单脒基铝络合物催化己内醋聚合及己内醋/丙交醋共聚

将单脒基铝络合物用于催化6-己内酯(e-CL)开环聚合反应,结果表明,该类铝络合物表现出很高的催化活性:25℃时络合物({PhC(N-2,6-iPr2C6H3)2)A1Me2](Cl)催化ε-CL聚合1h,单体转化率为91%;70℃时络合物[{PhC(N-2,6-iPr2C6H3)-(N-2,6-Me2C6H3)}Al...     

Pyrolysis of poly(phenylene vinylene)s with polycaprolactone side chains

The thermal degradation characteristics of a new macromonomer poly(-caprolactone) with central 4,4′-dicarbaldehyde terphenyl moieties and poly(phenylene vinylene)s with well defined (-caprolactone), (PPV/PCL) as lateral substituents were investigated via direct pyrolysis mass spectrometry. The unexpectedly high thermal stability of the macromonomer was attributed to intermolecular acetylation of benzaldehyde yielding a hemiacetal and causing a crosslinked structure during the pyrolysis. Increased thermal stability of the PCL chains was detected for all samples. The increase in stability of PCL chains was much more pronounced than was detected for poly(p-phenylene)-graft-poly(-caprolactone) copolymer (PPP/PCL); the upward temperature shift was about 100 °C for PPV/PCL and only 20 °C for PPP/CL. This pronounced effect may be due to higher thermal stability of PPV compared to PPP and the decrease in steric hindrance for PPV with PCL side chains.     

Zein supports scaffolding capacity toward mammalian cells and bactericidal and antiadhesive properties on poly(ε-caprolactone)/zein electrospun fibers

Studies investigate the electrospinnability of poly(ε-caprolactone)/protein blends to produce fibers for tissue engineering applications. However, no reports show that zein can improve the scaffolding capacity toward stem cells and promote antiadhesive and bactericidal properties to the poly(ε-caprolactone)/zein fibers. We create fibers with average diameters ranging from 200 to 400 nm from the electrospinning of poly(ε-caprolactone)/protein mixtures. Poly(ε-caprolactone)/zein blends are electrospinnable at zein concentration between 20 and 40 wt% in a 70/30 formic acid/acetic acid mixture. Water contact angle measurements indicate that zein increases fiber hydrophilicity. The water contact angle decreases from 118° (pure poly(ε-caprolactone) fiber) to 73° for the scaffold containing 40 wt% zein. The zein (40 wt%) significantly increases Young's modulus from 260 MPa (pure poly(ε-caprolactone) fibers) to 980 MPa (poly(ε-caprolactone)/zein fibers) with no substantial influence on elongation at break (ε ≥ 125%) and tensile strength (≥0.040 MPa). The electrospun scaffolds containing zein also promote cell adhesion, proliferation, and spreading of adipose-derived human mesenchymal stem cells for at least 7 days of culture. The zein on poly(ε-caprolactone)/zein fibers can prevent the attachment and proliferation of Escherichia coli and Staphylococcus aureus. We propose these materials for wound healing and skin repair.     

Regioselective acylation of resveratrol catalyzed by lipase under microwave

The enzymatic regioselective acylation of resveratrol was achieved in organic solvents catalyzed by the lipase from Candida sp. 99–125 (CSL) under microwave irradiation. Influences of various reaction conditions have been studied. After selecting the optimum conditions [MTBE (20?ml, a_w?=?0.38), resveratrol (0.1?mmol), vinyl acetate (1.0?mmol) and CSL (100.0?mg) under microwave irradiation (35°C, 400 W)], CSL exhibited a satisfied enzyme activity (281?±?11?μmol/g/h) and yield of 75% for 4′-O-acetyl- resveratrol could be obtained in about 4?h when performing the reaction on a 25-fold-larger scale.

Schematic illustration of the enzymatic regioselective acylation of resveratrol catalyzed by the lipase from Candida sp. 99–125 (CSL) under microwave irradiation.     

