紫外辐射法制备聚羟基丁酸酯/聚乙二醇接枝共聚物

利用紫外辐射法制备了聚羟基丁酸酯/聚乙二醇(PHB/PEG)接枝共聚物,共聚物中聚乙二醇接枝含量分别为1.7%、2.6%、3.8%、6.4%和10.1%.利用红外光谱(FT-IR)、差示扫描量热(DSC)、广角X射线衍射(WAXD)、表面接触角及力学性能测试对不同聚乙二醇接枝含量的共聚物进行了分析研究.结果表明,接枝聚...     

偶联法制备聚羟基丁酸酯/聚乙二醇共聚物及其性能

利用二异氰酸酯为偶联剂,采用不同分子量的聚乙二醇(PEG)与聚羟基丁酸酯(PHB)进行偶联反应,制备一系列聚羟基丁酸酯/聚乙二醇共聚物。利用红外光谱(FT-IR)、差示扫描量热(DSC)、广角X射线衍射(WAXD)、表面水相接触角及力学性能实验对共聚物进行了分析研究。结果表明,偶联聚乙二醇后,PHB链的规整度降低,PHB的结晶度下降,非结晶区增大,同时表面亲水性变好,当采用高分子量的PEG后,共聚物的拉抻应力-应变曲线中出现了明显的屈服点,断裂伸长率也有了较大的提高,达到了11%,韧性得到改善,力学性能有一定程度的提高。     

Compositional study and cytotoxicity of biodegradable poly(ester urethane)s consisting of poly[(R)-3-hydroxybutyrate] and poly(ethylene glycol)

Biodegradable PHB–PEG multi-block polyurethane copolymers comprising PHB blocks (M_n: 1100, 1740 and 3240) and PEG blocks (M_n: 1960, 3250, 4150 or 7950) were synthesized followed by characterization by GPC, ¹H NMR, and FT-IR. The PHB contents ranged from 9 to 62% by weight. The copolymers displayed improved thermal stabilities compared with their respective precursors. The morphological structures of the copolymers were studied by FT-IR, DSC and XRD. FT-IR revealed the existence of amorphous and crystalline phases of PHB. Both DSC and XRD analyses showed that separate crystalline phases are formed by PEG and PHB blocks in the copolymers. Upon annealing, the melting transition temperature (T_m), melting enthalpy (ΔH_m) and the fractional crystallinity (X_c) of the PEG block increased when the length of PEG incorporated into the copolymer increased. These values were higher when the PHB block length is shorter as the shorter PHB chain does not disrupt the crystallization of PEG as much as the longer PHB chain. A similar disruptive effect on the crystallization of PHB segments was observed by varying PEG chain lengths but the effect is less pronounced compared with the PEG segments. A comparison of the swelling properties of the poly(ester urethane)s showed that the length and crystalline properties of the PHB block significantly affects the water uptake properties of the copolymers. The crystalline properties and the water uptake capacities of the copolymers could be fine-tuned by consideration of the length of the PHB and PEG block incorporated. The results of the cytotoxicity tests demonstrated that the poly(PHB/PEG) urethanes were non-cytotoxic and could potentially be used for biomedical purposes.     

Modification of titanium surfaces by adding antibiotic-loaded PHB spheres and PEG for biomedical applications

Novel researches are focused on the prevention and management of post-operative infections. To avoid this common complication of implant surgery, it is preferable to use new biomaterials with antibacterial properties. Therefore, the aim of this work is to develop a method of combining the antibacterial properties of antibiotic-loaded poly(3-hydroxybutyrate) (PHB) nano- and micro-spheres and poly(ethylene glycol) (PEG) as an antifouling agent, with titanium (Ti), as the base material for implants, in order to obtain surfaces with antibacterial activity. The Ti surfaces were linked to both PHB particles and PEG by a covalent bond. This attachment was carried out by firstly activating the surfaces with either Oxygen plasma or Sodium hydroxide. Further functionalization of the activated surfaces with different alkoxysilanes allows the reaction with PHB particles and PEG. The study confirms that the Ti surfaces achieved the antibacterial properties by combining the antibiotic-loaded PHB spheres, and PEG as an antifouling agent.     

