P-dioxanone Research Articles

Preparation, characterization, and in vitro drug release behavior of biodegradable chitosan-graft-poly(1, 4-dioxan-2-one) copolymer

A novel copolymer of chitosan-g-poly( p-dioxanone) (CGP) was synthesized in bulk by ring-opening polymerization of p-dioxanone (PDO) initiated by the hydroxyl group or amino group of chitosan using SnOct 2 as catalyst. The chemical structure was determined by 1H NMR. It was found that the feed ratio of chitosan to PDO had a great effect on the degree of polymerization (DP) and the substitution (DS) of PDO. The thermal stability and crystallization behavior of graft copolymer CGP were closely related to the values of DP and DS. When the resulting copolymer was used as Ibuprofen carrier, the release rate of Ibuprofen decreased compared with that of pure chitosan carrier. The drug release behavior was also influenced by the structure of graft copolymers.

Microwave‐assisted ring‐opening polymerization of p‐dioxanone

AbstractThe ring‐opening polymerization (ROP) of p‐dioxanone (PDO) under microwave irradiation with triethylaluminum (AlEt3) or tin powder as catalyst was investigated. When the ROP of PDO was catalyzed by AlEt3, the viscosity‐average molecular weight (Mv) of poly(p‐dioxanone) (PPDO) reached 317,000 g mol−1 only in 30 min, and the yield of PPDO achieved 96.0% at 80 °C. Tin powder was successfully used as catalyst for synthesizing PPDO by microwave heating, and PPDO with Mv of 106,000 g mol−1 was obtained at 100 °C in 210 min. Microwave heating accelerated the ROP of PDO catalyzed by AlEt3 or tin powder, compared with the conventional heating method. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3207–3213, 2008

Synthesis and thermal properties of novel multiblock biodegradable copolymers derived from polyethylene glycol, ε -caprolactone and p-dioxanone

Multiblock copolymers from polyethylene glycol (PEG), e-caprolactone (CL), and p-dioxanone (PDO) were synthesized and characterized. Triblock copolymers were first synthesized from PEG with number-averaged molecular weights (M n ) of 3000, 4000, and 15000 Daltons, and e-caprolactone in the presence of Sn(Oct) 2 . 1 H-NMR spectra of these copolymers were recorded. Thermal behaviour and thermal stability of these copolymers were evaluated by differential scanning calorimetry (DSC) and TGA thermograms, respectively. These triblock copolymers with two hydroxyl functional groups were subjected to further block copolymerization with PDO in the presence of Sn(Oct) 2 as catalyst. Thermal behaviours of these copolymers were evaluated by DSC and TGA thermograms. For comparison of block and random copolymer thermal behaviour, random triblock copolymer from PEG, CL, and PDO was prepared and its thermal behaviour was characterized by DSC and TGA.

Surface-initiated ring-opening polymerization of p-dioxanone on Wang resin bead

Biodegradable poly(p-dioxanone) (PPDO) was formed on Wang resin surface by surface-initiated ring-opening polymerization (SI-ROP). The SI-ROP of p-dioxanone (PDO) was achieved by heating a mixture of Tin(II) bis(2-ethylhexanoate) [Sn(Oct)2], hydroxyl functionalized Wang resin, and PDO in anhydrous toluene at 80 °C. The resultant polymer-grafted Wang resin (Wang-g-PPDO) was characterized by fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), optical microscopy (OM), and field-emission scanning electron microscopy (FE-SEM). The FTIR spectra of Wang-g-PPDO show peak characteristic of PPDO at 2943 cm−1 (CH stretch), at 1741 cm−1 (CO stretch), and 1136 cm−1 (COC stretch) indicating the formation of ester linkage between PPDO and hydroxyl terminated Wang resin. The DSC thermogram show melting peak corresponding to PPDO polymer on Wang resin surface. Thermogravimetric investigation shows increase in PPDO content on the Wang resin surface in terms of percentage of weight loss with increase in reaction time. The OM and SEM photographs clearly show the formation of PPDO polymer on the Wang resin surface without altering the spherical nature of Wang resin bead. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1178–1184, 2008

