Hyperbranched soluble resins

Besides the water absorption, the unexpected high hydrophilic character of the hydroxyl functional hyperbranched polyesteramides is also reflected in its solubility behavior. A resin, based on hexahydrophthalic anhydride and diisopropanolamine (see Fig. 7), is soluble in water/ethanol mixtures with up to 50% water By means of GPC we followed the hydrolytic stability of this resin in 50 50 water/ethanol mixtures at different pH values (4, 7, and 10) at room temperature. Even after 28 days no degradation was observed. Only under drastic conditions, such as reflux in 50 50 ethanol/water mixture at pH 14 for 16 h was the resin completely destroyed. At other pH values such as 1 or 12, but under the same conditions, the hyperbranched polyesteramide was partly degraded. 

Our future research will lead to new types of hyperbranched polyesteramides. The ideas presented will enable properties such as water solubility (poly(ethyleneoxide) functional groups) or reduction of surface tension (fluoro-alkyl functionalized resins) to be precisely controlled. Last, but not least, mixed functional highly branched molecules with their (expected) unique set of combined properties have a huge potential to enter numerous technical fields. 

Finally, first attempts were made to extend the concept of soluble hyperbranched polymers to dendronized sohd-phase materials. Recently, the first dendronized sohd phase, accessible in only one reaction step was reported (Fig. 7.4) [36]. The coupling of hyperbranched polyglycerol to Merrifield resin yields a new type of high-loading sohd-phase hybrid material with loading capacities of ca. 3 mmol g and good swelling properties even in protic solvents (see also Section 3.4). 

Hyperbranched polymers differ greatly from linear or moderately branched polymers. For example, the solubility is much higher for hyperbranched polymers but not as high as for dendrimers. Hyperbranched polymers normally exhibit an amorphous, nonentangled behavior, i.e., a Newtonian behavior in the melt. The nonentangled state also makes hyperbranched polymers rather brittle. Several thermoset resin materials have been described where the hyperbranched polymer exhibits a low resin viscosity, thereby reducing the need for solvents to attain the application viscosity. At the same time. 

Nonlinear, dendritic or hyperbranched polymers have received considerable attention in recent years. These polymers have seen little use as supports for oligosaccharide synthesis compared to Merrifield or soluble MPEG resins. Nevertheless, some interesting applications of hyperbranched polymers such as hyperbranched polyester and poly(amidoamine) to oligsaccharide synthesis have been reported. 

In an interesting paper. You and Pan described the production of superbranched polymers. The first monomer was obtained from a-bromobutyric chloride and glycerol. The second monomer was obtained in porous resin treated with NaOH and then by CS2, and was in the form of a CS2 ion. By polycondensation of a trifunctional monomer (with three Br atoms in the molecule) and a 82 " group after repeated procedures, hyperbranched polymer was obtained. The polymer was soluble in tetrahydrofurane (THF). In contrast, polymerization of the same tribromo compotmd with trithio-carbonate anion lead to the crosslinked, insoluble polymer. 

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