Cyclization in Hyperbranched Polymer Syntheses:  Characterization by MALDI-TOF Mass Spectrometry

Abstract

Matrix-assisted laser desorption/ionization (MALDI)-time-of-flight (TOF) mass spectrometry allowed direct determination of the extent of macrocycle formation that occurred during the polymerization and copolymerization of A2B and A4B monomers. Cyclization in hyperbranched pentafluorophenyl-terminated poly(benzyl ether)s was indicated by the presence of ions 20 Da less than the masses of acyclic species, owing to the loss of the HF chain ends during polymerization. This loss occurs by intramolecular nucleophilic aromatic substitution of the benzyl oxide focal point functionality upon a pentafluorophenyl chain end. Homopolymerizations and copolymerization of A2B and A4B monomers gave cyclic products in all cases, and the extent of cyclization depended on counterion, reaction time, and reaction temperature. In the copolymerization, product distributions revealed that larger proportions of A2B repeat units in the product led to increased amounts of cyclic products.

Cyclic polymers: Synthetic strategies and physical properties

“…This means that with increasing conversion more and more hyperbranched oligomers and polymers change from a treeshaped to a sun-shaped structure. However, with one exception, 47 the extent of cyclization was not studied by other research groups. A reinvestigation of polycondensations based on 3,5-bis(4-fluorobenzoyl) phenol (Scheme 9) performed by the authors 48 yielded a product almost completely consisting of hyperbranched poly(ether ketone)s having a cyclic core.…”

Employing MALDI-MS on Poly(alkylthiophenes): Analysis of Molecular Weights, Molecular Weight Distributions, End-Group Structures, and End-Group Modifications

“…6,7 More recently, it has also been used to characterize many synthetic polymers. [8][9][10][11][12] It has been shown to be a viable tool for end-group analysis as well as product confirmation for synthetic polymers. Another advantage of MALDI-TOF MS for synthetic polymer analysis is that the absolute molecular masses can be determined as opposed to relative molecular weights by GPC, and this determination is independent of polymer structures.…”

Role of cyclization in the synthesis of hyperbranched aliphatic polyesters

“…At present, cyclization has been investigated experimentally only to a very limited extent [14][15][16][17] in AB m -polycondensations without B f core molecules. Only in recent publications, first attempts to treat this problem theoretically have been reported, using simplified models or lattice simulation 18,19) .…”