Post-polymerization functionalization

There is a current drive in microlithography to define submicron features in bilevel resist structures. The introduction of organometallic components, most notably organosilicon substituents, into conventional resists is one promising approach. To this end, organosilicon moieties have been primarily utilized in starting monomers (1-4) or in post-polymerization functionalization reactions on the polymer (5,6). Little work has been done on the reaction of preformed reactive oligomers to synthesize block copolymer systems. 

In this review, advances in the preparation of functionalized polysilanes by both pre- and post-polymerization functionalization and their properties will be reviewed. First, polymers with remote side-chain functionalities are covered, then those with the functionality directly attached to the main chain and finally those which are end group-functionalized. Chiral functionalization will be treated separately (see Section 3.11.6). 

If the functional group is remote from the main chain, due to the presence of an intervening alkyl or aryl spacer, prepolymerization functionalization may be possible, although if the functional group is sensitive to the conditions of the polymerization reaction, post-polymerization functionalization will be necessary. 

Related crown ether-pendant polysilanes 45 were recently prepared by hydrosilylation post-polymerization functionalization of poly[methyl(H)silylene- -methylphenylsilylene], 37, although due to the low molecular weight of 37, the product 45 is also of low molecular weight.153... 

Polyolefins with vinyl end groups can be readily transformed into end-functionalized polyolefins by post-polymerization functionalization to yield a wide variety of end-functionalized polyolefins, which include epoxy-, amine-, and hydroxy-terminated polyolefins. Brookhart, Gibson, and co-workers reported on diimine-pyridine-ligated Fe complexes incorporating sterically less hindered alkyl substituents such as a methyl group ortho to the imine-A s, F12-1, that selectively converted ethylene to oligomers, affording linear a-olefin mixtures (>99%) (see also Section... 

This chapter surveys the synthesis of functional polymers by direct methods, such as anionic, cationic, bee radical and coordination polymerization, as weU as post-polymerization functionalization of chains in the bulk or on the surface. Special emphasis is given to more modem techniques that allow for controlled and directed functionalization via living polymerization. Moreover, an introduction to typical applications of functional polymers is presented. 

Boaen NK, Hillmyta- MA (2005) Post-polymerization functionalization of polyolefins. Chem Soc Rev 34(3) 267-275... 

Post-polymerization functionalization has also been applied to the synthesis of terpyridine-modified polymers [ 126]. In a recent approach, Schubert and colleagues employed this method to prepare poly(pentafluorostyrene) with terpyridines in the side chains [127]. First, poly(pentafluorostyrene) with a narrow polydispersity index of just 1.08 was synthesized by nitroxide-mediated polymerization. In a second step, this polymer was converted with amine-functionalized terpyridine under microwave heating, selectively substituting the para-fluorines. Addition of iron(II) sulfate to a solution of the terpyridine-functionalized polymer in a mixture of chloroform and methanol leads to gelation at a polymer concentration of 33 g In another work, Schubert and coworkers prepared metal-cross-Iinked polymer networks from linear and tri-arm PEG precursors, both functionalized with terpyridine at their OH-termini [128]. Quantitative functionalization of these precursors was achieved by conversion of the hydroxy-functionalized PEG derivatives with 4-chloro-2,2 6, 2"-terpyridine under basic conditions. However, quantitative cross-linking with iron(II) chloride was not observed in methanol solutions, neither at room temperature nor at elevated temperature, but only a small quantity of cross-linked material precipitated from the solution. This observation was attributed to a strong tendency of the tri-arm PEG to form intramolecular complexes, acting as a chain stopper rather than as a cross-linker. 

Double hydrophilic block copolymers (DHBCs) are a class of polymers that combine the self assembly ability of block copolymers with the water solubility of hydrophilic macromolecular chains. Numerous sophisticated works have been already described in the literature, indicating the potential of this class of copolymers in emerging technologies. The synthesis of novel DHBCs, using either new monomers or post polymerization functionalization schemes, is the subject of intense investigation during the current years. 

Besbes, M., G. Trippe, E. Levillain, M. Mazari, E Le Derf, I.E Perepichka, A. Derdour, A. Gorgues, M. Salle, and J. Roncali. 2001. Rapid and efficient post-polymerization functionalization of poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives on an electrode surface. Adv Mater 13 1249-1252. 

Bauerle, R, M. Hiller, S. Scheib, M. Sokolowski, and E. Umbach. 1996. Post-polymerization functionalization of conducting polymers Novel poly(alkylthiophene)s substituted with easily replaceable activated ester groups. Adv Mater 8 214-218. 

P(NB/MA) Functional Group Transformations. Functional group transformation is one approach which is possible for the alteration of the hydrolytic latency of P(NB/MA) copolymers. Of the potentially useful post-polymerization functionalizations of P( /MA), hydrolysis, alcoholysis (to yield half-esters), imidization, amidization, and reduction were explored briefiy(2d). 

Nevertheless, most of the work reported on the post-polymerization modification of poly(all lene H-phosphonate)s concerns the functionalization with reactive pendant groups that include hydroxyl or amino groups, which make possible the introduction of a wide range of (bio)ac-tive molecules and leading to new reactive PPEs with tunable properties for biomedical applications. Most of the post-polymerization functionalization methods involve the corresponding polymeric chlorophosphite, since it was early demonstrated that cyclic allgrlene chlorophosphites such as 2-chloro-2-oxo-l,3,2-dioxaphospholane cannot be polymerized efficiently. ... 

Scheme 2.1) followed by selective cross-coupling gives head-to-tail coupled poly(3-alkylthiophene)s. Substituents may be limited by the organolithium intermediates required to access the cross-coupling competent monomer. However, designing for post polymerization functionalization provides a partial solution [46-48]. Telechelic synthesis [43, 49] or isolable monomers, allowing polymerization in diverse solvents, are notable advantages. 

A convenient alternative to protection relies on the incorporation of a labile moiety available for post-polymerization functionalization by nucleophilic substitution [84]. A more versatile approach incorporates a terminally halogenated alkyl substituent as a site for post-polymerization via nucleophilic substitution. Anthraquinone, amine, thiol and carboxylic acid derivatives have been prepared thereby. Complete conversion is possible [46, 47]. Irregular examples include conversion to iodo and thiol derivatives [85]. 

L. Zhai, R. L. Pilston, K. L. Zaiger, K. K. Stokes and R. D. McCullough. A simple method to generate side-chain derivatives of regioregular polythiophene via the GRIM metathesis and post-polymerization functionalization. Macromolecules 36(1), 61-64 (2003). 

POST-POLYMERIZATION FUNCTIONALIZATION OF TACTIC POLYPROPYLENES BY NON-RADICAL-GRAFTING METHODS... 

Figure 12.22 Structures of some functional initiators (XVIII)-(XXI) and post-polymerization functionalizing agents (XXII)-(XXIV). Source (XVIII) Mantovani, et al. (2005) (XIX) Mantovani, et al. (2005) (XX) Erdogan et al. (2002) (XXI) Tuncaetal. (2004) (XXII) Oishi and Fujimoto (1992) (XXIII) Oishi and Fujimoto (1992) (XXIV) Lei and Porco (2004). (Atote For methods of synthesis of these special compounds refer to answers in Solutions Manual to Exercise 12.16.)...

Brie y outline the methods of synthesis of (a) the functional initiators (XVIII) - (XXI) and (b) the post-polymerization functionalizing agents (XXII) and (XXIII), referring to Fig. 12.22. 

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