Summary: A phenolic group containing hyperbranched polyester (HBP) was synthesized and employed as chain transfer agent in cationic photopolymerization of a biscycloaliphatic epoxy monomer (CE). The epoxy group conversion increases by increasing the amount of HBP in the photocurable resin, due to a chain transfer reaction involving the phenolic‐OH groups. HBP acts as a plasticizer inducing decrease of the Tg values together with an increase of the toughness properties. Meanwhile gel content increases together with the E′ values. By increasing the amount of HBP in the photocurable resin an increase of the density is evident indicating a decrease of free volume. Therefore an improvement of the gas barrier properties might be expected; at the same time an increase of the thermal stability is evident.

Reaction of methyl trimethylsiloxycyclopropanecarboxylates 3 with amino acids, tert-butylisonitrile and methanol furnished amino diacid derivatives 2 as the result of an Ugi 5-center 4-component reaction. This one-pot reaction involves b-formyl esters such as 1 as intermediate, which are liberated in situ. Adducts 2 could be thermally cyclized to provide g-lactams 4 in good yields.The multi component reaction was combined with this cyclization process to a fairly efficient one-pot procedure. Thus, cyclopropane derivative 3a was converted into g-lactam 4a in good yield. Two of the g-lactams 4 were reduced with lithium aluminum hydride to give pyrrolidine derivatives 5. Based on an X-ray analysis of the major diastereomer of compound 5d, the diastereoselectivity of the 4-component reaction is discussed.

In this paper the influence of the hyperbranched polyester based on 4,4‐bis(4‐hydroxyphenyl)valeric acid on the properties of an ester diol oligomer will be discussed. The hyperbranched polyester was added to an ester diol in different amounts and the resulting bulk viscosity values were measured. Surprisingly, the resulting viscosity depends on the mixing temperature of both substances. Glass transition temperatures gave an idea about the phase behavior in the blend. H bond formation in the ester diol was intensively studied by temperature dependent IR measurements. The weakening of H bonds in the ester diol oligomer with increasing temperature was proven by IR measurements and correlates with results from viscosity measurements. These changes allow increased interactions between the ester diol and the hyperbranched polyester which causes different viscosity values depending on the mixing temperature. The overall changes in the behavior of the mixture were proven by temperature dependent AFM measurements.Frequency dependent viscosity measurement for the mixture containing of 20 wt.‐% of the hyperbranched polyester.magnified imageFrequency dependent viscosity measurement for the mixture containing of 20 wt.‐% of the hyperbranched polyester.

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The influence of hyperbranched polyesters with different functional end groups on the surface tension of mixtures with an oligo(ester diol) was investigated. The temperature dependence of the surface tension of the pure components and of the mixtures was measured by a modified Wilhelmy balance technique. The results indicate that the surface tension of the pure hyperbranched polyesters strongly depends on the functionality of the end groups. The functionalization of the hydroxyl end groups by short alkyl chains (methyl, tert-butyl) reduced the surface tension depending on the degree of substitution. The surface tension of the mixtures with the hydroxyl-terminated hyperbranched polyester was slightly increased at higher concentrations of the hyperbranched polymer compared to the surface tension of the pure ester diol. On the other hand, the surface tension of mixtures could be considerably decreased using 1% of hyperbranched polyester polyols partially substituted with short alkyl chains. In that case, the modified hyperbranched polyesters act as surface active agents. On the molecular level, the enrichment of the modified hyperbranched polyester in the surface region was proven by X-ray photoelectron spectroscopy measurements.