Oligomers Subject

A two-step methanolysis-hydrolysis process37 has been developed which involves reaction of PET with superheated methanol vapors at 240-260°C and atmospheric pressure to produce dimethyl terephthalate, monomethyl terephthalate, ethylene glycol, and oligomeric products in the first step. The methanolysis products are fractionally distilled and the remaining residue (oligomers) is subjected to hydrolysis after being fed into the hydrolysis reactor operating at a temperature of ca. 270°C. The TPA precipitates from the aqueous phase while impurities are left behind in the mother liquor. Methanolysis-hydrolysis leads to decreases in the time required for the depolymerization process compared to neutral hydrolysis for example, a neutral hydrolysis process that requires 45 min to produce the monomers is reduced... 

This type of one-pot reaction represents a simple method for the synthesis of a large variety of cyclic OPV oligomers of different sizes and composed of different arylene building blocks, such as phenylene, biphenyl-diyl and naphthylene. The compounds are suitable subjects for the study of photoinduced Z/ -isome-risation and photocyclization. 

The preparation of a functional segmented block copolymer was also investigated (scheme ll).15 First hydroboration polymerization of the oligomer using thexylborane was carried out. Then the obtained organoboron polymer was subjected to a chain-transformation reaction (DCME rearrangement). DCME and lithium alkoxide of 3-ethyl-3-pentanol in hexane was added to a THF solution of the polymer at 0°C. 

Every peak was uniform with respect to m, but each one had a distribution in block length with respect to the PEO blocks (n). To identify fractions, they were collected and subjected to mass spectrometry. The first fraction contained polyethylene glycol and block oligomers with a degree of polymerization m(PO) 1-3. The second fraction was homogeneous with respect to PO and contained m(PO) 4, while fraction 3 resulted from m(PO) = 5. 

Poly(2,5-pyridyl) commonly know as poly(pyridine) has been the subject of considerable research effort as it luminesces in the blue region of the spectrum and may have uses in light emitting diodes (LEDs). Vaschetto and co-workers [103] reported a series of calculations on the molecule and its oligomers. The calculations included both the B3LYP and B3P88 density functions, Hartree-Fock calculations and a periodic solid-state DFT calculation using linear muffin tintype orbitals (LMTO). 

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