Biocompatibility and biodegradation of poly(hydroxybutyrate)/poly(ethylene glycol) blend films

Using chloroform as co-solvent, a series of poly(3-hydroxybutyrate) (PHB) and polyethylene glycol (PEG) blend materials with different ratio ranging from 80 : 20 (wt %) to 20 : 80 (wt %) were prepared by solution blend. The blood-compatibility was evaluated by means of platelet clotting time test and exploring its morphological changes. The results showed that PEG played an important role in resisting platelet adhesion. With the increased addition of PEG, the clotting times became longer and the number of platelet adhesion decreased apparently. All platelets were in discrete state, no pseudopodium had been found and no collective phenomenon had been happened. The cell-compatibility was evaluated via Chinese Hamster Lung (CHL) fibroblast cultivation in vitro. The cells cultured on the matrix spread and proliferated well. With the increase of PEG content in the blend films, the number of live cells became more and more. These results indicated that PHB exhibited satisfying cell-compatibility and the addition of PEG also could improve the cell-compatibility of PHB. The biodegradation experiment indicated that the degradation of PHB/PEG was accelerated by enzyme in vitro and the blending of PEG was favorable to degradation.     

聚乙二醇-纤维素接枝物固态相变材料的贮热性能

用化学偶联法,将聚乙二醇(PEG)接枝到纤维素分子链上,制备聚乙二醇-纤维素接枝物。用差示扫描量热(DSC)研究了接枝物的热力学性质。结果表明,PEG-CELL接枝物的相变焓、相变温度与PEG的分子量、PEG的质量百分比有关。当PEG的分子量在2000以下时,制备的接枝物相变焓很低;当PEG的分子量大于4000时。同等分子量情况下,相变焓、相变温度随PEG的质量百分含量减少而下降．所制备的PEG-CELL接枝物为固态相变材料,热滞后性降低,具有很好的热稳定性。     

用液晶PET(40)/PHB(60)共聚酯对PET共混改性的研究

用热致性液晶高分子材料对塑料进行共混改性,借助液晶的在位复合制取自增强塑料是近年来许多人感兴趣的课题,我们合成了质量比为４０／６０的ＰＥＴ／ＰＨＢ共聚酯,用它对ＰＥＴ进行共混改性,用差示扫描量热（ＤＳＣ）、动态力学粘弹谱,以及小角激光光散射（ＳＡＬＳ）进行结构和性能的考察,表明ＰＥＴ／ＰＨＢ共聚酯对ＰＥＴ有增塑和促进结晶的作用。     

Effect of the molecular weight of polyethylene glycol (PEG) on the properties of chitosan-PEG-poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) hydrogels

Our prior study has shown that polyethylene glycol (PEG) played a crucial role in improving the properties of the physically crosslinked chitosan-PEG-poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. In this paper, we further investigated the effect of the molecular weight (MW) of PEG on the properties of the chitosan-based physical hydrogels. Fourier Transform Infrared Spectroscopy (FTIR) study showed that the interaction between PEG and other components in the physically crosslinked hydrogels became stronger as the MW of PEG increased. The wide angle X-ray diffraction (WAXD) study indicated that the crystallinity of the physical hydrogels decreased with an increase in the MW of PEG. The thermal study using differential scanning calorimetry (DSC) revealed the crystallizability of the physical hydrogels first reduced with an increase in the MW of PEG, but slightly increased thereafter with a further increase in the MW of PEG. The swelling test showed the water uptake capability of the physical hydrogels increased with an increase in the MW of PEG. The results obtained by scanning electron microscope (SEM) found that the morphological changes of the physical hydrogels with MW of PEG were consistent with the results of swelling and thermal properties; and, contrary to pure PNIPAAm hydrogels which showed a compact and dense network structure at a temperature (37 degrees C) above its LCST, the physical chitosan-PEG-PNIPAAm hydrogels exhibited porous network structure at 37 degrees C instead. The mechanical property of the physical hydrogels was initially increased with an increase in PEG MW, but deteriorated with a further increase in PEG MW. Therefore, the MW of PEG played a key role in controlling the property of the chitosan-based physical hydrogels.     

