Telechelic polymers quenching

For the determination of the methoxycarbonyl chain end fimctionality, a model compound was synthesized under similar conditions to that of the telechelic polymer. TMPCl was capped with DPE, followed by end quenching with MTSMP. This model compound was used for the assignments of both the H NMR and the NMR chemical shifts corresponding to the methoxycarbonyl chain end, as well as for calibration for IR measurements. The H NMR spectrum of the model compound is shown with the assignments in Figure 1. The peaks corresponding to protons c-i are... 

Functionalized poly(vinyl ether)s can be prepared by the functionalized initiator method by the use of a HI/I2 initiating system and a functionalized vinyl ether, resulting in a-functionalized polymers. Carboxylic add- and amine-terminated polymers were prepared by this method with high degrees of functionality as determined by H NMR. This method can be extended to the preparation of telechelic polymers by quenching the polymerization with the appropriate nucleophile. Methacrylate-functionalized poly(vinyl ether) s... 

The growing living species 1 can be quenched cleanly with so-diomalonic ester to form the target hetero-telechelic polymers (17). The terminal (head) function X (arising from 1 ) may be acetate or imide that in turn leads to a carboxylic acid or an amine, respectively. Another terminal carries a malonate (from the malonate terminator), which can be converted to a carboxylic acid by hydrolysis/ decarboxylation. One of the advantages of the polymer synthesis via the base-stabilized species is the rather high operational temperature up to +60 °C. 

The synthesis, starting from a bifunctional initiator followed by quenching the double-headed living ends, gives homotelechelic polymers (method B). Carboxylate-capped telechelic poly(isobutyl vinyl ether) has been obtained in this way [82], where the adduct of a bifunctional vinyl ether with trifluoroacetic acid is the initiator, and the quencher is the malonate anion. For method C, a bifunctional trimethylsilyl enol ether, CH2=C[OSi(CH3)3]C6H4OCH2CH20C6H4[(CH3)3SiO]C=CH2, is a useful terminator (chain coupler) for vinyl ethers [142,147] and a-methyl-styrene [159] (see also Section VI.B.4). 

A one-pot synthesis of telechelic and semitelechelic poly(alkyl acrylates) with unsaturated end groups has been developed by Bielawski et al. [1]. ATRP of methyl acrylate or -BA was initiated with either ethyl cy-bromomethyl-acrylate or methyl dichloro acetate, as a monofunctional or a difunctional initiator, respectively, and was mediated with various Cu-amine complexes. Addition of excess ethyl 2-bromomethylacrylate was found to immediately quench the polymerization, but also to insert 2-carbethoxyallyl moieties at the ends of the polymer chains (Scheme 24). Thus, the synthesis of telechelic poly(alkyl acrylates) with unsaturated end groups has been accomplished, with very good functionality (f 2) (Scheme 24). 

Polystyrene and Derivatives. Telechelic polystyrene, poly(2,4,6-trimethylst5Tene), poly(p-methylstyrene), and poly(p-chlorostyrene) can be prepared by living carbocationic polymerization (269-271) or by inifer method (272). While end-quenching the living carbocationic polsrmerization gave quantitatively polymers with sec-benzylic termini, the diciunyl chloride/BClg inifer system yielded a,with olefine end groups were also prepared by dehydrochlorination (272,273). 

Naturally, anionic polymerization is not compatible with H-bonding moieties, thus requiring efficient modification after the polymerization reaction (Ilhan et al., 2001 Schadler et al., 1998). An excellent example (Karatzas et al, 2006) of an efficient postmodification method was presented starting from living PS-PI anions, which was quenched by only one unit of oxirane, furnishing the hydroxy-telechelic PS-PI BCP (15). This in turn was reacted with the isocyanate (16), attaching the ureidopyrimidone moiety to the final polymer (17). 

Figure 3.10 (a) Direct copolymerization of H bonds via ROMP and the alternative reaction pathway to yield a similar polymer, (b) End-group-modified telechelic polynorbomenes via quench with functionalized ethyl-vinyl ethers. 

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