Homo‐ and random copolymerizations of ω‐pentadecalactone with ε‐caprolactone using isothiourea‐based dual catalysis

In this study, the catalytic behavior of dual catalysis based on isothioureas (ITUs) for ring‐opening polymerization (ROP) of macrolactone ω‐pentadecalactone (PDL) and its copolymerization with ε‐caprolactone (CL) has been investigated in detail. In the presence of benzyl alcohol (BnOH) initiator, 2,3,6,7‐tetrahydro‐5H‐thiazolo[3,2‐a]pyrimidine (THTP) acted as a representative organic compound, which coupled with magnesium halides (MgX₂) as cocatalysts and catalyzed the polymerization in toluene at 70 °C. Under suitable conditions, an array of polymers with controlled molecular weights and relatively narrow molecular weight distributions were synthesized. The formation of homopolymers and copolymers with different architectures was verified using GPC, DSC, NMR, and matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐ToF) mass. The MALDI‐ToF mass spectrometry (MS) analysis of poly(ω‐pentade‐calactone) (PPDL) provided direct evidence for the successful initiation of ROP of PDL using BnOH to obtain linear PPDL with a very small amount of oligomer. The NMR analysis indicated that the arrangements of PDL and CL units in the copolymer chains were completely random. The thermal stability of copolymers was composition dependent and increased with the increase in the content of PDL unit. Furthermore, the proposed polymerization mechanism is a dual catalytic mechanism. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019     

Enzymatic ring opening polymerization of ω‐Pentadecalactone in different solvents in a variable‐volume view reactor

The use of enzymes as catalyst in polyesters production enables the creation of new materials for use in biomedical applications. In this work, a polyester derived from ω‐pentadecalactone was synthesized. The polymer synthesis was performed using lipase Novozym 435 as catalyst and several solvents at 70 °C. The use of a closed variable volume reactor allowed the use of solvents with a boiling point lower than the reaction temperature, without affecting the ratio of solvent to monomer. Yields above 49 wt% and high molecular weights were obtained for all tested solvents. Dichloromethane (DCM) and chloroform were used as solvents for the evaluation of water content on enzyme and reaction time over the properties of final polymer. The amount of water on enzyme has a direct influence on reaction yields though higher molecular weights were obtained in reactions with lower water content. Yields of around 90 wt% were obtained in 6 h of reaction and molecular weights up to 42,300 and 51,900 g mol^?1 were obtained in 2 h of reactions using DCM and chloroform as solvents. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55 , 1219–1227     

Cyclic poly(ε‐caprolactone) synthesized by combination of ring‐opening polymerization with ring‐closing metathesis,ring closing enyne metathesis,or “click” reaction

This article described the synthesis of cyclic poly(ε‐caprolactone) (PCL) via ring‐closing metathesis (RCM), ring closing enyne metathesis (RCEM), and “click” reaction of different difunctional linear PCL. Linear PCL precursors were prepared by ring‐opening polymerization (ROP) of ε‐caprolactone in bulk using 10‐undecen‐1‐ol or propargyl alcohol as the initiator, followed by reacting with corresponding acyl chloride containing vinyl or azido end group. The subsequent end‐to‐end intramolecular coupling reactions were performed under high dilution conditions. The successful transformation of linear PCL precursor to cyclic PCL was confirmed by Gel permeation chromatography, ¹H NMR, and Fourier transform infrared measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3022–3033, 2009     

Preparation of poly(alkylenebenzimidazole) by ruthenium complex catalyzed polycondensation of 3,3′‐diaminobenzidine with α,ω‐diols

