Temperature-Controlled Cyclic Polyester Molecular Weights in Ring-Expansion Polymerization.

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Synthesizing cyclic polyesters via ring-expansion polymerization is challenging, particularly in controlling molecular weight.
• Precise molecular weight control is crucial for tailoring polymer properties.

Purpose of the Study:

• To develop a method for easily controlling the molecular weight of cyclic polyesters.
• To investigate the relationship between polymerization temperature and molecular weight control.
• To synthesize poly(salicylic phenyl glycolide) with tunable molecular weights and high glass transition temperatures.

Main Methods:

• Chain-growth polymerization of cyclic esters was employed.
• Polymerization temperature was adjusted to regulate polymerization and cyclization rates.
• Molecular weights were characterized using gel permeation chromatography, mass spectrometry, and atomic force microscopy.

Main Results:

• Molecular weights of poly(salicylic phenyl glycolide) were successfully controlled, ranging from 32.2 to 189.0 kg/mol.
• An inverse relationship was observed between the natural logarithm of molecular weights and polymerization temperatures.
• The glass transition temperature reached 116.6 °C due to phenyl group incorporation.

Conclusions:

• Adjusting polymerization temperature offers an effective strategy for controlling cyclic polyester molecular weights.
• This approach facilitates the synthesis of tailored cyclic polyesters with desirable thermal properties.