Thiourea-poly complex

Association Complexes. The unshared electron pairs of the ether oxygens, which give the polymer strong hydrogen bonding affinity, can also take part in association reactions with a variety of monomeric and polymeric electron acceptors (40,41). These include poly(acryhc acid), poly(methacryhc acid), copolymers of maleic and acryflc acids, tannic acid, naphthoHc and phenoHc compounds, as well as urea and thiourea (42—47). 

Series of various mono,- bi-, and poly-(thio)urea-functionalized (poly)saccha-rides have already been synthesized and studied for molecular recognition of, e.g., dimethyl and phenylphosphate as model compounds for monoanionic and polyanionic phosphate esters, respechvely [111]. Thiourea derivatives such as 195-197 were analyhcally identified to provide double hydrogen bonding mediated host-guest complexes of well-defined dimension and orientations and were also reported to serve as phosphate binders even in the hydrogen bonding environment of water (Figure 6.57) [111]. 

Allyl nickel complexes yield crystalline poly(l,3-cyclohexadienes) with 90% 1,4-structures and melting points between 180 and 270 °C [425]. Thiourea inclusion templates give polymers with purely 1,4 structures and unusually high melting points, between 370 and 380 °C. Additional polymers of cyclic dienes are listed in Table 22 [331,426-429]. 

The ether oxygen atoms in poly(ethylene oxide) chains have a strong hydrogen-bonding affinity that results in the formation of association or interpolymer complexes when the polymer chain interacts with polymeric acids such as poly(acrylic acid) and poly(methacrylic acid) in solution (104) and with compounds such as urea and thiourea in bulk (105-107). The subject of association complexes has been reviewed with a particular emphasis on the polyoxyethylene complexes (108) and on polyoxyethylene-based surfactant complexes (109). 

Thiourea forms crystalline complexes with high molecular weight (several hundred to 4 million) poly(ethylene oxide). Complexes have been formed by mixing thiourea with this type of poly(ethylene oxide) on a hot roller mill and then precipitating the complex from a benzene solution. The most dramatic method of complex formation, however, is observed when finely... 

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