The reactions of 3,3′‐diaminobenzidine with 1,12‐dodecanediol in 1 : 1–1:3 molar ratios in the presence of RuCl₂(PPh₃)₃ catalyst give poly(alkylenebenzimidazole), [ (CH₂)₁₁ O (CH₂)₁₁ Im / (CH₂)₁₀ Im ]_n (Im: 5,5′‐dibenzimidazole‐2,2′‐diyl) (I_a‐I_d) in 71–92% yields. The relative ratio between the [(CH₂)₁₁ O (CH₂)₁₁ Im ] unit (A) and the [‐ (CH₂)₁₀ Im ] unit (B) in the polymer chain varies depending on the ratio of the substrates used. The polymer I_a obtained from the 1 : 3 reaction contains these structural units in a 98 : 2 ratio. The polymers are soluble in polar solvents such as DMF (N,N‐dimethylformamide), DMSO (dimethyl sulfoxide), and NMP (N‐methyl‐2‐pyrrolidone) and have molecular weights M_n (M_w) of 4,200–4,800 (4,800–6,500) by GPC (polystyrene standard). The polymerization of the diol and 3,3′‐diaminobenzidine in higher molar ratios leads to partial cross‐linking of the resulting polymers I_e and I_f via condensation of imidazole NH group with CH₂OH group. Similar reactions of 3,3′‐diaminobenzidine with α,ω‐diols, HO(CH₂)_mOH (m = 4–10), in a 1 : 3 molar ratio give the polymers containing [ (CH₂)_m−1 O (CH₂) _m−1 Im ] and [ (CH₂) _m−2 Im ] units with partial cross‐linked structures. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1383–1392, 1999     

Synthesis and characterization of well‐defined ABC 3‐Miktoarm star‐shaped terpolymers based on poly(styrene), poly(ethylene oxide), and poly(ϵ‐caprolactone) by combination of the “living” anionic polymerization with the ring‐opening polymerization

A series of well‐defined ABC 3‐Miktoarm star‐shaped terpolymers [Poly(styrene)‐Poly(ethylene oxide)‐Poly(ε‐caprolactone)](PS‐PEO‐PCL) with different molecular weight was synthesized by combination of the “living” anionic polymerization with the ring‐opening polymerization (ROP) using macro‐initiator strategy. Firstly, the “living” poly(styryl)lithium (PS^?Li⁺) species were capped by 1‐ethoxyethyl glycidyl ether(EEGE) quantitatively and the PS‐EEGE with an active and an ethoxyethyl‐protected hydroxyl group at the same end was obtained. Then, using PS‐EEGE and diphenylmethylpotassium (DPMK) as coinitiator, the diblock copolymers of (PS‐b‐PEO)_p with the ethoxyethyl‐protected hydroxyl group at the junction point were achieved by the ROP of EO and the subsequent termination with bromoethane. The diblock copolymers of (PS‐b‐PEO)_d with the active hydroxyl group at the junction point were recovered via the cleavage of ethoxyethyl group on (PS‐b‐PEO)_p by acidolysis and saponification successively. Finally, the copolymers (PS‐b‐PEO)_d served as the macro‐initiator for ROP of ε‐CL in the presence of tin(II)‐bis(2‐ethylhexanoate)(Sn(Oct)₂) and the star(PS‐PEO‐PCL) terpolymers were obtained. The target terpolymers and the intermediates were well characterized by ¹H‐NMR, MALDI‐TOF MS, FTIR, and SEC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1136–1150, 2008     

Synthesis and characterization of amphiphilic poly(N‐vinyl pyrrolidone)‐b‐poly(ε‐caprolactone) copolymers by a combination of cobalt‐mediated radical polymerization and ring‐opening polymerization

An amphiphilic block copolymer of poly(N‐vinyl pyrrolidone)‐b‐poly(ε‐caprolactone) (PVP‐b‐PCL) was synthesized by a combination of cobalt‐mediated radical polymerization (CMRP) and ring‐opening polymerization (ROP). The micellar characteristics of this copolymer were subsequently investigated. PVP (M_n = 11,400, M_w/M_n = 1.32) was synthesized at 20 °C via CMRP using a molar ratio of [VP]₀/[V‐70]₀/[Co]₀ = 150/8/1. The PVP was then reacted with 2,2′‐azobis[2‐methyl‐N‐(2‐hydroxyethyl)propionamide] (VA‐086) to modify its cobalt complex chain end to a hydroxyl group. The cobalt (Co) content in the resulting PVP‐OH was 1.2 ppm, indicating that all of the covalent Co? C bonds were cleaved and reacted with VA‐086, and that the separated cobalt complexes were successfully removed. The ROP of CL was subsequently carried out using the produced PVP‐OH as a macroinitiator at 110 °C. The GPC trace of PVP‐b‐PCL was monomodal without any tailing caused by the residual PVP‐OH, indicating that the initiation efficiency was very high. The critical micelle concentration (CMC) of PVP‐b‐PCL (M_n = 18,000, M_w/M_n = 1.35) was 0.015 mg/mL. The PVP‐b‐PCL micelles were spherical in shape with an average diameter of 105 nm. The nanosized PVP‐b‐PCL micelles show promise as novel drug carriers in biomedical and pharmaceutical applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3078–3085, 2009     

