Solvent‐free polycondensation of 1,3‐bis(hydroxyphenylmethyl)benzene. II. The dramatic difference in the polymerization behavior between meso and racemic isomers

Abstract

The meso and racemic forms of 1,3‐bis(hydroxyphenylmethyl)benzene underwent solvent‐free polycondensation with the aid of an acid catalyst giving polyether. Very interestingly, the diastereoisomerism caused a considerable difference in the polymerization behavior. The meso isomer (mp = 96–98 °C) was polymerized even at 65 °C, whereas the racemic one (mp = 158–160 °C) required heating at 100 °C to undergo polymerization. However, the latter produced a much higher molecular weight than the former (30,000 vs 4000). The contamination of the meso isomer with the racemic one very sensitively reduced the polymerization temperature: the 98.5% meso monomer underwent polymerization at 50 °C. In contrast to solvent‐free polymerization, two diastereomeric monomers showed almost identical behavior in solution polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3564–3571, 2003

Microscopy study of powder‐to‐powder polycondensation of DL‐1,3‐bis(hydroxyphenylmethyl)benzene

“…DL ‐1,3‐BHPMB was prepared according to our previous article 2. CSA [Aldrich; mp = 193–195 °C (decomposition)] was used as received.…”

“…1, 2 The reaction mixture of DL ‐1,3‐BHPMB (mp = 158–160 °C) was white and powdery without any change in the macroscopic appearance throughout the polymerization at 100 or 110 °C; the melting was not observed at all macroscopically 3. On the other hand, in the polymerization (65 °C) of meso ‐1,3‐BHPMB (mp = 96–98 °C), the powdery particles partially fused, mutually adhering to their surfaces 2. Additionally, the melt polymerization (100 °C) of the meso monomer resulted in a much lower molecular weight polymer [ M p (GPC) = 5600]4 than the powder‐to‐powder polycondensation of the DL ‐monomer at 100 °C [ M p (GPC) = 33,000].…”

A novel and green method for polycondensation reaction of 4‐substituted phenylurazoles with different diisocyanates under solvent‐free conditions

“…Research work on polymerization under solid state conditions was begun in 1954 with a series of publications by Mersobian et al1–3 Solid state polymerization (SSP) has certain advantages which render its application very attractive. SSP polymers often have improved properties, because monomer cyclization and other side reactions are limited, or even avoided 4–8. Only linear chains seem to be formed,9 and usually SSP products show greater heat stability in the molten state than samples prepared in the melt; on the other hand, their monomer and oligomers content is so low because of which there is no necessity for it to be removed.…”

“…SSP polymers often have improved properties, because monomer cyclization and other side reactions are limited, or even avoided. [4][5][6][7][8] Only linear chains seem to be formed, 9 and usually SSP products show greater heat stability in the molten state than samples prepared in the melt; on the other hand, their monomer and oligomers content is so low because of which there is no necessity for it to be removed. Furthermore, the increase in the molecular weight during SSP is accompanied by increased crystallinity and crystal perfection, 10,11 while drying the polymer, which is important because moisture content may influence processability in the manufacture of yarns.…”