LDPE/MMT/PEG相变材料的制备及性能

以聚乙二醇(PEG)为相变物质,同层状纳米蒙脱土(MMT)进行插层复合,选择聚乙烯接枝马来酸酐(LDPE-gMAH)为增容剂在Brabender塑化机中同低密度聚乙烯(LDPE)树脂熔融共混制备复合相变材料.采用红外光谱(IR)、差示扫描量热仪(DSC)和偏光显微镜(PLM)对LDPE/MMT/PEG复合相变材料的结构...     

PEG嵌段热塑性聚氨酯弹性体的形态结构和性能

采用熔融预聚二步法合成了以环氧乙烷-四氢呋喃无规共聚醚和聚乙二醇混合聚醚为软段,异佛尔酮二异氰酸酯和1,4-丁二醇为硬段的热塑性体,利用TEM、WAXD、DSC对聚合物进行了表征,并测试了其力学性能,结果表明,聚合物具有微相分离的特征,随着聚乙二醇分子量的增大,微相分离程度增加,拉伸强度和延伸率也随着增加。当PEG分子量为4000时,聚合物的综合性能达到最优。     

GTA改性的PLA/PHB复合包装膜性能研究

目的研究三乙酸甘油脂(GTA)对PLA/PHB包装膜性能的影响。通过添加GTA提高PLA与PHB的相容性,改善包装膜的力学和透湿透氧性能。方法以GTA为增塑剂,聚乳酸(PLA)和聚β-羟基丁酸酯(PHB)为原料,利用熔融共混吹膜的方法制备PLA/PHB复合膜,通过对复合材料的DSC测试,以及透湿透氧性能、力学性能和红外光谱分析,研究GTA质量分数不同时对复合材料的拉伸性能、断裂伸长率、透湿透氧性能和相容性的影响。结果随着GTA含量的增加,薄膜拉伸强度整体呈下降趋势,同时断裂伸长率不断增大。当GTA质量分数大于4%时,拉伸强度急剧下降,断裂伸长率由原先的快速增长变为缓慢增长。透湿性能随GTA质量分数的增加先不断增大后减小,透氧性能增长不明显。通过DSC图结合包装膜断面结构微观图发现,GTA的加入减弱了聚合物分子链段之间的作用力,促进了链段的运动,使得薄膜断面上的微孔消失,形成层状结构。结论 GTA的加入改善了PLA和PHB的相容性,并且在GTA质量分数为4%时,复合包装膜既具有较好的拉伸性能和断裂伸长率,还具有较好的透湿透氧性能。     

PHB／PPO共混体系的相容性和结晶

采用溶液共混方法对聚β－羟基丁酸酯／聚氧化丙烯共混体系的相容性和结晶行为进行了研究，ＤＳＣ，ＰＯＭ，ＷＡＸＤ等实验结果表明，该体系不是相容体系。但在特殊的组成比下有相容的第三相存在。ＰＰＯ对ＰＨＢ的结晶结构无影响，但对ＰＨＢ的结晶速率和结晶完整性有很大的作用。     

聚乙二醇/聚丙烯酰胺相变材料非等温固-固相变动力学

通过在丙烯酰胺聚合反应中加入聚乙二醇的方法制得的聚乙二醇(PEG)/聚丙烯酰胺(PAAm)相变材料具有固-固相转变的性质。对聚乙二醇及五种相变材料分别进行不同速率的非等温DSC测试,采用K iss inger和O zaw a两种动力学模型研究了非等温固-固相变动力学,计算了固-固相变过程的活化能和反应级数,两种方法求得的表观活化能Ea值相一致。     

Optical nanocomposites prepared by incorporating bacterial cellulose nanofibrils into poly(3-hydroxybutyrate)

A biocompatible polymeric nanocomposite was prepared by incorporating bacterial cellulose (BC) into a poly(3-hydroxybutyrate) (PHB) matrix. The transparency of the PHB/BC nanocomposite was high due to the homogeneous nano-sized spherulite and nanofibril of PHB and BC, which are smaller than the wavelength of visible rays. The X-ray diffraction patterns of the PHB in the nanocomposite film showed peaks corresponding to the crystallized PHB. The thermal stability of PHB in the nanocomposite film has been improved. The morphology studies showed that the PHB molecules filled vacancies between BC nanofibrils. An increase in the mechanical properties was observed by incorporating the BC into the PHB matrix. This PHB/BC nanocomposite can be considered for various applications, such as display devices, tissue engineering scaffold, and food packaging, because of its improved mechanical properties along with biodegradability and biocompatibility.     

