Oligomer/polymer interaction

We have little information on the way low molecular weight molecules and oligomers adsorb (19). Apparently below DP s of about 100 they lie flat on the surface for concentrations up to a monolayer of segments, then seem to form thicker islands of smectic or nematic structure. Ordered condensed mono, -di, -or multi-layers are primarily the arrangements of smaller, especially amphipa-tic molecules on liquid-liquid interfaces. Polymers are too large to adsorb, in the ordinary sense, on micelles but segments of linear polymers may act as nucleation centers for micelles of small molecules which probably is one of the mechanisms for the lipid-, or detergent-, polymer interaction. 

For instance, it has been shown for PEO (oligomer) — PMA (polymer) interaction that the reaction heat calculated per monomer unit does not depend on the DP of the oligomer26). Then the probability of oligomer-polymer association is... 

Assembly of Functionalized NCs with Functionalized Conjugated Oligomers (Polymers) by Means of Noncovalent Interactions (Scheme 5.2, Route XI)... 

Lourdin, D., Ring, S.G., and Colonna, P. Study of plasticizer-oligomer and plasticizer-polymer interactions by dielectric analysis maltose-glycerol and amylose-glycerol-water systems, Carbohydr. Res., 306, 551, 1998. 

The experimental setup of the ellipsometry provides directly temperature dependent data of the interfacial thickness X, which can be used to calculate the polymer-polymer interaction parameter Xab as a function of temperature The temperature dependence in the system PS/PMMA can independently be confirmed by measuring phase diagrams of oligomers and their PVT data. Having these data, it is possible to calculate XAh(T) by using the Flory- Huggins theory or an equation-of-state (EOS) theory. 

Replacing the DMF solvent with l-Methyl-2-pyrrolidinone (NMP), the situation returned to the normal behaviour similar to the MDI based PUs reaction in solution. In this case the interaction between oligomer-solvent was always higher than the interaction between oligomer-oligomer (polymer-polymer), and it obtained only a single type of soluble copolymer [257]. 

The interaction parameters xm were determined using eqn (5.20) they represent a direct measure of the thermod3mamic compatibility of two non-volatile components [24, 25, 27, 28] and were determined for the following types of mixtures oligomers [29], macro- and micromole-ctdes [24], polymers and plastifiers [26], compatible homopolymers [27, 28, 30], incompatible homopolymers [31], homopolymers and statistical copolymers [32]. The polymer-polymer interaction parameters, xm for block copolymers may be considered as a quantitative measure of the block compatibility [31]. Such measurements have been performed for block copolymers with both compatible [33] and incompatible chains [31]. 

Here [M]g denotes the equilibrium concentration of the monomer and K the equilibrium constant of propagation. The equilibrium concentration of the monomer depends on the system, i.e., on the nature of monomer, of solvent and temperature, but its value is not affected by the mechanism of polymerization. Determination of [M]g over a temperature range allows us to calculate AH and AS of propagation, and its dependence on polymer concentration and the nature of solvent provides information on the solvent-polymer interaction. A thorough discussion of these topics is reported elsewhere However, it should be stressed that the above thermodynamic ramifications apply to high-molecular weight polymers and the treatment has to be modified when one deals with oligomers. ... 

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

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