Enzyme-catalyzed direct three-component aza-Diels–Alder reaction using lipase from Candida sp.99–125

The direct three-component aza-Diels–Alder reaction was conducted with lipase as a catalyst for the first time. Under the optimized conditions, the aza-Diels–Alder reaction catalyzed by lipase from Candida sp.99–125 provided the products in moderate to excellent yields. Meanwhile, the endo/exo ratio reached up to 88:12.     

Lactone polymers. VIII. Dynamic mechanical properties of ϵ-caprolactone and γ-(tert-butyl)-ϵ-caprolactone copolymers

The temperature dependencies of dynamic mechanical properties have been determined with a torsional pendulum for copolymers of ?-caprolactone and γ-(tert-butyl)-?-caprolactone over the entire composition range. Copolymers containing at least 25 mol % (33 wt %) of γ-(tert-butyl)-?-caprolactone units are amorphous in nature. The experimentally obtained glass transition temperatures of the copolymers and poly(γ-(tert-butyl)-?-caprolactone) were used to calculate the glass transition temperature of amorphous of poly(?-caprolactone) according to the Fox relation. This value of ?70°C is in excellent agreement with values obtained from similar calculations based on compatible blends of poly(?-caprolactone) with other homopolymers.     

功能化纳米粒子作为药物载体的研究

将合成的含有羧基侧基官能团的己内酯类聚合物, 用溶剂挥发与超声乳化相结合的方法制备成表面可供修饰的纳米粒子. 利用扫描电镜(SEM)研究了纳米粒子在水溶液中的形态. 使用5-氟脲嘧啶(5-FU)作为模型药物制备了载药纳米粒子, 利用紫外分光光度计法、差示扫描量热法(DSC)、X射线衍射法(XRD)研究了纳米粒子的载药及释放性能. 研究表明, 载药纳米粒子可以控制5-FU的释放速率. 释放时间可持续至96 h 以上, 符合Higuchi 动力学方程.     

具有抗凝性能的肝素化ε-己内酯/L-丙交酯共聚酯的合成及电纺丝加工

以辛酸亚锡为催化剂, 1,4-丁二醇为引发剂, 制备出ε-己内酯/L-丙交酯共聚酯(PLCL). 以1-(3-二甲氨基丙基)-3-乙基碳二亚胺/N-羟基琥珀酰亚胺为缩合剂将肝素连接在PLCL两侧端基上. 采用 1H NMR技术测定了共聚酯端基的肝素化率; 用XPS分析了肝素化后聚酯中N和S含量, 利用甲苯胺蓝紫外分光光度计法测定了表面肝素含量, 并根据静态接触角测定结果讨论了材料表面的亲水性变化. 凝血酶原时间、凝血酶时间和部分凝血活酶时间测试数据表明, 肝素化后PLCL的抗凝血性能得到明显改善. 探索了该共聚酯进行电纺丝加工的可行性.     

Synthesis and evaluation of biodegradable copolyesters of octadecane-1,18-dicarboxylic acid and poly(ε-caprolactone) diol

Copolyesters of poly(ε-caprolactone) diol and 1,18-octadecane dicarboxylic acid were synthesized by polyaddition. The copolymers have a "mixed" structure of ’polyester-polyethylene’. Characterization was carried out by using ¹H and ¹³C NMR, FT-IR, viscosities, DSC, and GPC. The tensile strength varied from 11.9 to 19.9 MPa, and elongation at break varied from 370 to 660 %, respectively. Biodegradability was evaluated by enzymatic hydrolysis (lipases from Rhizopus arrhizus and Candida cylindracea and an esterase form hog liver) and by soil burial test. Both tests showed that the copolyesters were characterized by enhanced biodegradability.     

Synthesis, characterization and degradability of the comb-type poly(4-hydroxyl-ε-caprolactone-co-ε-caprolactone)-g-poly(l-lactide)