Synthesis of metal‐free poly(1,4‐dioxan‐2‐one) by enzyme‐catalyzed ring‐opening polymerization

To avoid the harmful effects of metallic residues in poly(1,4‐dioxan‐2‐one) (PPDO) for medical applications, the enzymatic polymerization of 1,4‐dioxan‐2‐one (PDO) was carried out at 60 °C for 15 h with 5 wt % immobilized lipase CA. The lipase CA, derived from Candida antarctica, exhibited especially high catalytic activity. The highest weight‐average molecular weight (M_w = 41,000) was obtained. The PDO polymerization by the lipase CA occurred because of effective enzyme catalysis. The water component appeared to act not only as a substrate of the initiation process but also as a chain cleavage agent. A slight amount of water enhanced the polymerization, but excess water depressed the polymerization. PPDO prepared by enzyme‐catalyzed polymerization is a metal‐free polyester useful for medical applications. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1560–1567, 2000     

Synthesis and characterization of poly(β‐hydroxybutyrate) and poly(ϵ‐caprolactone) copolyester by transesterification

To synthesize the copolyester of poly(β‐hydroxybutyrate) (PHB) and poly(?‐caprolactone) (PCL), the transesterification of PHB and PCL was carried out in the liquid phase with stannous octoate as the catalyzer. The effects of reaction conditions on the transesterification, including catalyzer concentration, reaction temperature, and reaction time, were investigated. The results showed that both rising reaction temperature and increasing reaction time were advantageous to the transesterification. The sequence distribution, thermal behavior, and thermal stability of the copolyesters were investigated by ¹³C NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction, optical microscopy, and thermogravimetric analysis. The transesterification of PHB and PCL was confirmed to produce the block copolymers. With an increasing PCL content in the copolyesters, the thermal behavior of the copolyesters changed evidently. However, the introduction of PCL segments into PHB chains did not affect its crystalline structure. Moreover, thermal stability of the copolyesters was little improved in air as compared with that of pure PHB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1893–1903, 2002     

Synthesis of poly(ω‐pentadecalactone)‐b‐poly(acrylate) diblock copolymers via a combination of enzymatic ring‐opening and RAFT polymerization techniques

Herein the first reported preparation of diblock copolymers of the polyethylene‐like polyester poly(ω‐pentadecalactone) (PPDL) via a combination of enzymatic ring‐opening polymerization (eROP) and reversible addition‐fragmentation chain‐transfer (RAFT) polymerization techniques is described. PPDL was synthesized via eROP using Novozyme 435 as a catalyst and a bifunctional initiator/chain transfer agent (CTA) appropriate for the eROP of ω‐pentadecalactone (PDL) and RAFT polymerization of acrylic and styrenic monomers. Chain growth of the PPDL macro‐CTA was performed to prepare acrylic and styrenic diblock copolymers of PPDL, and demonstrates a facile, metal‐free, and “greener” alternative to preparing acrylic diblock copolymers of polyethylene (PE). Diblock copolymer architecture was substantiated via analysis of ¹H NMR spectroscopic, UV‐GPC chromatographic, DSC onset crystallization (T_c), and MALDI‐ToF mass spectrometric data. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3326–3335     

High‐molecular‐weight poly(1,5‐dioxepan‐2‐one) via enzyme‐catalyzed ring‐opening polymerization

To avoid organometallic catalysts in the synthesis of poly(1,5‐dioxepan‐2‐one), the enzymatic ring‐opening polymerization of 1,5‐dioxepan‐2‐one (DXO) was performed with lipase CA (derived from Candida antarctica) as a biocatalyst. A linear relationship between the number‐average molecular weight and monomer conversion was observed, and this suggested that the product molecular weight could be controlled by the stoichiometry of the reactants. The monomer consumption followed a first‐order rate law with respect to the monomer, and no chain termination occurred. Water acted as a chain initiator, but it could cause polymer hydrolysis when it exceeded an optimum level. An initial activation via the heating of the enzyme was sufficient to start the polymerization, as the monomer conversion occurred when samples were left at room temperature after an initial heating at 60 °C. A high lipase content led to a high monomer conversion as well as a high molecular weight. An increase in the monomer conversion and molecular weight was observed when the polymerization temperature was increased from 40 to 80 °C. A further increase in the polymerization temperature led to a decrease in the monomer conversion and molecular weight because of the denaturation of the enzyme at elevated temperatures. The polymerization behavior of DXO under lipase CA catalysis was compared with that of ε‐caprolactone (CL). The rate of monomer conversion of DXO was much faster than that of CL, and this may have been due to differences in their specificity toward lipase CA. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4206–4216, 2005     

