Anionic ring opening polymerization of oxygenated heterocycles with supported Zirconium and rare earths alkoxides as initiators in protic conditions. Towards a catalytic heterogeneous process

Controlled ring‐opening polymerization of ε‐caprolactone using polymer‐supported scandium catalyst

“…From that perspective, a solid-supported system is very important. Although some metal complexes might be grafted onto a silica or alumina support, 13,[20][21][22][23] the regeneration and recycle was unsuccessful. 20 From the perspective of green chemistry, further development of a recoverable polymer-supported catalyst is desired.…”

A Recoverable, Metal-Free Catalyst for the Green Polymerization of ε-Caprolactone

“…Previous examples of metal complexes used as catalysts include tin, 2,6,[15][16][17][18][19][20][21] aluminum, 6,10,18,19,[22][23][24][25][26][27] iron, 6,18 scandium, 1,12,28 yttrium, 14,18,[29][30][31][32][33][34][35] zinc, [36][37][38][39] and other metals. 1,14,18,19,24,25,[30][31][32][33][34][40][41][42][43] Although in a few of these systems the metal com...…”

Elucidating the role of silica surfaces in the ring-opening polymerization of lactide: catalytic behavior of silica-immobilized zinc β-diiminate complexes

“…Using Sn-exchanged clays for polymerization, only oligomeric products were reported for δ-valerolactone polymerization [9]. Similar observations (primarily oligomeric products) were made for lactone or cyclic carbonate polymerization with silica-supported metal alkoxides [5][6][7]. The similarity of all these observations leads to the hypothesis that there is something inherent about silica-based catalysts that gives only low molecular weight products.…”

“…Table 1. Data points correspond to times of 0.5, 2, 4, and 20 h. polymers with exceeding low molecular weights [5][6][7][8][9]. 3 Over acidic Al-MCM-41 mesoporous silicates (27 Å pores), Aida and co-workers oligomerized lactones to numberaverage molecular weights of 1000-8200 over exceedingly long reaction times (up to 60 days) [8].…”

“…1 There are only a few reports of ring-opening polymerization of lactones and lactides using solid catalysts. Hamaide and co-workers developed silicabased catalysts that utilize grafted aluminum, transition metal, or rare earth alkoxide species as active centers for the ROP of oxygenated heterocycles such as ε-caprolactone [5,6] and 2,2-dimethyltrimethylene carbonate [7]. Aida, Tatsumi, and co-workers used a similar approach utilizing Al-MCM-41 as a solid catalyst for polymerization of ε-caprolactone and δ-valerolactone [8].…”