The novel comb-type biodegradable graft copolymers based on ε-caprolactone and l-lactide were synthesized. Firstly, 2-oxepane-1,5-dione (OPD) was synthesized by the Baeyer-Villiger oxidation of 1,4-cyclohexanedione, and was subsequently copolymerized with ε-caprolactone (CL) to produce poly(2-oxepane-1,5-dione-co-ε-caprolactone) (POCL) catalyzed by stannous(II) 2-ethylhexanoate in toluene. Then, POCL was converted into poly(4-hydroxyl-ε-caprolactone-co-ε-caprolactone) (PHCL) using sodium borohydride as reductant. Finally, poly(4-hydroxyl-ε-caprolactone-co-ε-caprolactone)-g-poly(l-lactide) (PHCL-g-PLLA) were prepared successfully by bulk ring-opening polymerization of l-lactide using PHCL as a macro-initiator. All the copolymers have been characterized by ¹H and ¹³C NMR, DSC, and GPC. Compared with the random copolymer of poly(CL-co-LA), the elongation is highly increased. And the thermal analysis showed that the crystallization rate of the PCL backbone in the graft copolymers was greatly reduced compared to the PCL homopolymer. The hydrolytic degradation of the copolymer was much faster in a phosphate buffer (pH = 7.4) at 37 °C, which is confirmed by the weight loss and change of intrinsic viscosity.     

Degradation of polyesteramides prepared by the anionic polymerisation of -caprolactam in the presence of poly(-caprolactone)

Poly[(-caprolactam)-co-(-caprolactone)] was prepared by the anionic polymerisation of -caprolactam in the presence of poly(-caprolactone) initiated by -caprolactam magnesium bromide. Copolymers with 10–25% -caprolactone structure units were subjected to degradation. After 8-weeks abiotic hydrolysis at 60 °C the molar mass of the copolymer was significantly reduced as seen from viscosity measurements. IR spectroscopy was employed to clarify the mechanism of hydrolysis. Only small changes in molar mass were observed after composting and fungal treatment. Therefore, the effect of degradation temperature was crucial. The thermal properties of polyesteramides were studied by DSC, which showed the shift of melting endotherm and enthalpy of fusion to higher values of degraded samples compared to original one. This indicated an increase in crystalline phase content caused by reorganization of amorphous phase. Physical degradation of films was observed using SEM. Film-surface changes were apparent mainly on samples with 25% -caprolactone units.     

Semi-crystalline poly(ε-caprolactone) brushes on gold substrate via “grafting from” method: New insights with AFM characterization

This paper is the first report about the morphology of semi-crystalline poly(ε-caprolactone) (PCL) brushes studied by Atomic Force Microscopy (AFM) in tapping mode. This represents a convenient way to observe how the growth of a polymer proceeds from a thiol monolayer on gold substrate in terms of grafting density and thiol monolayer stability. The synthesis of semi-crystalline PCL brushes was carried out by Ring-Opening Polymerization (ROP) of ε-caprolactone (ε-CL) from hydroxyl end-group of thiol monolayer on gold surface as catalyzed with tin octoate (Sn(Oct)₂) at 50 °C. Addition of a sacrificial initiator was also attempted in order to get a finer control over PCL crystals. For a sake of comparison, triazabicyclo[4.4.0]dec-5-ene (TBD) was also investigated as another ROP catalyst active at ambient temperature. The composition and the morphology of resulting semi-crystalline PCL brushes were characterized using X-ray Photoelectron Spectroscopy (XPS) and AFM. In the case of Sn(Oct)₂-promoted ROP of CL with or without free (sacrificial) initiator (i.e., benzyl alcohol), different types of morphologies were observed on the gold substrate, due to the thermal instability of thiol-gold bond under the experimental conditions. When TBD was used at ambient temperature, a regular and homogeneous crystalline morphology, i.e., compact PCL crystals, could be observed.     

Synthesis, characterization and degradability of the novel aliphatic polyester bearing pendant N-isopropylamide functional groups

