Dormant Polymers and Their Role in Living and Controlled Polymerizations; Influence on Polymer Chemistry, Particularly on the Ring Opening Polymerization

Living polymerization discovered by Professor Szwarc is known well to all chemists. Some of the living polymerizations involve dormancy, a process in which there is an equilibrium (or at least exchange) between two types of living polymers, namely active at the given moment and dormant at this moment and becoming active in the process of activation. These processes are at least equally important although less known. This mini review is devoted to these particular living polymerizations, mostly polymerizations by the Ring-Opening Polymerization mechanisms (ROP) compared with some selected close to living vinyl polymerizations (the most spectacular is Atom Transfer Radical Polymerization (ATRP)) involving dormancy. Cationic polymerization of tetrahydrofuran was the first one, based on equilibrium between oxonium ions (active) and covalent (esters) dormant species, i.e., temporarily inactive, and is described in detail. The other systems discussed are polymerization of oxazolines and cyclic esters as well as controlled radical and cationic polymerizations of vinyl monomers

Formation of Poly(ethylene phosphates) in Polycondensation of H3PO4 with Ethylene Glycol. Kinetic and Mechanistic Study

Conditions of synthesis of poly(ethylene phosphates) in reaction of H3PO4 with HOCH2CH2OH (EG), the actual path of polycondensation, and structure of the obtained polymers (mostly oligomers) and kinetics of reaction are described. Preliminary kinetic information, based on the comparison of the MALDI-TOF-ms and 31P{1H} NMR spectra as a function of conversion is given as well. Because of the dealkylation process fragments derived from di- and triethylene glycols are also present in the repeating units. Structures of the end groups (-CH2CH2OH or -OP(O)(OH)2) depend on the starting ratio of [EG]0/[H3PO4]0, although even at the excess of EG the acidic end groups prevail because of the dealkylation process. In MALDI-TOF-ms products with Pn equal up to 21 have been observed. The average polymerization degrees (Pn) are lower and have been calculated from the proportion of the end groups.