Multicyclic Polyesters of Trimesic Acid and Alkanediols and the Theory of Network Formation

Trimesoyl chloride is polycondensed with various α,Ώ‐alkanediols in dichloromethane at different concentrations using equifunctional feed ratios. As evidenced by MALDI‐TOF (matrix assisted laser desorption/ionization‐time of flight) mass spectrometry the soluble reaction products mainly consist of perfect multicyclic oligomers and polymers. The solphase extracted from the gels also consists of perfect multicycles. SEC (size exclusion chromatography) measurements show that both soluble reaction products and extracted solphases also contain a high molar mass fraction of perfect and nonperfect multicycles extending up to masses beyond 105 g mol−1. When the polycondensation is stopped after a few minutes perfect multicycles are already detectable in the reaction mixture along with functional (multi)cyclic oligomers. These results prove that at initial monomer concentrations < 0.2 mol L−1 networks and large multicyclic polymers are synthesized from functional cyclic oligomers formed in early stages of the polycondensation and not from hyperbranched polymers. This interpretation is presented as “egg‐first theory” and compared with the “hen‐first theory” of Stockmayer and Flory. Depending on the reaction conditions, polycondensations of trifunctional monomers yield soluble nanogels or insoluble networks. At moderate monomer concentrations the initially formed functional cyclic and multicyclic oligomers (the “eggs”) serve as building blocks for the larger nanogels or networks. Polycondensations in bulk yield at first hyperbranched oligomers and polymers (the “hens”) which form small cyclic units in a later stage of the polycondensation.