Hydroxy-functional hyperbranched

Figure 8.1 A schematic representation of the hydroxy-functional hyperbranched polyester Boltorn H20, based on ethoxylated pentaerythritol and 2,2-bis(methylol)propionic acid [10]...

Figure 8.2 A schematic representation of hydroxy-functional hyperbranched poly(ester-amide) Hybrane based on diisopropanolamine and an anhydride [11]...

The degree of branching was initially reported to be close to 0.8 [1], but was recently reevaluated after it was shown that the hydroxy-functional hyperbranched polyesters undergo facile acetal formation. The acetal formation was catalyzed by residual trace amounts of acid remaining in the sample. After reevaluation in DMSO the degree of branching was close to 0.45 which is in accordance with most other hyperbranched polymers. (1. Malmstrom, E., Johansson, M. and Hult, A. Macromolecules, 28, 1698 (1995) 2. Malmstrom, E., Trollsas, M., Hawker, C.J., Johansson, M. and Hult, A. Polym. Mat. Sci. Eng., 77,151 (1997). 

Fig. 11. Melt viscosity at 85 °C vs molar mass for hydroxy-functional hyperbranched aliphatic polyesters based on bismethylol propionic acid. Theoretical molar mass based on core bis-MPA ratio ( ) and Mn determined with SEC relative to linear polystyrene standards (O) [117]...

Three different acrylates have been synthesized and characterized. The same hydroxy-functional hyperbranched polyester (H3) was used as a base for all resins. Approximately 50% of the terminal hydroxyls were acrylated and the rest either... 

Radiation curable epoxy functionahsed hyperbranched polyester resin has been synthesised from a hydroxy functional hyperbranched polyether polyol and an epoxy functional fatty acid, vernolic acid. The resin was cationically polymerised in the presence of differing amounts of vernolic acid methyl ester as a reactive diluent. Similarly, Mesua ferrea L. seed oil-based hyperbranched polyesters are prepared using anhydride-based... 

Mg. 7. Cationic ring-opening pol3mierization of 3-ethyl-3-(hydroxymethyl)oxetane to a hydroxy-functional hyperbranched polyether (45,46). 

Anionic polymerization of 2-hydroxymethyloxetane is imsuccessfiil (34). The failure of such a reaction is most likely due to the fact that oxetanes are not known to ring-open imder basic conditions. The successful cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane gave hydroxy-functional hyperbranched polyethers (45,46) (Fig. 7). The cationic polymerization can proceed according to two different mechanisms, activated chain end (ACE) or activated monomer mechanism (AMM) (45) (Fig. 8). 

Caprolactone was grafted on hydroxy-functional hyperbranched aliphatic polyesters forming semicrystalline copolymers (Fig. 15). The crystallinity and rheological properties were found to be tailorable by means of the appropriate choice of hyperbranched polyester and the degree of polymerization of the crystalline... 

The use of aliphatic monomers for hyperbranched polyesters has been debated because aliphatic monomers are said to be prone to thermal degradation reactions such as decarboxylation, cyclization, or dehydration [77]. The only commercial hyperbranched polymer is a hydroxy-functional aliphatic polyester, Boltorn, available from Perstorp AB, Sweden. 

A somewhat different approach was presented by Rannard and Davis where they first reacted bis-MPA with carbonyl diimidazole, allowing a highly selective base-catalyzed reaction to form a hyperbranched polyester. The resulting polymers were hydroxy-functional and reported to be water-soluble [84]. 

Amongst the first studies presenting the use of dendritic polymers for thermoset applications was the work of Hult et al. [62]. They modified hyperbranched hydroxy functional polyesters with various ratios of maleate-allyl ether/alkyl ester end groups. Dependent on this ratio, resins with different vis-... 

M /g.mol = 1620, MJg.mol = 2100, 16 OH groups per macromolecule, hydroxyl no. = 490-520 mg KOH/g, acid no. = 5-9 mg KOH/g, hydroxyl functional hyperbranched polyesters produced from polyalcohol cores and hydroxy acids, Boltom H20, Perstorp Specialty Chemicals AB, Sweden... 

Ring-opening polymerization of hydroxy-fimctional cyclic ethers could, in accordance with hydroxy-functional lactones, give rise to hyperbranched polyethers. 

The hyperbranched polymers could be functionalized at the remaining double bonds after the polymerization. Further, hydroboration leads to boranes, used as cocatalysts for olefin polymerization (5). Treatment with H2O2 results in terminal hydroxy functionalities, with the addition of chloromethyldimethyl-silane chloromethylsilane endgroups are obtained (4). 

The terminal halogens in hyperbranched polymers (see Fig. 11.30) can be replaced by more useful functionalities, such as azido, amino, hydroxy, and epoxy. The multifunctional polyols and polyepoxides resulting in the latter two cases can be potentially used to perform thermosetting operations. 

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