One-Step Route to α-Hydroxyl-ω-(carboxylic acid) Polylactones Using Catalysis by Decamolybdate Anion

Abstract

Asymmetric telechelic α-hydroxyl-ω-(carboxylic acid) poly(ε-caprolactone) (HA-PCL) and α-hydroxyl-ω-(carboxylic acid) poly(δ-valerolactone) (HA-PVL) were synthesized by ring-opening polymerization of ε-caprolactone (CL) and δ-valerolactone (VL), respectively. HA-PCL oligomers were obtained at 150 °C in 2 h using ammonium decamolybdate (NH4)8[Mo10O34] as catalyst and water as initiator. A control of the number-average molecular weight (measured by NMR) can be achieved in the range between 212 and 2198 Da, based on the initial monomer/initiator ratio. Number-average molecular weight (M n) shows a linear dependence with CL/H2O ratio in this range. The nature of hydroxyl and carboxylic acid end groups of HA-PCL and HA-PVL was studied by MALDI-TOF and 1H and 13C NMR. Changes in the chemical shifts observed in the NMR spectra as a function of molecular weight were explained in terms of hydrophobic interactions. Formation of macrocyclic species was studied by MALDI-TOF. It was found that macrocyclic species are favored at longer reaction times. Insertion of alcohols and polycondensation reactions occurring after complete monomer conversion were also studied. Alcohol insertion for this system depends on the nature of alcohol. Polycondensation reactions vary with reaction times and affect the polymer molecular weight in a nonlinear manner. Finally, the α-hydroxyl-ω-(sodium carboxylate) PCL salt (HC-PCL) was prepared from HA-PCL and characterized by FT-IR and solution and solid-state NMR. Important differences between CP-MAS and MAS spectra are observed and discussed in terms of morphology and polarization transfer.

Hydrolytic degradation of poly(ε‐caprolactone) with different end groups and poly(ε‐caprolactone‐co‐γ‐butyrolactone): characterization and kinetics of hydrocortisone delivery

“…Ammonium heptamolybdate tetrahydrate (NH 4 ) 6 [Mo 7 O 24 ] (Hep)(Fluka) was grounded in a mortar and passed through a 100 mesh sieve before used [2,5] .…”

“…α-Hydroxyl-ω-(carboxylic acid)-poly(ε-caprolactone) (HA-PCL), α-hydroxyl-ω-(benzyl ester)-poly(ε-caprolactone) (HBz-PCL) and α-hydroxyl-ω-(carboxylic acid)-poly(ε-caprolactone-co-γ-butyrolactone) (HA-PCB) were synthesized by ring-opening polymerization with ammonium decamolybdate (NH 4 ) 8 [Mo 10 O 34 ] (Dec) as catalyst, using an initial monomer/catalyst ratio of 20,000, as described elsewhere [5,6] . …”

“…PCL shows a high degree of permeability toward low molecular weight drugs (<400 Da), and this property made it attractive for the manufacture of long-term and diffusion-controlled delivery drug delivery systems. In the scope of the local drug delivery applications, PCL has been successfully tested as a vehicle for slow release of drugs at tumor reactions sites [4,5] .…”

“…Different catalysts have been used to catalyze the polymerization and lowmolecular weight alcohols can be used as initiators and to control the final polymer molecular weight. We have reported the use of ammonium decamolybdate ((NH 4 ) 8 [Mo 10 O 34 ] as an efficient catalyst to obtain aliphatic polyesters and their copolymers with different architectures [5,6] . In this work, we have used this catalyst to obtain the polymers tested for degradation and as drug delivery carriers.…”

Using MALDI-TOF MS imaging and LC-HRMS for the investigation of the degradation of polycaprolactone diol exposed to different wastewater treatments

“…1D), the presence of a second series of oligomers, likewise, spaced by m/z 114 (i.e., m/z 1051.6 and 1165.6) and separated from the homolog peaks of the main series by m/z 104. It was attributed to PCL (Table 1) formally corresponding to a loss of the diethylenglycol unit from PCLD polymer and they were identified as PCL cyclic oligomers [21][22][23][24], previously reported as a possible degradation pathway of PCL (Fig. 1) [25].…”