共查询到20条相似文献,搜索用时 31 毫秒
1.
J. H. An H. S. Kim D. J. Chung D. S. Lee Sanghyo Kim 《Journal of Materials Science》2001,36(3):715-722
Thermal behavior of poly(-caprolactone)-poly(ethylene glycol)-poly(-caprolactone) tri-block copolymers with different block lengths is examined. Thermal behavior of specimens crystallized under the isothermal and dynamic condition are characterized by DSC. Also WAXD and SAXS are employed to investigate the structure. Depending on the relative length of each block, tri-block copolymers can be classified into three groups: PCL dominant crystallization; PEG dominant crystallization; and the competing case. When the crystallization of PEG and PCL are competing, the crystallization of each block shows strong dependency on the thermal hystory of crystallization, leading to multiple melting and crystallization peaks. Also, the typical micro-phase separation of block copolymers seems to play an important role, competing with crystallization, especially under the dynamic crystallization condition. 相似文献
2.
Gou ML Qian ZY Wang H Tang YB Huang MJ Kan B Wen YJ Dai M Li XY Gong CY Tu MJ 《Journal of materials science. Materials in medicine》2008,19(3):1033-1041
In this article, nano-magnetite particles (ferrofluid, Fe3O4) were prepared by chemical co-deposition method. A series of biodegradable triblock poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone)
(PCL-PEG-PCL, PCEC) copolymers were synthesized by ring-opening polymerization method from ε-caprolactone (ε-CL) initiated
by poly(ethylene glycol) diol (PEG) using stannous octoate as catalyst. And the magnetic PCEC composite microspheres were
prepared by solvent diffusion method. The properties of the ferrofluid, PCEC copolymer, and magnetic PCEC microspheres were
studied in detail by SEM, VSM, XRD, Malvern Laser Particle Sizer, 1H-NMR, GPC, and TG/DTG. Effects of macromolecular weight and concentration of polymer, and the time for ultrasound dispersion
on properties of magnetic microspheres were also investigated. The obtained magnetic PCEC microspheres might have great potential
application in targeted drug delivery system or cell separation.
This work was financially supported by Chinese Key Basic Research Program (2004CB518800 and 2004CB518807), and Sichuan Key
Project of Science and Technology (06(05SG022-021-02)).
Qian ZY and Wang H did the even work with Gou ML, and are the co-first authors for this paper. 相似文献
3.
Zhixiang Cui Brenton Nelson YiYan Peng Ke Li Srikanth Pilla Wan-Ju Li Lih-Sheng Turng Changyu Shen 《Materials science & engineering. C, Materials for biological applications》2012,32(6):1674-1681
In this study, poly(ε-caprolactone) (PCL)/sodium chloride (NaCl), PCL/poly(ethylene oxide) (PEO)/NaCl and PCL/PEO/NaCl/hydroxyapatite (HA) composites were injection molded and characterized. The water soluble and sacrificial polymer, PEO, and NaCl particulates in the composites were leached by deionized water to produce porous and interconnected microstructures. The effect of leaching time on porosity, and residual contents of NaCl and NaCl/HA, as well as the effect of HA addition on mechanical properties was investigated. In addition, the biocompatibility was observed via seeding human mesenchymal stem cells (hMSCs) on PCL and PCL/HA scaffolds.The results showed that the leaching time depends on the spatial distribution of sacrificial PEO phase and NaCl particulates. The addition of HA has significantly improved the elastic (E′) and loss moduli (E″) of PCL/HA scaffolds. Human MSCs were observed to have attached and proliferated on both PCL and PCL/HA scaffolds. Taken together, the molded PCL and PCL/HA scaffolds could be good candidates as tissue engineering scaffolds. Additionally, injection molding would be a potential and high throughput technology to fabricate tissue scaffolds. 相似文献
4.
Shape-memory polymer networks from sol–gel cross-linked alkoxysilane-terminated poly(ε-caprolactone)
Katia Paderni Stefano Pandini Simone Passera Francesco Pilati Maurizio Toselli Massimo Messori 《Journal of Materials Science》2012,47(10):4354-4362
A novel type of covalently cross-linked semi-crystalline polymer with shape-memory and biocompatibility properties was prepared
from alkoxysilane-terminated poly(ε-caprolactone) (PCL) by sol–gel process that allowed the generation of silica-like cross-linking
points. A fine tuning of the cross-linking density and thermal properties (melting temperature) of the materials was obtained
by controlling the molecular weight of the PCL precursor (and thus the molecular structure of the resulting network) and the
curing conditions. The shape-memory behaviour was investigated with bending tests. Recovery times of less than one second
were observed in water depending on the temperature, and a linear correlation of the recovery time with cross-linking density
and molecular weight of PCL network precursor was observed. 相似文献
5.
