graft copolymers with poly(oxyethylene)side chains synthesis via activated ester intermediates—properties. J Polym Sci Part A Polym Chem 1994 32 1523-1530. 

An interesting example of intra-polymeric catalysis is provided by the effect of polymer side chains on the aminolysis of polymer-bound nitrophenyl ester [41a], as illustrated in Fig. 10. Thus, apparent reactivity of the polymer-bound carbonyl groups is substantially increased by changing the polymer side chains from phenyl to methoxycarbonyl, and to dimethylamide. This type of intra-polymeric catalysis (shown schematically by species 9 in Fig. 11) assumes special significance in crosslinked polymers and solid phase synthesis. An important implication of this catalytic effect for polymer synthesis is that when an activated polymer intermediate (8) is not sufficiently reactive towards a given nucleophile, polymer reactivity can be enhanced by partial aminolysis with dimethyl-amine [25]. 

Fig. 2.—Two Theoretically Possible Methods of Chain Elongation in O Side-chain Synthesis, Considered by Bray and Robbins," (In method A, a repeating unit monomer is added to the nonreducing end of the growing O side-chain, which is linked to PP-ACL. In method B, a polymer of the repeating units is transferred onto the nonreducing, terminal sugar of a repeating unit monomer, linked to PP-ACL.)...

Kubisa et al. [64] have been exploring the use of chiral ionic liquids in polymer synthesis. Using ionic liquids with a chiral substituent on the imidazolium ring for the ATRP of methyl acrylate gave a small but definite effect on polymer tacticity, with more isotactic polymer formed than in simple [BMIM][PF6]. They also found that the use of ionic liquids led to fewer side reactions. Ionic liquids have been used as solvents in biphasic ATRP to facilitate the separation of the products from the catalysts [65]. 

Another field of enzymatic polymer synthesis is the enzyme-catalyzed modification of preformed polymers by esterification or transesterification. Thereby, it is possible to either introduce functional side groups into an existing polymer with a stable backbone (no polyester) to synthesize functional homopolymers as well as random copolymers or to generate multiblock copolymers by enzymatic transesterification between two different homopolymers. 

Figure 31.4 The three distinct methods through which carbenes have been utilized for polymer synthesis. Type 1 Carbenes are essential to the polymerization process Type 2 Carbenes as side-group functionalities or reagents for post-polymerization modification Type 3 Carbenes are used as catalysts or ligands for polymerization catalysts.

More AS, Menon SK, Wadgaonkar PP. New poly(l,3,4-oxadiazole)s bearing pentade-cyl side chains synthesis and characterization. J Appl Polym Sci 2012 124(2) 1281-9. 

Wang, Q.Y., et al. 2003. Grafted conjugated polymers Synthesis and characterization of a polyester side chain substituted poly(p r phenyleneethynylene). Chem Commun 1624. 

Melucci, M., G. Barbarella, M. Zambianchi, M. Benzi, F. Biscarini, M. Cavallini, A. Bongini, S. Fabbroni, M. Mazzea, M. Anni, and G. Gigli. 2004. Poly(alpha-vinyl-omega-alkyloligothiophene) side-chain polymers. Synthesis, fluorescence, and morphology. Macromolecules 37 5692-5702. 

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