Synthesis of poly(3‐hexylthiophene)‐block‐poly(ethylene)‐block‐poly(3‐hexylthiophene) via a combination of ring‐opening olefin metathesis polymerization and grignard metathesis polymerization

Novel rod–coil–rod ABA triblock copolymers, poly(3‐hexylthiophene)‐block‐poly(ethylene)‐block‐poly(3‐hexylthiophene) (P3HT‐b‐PE‐b‐P3HT) were synthesized by using a combination of a Ru‐catalyzed ring‐opening metathesis polymerization of 1,4‐cyclooctadiene in the presence of a suitable chain transfer agent (CTA) and a Ni‐catalyzed Grignard metathesis polymerization of 5‐chloromagnesio‐2‐bromo‐3‐hexylthiophene followed by hydrogenation. Using this methodology, the molecular weights of the poly(butadiene) (PBD) or the P3HT blocks were controlled by adjusting the initial monomer/CTA or the initial monomer/macroinitiator ratio, respectively. In addition, the triblock structure was confirmed by selective oxidative degradation of the PBD block found in the intermediate P3HT‐b‐PBD‐b‐P3HT copolymer produced in the aforementioned method, followed by analysis of the degradation products. Thermal analysis and atomic force microscopy of P3HT‐b‐PE‐b‐P3HT revealed that the material underwent phase separation in the solid state, a feature which may prove useful for improving charge mobilities within electronic devices. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3810–3817     

Synthesis of branch‐ring‐branch tadpole‐shaped [linear‐poly(ε‐caprolactone)]‐b‐[cyclic‐poly(ethylene oxide)]‐b‐ [linear‐poly(ε‐caprolactone)] by combination of glaser coupling reaction with ring‐opening polymerization

A novel amphiphilic branch‐ring‐branch tadpole‐shaped [linear‐poly(ε‐caprolactone)]‐b‐[cyclic‐poly(ethylene oxide)]‐b‐[linear‐poly(ε‐caprolactone)] [(l‐PCL)‐b‐(c‐PEO)‐b‐(l‐PCL)] was synthesized by combination of glaser coupling reaction with ring‐opening polymerization (ROP) mechanism. The self‐assembling behaviors of (l‐PCL)‐b‐(c‐PEO)‐b‐(l‐PCL) and their π‐shaped analogs of poly(ε‐caprolactone)/poly(ethylene oxide)]‐b‐poly(ethylene oxide)‐b‐[poly(ε‐caprolactone)/poly(ethylene oxide) with comparable molecular weight in water were preliminarily investigated. The results showed that the micelles formed from the former took a fiber look, however, that formed from the latter took a spherical look. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation and physical properties of poly(4,4′‐diamino‐3′‐carbamoylbenzanilide terephthalamide) and poly(4,4′‐diamino‐3′‐carbamoylbenzanilide isophthalamide) films

To prepare thermally stable and high‐performance polymeric films, new solvent‐soluble aromatic polyamides with a carbamoyl pendant group, namely poly(4,4′‐diamino‐3′‐carbamoylbenzanilide terephthalamide) (p‐PDCBTA) and poly(4,4′‐diamino‐3′‐carbamoylbenzanilide isophthalamide) (m‐PDCBTA), were synthesized. The polymers were cyclized at around 200 to 350 °C to form quinazolone and benzoxazinone units along the polymer backbone. The decomposition onset temperatures of the cyclized m‐ and p‐PDCBTAs were 457 and 524 °C, respectively, lower than that of poly(p‐phenylene terephthalamide) (566 °C). For the p‐PDCBTA film drawn by 40% and heat‐treated, the tensile strength and Young's modulus were 421 MPa and 16.4 GPa, respectively. The film cyclized at 350 °C showed a storage modulus (E′) of 1 × 10¹¹ dyne/cm² (10 GPa) over the temperature range of room temperature to 400 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 775–780, 2000     

