Functional oligomers synthesis

The effect of the initiation and termination processes on compositional heterogeneity can be seen in data presented in Figure 7.3 and Figure 7.4. The data come from a computer simulation of the synthesis of a hydroxy functional oligomer prepared from S, BA, and HEA with a thiol chain transfer agent. The recipe is similar to those used in some coatings applications. 

In many cases, these cyclic siloxanes have to be removed from the system by distillation or fractionation, in order to obtain pure products. On the other hand, cyclic siloxanes where n = 3 and n = 4 are the two most important monomers used in the commercial production of various siloxane polymers or oligomers via the so-called equilibration or redistribution reactions which will be discussed in detail in Sect. 2.4. Therefore, in modern silicone technology, aqueous hydrolysis of chloro-silanes is usually employed for the preparation of cyclic siloxane monomers 122> more than for the direct synthesis of the (Si—X) functional oligomers. Equilibration reactions are the method of choice for the synthesis of functionally terminated siloxane oligomers. 

For equilibration processes, one must synthesize both oligomers and what are termed dimers, or disiloxanes. Our primary interest is in the utilization of these functional oligomers for the synthesis of both linear block or segmented copolymers, and also surface modified, oughened networks such as the epoxy and imide systems (3-27). The generalized structure of the oligomers of interest is shown in Scheme 1. 

The criteria for the thermally decomposable coblock include the synthesis of well-defined functional oligomers, compared with the synthesis of polyimide. This block must also decompose quantitatively into non-reactive species that can easily diffuse through a glassy polyimide matrix. The temperature at which decomposi-... 

The use of appropriate functionalized oligomers is a key to the success of this synthesis. The necessary functionalized oligomers were prepared by polymerization of ferf-butyl acrylate (n = ca. 120) with a functional AIBN initiator (Eq. 1). Since... 

The synthesis of telechelic oligomers by oxidative cleavage has been extensively studied by numerous authors and Cheradame [117] reviewed the main reactions leading to telechelic polymers starting from high molecular polymers. As he showed, ozonolysis remains one of the preferred method in addition to Ruthenium tetroxide oxidation to obtain a-co functional oligomers. 

Numerous authors took advantage of the reactivity of double bonds towards ozone to prepare a-(0 functional oligomers usable in the synthesis of multiblock copolymers by copolycondensation, or in the synthesis of precursors of surfactants or ionomer resins. Results in this field of investigation are numerous, mainly in terms of industrial applications. 

Synthesis of Physically Persistent Stabilizers Based on Functionalized Oligomers and Polymers... 

Transient siloxanolate anionic catalysts prepared by reacting four moles of D-4 with one of tetramethyl ammonium hydroxide at 80 C are effective for equilibrating "neutral" systems such as the epoxy ( ), "basic" dimethyl-amino (64) or aminopropyl (59,67) end-blockers and D-4. With "acidic" functionality on the end-blocker, we have successfully utilized trifluoroacetic acid for the equilibrations. Further details of the oligomer synthesis and their utilization in segmented copol)nners will be described in future publications. 

The synthesis of the corresponding poly(amic alkyl ester), on the other hand, involved the incremental addition of PMDA diethyl ester diacyl chloride in methylene chloride to a solution of the oligomer and 3FDA in NMP containing pyridine as the acid acceptor (Scheme 9). Alternatively, the diamino functional oligomers could be utilized in an analogous fashion to yield the graft copolymers (Scheme 10). In these experiments, the meta isomer of PMDA diethyl ester diacyl chloride was used primarily due to its enhanced solubility and lower soften-... 

Enzymatic synthesis of functional oligomers, 1 lipase catalyzed polymerization of hydroxy acids. Makromolekulare Chem. Rapid Commun., 7 (6), 369-373. 

Synthesis of Functional Oligomers and Network Formation Studies... 

We have chosen to use hydroxy vinyl ethers (CH2—CH-O-R-OH) as intermediates in the synthesis of vinyl ether functionalized oligomers. Hydroxy vinyl ethers are easily obtained as by-products of the synthesis of dlvlnyl ether monomers (Equation 1). The hydroxy group may be reacted to form a link to the oligomer backbone while the vinyl ether moiety remains free to be polymerized in a radiation induced reaction at a later time. 

Tlie synthesis of very low molecular weight functional oligomers with control of both tlie number and type of functional group(s). 

Anionic and Cationic Polymerizations o Radical Polymerization Advances o Coordination Polymerizations 0 Step-Growth Polymerization Advances 0 Synthesis of Tactic Polymers o Stereoblock Copolymers o Dispersion Polymerizations o Cellulosic Graft Copolymers o Diels-Alder Polymer Forming Reactions o A New Path To Phenolic Resins o Nitrogen Heterocycle Polymerizations o Optically Active Polymers o Poly (Phenylene Sulfide) o Poly (Aryl Ethers) o (Poly (Aryl Ether Sulfones) o Epoxy and Isocyanate Resin Replacement o Azlactone Functionalized Oligomers o Epoxy Resin-Isocyanate Reactions o Chelating Polymers o Oxazoline Functionalized Polymers o Poly (Alkyl Methacrylates) o Macromers... 

Riffle, J. S. Yilgor, I. Tran, C. Wilkes, G. L. Mcgrath, J. E. Bantia, A. K. Elastomeric Polysiloxane Modifiers for Epoxy Networks. Synthesis of Functional Oligomers and Network Formation Studies Epoxy Resin Chemistry II , ACS Symp. Sen, 1983, ,2i,... 

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