The synthesis, characterization, and degradability of the novel aliphatic polyester bearing pendant N-isopropylamide functional group are reported for the first time. 2-(N-Isopropyl-2-carbamoylethyl)cyclohexanone (CCH) was first synthesized by the Michael reaction of N-isopropylacrylamide with cyclohexanone and was subsequently converted into 6-(N-isopropyl-2-carbamoylethyl)-?-caprolactone (CCL) by the Baeyer-Villiger oxidation reaction using 3-chloroperoxybenzoic acid (mCPBA) as the oxidant. Finally, the novel functionalized poly(?-caprolactone) bearing the pendant N-isopropylamide functional groups, poly(6-(N-isopropyl-2-carbamoylethyl)-?-caprolactone-co-?-caprolactone)s (poly(CCL-co-CL)), were carried out successfully by bulk ring-opening polymerization of CCL and ?-CL initiated by Sn(Oct)₂. Poly(CCL-co-CL) were characterized by ¹H NMR, ¹³C NMR, SEC and DSC. The copolymer containing 9.1 mol% CCL formed flexible films and was used to study its degradability. A phosphate buffer (pH = 7.4) with temperature 37 °C was adopted to proceed the degrading study all through. Compared with poly(?-caprolactone), the hydrolytic degradation of poly(CCL-co-CL) was much faster, which is confirmed by the weight loss and change of intrinsic viscosity.     

Synthesis and barrier properties of poly(ε-caprolactone)-layered silicate nanocomposites

A new polymer-ceramic nanocomposite has been synthesized consisting of well-dispersed, two-dimensional layers of an organically modified mica-type silicate (MTS) within a degradable poly(ε-caprolactone) matrix. A protonated amino acid derivative of MTS was used to promote delamination/dispersion of the host layers and initiate ring-opening polymerization of ε-caprolactone monomer, resulting in poly(ε-caprolactone) chains that are ionically bound to the silicate layers. The polymer chains can be released from the silicate surface by a reverse ion-exchange reaction and were shown to be spectroscopically similar to pure poly(ε-caprolactone). Thick films of the polymer nanocomposite exhibit a significant reduction in water vapor permeability that shows a linear dependence on silicate content. The permeability of nanocomposite containing as low as 4.8% silicate by volume was reduced by nearly an order of magnitude compared to pure poly(ε-caprolactone). © 1995 John Wiley & Sons, Inc.     

High-pressure phase equilibrium data for systems involving carbon dioxide,globalide, ε-caprolactone,poly(globalide-co-ε-caprolactone) and dichloromethane

The growing interest in producing biocompatible polymers, free of any kind of toxic residues, increasingly encourages the development of researches on clean processes. The use of supercritical carbon dioxide, replacing organic solvents, has shown to be a green alternative to traditional polymerization processes. Aiming at providing fundamental information to conduct polymerization reactions in supercritical carbon dioxide, this work reports experimental phase equilibrium data for the quinary system involving carbon dioxide, globalide, ε-caprolactone, poly(globalide-co-ε-caprolactone) and dichloromethane. The experiments were performed using a variable-volume view cell over the temperature range from 313.15 to 343.15 K, and different mass fractions of carbon dioxide in relation to monomers and copolymer (globalide + ε-caprolactone + poly(globalide-co-ε-caprolactone)) and a fixed mass ratio of dichloromethane to globalide + ε-caprolactone + poly(globalide-co-ε-caprolactone), of 1:1, were studied. To simulate a polymerization reaction of ε-caprolactone + globalide to poly(globalide-co-ε-caprolactone) different monomers to copolymer conversions (1.25, 2.50, 3.75 and 5.00%) were analyzed. Phase transition of vapor-liquid bubble point (VLE-BP), in a pressure range from 6.31 to 12.58 MPa, and liquid-liquid (LLE), in a pressure range from 10.49 to 26.50 MPa, are reported, together with the lower critical solution temperature (LCST) behavior observed for the systems investigated. The pressure of the systems varied from 6.31 MPa to 26.50 MPa.     

交联酶聚集体与仿生硅化技术结合制备固定化脂肪酶

将交联酶聚集体(CLEAs)与仿生硅化技术相结合,制备了交联脂肪酶Candidasp.99-125杂化生物催化剂.以京尼平为交联剂,在最佳条件下制得的脂肪酶CLEAs的酶活达771U/g,回收率达75%;保护剂聚乙烯亚胺(PEI)与Candidasp.99-125脂肪酶共沉淀制备P/CLEAs,其酶活达897U/g,回收率约88%;利用PEI的诱导作用,在P/CLEAs表面形成氧化硅涂层,制得的脂肪酶CLEAs(Coated-CLEAs)显示出良好的稳定性,特别是其抗蛋白酶水解能力、有机溶剂耐受能力、重复使用性能等方面明显提高.     