Peptide‐poly(ε‐caprolactone) biohybrids by grafting‐from ring‐opening polymerization: Synthesis,aggregation, and crystalline properties

Well‐defined peptide‐poly(ε‐caprolactone) (Pep‐PCL) biohybrids were successfully synthesized by grafting‐from ring‐opening polymerization (ROP) of ε‐caprolactone (CL) using designed amine‐terminated sequence‐defined peptides as macroinitiators. MALDI‐TOF‐MS and ¹H NMR analyses confirmed the successful attachment of peptide to the PCL chain. The gel permeation chromatography (GPC) measurement showed that the Pep‐PCL biohybrids with controllable molecular weights and low polydispersities (PDI <1.5) were obtained by this approach. The aggregation of Pep‐PCL hybrid molecules in THF solution resulted in the formation of micro/nanospheres as confirmed through FESEM, TEM, and DLS analyses. The circular dichroism study revealed that the secondary structure of peptide moiety was changed in the peptide‐PCL biohybrids. The crystallization and melting behavior of Pep‐PCL hybrids were somewhat changed compared with that of neat PCL of comparable molecular weight as revealed by DSC and XRD measurements. In Pep‐PCL biohybrids, extinction rings were observed in the PCL spherulites, in contrast with the normal spherulite morphology of the neat PCL. There was a substantial decrease (4–5 folds) in the spherulitic growth rate after the incorporation of peptide moiety at the end of PCL chain as measured by polarizing optical microscopy. Pseudomonas lipase catalyzed enzymatic degradation was studied for Pep‐PCL hybrids and neat PCL. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Zinc(II) complexes of Triaza and Amidinate ligands: Efficient initiators for the ring‐opening polymerization of ε‐Caprolactone and rac‐Lactide

Zinc complexes supported by tertiary 1,3,5‐triazapenta‐1,3‐dienate ligand (L¹) and N ‐benzoyl‐N′ ‐arylbenzamidinate [aryl =2,6‐diisopropylphenyl (L²), phenyl (L³)] ligands have been synthesized and characterized. The reaction of L¹H with ZnEt₂ affords a mononuclear zinc complex [L¹ZnEt] ( 1 ) in good yield. Tetra nuclear zinc complex [(L¹)₂Zn₄O(OAc)₄] ( 2 ) is prepared by treating L¹H with one equivalent of Zn(OAc)₂ in toluene. Further, dinuclear zinc complexes [L²ZnEt]₂ ( 3 ) and [L³ZnEt]₂ ( 4 ) are obtained in good yields from L²H and L³H with ZnEt₂ in toluene respectively_. The complexes 1–4 have been characterized by ¹H/¹³C NMR spectroscopy and single crystal X‐ray diffraction studies. All of the complexes have been explored for their catalytic activity toward the ring‐opening polymerization (ROP) of ε ‐caprolactone. It has been found that complex 1 is an active catalyst for the polymerization of ε ‐caprolactone in presence of a cocatalyst benzyl alcohol (BnOH). While complex 2 is as active as 1 there is no need for a cocatalyst for the polymerization to proceed. Dinuclear zinc complexes 3 and 4 show very high activity for the ROP of ε ‐caprolactone (CL) and rac ‐lactide (LA) without requiring a cocatalyst. The resultant polymers are found to have very high molecular weight (M _n = 296 X 10³ g mol⁻¹) and relatively narrow polydispersity index compared to 1 and 2 .     

