Polymer-urea complexes

In the disordered crystal structure of the urea inclusion compounds of C 2n 2 (n = 12, 16), the orientation of the included paraffin chain was deduced and the hydrogen (deuterium) position determined for the hexadecane complex (n = 16) using neutron diffraction data [33]. A wide variety of guest molecules accommodated within urea channels were reported recently, including the synthesis and structural characterizations of a dialkylamine adduct [59] and a series of polymer-urea inclusion compounds [39e], Inteichannel ordering of n-alkane guest molecules have been experimentally and theoretically studied [57]. 

In this chapter we discuss the nature of the interaction of LiBr with several segmented copolyether-urethane-ureas and the morphological changes resulting from these polymer-salt complexes. 

Silicon nitride has been obtained by the pyrolysis (in a stream of NHj) of the perhydropolysilazane prepared by the ammonialysis of the H SiClj-pyridine adduct [23, 24]. The gas stream employed during the pyrolysis of the preceramic polymer plays a crucial role [25]. Pyrolysis of [B, H,j diamine] polymers in an NHj stream gives BN [26]. TiN is similarly obtained by the pyrolysis of an amine precursor [27]. TiN has been prepared from titanazane [28]. Pyrolysis of Nicalon in NHj is reported to give SijN [24]. Besides single-phase ceramics, multiphase ceramics (e.g. composites of SiC and TiC, BiN and SijN ) have been prepared from precursors [29, 30]. Group 13 metal nitrides (GaN, AIN, hiN) have been prepared by the decomposition of urea complexes [31]. This method has been extended for the synthesis of BN, TiN and NbN [32]. 

Y. Ito, M. Sisido and Y. Imanishi, Synthesis and antithrorabogenicity of polyetherurethane urea containing quaternary ammonium groups in the side chains and of the polymer/ heparin complex./. Biomed.Mater. Res. 20 1017-1033,1986. 

Poly(metal phthalocyanine) was formed by the reaction of tetracyanoben-zene (TCB) with metal salts and urea. This type of polymer-metal complex makes use of a template reaction. Generally the reaction of ligands containing four functional groups with a metal ion results in a two-dimensional network-chelated structure. 

Poly(ethylene glycol) (PEG)-urea complexes have been investigated in detail by X-ray diffraction, infrared spectroscopy, and [ C]-NMR [8,9]. However, until recently, because no suitable polymer urea single crystal was available, and because of the disordered nature of the guest caused by the highly symmetric host lattice, no conclusive data were obtained for the position or the conformation of the polymer itself within the channel. In a... 

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). 

Rhodium precipitation in solubilized rhodium-phosphite complex catalyzed liquid recycle hydroformylation may be minimized or prevented by carrying out product recovery in the presence of an organic polymer containing polar functional groups such as amides, ketones, carbamates, ureas and carbonates.[20] Patent examples include the use of polyvinylpyrrolidone and vinylpyrrolidone-vinyl acetate copolymer with diorganophosphite-modified rhodium catalysts. 

Figure 5.19 Homogenous polymer blend of 2,7-diamido-l,8-naphthyridine (DAN) functionalized polystyrene and urea of guanosine (UG) functionalized poly(butyl methacrylate) (14), based on the four-point complementary complex formation between DAN and UG.

Schmidt, G, Enkelmann, V., Westphal, U., Droscher, M., and Wegner, G. (1985) Preparation of urea-poly(tetrahydrofuran) complexes and their application for fractionation of oligomers, Colloid Polym. Sci. 263, 120-127. 

Crystalline inclusion complexes (IC s) have been also formed between polymers and another small-molecules, host clathrated provide a unique environment for observing the solid - state behavior of isolated polymer chains. In their IC s with small-molecule, host clathrates, such as urea (U) [1] and perhydrotriphenylene (PHTP) [57], the included polymer chains are confined to occupy narrow channels (ca. 5.4 A in diameter) where they are extended and separated from neighboring chains by the channel walls, which are composed exclusively of the host clathrate, crystalline matrix. Choi et al. [58] have been studied the behavior of isolated, extended polymer chains included in their IC s with U and PHTP by a combination of molecular modeling [59,60] and experimental observations in an effort to determine their conformations and mobilities in these well-defined, containing environments. 

However, more frequently the name of a PCMU is made up of that of a polymer and metal compound (MXn). Thus compounds 5 and 6 are termed a complex of iron(III) chloride with a dipyridyl methane-based polymer [12] and that of copper(II) with the condensation product of p-hydroxybenzoic acid, urea and formaldehyde [26], respectively ... 

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