Urethane polymer bound

In the first step, isocyanate 119 was attached to the support affording urethane derivative 120. Subsequent treatment with 6 different amines furnished the corresponding polymer-bound sulfonamides 121. Basic hydrolysis released analytically pure products 122 in high overall yields (95-97%) and purities. Reactions were monitored by NMR spectroscopy. 

The catalyst is reported to be highly compatible with the final polyurethane product and may become chemically bound into the polymer backbone where used in polyester-based urethanes. 

Preformed polymers can also be employed to prepare imprinted core-shell particles [143]. The group of Chang recently prepared a poly(amic acid) bearing oestrone as a template molecule covalently bound to the polymer through a urethane linker (see Fig. 2). A layer of this polymer was subsequently deposited on silica particles (10 pm diameter) prefunctionalised with amino groups at their surface. Thermal imidisation of the polymer yielded finally a polyimide shell (thickness about 100 nm) on the silica particles. Subsequent template removal yielded the imprinted cavities, which exhibited selective rebinding of oestrone in HPLC experiments. 

Because the components must initially form miscible solutions or swollen networks a degree of affinity between the reacting components is needed. Therefore, most of the investigations into epoxy IPNs have involved the use of partially miscible components such as thermoplastic urethanes (TPU) with polystyrenes [57], acrylates [58-61] or esters which form loose hydrogen-bound mixtures during fabrication [62-71 ]. Epoxy has also been modified with polyetherketones [72],polyether sulfones [5] and even polyetherimides [66] to help improve fracture behavior. These systems, due to immiscibility, tend to be polymer blends with distinct macromolecular phase morphologies and not molecularly mixed compounds. 

While it may be expected that the interchain separation will be a function of the length of the pendant sidechain, the relation is unlikely to be linear. For example, folding becomes more likely with an increasing number of constituents in the methylene chains connecting the urethane functional group to the polymer spine. Upper bounds on the interchain distances for the PDAs investigated are given in Table II. 

Kim et al. [40] synthesized a fluorosilicone polymer with a hydrocarbon backbone and fluorinated and siloxane pendant groups covalently bound by urethane. The structure of urethane graft-co-(septadecafluorodecylacrylate)-[tra(trimethyl... 

Most of the activation methods known from conventional peptide synthesis in solution were explored on polymer concerning their desired reactivity in relation to side reactions, which are particularly unfavorable if the by-products are also bound to the support. Though urethane-masked amino acids generally are shielded from racemization under controlled conditions, this problem limits the use of peptidic building blocks C-terminally activated, since they tend to form the redoubtable oxazolinone intermediate from which the abstraction of a -proton is facilitated (Fig. 40). Recent results indicated a chance to overcome this problem and will be mentioned in the proper section of this chapter. 

The close relation between the composition and the mechanical properties of these polymers is reflected in the stress-strain diagrams measured at 300 K and 348 K (Figs. 47 and 48). Hence, at ambient temperature for the spedfied experimental conditions a distinct increase of initial modulus (11. 45 and 1 MNm ), stress-hysteresis (ratio of area bounded by a strain cycle to the total area underneath the elongation curve 60,80 and 90 %) and extension set (30,65 and 100 %) can be obsened with increasing hard segment content of polyester urethane (a) to (c). 

Some spacer molecules and the corresponding carrier polymers are shown in Table 3. Benzoquinone was bound to the surface of a polyfcarbonate urethane) modified with poly(4-hydroxybutyl acrylate) (PCU/HBA) and to the vinyl acetate grafted and saponified poly(ether urethane) (Mitrathane) (PEU/VA-plas-ma) [136-139],... 

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