Synthesis of well‐defined star‐shaped poly(ε‐caprolactone)/poly(ethylbene glycol) amphiphilic conetworks by combination of ring opening polymerization and “click” chemistry

Well‐defined star‐shaped hydrophobic poly(ε‐caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) amphiphilic conetworks (APCNs) have been synthesized via the combination of ring opening polymerization (ROP) and click chemistry. Alkyne‐terminated six arm star‐shaped PCL (6‐s‐PCLx‐C?CH) and azido‐terminated PEG (N₃‐PEG‐N₃) are characterized by ¹H NMR and FT‐IR. The swelling degree of the APCNs is determined both in water and organic solvent. This unique property of the conetworks is dependent on the nanophase separation of hydrophilic and hydrophobic phases. The morphology and thermal behaviors of the APCNs are investigated by SEM and DSC respectively. The biocompatibility is determined by water soluble tetrazolium salt reagents (WST‐1) assay, which shows the new polymer networks had good biocompatibility. Through in vitro release of paclitaxel (PTX) and doxorubicin (DOX), the APCNs is confirmed to be promising drug depot materials for sustained hydrophobic and hydrophilic drugs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 407–417     

Synthesis,structural analysis,and visualization of poly(2‐ethynyl‐9‐substituted carbazole)s and poly(3‐ethynyl‐9‐substituted carbazole)s containing chiral and achiral minidendritic substituents

The synthesis of 2‐ethynyl‐9‐substituted carbazole and 3‐ethynyl‐9‐substituted carbazole monomers containing first‐generation chiral and achiral dendritic (i.e., minidendritic) substituents, 2‐ethynyl‐9‐[3,4,5‐tris(dodecan‐1‐yloxy)benzyl]carbazole (2ECz), 3‐ethynyl‐9‐[3,4,5‐tris(dodecan‐1‐yloxy)benzyl]carbazole (3ECz), 2‐ethynyl‐9‐{3,4,5‐tris[(S)‐2‐methylbutan‐1‐yloxy]benzyl}carbazole (2ECz*), and 3‐ethynyl‐9‐{3,4,5‐tris[(S)‐2‐methylbutan‐1‐yloxy]benzyl}carbazole (3ECz*), is presented. All monomers were polymerized and copolymerized by stereospecific polymerization to produce cis‐transoidal soluble stereoisomers. A structural analysis of poly(2ECz), poly(2ECz*), poly(3ECz), poly(3ECz*), poly(2ECz*‐co‐2ECz), and poly(3ECz*‐co‐3ECz) by a combination of techniques, including ¹H NMR, ultraviolet–visible, and circular dichroism spectroscopy, thermal optical polarized microscopy, and X‐ray diffraction experiments, demonstrated that these polymers had a helical conformation that produced cylindrical macromolecules exhibiting chiral and achiral nematic phases. Individual chains of these cylindrical macromolecules were visualized by atomic force microscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3509–3533, 2002     

Preparation and characterization of biodegradable poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone) copolymers

A series of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone) copolymers were prepared with varying feed rations by using two step polymerization reactions. Poly(trimethylenecarbonate)(ε‐caprolactone) random copolymer was synthesized with stannous‐2‐ethylhexanoate and followed by adding p‐dioxanone monomer as the other block. The ring opening polymerization was carried out at high temperature and long reaction time to get high molecular weight polymers. The monofilament fibers were obtained using conventional melting spun methods. The copolymers were identified by ¹H and ¹³C NMR spectroscopy and gel permeation chromatography (GPC). The physicochemical properties, such as viscosity, molecular weight, melting point, glass transition temperature, and crystallinity, were studied. The hydrolytic degradation of copolymers was studied in a phosphate buffer solution, pH = 7.2, 37 °C, and a biological absorbable test was performed in rats. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2790–2799, 2005     

Synthesis,characterization, and degradation of poly(ethylene‐b‐ε‐caprolactone) diblock copolymer

Poly(ethylene‐b‐ε‐caprolactone) (PE‐b‐PCL) diblock copolymers were synthesized by ring‐opening polymerization (ROP) of ε‐caprolactone (CL) with α‐hydroxyl‐ω‐methyl polyethylene (PE‐OH) as a macroinitiator and ammonium decamolybdate (NH₄)₈[Mo₁₀O₃₄] as a catalyst. Polymerization was conducted in bulk (130–150°C) with high yield (87–97%). Block copolymers with different compositions were obtained and characterized by ¹H and ¹³C NMR, MALDI‐TOF, SAXS, and DSC. End‐group analysis by NMR and MALDI‐TOF indicates the formation of α‐hydroxyl‐ω‐methyl PE‐b‐PCL. The PE‐b‐PCL degradation was studied using thermogravimetric analysis (TGA) and alkaline hydrolysis. The PCL block was hydrolyzed by NaOH (4M), without any effect on the PE segment. Copyright © 2009 John Wiley & Sons, Ltd.