The ring-opening polymerization of δ-valerolactone (δ-VL) and ε-caprolactone (ε-CL) using 3-phenyl-1-propanol (PPA) as the initiator and diphenyl phosphate (DPP) as the catalyst in toluene at room temperature with the [δ-VL or ε-CL]0/[PPA]0/[DPP] ratio of 50/1/1 homogeneously proceeded to afford poly(δ-valerolactone) (PVL) and poly(ε-caprolactone) (PCL) with narrow polydispersity indices. The molecular weights determined from a 1H NMR analysis (PVL, M n,NMR = 5170 g mol−1 and PCL, M n,NMR = 5920 g mol−1) showed good agreement with those estimated from the initial ratio of [δ-VL or ε-CL]0/[PPA]0 and monomer conversions (PVL, M n,theo = 4890 g mol−1 and PCL, M n,theo = 5680 g mol−1). The 1H NMR, SEC, and MALDI-TOF MS measurements of the obtained PVL and PCL clearly indicated the presence of the initiator residue at the chain end, confirming that the DPP-catalyzed ROP of lactones proceeded through an activated monomer mechanism. The kinetic and chain extension experiments confirmed the controlled/living nature for the DPP-catalyzed ROP of lactones. In addition, the block copolymerization of PVL and PCL successfully proceeded to afford PVL-b-PCL regardless of the monomer addition sequence. The DPP-catalyzed ROP of δ-VL and ε-CL using functional initiators, such as 2-hydroxyethyl methacrylate, 4-vinylbenzyl alcohol, propargyl alcohol, and 6-azido-1-hexanol, produced the corresponding end-functionalized PVLs and PCLs with narrow molecular weight distributions.

The ring-opening polymerization (ROP) of cyclic carbonates with diphenyl phosphate (DPP) as the organocatalyst and 3-phenyl-1-propanol (PPA) as the initiator has been studied using trimethylene carbonate (TMC), 5,5-dimethyl-1,3-dioxan-2-one, 5,5-dibromomethyl-1,3-dioxan-2-one, 5-benzyloxy-1,3-dioxan-2-one, 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one, and 5-methyl-5-propargyloxycarbonyl-1,3-dioxan-2-one. All the polymerizations proceeded without backbiting, decarboxylation, and transesterification reactions to afford polycarbonates having narrow polydispersity indices. In addition, 6-azido-1-hexanol, propargyl alcohol, and N-(2-hydroxyethyl)maleimide were used as functional initiators for the DPP-catalyzed ROP to produce the end-functionalized poly(trimethylene carbonate)s. For further modification of the azido end-functionlized polycarbonate, the macrocyclic poly(trimethylene carbonate) was synthesized by the intramolecular click cyclization of the α-azido, ω-ethynyl poly(trimethylene carbonate). The DPP-catalyzed ROP was applicable for the block copolymerization of TMC and δ-valerolactone or ε-caprolactone to afford poly(trimethylene carbonate)-block-poly(δ-valerolactone) and poly(trimethylene carbonate)-block-poly(ε-caprolactone), and for that of TMC and l-lactide using DPP coupled with 4-dimethylaminopyridine without quenching to produce poly(trimethylene carbonate)-block-poly(l-lactide).

For the living ring‐opening polymerization (ROP) of epoxy monomers, the catalytic activity of organic superbases, tert‐butylimino‐tris(dimethylamino)phosphorane, 1‐tert‐butyl‐2,2,4,4,4‐pentakis(dimethylamino)‐2Λ5,4Λ5‐catenadi(phosphazene), 2,8,9‐triisobutyl‐2,5,8,9‐tetraaza‐1‐phosphabicyclo[3.3.3]undecane, and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris(dimethylamino)phosphoranylidenamino]‐2Λ5,4Λ5‐catenadi(phosphazene) (t‐Bu‐P4), was confirmed. Among these superbases, only t‐Bu‐P4 showed catalytic activity for the ROP of 1,2‐butylene oxide (BO) to afford poly(1,2‐butylene oxide) (PBO) with predicted molecular weight and narrow molecular weight distribution. The results of the kinetic, post‐polymerization experiments, and MALDI‐TOF MS measurement revealed that the t‐Bu‐P4‐catalyzed ROP of BO proceeded in a living manner in which the alcohol acted as the initiator. This alcohol/t‐Bu‐P4 system was applicable to the glycidol derivatives, such as benzyl glycidyl ether (BnGE) and t‐butyl glycidyl ether, to afford well‐defined protected polyglycidols. The α‐functionalized polyethers could be obtained using different functionalized initiators, such as 4‐vinylbenzyl alcohol, 5‐hexen‐1‐ol, and 6‐azide‐1‐hexanol. In addition, the well‐defined cyclic‐PBO and PBnGE were successfully synthesized using the combination of t‐Bu‐P4‐catalyzed ROP and click cyclization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

A high enantiomer-selectivity for the polymerization of rac-lactide was achieved using chiral binaphthol-derived monophosphoric acids as organocatalysts. During the polymerization, d-lactide (DLA) preferentially polymerized via kinetic resolution with the maximum selectivity factor (kD/kL) of 28.3. The selective polymerization of DLA was derived from a dual activation, i.e., monomer activation and chain-end activation.

The ring-opening polymerizations (ROPs) of e-caprolactone (e-CL) and L-lactide (LLA) have been studied using the organocatalysts of diphenyl phosphate (DPP) and 4dimethylaminopyridine (DMAP). The "dual activation" property of DPP and the "bifunctional activation" property of DPP/DMAP were confirmed by the NMR measurement for e-CL and its chain-end model of poly(e-caprolactone) and for LLA and its chain-end model of poly(L-lactide) (PLLA), respectively. The molar ratio of DPP/DMAP was optimized as 1/2 for the ROP of LLA leading to the well-defined PLLA, such as the molecular weight determined from 1 H NMR measurement of 19,200 g mol 21 and the narrow polydispersity of 1.10. Additionally, functional initiators were utilized for producing the end-functionalized PLLAs. The DPP-catalyzed ROPs of e-CL and its analogue cyclic monomers and then the DPP/DMAP-catalyzed ROP of LLA produced block copolymers.