《Drug development and industrial pharmacy》2013,39(4):456-469
Background: The high water solubility and the low molecular weight of cytarabine (Ara-C) are major obstacles against its particulate formulation as a result of its low affinity to the commonly used hydrophobic polymers. Methods: Biodegradable cytarabine loaded-microparticles (Ara-C MPs) were elaborated using poly(?-caprolactone) (PCL) and monomethoxy polyethylene glycol (mPEG)–PCL diblock copolymer in order to increase the hydrophilicity of the polymeric matrix. For this purpose, a series of mPEG–PCL diblock copolymers with different PCL block lengths were synthesized. Compositions and molecular weights of obtained copolymers were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, size exclusion chromatography, and size exclusion chromatography–multi-angle laser light scattering. Ara-C MPs were prepared by double emulsion-solvent evaporation method. The effects of varying PCL block lengths on microparticle encapsulation efficiency, size, and zeta potential were evaluated. Results: Increasing the PCL block lengths of copolymers substantially increased the Ara-C encapsulation efficiency and the microparticle size but it decreased their zeta potential. Microparticles were spherical in shape, with a smooth surface and composed of homogenously distributed Ara-C-containing aqueous domains in the polymer matrix. The in vitro drug release kinetics of the optimized microparticles showed a hyperbolic profile with an initial burst release. Conclusion: These results showed the important role of the amphiphilic diblock copolymers as stabilizing agent in the encapsulation of Ara-C in PCL microparticles, suggesting their potential use for the microparticulate formulations of other small hydrophilic bioactive molecules. 相似文献
6.
G. B. C. Cardoso S. L. F. Ramos A. C. D. Rodas O. Z. Higa C. A. C. Zavaglia A. C. F. Arruda 《Journal of Materials Science》2010,45(18):4990-4993
Scaffolds of Poly (ε-caprolactone)/hydroxyapatite were produced and studied for tissue engineering applications. The materials
were selected due to its biodegradability (PCL) and bioactivity (HA), and above all their biocompatibility toward the human
tissue. The composites produced were characterized by SEM, XRD, and EDS. By analyzing these characterizations it was possible
to obtain further information about the composition and morphology aspects of all portions of the composite scaffold. 相似文献
7.
A. V. Machado S. Amorim G. Botelho I. C. Neves A. M. Fonseca 《Journal of Materials Science》2013,48(9):3578-3585
Organic–inorganic hybrid nanocomposites were prepared via in situ sol–gel process. The organic phase is a biodegradable polymer, poly(ε-caprolactone) (PCL), while the tetrabutyl titanate (TBT, Ti(OBu)4) was used as inorganic precursor. Synthesis parameters like acidity medium and precursor amount were investigated in order to assess their influence on hybrid properties. The obtained nanocomposites were characterised by thermal analysis, spectroscopic techniques, transmission electronic microscopy (TEM) and X-ray diffraction to gather information on the structure of the nanocomposites. Mechanical properties and biodegradability were also evaluated. A reaction mechanism based on Fourier transform infrared spectroscopy and NMR results was proposed using methyl acetate as model compound. TEM micrographs of the nanocomposites show a fine good nanoparticles dispersion. Acidic conditions and 10 wt% of precursor lead to a nanocomposite with higher mechanical properties and biodegradability than PCL. 相似文献
8.
Meseguer-Dueñas JM Más-Estellés J Castilla-Cortázar I Escobar Ivirico JL Vidaurre A 《Journal of materials science. Materials in medicine》2011,22(1):11-18
Alkaline hydrolysis of a polycaprolactone (PCL) network obtained by photopolymerization of a PCL macromer was investigated.
The PCL macromer was obtained by the reaction of PCL diol with methacrylic anhydride. Degradation of PCL network is much faster
than linear PCL; the weight loss rate is approximately constant until it reaches around 70%, which happens after approximately
60 h in PCL network and 600 h in linear PCL. Calorimetric results show no changes in crystallinity throughout degradation,
suggesting that it takes place in the crystalline and amorphous phases simultaneously. Scanning electron microscopy microphotographs
indicate that degradation is produced by a different erosion mechanism in both kinds of samples. The more hydrophilic network
PCL would follow a bulk-erosion mechanism, whereas linear PCL would follow a surface-erosion mechanism. Mechanical testing
of degraded samples shows a decline in mechanical properties due to changes in sample porosity as a consequence of the degradation
process. 相似文献
9.