PDMS migration at poly(vinyl chloride)/poly(ɛ-caprolactone)/poly(ɛ-caprolactone)-b-poly(dimethylsiloxane) blends surfaces

Films composed of poly(vinyl chloride)/poly(?-caprolactone)/poly(?-caprolactone)-b-poly(dimethylsiloxane) [PVC/PCL/(PCL-b-PDMS)] blends were prepared by solvent casting from tetrahydrofuran. The PVC content was kept constant (60 wt %) while varying the PCL and PCL-b-PDMS contents, part of the PCL (0–20 wt %) in the PVC/PCL (60/40) blend being replaced with PCL-b-PDMS with different molecular weights of the PCL blocks. The prepared blends were investigated by infrared spectroscopy and contact angle measurements. FTIR analysis and contact angle measurements indicate that the PDMS blocks tend to migrate towards the surface and this migration is preferential to the side in contact with air.     

Convenient double-enzymatic synthesis of both enantiomers of 6-methyl-ε-caprolactone

Both enantiomers of 6-methyl-ε-caprolactone (6-MeCL) are obtained in high enantiomeric excess by the combination of an enzymatic ring opening of racemic 6-methyl-ε-caprolactone and subsequent enzymatic ring closure. Immobilized Candida antarctica lipase B (Novozym 435) was selected as the biocatalyst for both the ring-opening and the ring-closing reaction. This route provides ready access to enantiopure (S)-6-MeCL (ee = 99.6%) and (R)-6-MeCL (ee = 98.8%).     

Preparation,Characterization and Drug Release Behavior of 5-Fluorouracil Loaded Carboxylic Poly(ε-caprolactone) Nanoparticles

In this paper, 5-Fluorouracil (5-FU) loaded carboxylic poly(ε-caprolactone) nanoparticles have been prepared by emulsification/solvent evaporation o/w method, and the drug release behaviors of 5-FU were investigated. The novel carboxylic poly (ε-caprolactone) (P(CL-OPD)-mal) was synthesized via conjugation of maleic anhydride to sodium borohydride (NaBH₄) reduced poly(ε-caprolactone-co -4- carbonyl -ε-caprolactone) (P(CL-OPD)), while P(CL-OPD) was synthesized in bulk by ring-opening polymerization of ε-caprolactone and 4-carbonyl-ε-caprolactone (OPD) with stannous octoate as a catalyst. Their structures were confirmed by ¹HNMR, FT-IR and GPC. Dynamic light scattering (DLS), transmission electron microscopy (TEM), zeta potential measurements were used for nanoparticle characterization. TEM and DLS showed the nanoparticles were with spherical shape and uniform size distribution (mean diameter 70～100 nm), respectively. Zeta potential analysis revealed that the nanoparticles had an increased negative surface with the increase of carboxyl group concentration. UV spectroscopy was adopted to study the entrapment and release behaviour. The maximum 5-FU loading efficiency was 14.39% with the entrapment efficiency be 42%. In vitro release studies were performed in PBS at 37°C. Results of the study showed that the release behavior can be well-controlled, and the balanced release was up to 96 h. P(CL-OPD)-mal nanoparticles would provide increased benefit in biomedical and pharmaceutical applications.     

Enzymatic Synthesizing of Phytosterol Oleic Esters

A method of synthesizing the phytosterol esters from oleic acid and sterols was studied, using immobilized lipase Candida sp. 99-125 as catalyst. Molar ratio (oleic acid/phytosterols), temperature, reaction period, organic solvents, catalyst, and silica-gel drier were optimized, and the result showed that 93.4% of the sterols had been esterified under the optimal synthetic condition: the molar ratio of oleic acid/phytosterol is 1:1 in 10 mL iso-octane, immobilized lipase (w, 140% of the sterols), incubated in an orbital shaker (200 rpm) at a temperature of 45 °C for 24 h. The immobilized lipase could be reused for at least 13 times with limited loss of esterification activity. The conversion still maintained up to 86.6%. Hence, this developed process for synthesizing phytosterol esters could be considered as simple and low-energy consumption compared to existing chemical processes.