Solvents m-cresol

Room-temperature solution polycondensation is used for the preparation of hexafluoroisopropylidene-unit-containing poly(azomethine)s. At the end of the reaction, the water liberated by the reaction is thoroughly taken off as an azeotrope by vacuum distillation to allow the reaction to go to completion. Among DMF, DMSO, HMPA, NMP, and m-cresol used as reaction solvents, m-cresol yields a polymer with higher reduced viscosity in higher yield. The reaction proceeds rapidly and is essentially completed in 30 min. 

Figure 6 shows how the transition of poly(e-carbobenzoxy L-lysine) (PCBL) in m-cresol is affected by the chain length of the sample (23). The trend displayed here is general and conforms to the theoretical prediction deduced from Fig. 1 the transition curve becomes sharper as chain length increases. Comparison with Fig. 5 indicates that in the same solvent, m-cresol, the direction of transition of PCBL is opposite to that of PBLA and the two transitions differ markedly in sharpness. This again illustrates the crucial importance of polymer-solvent interactions in the transitions of polypeptides. 

The intrinsic viscosities of POT and POS in the different solvent/non- solvent mixture are higher than the corresponding intrinsic viscosities in the pure solvent. These positive deviations of [tt ] relative to the solvent m - cresol suggest that the m -cresol/cyclohexane mixture has a GE > O [90],... 

DBSA is also very sensitive to the nature of the organic solvent. Oh and coworkers103 reported that this NIR band is more intense in relatively nonpolar solvents such as chloroform than in the aromatic solvents m-cresol or benzylalcohol, and is markedly reduced in the polar solvents DMSO and /V-methyl pyrrolidinone (NMP) as well as blue-shifted to ca. 850-900 nm. These spectral changes were attributed to micelle formation by the DBSA and solvent interactions with the PPy chains. This leads to rearrangement of the polymer backbone from an extended coil conformation in chloroform to a relatively compact coil one in NMP and DMSO. 

The synthesized sulfide-containing polynaphthoylenebenzimidazoles are soluble not only in H2SO4. but in phenolic solvents (m-cresol, phenol tetrachloroethane mixtures), which in combination with high softening (310-380 °C) and decomposition (450-470 °C) temperatures stimulate interest in the systems. 

For the PPI, the presence of a bulky substituent in a perylene fragment ensured solubility in organic solvents [(m-cresol, N-methylpyrrolidone (NMP)]. Dark-red transparent films were cast from these solutions. Table 1.3 shows that PPI solubility grows with an increase in the bulkiness of the side substituents. 

From the beginning one of the critical points in the chemistry of addition polyimides was to adjust the formulations in order to prevent brittleness of the final curing material. The first approach for improving the mechanical behaviour of poly(bismaleimides) was the incorporation of moieties which provide a separation of the two active maleimide groups. Diamines and dithiols have worked as very suitable spacers, capable to react with the double bonds of bismaleimides [301-304]. The reaction takes place by nucleophilic addition (Michael addition) on the electron-deficient double bond, which is activated by the two adjacent carbonyl groups (Scheme 56). The reaction is usually carried out in acidic solvents (m-cresol or DMF/acetic acid mixtures) to avoid cross-linking that occurs by reaction of the anionic intermediate with maleimide double bonds [305,306]. The mechanism for the reaction of thiols and maleimides is depicted in Scheme (56). 

Good solvent - m-cresol, phenol, sulfolane (hot), trichloroethanol ... 

Non-solvent m-cresol sym-tetrachloroethane 1-methyl-2-pyrollidinone N,N-dimethylacetamide N,N-dimethylformamide dimethylsulf-oxide and hexamethylphosphoric triamide ... 

This sequence is not that of the molar Gibbs energy of hydration of the anions (Table 4.1) because it depends also on the solvating ability of the protic solvent, m-cresol. The order of the sequence (8.16) results from a balance of the hydration ability of water molecules and of the prolic solvent, as well as from the space available around the anion for solvation by the small water molecules and the bulky protic solvent ones. A further complicating factor is possible ion pairing of the crown-solvated... 

Polyamide 11 and 12 exhibit limited resistance to concentrated acids, phenols and some chlorinated solvents. M-cresol, sulfuric acid, formic acid, and alcohol/phenol mixtures act as solvents for polyamide 11 and 12. While polyamide 6 and 66 are soluble in concentrated formic acid or sulfuric acid at ambient temperature, this is not the case for polyamide 11 and 12. Table 5.84. 

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