Papers by Keyword: ε-Caprolactone

Abstract: Poly (L-lactide-co-ε-caprolactone) 75:25 % mol, P(LL-co-CL), was synthesized via bulk ring-opening polymerisation (ROP) using a novel tin (II) alkoxide initiator, [Sn (Oct)]₂DEG, at 130°C for 48 hrs. The effectiveness of this initiator was compared withthe well-known conventional tin (II) octoateinitiator, Sn (Oct)₂. The P(LL-co-CL) copolymersobtained were characterized using a combination of analytical technique including: nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), thermogravimetry (TG) and gel permeation chromatography (GPC). The P(LL-co-CL) was melt-spun into monofilament fibres of uniform diameter and smooth surface appearance. Modification of the matrix morphology was then built into the as-spun fibresvia a series of controlled off-line annealing and hot-drawing steps.

Abstract: Four metal tert-butoxides, namely: aluminum (III) tert-butoxide, Al (Ot-C₄H₉)₃, tin (II) tert-butoxide, Sn (Ot-C₄H₉)₂, titanium (IV) tert-butoxide, Ti (Ot-C₄H₉)₄, and lithium tert-butoxide, Li (Ot-C₄H₉), were used as initiators in the bulk ring-opening polymerization (ROP) of ε-caprolactone (CL). The polymerizations were carried out at 120 °C for 72 hrs. It was found that the Al (Ot-C₄H₉)₃ only partially dissolved in the CL monomer and gave a low % conversion. The Li (Ot-C₄H₉) initiator did not dissolve and gave no polymerization. In contrast, the Sn (Ot-C₄H₉)₂ initiator dissolved completely, albeit very slowly, and gave a high % conversion. The Ti (Ot-C₄H₉)₄ initiator was by far the easiest and quickest to dissolve and also gave a high % conversion. Consequently, Ti (Ot-C₄H₉)₄-initiated polymerization was studied further by dilatometry at 120°C. From the kinetic results, a first-order rate constant, k_p, of 0.120 l mol^-1 min^-1 was obtained.

Abstract: The block copolymer poly (ε-caprolactone)-b-poly (N-isopropyl acrylamide) (PCL-b-PNIPAM) is synthesized via the combination of ring-opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT). PCL-b-PNIPAM can self-assemble into the micelles taking PCL as the cores and PNIPAM as the shells. Add α-CD into the micelles, because the inclusion complexation of α-CD to PCL chains and phenols is stronger than that to PCL, to regulate the hydrophilic and hydrophobic features of PCL chain. So PCL-b-PNIPAM block copolymers have potential application in drug delivery and gene transfection.

Abstract: Two novel tin(II) alkoxides, namely: tin(II) hexoxide, Sn(OC6H13)2, and tin(II) octoxide, Sn(OC8H17)2, have been synthesized for use as coordination-insertion initiators in the bulk ring-opening polymerization of ε-caprolactone. The kinetics of the polymerization reactions were studied at 140 °C by dilatometry. It was found that both alkoxides were slow to dissolve in the ε-caprolactone monomer due to their molecular aggregation in the solid state. As a result, the slow solubilization of the initiators gave rise to deviations from the expected first-order kinetics. Instead, the kinetic results adhered more closely to zero-order kinetics with apparent zero-order rate constants k0 of 6.58 x 10-2 and 4.63 x 10-2 mol l-1 min-1 for the hexoxide and octoxide respectively

Abstract: The purpose of this study is to develop a new system to control effective discharge of active substances such as agricultural chemicals. To synthesize a naturally dissolvable polymer; ε-caprolactone and diglycolide were copolymerized with ethylene glycol as an initiator to produce macrodiol. As macrodiol has hydroxyl groups in both ends, they are modified with methacryloyl chloride for photochemical networking. After standard macromonomer produced by this procedure was physically mixed with methylene blue, it was networked with ultra-violet rays to be filmed. This film is naturally dissolvable and hydrolytic. As a result of hydrolytic test with a crosslinked structure of 10 % methylene blue, it decreased by 9 % for seven weeks in 37 °C phosphate buffer solution (pH = 7). Thus, we verified that active substance can be discharged from a crosslinked structure for a long time at a constant rate under room temperature.

Abstract: Poly(ε-caprolactone) (PCL)-polystyrene (PS)star-block copolymer with a cross-linked microgel core were synthesized by the combination of atom transfer radical polymerization (ATRP) of St and lipase-catalyzed ring-opening polymerization (ROP) of ε-CL. The characterization of PCL-Br, PCL-PS-Br macroinitiator and PCL-PS Star-block copolymers was detected by GPC and 1H NMR. Results showed that the target star-block copolymers were successfully prepared.

Abstract: Polypropylene (PP) was modified by melt graft copolymerization with ε-caprolactone (ε-CL) in the absence of initiator. Fourier transform infrared (FTIR)
spectroscopy was used for qualitative and quantitative characterization of the reaction product. The graft copolymer was also characterized by 1H NMR, x-ray and thermogravimetric analysis (TG).