Polymerization oligomers

Benzene is a poor solvent for bisphenol-A oligomers, compared with tetrahydrofuran. At a rather low degree of polymerization, oligomers precipitate from benzene, thus suppressing the chain-building reaction. The GPC curves for benzene-soluble and benzene-insoluble fractions are shown in Figure 7. The benzene-insoluble product contains significantly... 

According to this mechanism, after quantitative polymerization, oligomer formation would not be possible any more because of the absence of monomer. At the present time it is not possible to decide by which mechanism the tetramers of oxe-tane and 3,3-dimethyl oxetane are formed. 

It is of great interest that when the heat-treated sample (1) of poly-DSP in Fig. 16 is heated to 330°C (with the same scanning speed), the X-ray diffraction pattern of the resulting sample (2) changes into a pattern which is exactly the same as that of the as-polymerized oligomer crystals prepared by selective monomer excitation (see Sect. m.b.). 

Resin composites can be classified according to filler particles as fine-particle, hybrid, microhybrid and microfilled other classifications such as flowable or packable are related to their manipulation [1-3]. Quartz and glass (several types) fillers in fine-particle composites have sizes of about 0.5 to 3 pm. Microfilled and hybrid composites contain colloidal silica particles of 0.01 to 0.02 pm diameter incorporated in the polymer matrix. The microfilled composites also contain these submicron particles in groimd 10 to 20 pm filler particles of the polymerized oligomers. The filler volume fraction for composite products varies widely from about 20% to 70%. Clinical selection of composites depends upon strength, wear resistance and esthetics needed for the particular tooth restoration. 

The increase of surface tension in the DEG-PEPA system is related to the change of surfactant solubility. The rate of aggregation of the surfactant molecules depends on the viscosity and the chemical composition of the polymerizing oligomer. Increase in system viscos-... 

Korolev G. Book of Ahstr. of the first All-Union conf. on chem. and physico-chem. of polymerizing oligomers, Chernogorlovka, 1977, p. 144. 

Figure 13.11 Time-resolved x-ray scattering data from solutions of oscillating microtubules. Large peak at left shows total extent of polymerization (oligomers and microtubules) smaller, central peak arises from microtubules. (Reprinted with permission from Mandelkow, E.-M. Lange, G. Jagla, A. Spann, U. Mandelkow, E. 1988. Dynamics of the Microtubule Oscillator Role of Nucleotides and Tubulin-MAP Interactions, EMBO J. 7, 357-365. C) 1988 Oxford University Press,)...

Aqueous Polymerization Oligomer (APO). Several replicate runs were made in which the polymerization was terminated prior to any sensible particle formation. The decrease in volume of the reac-... 

Latex Polymerization Oligomer (LPO). This polymer represents... 

A series of exception has been found recently with bridged alkoxysilanes. Bis(triaIkoxysilyl)alkanes with Q or Cg bridging alkylene chains typically phase separate against 50-70 fold molar amount of water relative to silicon under acidic conditions (Nakanishi et al., 2002). Relatively long alkylene chains buried in the siloxane network only moderately contribute to enhance the phase separation tendency of the polymerizing oligomers. 

Berlin, A.A. // Dokl. i Vsesojuznojj Konf. po Khimii i Fiziko-Khimii Polimerizacionnosposobnykh Oligomerov (Reports of The All - Union Conference on Physical Chemistry of Polymerizing Oligomers). Chemogolovka Ikhf RAN, 1977, T.l, S. 8 (in Russian). 

Morozov Ju. L. // Doklady i Vsesojuznojj Konferencii po Khimii i Fizikokhimii Polimerizacioimosposobnykh Oligomerov (Reports of i All-Union Conference on The Chemistry and Physical Chemistry of Polymerizing Oligomers).- Chemogolovka AN SSSR, 1977, V.2, P. 468 (in Russian). 

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