Search results for "Caprolactone"

Synthesis of polycaprolactone by microwave irradiation ? an interesting route to synthesize this polymer via green chemistry

2003

Poly(e-caprolactone) has become an important biocompatible and biodegradable polymer. Indeed, due to its multiple biomedical applications, the synthesis of polycaprolactone has received increased attention in the past few decades. Moreover, microwave irradiation is a very clean modern technique widely used for green chemistry. Here, several polymers were synthesized by microwave irradiation, without any solvent, using nontoxic, biologically acceptable lanthanide halides as initiators. Reaction times varied between 2 and 90 min. The molecular weights of the obtained polymer products were between 3,000 and 16,000 g/mol. After polymerization, the polycaprolactone polymers were functionalized b…

An Easy Way Towardɛ-Caprolactone Macromonomers by Microwave Irradiation Using Early Lanthanide Halides as Catalysts

2002

Poly(e-caprolactone) macromonomers were synthesized under microwave irradiation from commercial caprolactone, using commercial hydrated lanthanide halides as catalysts. The molecular weight of the polymers was in the range 3 000–5 000. Higher molecular weights (5 000–20 000) and lower polydispersity indices were obtained with THF adducts of the lanthanide halides as catalysts and also by applying longer reaction times or using diethylene glycol as a coupling reagent.

Preparation and mechanical characterization of polycaprolactone/graphene oxide biocomposite nanofibers

2016

Biocomposite nanofiber scaffolds of polycaprolactone (PCL) filled with graphene oxide (GO) were prepared using electrospinning technology. Morphological and mechanical properties of the scaffolds were characterized in dry and wet environment. The results showed that the successful incorporation of GO nanosheets into PCL polymer nanofibers improved their mechanical properties. Furthermore it was demonstrated the higher performance achieved when GO is filled at low concentration in the nanofibers.

Nanoscale Blends between Immiscible Polymers via Simultaneous Non-Interfering Polymerisation

2005

An important topic in polymer science seeks to improve the performances of polymer blends using nanoscale phase segregation. Here, blends between polystyrene and polycaprolactone are realised by a chemical route. The non-interfering character of the radical polymerisation of styrene and the lanthanide halide initiated ring-opening polymerisation of caprolactone is assessed. The molecular weights range from 2 000 to 3 500 for polycaprolactone and up to 140 000 for polystyrene, with reasonable polydispersity indexes. From calorimetry measurements, it is shown that polystyrene and low molecular weight polycaprolactone are immiscible. The morphology of the blends between the two immiscible poly…

Modular approach toward bioactive fiber meshes carrying oligosaccharides

2010

A modular strategy toward (bio)functional nanofiber meshes by electrospinning is described. In contrast to commonly established, multistep protocols or complex spinning setups, a straightforward single-step procedure is investigated to obtain polymer nanofibers with pentafluorophenyl (Pfp)-activated esters on the surface. The aim was to electrospin, for the first time, poly(pentafluorophenyl methacrylate) (PPfpMA) and PPfpMA/poly(epsilon-caprolactone) (PCL) blends, resulting in reactive nanofibers with fiber surfaces that can be functionalized with suitable bioactive entities. While PPfpMA fibers are brittle the spinning of PCL/PPfpMA blends leads to improved mechanical stability of the obt…

Diene/olefin/polar monomer copolymerisation: unprecedented functional polymers from a rare earth catalyst

2002

An ansasamarocene allyl system is an efficient initiator which polymerises 1,3-dienes, copolymerises dienes and long-chain α-olefins or α,ω-dienes to give functionalisable polymers. It also polymerises caprolactone and allows the controlled diblock copolymerisation of isoprene or isoprene/ α-olefin copolymer and caprolactone.

Polymerization of ε-caprolactone using heterobimetallic lanthanocene complexes

1997

The chiral heterobimetallic complexes Li[Ln(η 5 :η 1 -C 5 R 4 1 SiMe 2 NCH 2 CH 2 R 2 ) 2 ] (ln= Y, Lu; C 5 R 4 1 = C 5 Me 4 , C 5 H 4 , 3-C 5 H 3 tBu; R 2 = OMe, NMe 2 ) have been found to polymerize e-caprolactone to give a polymer of high molecular weight (M n > 20000) and moderate polydispersity (M w /M n < 2). Failure to observe a correlation between monomer/initiator ratio and molecular weight suggest a polymerization mechanism different from a pseudo-anionic mechanism

Aluminum complexes of sterically hindered tetradentate Schiff bases: Synthesis, structure, and reactivity toward ɛ-caprolactone

1997

Abstract The sterically hindered Schiff bases tbmSalenH2 [tbmSalen = N,N′-1,2-ethylenebis(3-tert-butyl-5-methylsalicylideneimine)] and tbmSalcenH2 [tbmSalcen = N,N′-trans-1,2-cyclohexanediyl-bis(3-tert-butyl-5-methylsalicylideneimine)] afforded a series of aluminum complexes of the general formulae [Al(tbmSalen)X] and [Al(tbmSalcen)X] (X = Cl, Me, Et). The molecular structure of [Al(tbmSalcen)Cl] was determined by single-crystal X-ray structural analysis which revealed a five-coordinate aluminum center with a distorted square pyramidal geometry. The alkyl complexes were found to oligomerize ɛ-caprolactone.

1976

The thermal degradation of poly(oxycarbonylpentamethylene), (poly-e-caprolactone), (3), was investigated at 220°C and 80 mm Hg under nitrogen. 3 was found to be thermally much more stable than poly(oxycarbonylethylene), (poly-β-propiolactone), (1), although it decomposed faster than poly(oxycarbonyl-1,1-dimethylethylene), (polypivalolactone), (2). The reaction was of the first order with a rate constant of k=6,2.10−4 min−1 and proceeded via a “zipper mechanism” to yield monomeric e-caprolactone. Der thermische Abbau von Poly(oxycarbonylpentamethylen), (Poly-e-caprolacton), (3), wurde bei 220°C im Stickstoffstrom bei 80 mm Hg untersucht. Dabei wurde gefunden, das 3 thermisch wesentlich stabi…

Über den thermischen abbau des poly(ɛ-caprolacton)s

1977

The thermal and electron impact induced degradation reactions of poly(e-caprolactone) {poly[oxy(1-oxohexamethylene)]} were investigated in a mass spectrometer. It can be shown that the favorated thermal degradation reaction is the cleavage of the ester bond and formation of ω-hydroxyl and ketene endgroups (Eq. (iii)) and with a lower intensity the cleavage of the OCH2-bond and formation of carboxyl-and pentenyl endgroups (Eq. (vii)). After electron impact and fragmentation of the pyrolysis products to carboxonium ions an elimination of caprolactone via a “zip”-mechanism can be observed (Eq. (v)).