Role of cyclization in the degree-of-polymerization distribution of hyperbranched polymers

Kinetic Evaluation of Hyperbranched A2 + B3 Polycondensation Reactions

“…At high conversion, there is almost no difference between K 4 , K 5 and K 6 . Since the degree of branching DB is only influenced by the ratio of B3 to B4, the situation in Equation (13) can not lead to any changes in the DB. This can be shown by graphing the DB for the two different situations (Figure 9).…”

“…The distribution over different structural units defines variations in the degree of branching (DB) and the sequence determines differences in the structural parameters of the hyperbranched polymer like shape and radius of gyration. In addition, side reactions like cyclization [13,14] or reaction of two equal functionalities with each other [15] may further complicate the situation. Thus, there is a great interest to understand how the structural units develop during the polycondensation process and how the structure (and property) profile can be manipulated.…”

Role of cyclization in the synthesis of hyperbranched aliphatic polyesters

“…1) should be distinguishable by careful analysis of the spectra. In fact, cyclization in the case of bulk polycondensation of pure BisMPA was detected by ESI-MS 19) . Molecular weights for the three possible reactions can be calculated using the following equations.…”

“…Only in recent publications, first attempts to treat this problem theoretically have been reported, using simplified models or lattice simulation 18,19) . Hyperbranched aliphatic polyesters were first described by Baker et al 20) and investigated by Hult et al 21) Hult et al used a portionwise monomer addition strategy, adding 2,2-bis(dihydroxymethyl)propionic acid (BisMPA = AB 2 monomer) in "pseudo-generation" equivalent portions to a 1,1,1-tris(hydroxymethyl)propane core molecule (TMP = B 3 core) under acidic catalysis.…”

Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

“…Random statistical procedures are commonly used to study the structure of hyperbranched polymers, but a series of deviations from the ideal situation are expected due to subsitution effects during polymerization, the occurrence of side reactions and intramolecular cyclization [18][19][20][21][22][23][24][25]. The high mass-average molecular weight and polymer dispersity of the resulting polymes can be controlled by means of the addition of small core molecules [18,19,26], a feature that can be easily incorporated into statistical models.…”