Altpeter H Bevis MJ Grijpma DW Feijen J 《Journal of materials science. Materials in medicine》2004,15(2):175-184
Biodegradable polymers such as poly(lactide) (PLA) and poly(epsilon-caprolactone) (PCL) are increasingly used in biomedical applications as temporary implants. However, melt processing of these materials in particular of PLA is difficult due to the temperature sensitivity. Within this study, PLA and PCL were injection molded conventionally and by using the process shear controled orientation in injection molding (SCORIM) in order to investigate the effect of processing parameters on the physical properties of the moldings. Therefore, flexural testing, differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), molecular weight (MW) and orientation measurements were performed. PLA showed high sensitivity to melt temperature. In the case of amorphous poly(DL-lactide), the molecular weight and subsequently the ductility is substantially reduced by processing at higher melt temperatures. In the case of crystallizable poly(L-lactide), higher melt temperatures and shear induced by the SCORIM process resulted in enhanced crystallinity, which compromised the mechanical properties. Generally, SCORIM processing improved the mechanical properties, in particular the ductility, by orientating the molecular structure. PCL was shown to be less sensitive to shear and temperature than PLA. Stress at yield and stiffness are more improved by SCORIM processing. However, the processing temperature in combination with the grade used proved to be influential for the mechanical properties of resulting moldings. 相似文献
10.
Non-isothermal crystallization behavior of poly(ε-caprolactone) (PCL)-grafted multi-walled carbon nanotubes (MWNTs) was studied in order to determine the effects of functionalized MWNTs (f-MWNTs) on its crystallization behavior. Differential scanning calorimeter measurements showed that an introduction of f-MWNTs into the PCL molecules induced heterogeneous nucleation and the crystal growth process was significantly affected. X-ray diffraction showed a decrease in the crystallinity of composites with the addition of f-MWNTs in PCL, likely due to the occurrence of more heterogeneous nucleation induced by f-MWNTs in the samples. The activation energy for crystallization of PCL drastically reduced with the presence of 2 wt.% f-MWNTs in the samples and increased slightly with increasing content of f-MWNTs. A spherulite structure of PCL-grafted MWNTs with MWNTs at the center was developed, clearly indicating the nucleating action of MWNTs in the crystallization process. The experimental data were also analyzed using various kinetic models e.g., Avrami, Tobin, Ozawa, etc. 相似文献
11.
Silicon-substituted hydroxyapatite/poly(ε-caprolactone) composite coatings were prepared on titanium substrate by electrophoretic
deposition in n-butanol and chloroform mixture. The effect of the concentration of poly(ε-caprolactone) in suspension on the morphology and
the microstructure of coatings were investigated, furthermore, the thermal behavior and in vitro bioactivity were also investigated.
The results show that the coarse and accidented silicon-substituted hydroxyapatite/poly(ε-caprolactone) composite coatings
were obtained by electrophoretic deposition when the concentration of poly(ε-caprolactone) in suspension was 6–16 g/l. The
adsorption of poly(ε-caprolactone) on the surface of Si–HA particles hinders the electrophoretic deposition of Si–HA. The
shear-testing experiments indicated that the addition of poly(ε-caprolactone) in suspension is in favor of improving the bonding
strength of the coatings. After immersion in simulated body fluid for 8 days, silicon-substituted hydroxyapatite/poly(ε-caprolactone)
composite coatings have the ability to induce the bone-like apatite formation. 相似文献
12.
Yongkang Bai Xinrui Zhang Qihua Wang Tingmei Wang 《Journal of Materials Science》2014,49(5):2252-2262
Preparation of shape memory polymers (SMPs) with broad transition temperature was an effective method to realize multishape memory effect. In this study, a novel SMP with a broad glass transition temperature (T g) based on microcrystalline cellulose was prepared. The structure of the SMP was analyzed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance, which can prove the successful synthesis of the material. The thermal properties were investigated with differential scanning calorimetry and dynamic mechanical analysis (DMA). The dual- and multishape memory effects were also quantificationally analyzed by DMA. Further, the influence of programming temperature within T g on dual-shape memory effect was investigated, and a 1D model was built to explain their relationship. 相似文献
13.
E. Ibarboure 《Thin solid films》2009,517(11):3281-968
We report the self-assembly behavior of graft polyurethanes combining in its structure soft lateral poly(n-butyl acrylate) (PnBuA) chains with rigid and crystallizable polycaprolactone (PCL) segments. Segmented polyurethanes microphase separated into high-glass transition temperature PCL hard and low-glass transition temperature PnBuA soft domains. The variation of the microstructure as a function of the hard segment content (ratio hard to soft segments) within the structure has been studied by using atomic force microscopy. Additionally, the crystallization mechanism appeared to be directly related to the properties of the substrates forming parallel lamellar structures on hydrophilic substrates and perpendicular lamellae with hydrophobic substrates. 相似文献
14.
