Synthesis of polymers via cationic ring-opening polymerization using (NH 4 ) 3 PW 12 O 40 -SiO 2 composite catalyst

Composite catalyst of heteropolyacid ammonium salt, (NH 4 ) 3 PW 12 O 40 , and SiO 2 was prepared by sol–gel method. The resultant catalyst ((NH 4 ) 3 PW 12 O 40 -SiO 2 , 3.38wt%) having W/Si molar ratio of 2/8 enabled to proceed ring-opening polymerizations of tetrahydrofuran (THF), ε-caprolactone (CL), and glycidyl phenyl ether (GPE) to give the corresponding poly(THF), poly(CL), and poly(GPE) having number-average molecular weights ( M n ) of 6610, 4010, and 2370 with polydispersity index ( M w / M n ) of 1.57, 1.36, and 1.49 in 24%, 88%, and 59% yields, respectively. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) spectra of poly(CL) and poly(GPE) exhibited that Brønsted acid induced from (NH 4 ) 3 PW 12 O 40 -SiO 2 is the only one species that initiates the polymerization.