Aminopropyl-terminated

Table 6. Characteristics of aminopropyl terminated poly-dimethylsiloxane oligomers synthesized in bulk, at 80 °C with 0.01 weight % tetramethylammonium hydroxide catalyst157-1641...

Table 10. Characteristics of aminopropyl-terminated poly(dimethyl-diphenyl)siloxane oligomers 66 171)...

The first example of siloxane-urea segmented copolymers were prepared by the direct reaction of aminopropyl-terminated polydimethyl siloxane oligomers and MDI (4,4 -diphenylmethane diisocyanate), in solution at room temperature as shown in the Reaction Scheme XI. 

The effect of structural variations in siloxane oligomers in the synthesis and properties of the resulting siloxane-urea copolymers have also been investigated 161). In these studies aminopropyl-terminated poly(dimethyl-diphenyl)siloxane and poly-... 

Table 14. Synthesis and characteristics of siloxane-urea segmented copolymers based on MDI and aminopropyl terminated PDMS oligomers 1571...

Poly(arylester)-polysiloxane multiblock copolymers have also been synthesized by the interfacial polymerization of aminopropyl terminated polysiloxane oligomers with bisphenol-A and a mixture of isophthaloyl and terephthaloyl chlorides117, 193-1951 as illustrated in Reaction Scheme XV. In these reactions the poly(arylester) blocks are formed in situ during the copolymerization, so the control of their block sizes is not very precise. It is also important to note that since aminopropyl terminated siloxane oligomers are employed, the linkages which connect the arylester and siloxane blocks are amide linkages. 

Siloxane-urea copolymers were synthesized by the reaction of the aminopropyl terminated PDMS oligomers with MDI or HMDI with no chain extenders (Reaction Scheme XI and Tables 14 and 15). Therefore, in these copolymers the hard segments consist of the aminopropyl end groups on the siloxane oligomers and MDI or HMDI backbones as shown below. The soft segment is pure polydimethylsiloxane. 

Some characteristics of aminopropyl terminated polydimethylsiloxane oligomers are illustrated in Scheme 5. 

In this paper we will discuss the synthesis of a, urhydroxybutyl terminated polydimethylsiloxane oligomers by cationic routes and a,u-aminopropyl terminated poly(dimethy1-diphenyl)siloxane oligomers by anionic methods respectively. Detailed procedures for the synthesis of aminopropyl, carhoxypropyl and glycidoxypropyl terminated polydimethylsiloxane oligomers have already been described elsewhere(1 1). ... 

Table II provides a summary of the results on the characteristics of aminopropyl terminated poly(dimethyl-diphenyl)-siloxane oligomers synthesized. These reactions were conducted in bulk at 160°C with K0H as the initiator. As can be seen from Table II the stoichiometric number average molecular weights sought and obtained are in very good agreement. The level of diphenylsiloxane incorporation was determined by UV spectroscopy. There is no absorption of dimethylsiloxane backbone in the spectral range of 240 to 280 nm. On the other hand, phenyl groups absorb very strongly over these wavelengths (Figure 3). For quantitative analysis we have used the absorption peak at 270 nm as the reference.

Characteristics of Aminopropyl Terminated Poly(Dimethyldiphenyl)siloxane Oligomers... 

Ekin A, Webster DC (2006) Library synthesis and characterization of 3-aminopropyl-terminated poly(dimethylsiloxane)s and poly(e-caprolactone)-b-poly(dimethylsiloxane)s. J Polym Sci Part A Polym Chem 44 4880-4894... 

A stirred solution of itaconic anhydride (71.8 mmol) dissolved in 70 ml CHC13 at 0°C was treated with the dropwise addition of 3-aminopropyl terminated poly(dimethyl-siloxy)silane (Mn 1000 Da 32.36 g) dissolved in 35 ml CHC13 over 1 hour. After an additional hour of stirring at 0°C, the cooling bath was removed, the solution warmed to ambient temperature, and stirred an additional 1 hour. The product was isolated after the solution was concentrated. 

An interesting variation of an ammonium silanolate catalyst was described by Hoffman and Leir40. They prepared tetramethylammonium 3-aminopropyldimethylsilanolate and used it to synthesize 3-aminopropyl terminated Polydimethylsiloxane (PDMS). 

Fig. 4. FTIR spectrum of a primary aminopropyl-terminated PDMS oligomer (Mn=1528)...

The synthesis and equilibration reaction kinetics involved in the preparation of aminopropyl-terminated polysiloxanes has been studied most extensively because of the utility of the amino-terminated species as components of a large number of segmented copolymers such as imides, amides, and ureas. 

The reaction scheme for the preparation of aminopropyl-terminated di-fimctionalized oligomers is illustrated in Scheme II. The reaction proceeds by the anionic equilibration of the cyclic siloxane tetramer, D4, in the presence of l,3-bis(3-aminopropyl)tetramethyldisiloxane. The equilibration process begins immediately upon addition of the siloxanolate catalyst, and samples were removed as a function of time for the purpose of the kinetic study. 

Scheme IL Synthesis of aminopropyl-terminated poly(dinwthykiloxane)s.

Supercritical-fluid-fractionation techniques have been explored to separate the aminopropyl-terminated oligomers into fractions of narrow poly-dispersity. The fractions have been fully characterized in terms of their structure, molecular weight, molecular weight distribution, and functionality. The results of selected studies are presented in this section. 

Table III. Fractionation of Aminopropyl-Terminated Poly(dimethylsiloxane) ...

Figure 10. GPC chromatograms of aminopropyl-terminated poly(di-methylsiloxane) and its fractions.

Significant differences were observed in the rate of incorporation of D4 and l,3-bis(3-aminopropyl)disiloxane for similar concentrations of potassium, tet-ramethylammonium, and tetrabutylphosphonium siloxanolate catalysts. The rate differences affected the reaction times that were required to obtain a completely equilibrated reaction mixture with the desired molecular weight. The potassium catalyst required excessively long reaction times or high concentrations before sufficient incorporation of the aminopropyldisiloxane was realized. The tetramethylammonium and tetrabutylphosphonium catalysts were much more efficient for the preparation of controlled-molecular-weight aminopropyl-terminated polysiloxane oligomers. 

The traditional approach used in poly(imide-siloxane) synthesis is the reaction of aminopropyl-terminated dimethylsiloxane oligomers with aromatic dianhydrides and additional diamines (9-13). Typically, subambient temperatures and dipolar aprotic solvents are used. The resulting high-molecular-weight polyamic acid solution can be heated to effect imidization and solvent evaporation. This procedure is analogous to the synthetic method used to prepare conventional polyimides for films and coatings. 

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