Ibuprofen-loaded poly(ε-caprolactone) layered silicate nanocomposites prepared by hot melt extrusion
Kayleen T. Campbell Duncan Q. M. Craig Tony McNally 《Journal of materials science. Materials in medicine》2010,21(8):2307-2316
Ibuprofen loaded poly(ε-caprolactone) (PCL) layered silicate nanocomposites were prepared by hot-melt extrusion. The morphology
and extent of dispersion of ibuprofen and layered silicate was studied using a combination of wide-angle X-ray diffraction
(WAXD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM).
Exhaustive examination across the length scales revealed the composite to have both an intercalated and exfoliated morphology.
The ibuprofen was well dispersed and distributed throughout the PCL matrix. Most significantly, the static tensile and dynamic
mechanical properties of PCL can be manipulated as a function of nanoclay loading and is dependent on the aspect ratio of
clay platelets. The glass transition of PCL increased by up to 16°C on addition of nanoclay, as determined from dynamic mechanical
thermal analysis (DMTA). This behaviour was attributed to the constrained mobility of PCL chains intercalated between clay
platelets and to the tethering of PCL chains by hydrogen bonding with platelet edges. As a consequence, PCL crystallisation
was inhibited and confirmed from non-isothermal crystallisation experiments using differential scanning calorimetry (DSC).
The fraction of PCL that was crystalline (Xc) decreased by 15% on addition of ibuprofen and nanoclay, although the temperature of crystallisation (Tc) did not change significantly. The dissolution of ibuprofen from PCL can be retarded by addition of layered silicates (nanoclays)
to the polymer matrix. 相似文献
15.
Li L Li G Jiang J Liu X Luo L Nan K 《Journal of materials science. Materials in medicine》2012,23(2):547-554
Development of fibrous scaffold of hydroxyapatite/biopolymer nanocomposite offers great potential in the field of bone regeneration
and tissue engineering. Hydroxyapatite (HA)/poly (ε-caprolactone) (PCL) fibrous scaffolds were successfully prepared by electrospinning
dopes containing HA and PCL in this work. It was found that pre-treating HA with γ-glycioxypropyltrimethoxysilane (A-187)
was effective in improving HA dispersion both in solutions and in a PCL matrix. Mechanical properties of the scaffolds were
greatly enhanced by the filling of A187-HA. The bioactivity of PCL was remarkably improved by the addition of HA and A187-HA.
Fibroblasts and osteoblasts were seeded on scaffolds to evaluate the effect of A-187 on biocompatibility of HA/PCL composites.
Based on this study, good dispersion of HA in PCL matrix was granted by pretreatment of HA with A-187 and A187-HA/PCL fibrous
scaffolds were obtained by electrospinning. These results demonstrated that the scaffolds may possess improved mechanical
performance and good bioactivity due to A187-HA incorporation. 相似文献
16.
Mi-Jin Kim Young-Hag Koh 《Materials science & engineering. C, Materials for biological applications》2013,33(4):2266-2272
We synthesized poly(ε-caprolactone) (PCL)/hydroxyapatite (HA) composite microspheres with an aligned porous structure and evaluated their potential applications in bone tissue engineering. A range of HA particles (0, 5, 10 and 20 wt.% in relation to the PCL polymer) were added to a PCL solution in order to improve the biocompatibility of the porous PCL/HA composite microspheres. All the synthesized microspheres showed that the HA particles were distributed well in the PCL matrix, while preserving their aligned porous structure. The average size of the PCL/HA composite microspheres increased from 62 ± 7 to 179 ± 95 μm with increasing HA content from 0 to 20 wt.%. The incorporation of the HA particles to the PCL polymer led to a considerable improvement in in vitro bioactivity, which was assessed by immersing the PCL/HA composite microspheres in simulated body fluid (SBF). A number of apatite crystals could be precipitated on the surface of the aligned porous PCL/HA composite microspheres after soaking in the SBF for 7 days. 相似文献
17.
