Polymerization dialdehyde

Microgels can not only be synthesized by polymerization but also by polycondensation or polyaddition [350]. In an early work on crosslinking of single linear macromolecules, it could be shown that if a crosslinking agent, such as terephthal dialdehyde, was added to a very dilute solution of a linear polymer such as polyvinyl alcohol, almost exclusively a intramolecular crosslinking of the individual macromolecules took place [351]. 

Under an argon atmosphere, to a stirred solution of equimolar quantities of dialdehyde 621 and 1,4-phenylenediacetonitrile in THF and tert-h Ay alcohol (1 1) was added dropwise 5mol% of Bu4NOH (1 M in methanol) at 45°C for 20 min. The resulting paste-like polymeric product that precipitated from the solution during polymerization was collected and thoroughly washed with methanol to remove ionic species and unreacted compounds. The scarlet polymeric product was dried in a vacuum oven at 40°C for 2 days. The polymer yield was 93%. GPC (THF, polystyrene standard) Mw= 1.5 x 106 g/mol, Mn = 3.1 x 105 g/mol. 

Dynamic polymeric systems utilizing the C=N exchange reaction have been reported by Lehn s group. They have suggested a polymerization system consisting of a fluorene-based dialdehyde monomer 4, cyclohexane diamine 5, and fluorene-based diamine 6 as a comonomer (Scheme 8.2) [20,21]. In principle, a 1 1 1 mixture of all monomers in ethanol was expected to yield the two-component polymers 7 and 8 together with all component-mixed polymers. However, polymer 7 was dominantly yielded (80%) due to the nucleophilicity of diamines. The nucleophilic-ity of aliphatic diaminocyclohexane is much higher than that of aromatic... 

The enantioselective addition of an allylsilane to an aldehyde catalyzed by chiral acyloxyborane (CAB) 13 is an excellent method for obtaining optically active homoallyl alcohols.Itsuno and Kumagai reported that the synthesis of a new optically active polymer with chirality on the mainchain is possible by applying this reaction to the asymmetric polymerization of bis(allylsilane) and dialdehyde (Scheme 12.11). ... 

Cyclopolymerization of dialdehydes was extensively studied by Aso and his coworkers (50). It was remarkable that o-phthalaldehyde could be polymerized readily (5Z-53), because aromatic aldehydes such as benzaldehyde, isophthalaldehyde and terephthalaldehyde did not polymerize with common ionic catalysts. In addition, the poly[o-phthal-aldehyde] obtained was composed of only cyclic structural units. These results suggested that the driving force for the polymerization of o-phthalaldehyde was apparently attributable to the formation of the five-membered ring in the course of cyclopolymerization. The ceiling temperature of the polymerization of o-phthalaldehyde was calculated to be — 43° C from the relationship between the equilibrium concentration of the monomer and the polymerization temperature (51,52). 

The selective oxidation of cellulose to dialdehyde by sodium periodate is well known. It has been postulated by Criegee (74) and by Waters (73) that this reaction proceeds by a free radical mechanism. Toda (76) and Morimoto, Okada, Okada, and Nakagawa (77) have concluded that sodium periodate oxidation should initiate graft polymerization. They succeeded in grafting methyl methacrylate and acrylonitrile onto cellulose substrates, such as rayon and paper. A similar procedure is recommended in a patent of Chemische Werke Huels (78) to graft vinyl monomers onto cotton, polyethylene oxide, copolymers of vinyl chloride-vinyl acetate, and others. 

A Wittig style polymerization, shown in Scheme 33, is the result of condensation of dialdehyde monomers with bis(phosphonium) salts containing aromatic cores, and was reported for the first time in 1960 [134]. Unfortunately, due to low reactivity and conversion, the Wittig polymerization typically only affords materials with a DP of 10. Despite its limitation to forming low molecular... 

The Knoevenagel reaction is a base-catalyzed condensation between a dialdehyde and an arene possessing two sites with relatively acidic protons. In this polymerization, shown schematically in Scheme 34, deprotonation affords a difunctional nucleophile that subsequently attacks the carbonyl functionalities present in the other monomers. Elimination is the final step in the Knoevenagel sequence, and the use of monomers with highly acidic protons drives the reaction to completion. A number of research groups have employed this method to obtain PPV and its substituted analogs 29 [126,140-146]. 

LI or III, yields the polymeric dialdehyde (LIII or LIV) M and starch, the molecule of which is built principally of the unit LV, produces oxidized starch, the chief unit of which is LVT.97 With the exception of... 

The alternating copolymers (PPOX-CAR and PMOX-CAR) are easily prepared by the Wittig condensation polymerization between the oxadiazole containing salt monomers and the carbazole dialdehyde. The copolymer, PPOXPV, composed of oxadiazole unit and phenylenevinylene unit, can be prepared by the same way as shown in Scheme 10. But the kinked PPOXPV copolymer is prepared in different synthetic pathway. Reaction of bis(2-bromo-5-hexyloxyben-zyl)-l,3,4-oxadiazole with p-divinyl benzene results in the formation of POOX-PV copolymer [69]. 

Overberger et al. (106) applied the concept of intra-intermolecu-lar polymerization for the polymerization of dialdehydes. Thus, glutar-aldehyde was polymerized with boron trifluoride at —78° C. yielding a product whose carbonyl absorption was negligible and the following structure was proposed ... 

Just about the same time Japanese workers (107) polymerized this dialdehyde with boron trifluoride etherate, p-toluene sulfonic acid, and titanium tetrachloride as well as with aluminum triethyl-water catalyst systems. Completely insoluble products were obtained with the cationic catalysts, whereas partially soluble materials were isolated with the latter initiator. On the basis of infrared evidence, the above structure was assigned to the soluble product. In spite of the fact that ether linkages were found by infrared analysis in the cationic product, the authors concluded that its structure was different from that of the soluble polymer obtained with organometallic catalyst. The structure of the soluble fraction was assumed to be ... 

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