Polyoxyethylene, polystyrene

E Bayer, M Dengler. B Hemmasi. Peptide synthesis on the new polyoxyethylene-polystyrene graft copolymer, synthesis of insulin B21.30. btt J Pept Prot Res 25, 178, 1985. 

SUT Sutton, D., Stanford, J.L., and Ryan, A.J., Reaction-induced phase separation in polyoxyethylene/polystyrene blends. I. Ternary phase diagram, J. Macromol. Sci-Phys. B, 43, 219, 2004. 

Cross-linked polyoxyethylene-polystyrene (POEPS) and polyoxyethylene-polyoxypropylene(POEPOP)... 

Lotz B., and Kovacs A. J. (1966) Proprietes des copolymeres bisequences polyoxyethylene-polystyrene. I. Preparation, composition, et etude microscopique des monocris-taux. Roll Z.u.Z. Polym. 209 97-114. 

Each stationary phase is characterised by a calibration curve made with iso-molecular standards of known masses, M polystyrene in THF or polyoxyethylenes, pullulanes, polyethyleneglycols in water (Fig. 7.3 and Table 7.1). The curves representing log(M) as a function of the elution volume have a sigmoidal shape. However, by mixing stationary phases, the manufacturers can provide columns for which the calibration curves are almost linear for a wide range of masses. 

Cogan and Gast [61] presented dynamic light scattering (DLS) data of polystyrene-polyoxyethylene diblock copolymers in cyclopentane in the presence... 

Block copolymers of polystyrene (PSt, hydrophobe) and polyoxyethylene (PEO, hydrophile) form spherical micelles in water when the length of water soluble PEO is significantly larger than that of the insoluble PSt portion of the molecule [62]. In analogy with low molecular weight surfactants, one defines the onset of intermolecular association as the critical micelle concentration (CMC). Theories of polymer micellization predict that the concentration of free, unassociated block copolymers is close to that of the CMC. 

Several groups have attempted the anchoring of ketone catalysts for use in combination with Oxone (404-407). One of the incentives for anchoring the catalyst is that the most suitable ketone, 1,1,1-trifluoroacetone, is highly volatile. A solid-bound, nonvolatile ketone therefore offers obvious handling and cost advantages. In one approach, 4-(trifluoroacetyl)benzoic acid was anchored to a graft copolymer of polystyrene and polyoxyethylene (17a) (406) alternatively, aliphatic ketones were covalently bound to silica (17b) (405, 407). 

Most synthetic methods for the generation of peptide libraries have been derived from various multiple parallel peptide synthesis techniques developed since 1984.bs-i l Consequently, the sohd supports used for hbrary synthesis are essentially the same as those used for multiple peptide synthesis. Standard divinylbenzene cross-linked polystyrene resins are typically used for hbraries that are cleaved from the resin and screened in solution.P Polyoxyethylene-grafted polystyrene resins,f l or acrylamide-polyoxyethylene copolymers, P on the other hand, are the sohd supports of choice for the synthesis of resin-bound peptide hbraries screened in sohd-phase binding assays.P Such resins are compatible with both organic solvents used for peptide synthesis, as well as aqueous buffers used in the bioassays. Various segmental supports previously employed for multiple peptide syntheses have also been utilized for the synthesis of peptide libraries, including polypropylene pins, PI cotton,t cellulose membrane,and glass shdes.P ... 

The flow behavior of blends depends on the compatibility of their components. The viscosity of a compatible blend, for example polystyrene and polyoxyethylene, is the average of the viscosity of the components (52). Blends made up of high viscosity incompatible polymers may have lower viscosity than either component (53) (see Fig. 13.29). This effect may be the... 

One may attempt to derive the ideal shear strength So of the van der Waals solid normal to the chain axis from the value of the lateral surface free energy, a. This value is well known for common polymers such as PE or polystyrene (PS) (Hoffman et al, 1976) or else can be calculated from the Thomas-Stavely (1952) relationship a = /a Ahf)y, where a is the chain cross-section in the crystalline phase, Ahf is the heat of fusion, and y is a constant equal to 0.12. If one now assumes that a displacement between adjacent molecules by Si within the crystal is sufficient for lattice destruction then the ultimate transverse stress per chain will be given by So = cr/31. The values so obtained are shown in Table 2.1 for various polymers. In some cases (nylon, polyoxymethylene, polyoxyethylene (POE)) the agreement with experiment is fair. In the others, deviations are more evident. In order to understand better the discrepancy between the experimentally observed and the theoretically derived compressive strength one has to consider more thoroughly the micromorphology of polymer solids and the phenomena caused by the applied stress before lattice destruction occurs. 

Figure 8.8 Structure of a copolymer of type A-B made from polystyrene and polyoxyethylene (a) in nitromethane (cylindrical structure) and (b) in butyl phthalate (layer structure). Nitromethane dissolves the poly(oxyethylene) part preferentially, but butyl phthalate dissolves the polystyrene...

Di erent polymer-solvent systems may have completely different phase diagrams. For some systems, such as polystyrene-cyclohexanone, UCST < LCST [Fig. 3.13(a)] but for others, e.g., highly polar systems like polyoxyethylene-water, UCST > LCST and closed solubility loop is found [Fig. 3.13(b)]. 

Cowell et al. (1978) have studied the dependence of the UCFT on the particle number concentration for a polystyrene latex of radius 87 nm stabilized by very low molecular weight (750) polyoxyethylene). Their results are displayed in Fig. 8.5 for three different MgSO concentrations. 

Fluorescence was to study the reaction of 5-dimethyl-amino-l-naphthalenesulfonyl chloride (dansyl chloride) with butylamine in ethyl acetate and chloroform at 60° and 40 °C, respectively. This study was conducted in the presence of polystyrene and polyoxyethylene (POE) as cosolvents as well as their respective low-molecular weight analogues, namely toluene and diethyloxyethane, respectively [180]. 

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