Zeeshan Khatri Ryu Nakashima Gopiraman Mayakrishnan Ki-Hoon Lee Young-Hwan Park Kai Wei Ick-Soo Kim 《Journal of Materials Science》2013,48(10):3659-3664
Recently, attempts have been made to develop nanofiber tubes suitable for nerve regeneration made of biodegradable nanofibers. Among all polymeric nanofibers, poly(ε-caprolactone) (PCL) is distinctively known for better mechanical stability and poly(l-lactic acid) (PLLA) for relatively faster biodegradability. Our purpose of study is to investigate their blending compatibility and the ability to form nanofiber tubes via electrospinning. We electrospun the PCL–PLLA nanofiber tubular using different blend ratios of PCL–PLLA. The electrospun nanofibers were continuously deposited over high speed rotating mandrel to fabricate nanofiber tubes having inner diameter of 2 mm and the wall thickness of 55–65 μm. The diameters of nanofibers were between 715 and 860 nm. The morphologies of PCL–PLLA nanofiber tubes were examined under scanning electron microscope, and showed better structural stability and formability than the neat PLLA nanofibers. Fourier transform infrared spectroscopy study revealed that the PCL–PLLA blend nanofiber exhibited characteristic peaks of both PCL and PLLA and was composition-dependent. Raman and X-ray diffraction studies showed that the increasing PCL ratio in the PCL–PLLA blend increased crystallinity of PCL–PLLA blends. Differential scanning calorimetry revealed recrystallization peaks in PCL–PLLA blends ratios of 1:2 and 1:1. Based on characterization, the electrospun PCL–PLLA nanofiber tubes is considered to be a better candidate for further in vivo or in vitro investigation, and resolve biocompatibility issues in tissue engineering. 相似文献
18.
Self-healing (SH) polymers are responsive polymeric materials that can repair mechanical damage such as cracks in an autonomous fashion. In most SH polymers studies reported to date, crack closure was either unaddressed or achieved by manual intervention. Here, we report a new strategy that utilizes shape memory (SM) to prepare novel SH polymers that are capable of simultaneously closing and rebonding cracks with a simple thermal trigger. This strategy, termed "shape memory assisted self-healing (SMASH)", is demonstrated in a blend system consisting of cross-linked poly(ε-caprolactone) network (n-PCL) with linear poly(ε-caprolactone) (l-PCL) interpenetrating the network, and exhibits a combination of SM response from the network component and SH capacity from the linear component. Thermomechanical analysis revealed that the thermoset, n-PCL, demonstrates reversible plasticity -a form of shape memory where large plastic deformation at room temperature is fully recoverable upon heating. This SM action assists to close any cracks formed during deformation and/or damage while l-PCL chains tackify the crack surfaces by diffusion to the free surface and ultimately across the area of damage during the same heating step as used for SM. In our study, we investigated the controlled damage and SMASH healing of blends with varying composition using tensile testing of essential work of fracture film specimens. The healing component, l-PCL used had a high M(w) (M(w) ~65k g/mol) to enable re-entanglement after diffusion across the interface while the shape memory component, n-PCL was prepared from PCL telechelic diacrylates and a tetrathiol cross-linker, yielding excellent shape memory. We found excellent self-healing of films by the SMASH mechanism, with near complete healing for l-PCL contents exceeding 25 wt %. Applications are envisioned in the area of self-healing bladders, inflated structure membranes, and architectural building envelopes. 相似文献
19.
Bo Lei Kwan-Ha Shin Da-Young Noh In-Hwan Jo Young-Hag Koh Hyoun-Ee Kim Sung Eun Kim 《Materials science & engineering. C, Materials for biological applications》2013,33(3):1102-1108
This study investigated the effect of the addition of sol–gel derived nanoscale bioactive glass (NBG) particles on the mechanical properties and biological performances of PCL polymer, in order to evaluate the potential applications of PCL/NBG composites for bone tissue regeneration. Regardless of the NBG contents (10, 20, and 30 wt.%), the NBG particles, which were synthesized through the sol–gel process using polyethylene glycol (PEG) polymer as a template, could be uniformly dispersed in the PCL matrix, while generating pores in the PCL/NBG composites. The elastic modulus of the PCL/NBG composites increased remarkably from 89 ± 11 MPa to 383 ± 50 MPa with increasing NBG content from 0 to 30 wt.%, while still showing good ultimate tensile strength in the range of 15–19 MPa. The hydrophilicity, water absorption and degradation behavior of the PCL/NBG composites were also enhanced by the addition of the NBG particles. Furthermore, the PCL/NBG composite with a NBG content of 30 wt.% showed significantly enhanced in vitro bioactivity and cellular response compared to those of the pure PCL. 相似文献
20.
Rodrigues Ana A. Batista Nilza A. Malmonge Sônia M. Casarin Suzan A. Agnelli José Augusto M. Santos Arnaldo R. Belangero William D. 《Journal of materials science. Materials in medicine》2021,32(11):1-12
Journal of Materials Science: Materials in Medicine - A thin endocrown restoration was often applied in endodontically treated teeth with vertical bite height loss or inadequate clinical crown... 相似文献