A new approach to prepare high molecular weight poly( p-dioxanone) by chain-extending from dihydroxyl terminated propolymers

As poly( p-dioxanone) (PPDO) with a high molecular weight (viscosity-average molecular weight ( M ν) > 100,000 g/mol) is not easy to be obtained in a short time, a new approach has been developed to produce high molecular weight poly( p-dioxanone) (HPPDO-T) by chain-extending reaction of hydroxyl-terminated PPDO (HPPDO) prepolymers using toluene-2,4-diisocyanate (TDI) as chain extender. Here HPPDO prepolymers were synthesized via ring-opening polymerization of p-dioxanone (PDO) monomer initiated by 1,4-butanediol (BD) with Stannous octoate (SnOct 2) as catalyst. The resulting polymers, having a highest M ν of 250,000 g/mol, were characterized by 1H NMR, TG, DSC and WXRD. HPPDO prepolymers can react with TDI more effectively than the PPDO prepolymers initiated by mono-functional initiators, and the molecular weights of resulting chain-extended products increase several decade times in an hour comparing to the prepolymers. The chain extended products HPPDO-T have better thermal stability, and higher glass transition temperatures and lower crystallization rates than PPDO homopolymer.

A rapid synthesis of poly (p-dioxanone) by ring-opening polymerization under microwave irradiation

A rapid synthesis of poly(p-dioxanone) (PPDO) was carried out smoothly and effectively from the monomer p-dioxanone (PDO) with constant microwave powers of 90, 180, 270, and 360 W, respectively, in a microwave oven at a frequency of 2.45 GHz. The temperature of the polymerization ranged from 158 to 198 °C. PPDO with a viscosity-average molecular weight (Mv) of 156,000g/mol and yield of 63% was obtained at 270W for 25 min using 1/1000 (mol/mol) Sn(Oct)2 as a catalyst, while it took more than 14h to obtain PPDO with high molecular weight and monomer conversion by conventional heating method when Sn(Oct)2 used as a catalyst. Therefore, it is obvious that the polymerization rate is faster than that of the conventional polymerization method when microwave irradiation is used in polymerization process.

Preparation and characterization of a novel biodegradable poly(p‐dioxanone)/montmorillonite nanocomposite

AbstractPoly(p‐dioxanone) (PPDO)/montmorillonite nanocomposites were prepared through the in situ ring‐opening polymerization of p‐dioxanone (PDO) and three types of montmorillonites (natural sodium montmorillonite, montmorillonite modified by octadecyltrimethyl ammonium chloride, and montmorillonite modified by hydroxyethylhexadecyldimethyl ammonium bromine) in the presence of triethylaluminum. Montmorillonite could accelerate the polymerization of PDO, and the viscosity‐average molecular weight of PPDO could reach 44,900 g/mol in 0.5 h. A nucleating effect of montmorillonite was observed, and the crystallization temperature of PPDO was increased by 18 °C. All three montmorillonites could improve the thermal stability of PPDO and increase the glass‐transition and melting temperatures of PPDO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2298‐2303, 2005

Mechanistic study on Sn(Oct)2-catalyzed, ring-opening polymerization of p-dioxanone by surface-initiated polymerization and x-ray photoelectron spectroscopy

Two mechanisms on Sn(Oct)2-catalyzed, ring-opening polymerization of p-dioxanone (PDX) were mainly proposed: activated monomer mechanism and coordination-insertion mechanism. The activated monomer mechanism assumes that alcohol complexed with Sn(Oct)2 reacts with monomer and forms a ternary complex. The initiation and chain growth then proceeds within the complex with liberation of the intact Sn(Oct)2. In contrast, the coordination-insertion mechanism hypothesizes that an actual initiator is the -Sn(OR) species and the polymerization proceeds on the -Sn-O-polymer. In this paper, to investigate the presence/absence of the Sn species in the PPDX chain, we used X-ray photoelectron spectroscopy (XPS) of poly(p-dioxanone) (PPDX) grown from a gold surface using the “grafting-from” approach, and the XPS data supports the coordination-insertion mechanism. After the polymerization of PPDX from the surface, the peaks from Sn were observed at 153, 486, and 495 eV in XPS spectrum, and the peaks disappeared after quenching with 1N HCl.

Functionalization of Shortened Single‐Walled Carbon Nanotubes with Poly(p‐dioxanone) by “Grafting‐From” Approach

AbstractSummary: It has been a real challenge to form carbon nanotube (CNT)/polymer composites where CNTs are well‐dispersed in the polymer matrix and the interactions between CNTs and polymers are effectively strong. In this paper, we applied surface‐initiated, ring‐opening polymerization (SI‐ROP) of p‐dioxanone (PDX) to shortened single‐walled carbon nanotubes (s‐SWCNTs) and successfully formed s‐SWCNT/PPDX composites (see Figure). Due to intimate interactions between s‐SWCNTs and PPDX, we observed dramatic changes in PPDX properties upon the formation of the composites: 10%‐weight‐loss‐temperature of PPDX increased by 20 °C (measured by thermogravimetric analysis) and the patterns of Tg and Tm were greatly altered. We did not observe any noticeable peaks from the composite up to 120 °C in differential scanning calorimetry (DSC), while DSC data of PPDX itself showed Tg and Tm at −13.4 and 103 °C respectively.Schematic representation of the procedure for formation of s‐SWCNT/PPDX composites.magnified imageSchematic representation of the procedure for formation of s‐SWCNT/PPDX composites.

Surface-initiated, ring-opening polymerization of p-dioxanone from gold and silicon oxide surfaces

A polymeric thin film of a biodegradable poly(p-dioxanone) (PPDX) was grown from flat solid surfaces by a combination of formation of self-assembled monolayers terminating in hydroxyl groups and surface-initiated, ring-opening polymerization (ROP) of p-dioxanone (PDX). Tin(II) octoate [Sn(Oct)2] was used as a catalyst, and gold and silicon oxide surfaces were chosen as model surfaces. A molecularly-ordered film (self-assembled monolayer, SAM) was formed by immersing gold and silicon oxide substrates in a solution of alkanethiolates and in a solution of triethoxysilanes, respectively. The polymerization was achieved by heating a mixture of Sn(Oct)2, PDX, and the SAM-coated substrate in anhydrous toluene for 24 h at 55 °C (for a gold substrate) or 70 °C (for a silicon oxide substrate). The characteristic IR peaks of PPDX (C–H stretching at ∼2923 cm−1 and the CO ester at ∼1748 cm−1) were observed in polarized infrared external reflectance spectroscopy (PIERS) spectra, indicating the presence of a PPDX film on the gold and silicon oxide surfaces. The average thickness of the PPDX film was measured to be 90 nm on the gold substrate and 46 nm on the silicon oxide substrate by ellipsometry. The PPDX films were further characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurement, and atomic force microscopy (AFM).

Synthesis and characterization of ABA type tri‐block copolymers derived from p‐dioxanone, L‐lactide and poly(ethylene glycol)

AbstractA series of triblock co‐polymers, consisting of a poly(ethylene glycol) (PEG) central block joined to two blocks of random p‐dioxanone‐co‐L‐lactide copolymers were synthesized by ring‐opening polymerization of p‐dioxanone (PDO) and L‐lactide (LLA) initiated by PEG in the presence of stannous 2‐ethylhexanoate catalyst. The resulting copolymers were characterized by various techniques including 1H and 13C NMR and FTIR spectroscopies, gel permeation chromatography, inherent viscosity, wide‐angle X‐ray diffractometry (WAXD) and differential scanning calorimetry (DSC). The conversion of PDO and L‐lactide into the polymer was studied various mole ratios and at different polymerization temperature from 1H NMR spectra. Results of WAXD and DSC showed that the crystallinity of PEG macroinitiator was greatly influenced by the composition of PDO and L‐lactide in the copolymer. The triblock copolymers with low molecular weight were soluble in water at below room temperature.© 2003 Society of Chemical Industry