Effect of the molecular weight of a polyethylene glycol on the photoluminescence spectra of porous TiO2 films for dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) are expected to be used for future clean energy. In general, when the titania porous electrode in DSCs is made, a polyethylene glycol (PEG) is added to obtain the porous structure. Although the conversion efficiency of the DSC became high when the high molecular weight of PEG was used, its reason was not clear. In the present study, the photoluminescence spectrum of titania films with the different molecular weight of PEG was measured at room temperature, and we discussed the relation between molecular weight and the conversion efficiency of the DSC.     

Effect of the Molecular Weight of Poly(ethylene glycol) on the Properties of Biocompatible Magnetic Fluids

The effect of the molecular weight of poly(ethylene glycol) (PEG) on the physical properties of water-based magnetic fluids with sodium oleate and PEG stabilization was investigated. The structure as well as magnetic, rheological, and thermal properties of the obtained samples were studied using transmission electron microscopy (TEM), photon cross correlation spectroscopy (PCCS), superconducting quantum interference device (SQUID), and differential scanning calorimetry (DSC) methods. The molecular weight of PEG had a strong effect on the rheological properties while the effect was rather insignificant on the particle size distribution and the self-heating of the studied magnetic fluids. The heating ability of the PEG-stabilized magnetic fluids was determined by calorimetric measurements of the specific absorption rate (SAR). The thickness of the PEG layer was calculated from the experimental data of the temperature rise rates as a function of the magnetic field strength using the Rosensweig theory.     

PEG200增塑改性ACNs/MMT/PHBH纳米复合包装膜

目的 制备聚乙二醇(PEG200)-乙酰化纤维素纳米晶体/蒙脱土/聚3-羟基丁酸酯-co-3-羟基己酸酯(PHBH)纳米复合包装膜,探究PEG200对三元纳米复合材料(ACNs/MMT/PHBH)性能的影响,以获得柔韧性、分散性等性能优良的纳米复合包装膜,增加复合包装膜在包装上的可应用性.方法 通过溶液共混法制备不同比例的PEG200-ACNs/MMT/PHBH纳米复合包装膜,应用扫描电镜、傅里叶红外光谱、偏光显微镜、热重分析、差式扫描量热仪、拉伸测试仪和透氧透湿测试仪,对复合膜的断面形貌、热稳定性、晶体形貌、力学性能和阻隔性能进行分析表征.结果 扫描电镜显示,加入适量的PEG200后,纳米颗粒上具有包覆作用,使得填料与PHBH基质间的相容性得到进一步改善.力学测试结果表明,PEG200的加入使复合包装膜的韧性有一定程度的提高,当PEG200的质量分数为6％时,与未添加PEG200的包装膜相比,其断裂伸长率增加了29.9％.阻隔性能测试结果显示,当PEG200的质量分数为4％时,复合膜的阻隔性能最佳,水蒸气透过率和氧气透过率分别为26.48 g/(m2·d)和28.46 cm3/(m2·d).结论 实验结果表明,加入少量的PEG200能够改善纳米粒子与PHBH之间的相容性,提高ACNs/MMT/PHBH纳米复合材料的韧性和阻氧阻湿性能.     

Enhancement of dissolution rate of valdecoxib using solid dispersions with polyethylene glycol 4000

The aim of the present study was to enhance the dissolution rate of valdecoxib using its solid dispersions (SDs) with polyethylene glycol (PEG) 4000. The phase solubility behavior of valdecoxib in the presence of various concentrations of PEG 4000 in water was obtained at 37°C. The solubility of valdecoxib increased with increasing amount of PEG 4000 in water. Gibbs free energy (ΔG°_tr) values were all negative, indicating the spontaneous nature of valdecoxib solubilization, and they decreased with increase in the PEG 4000 concentration, demonstrating that the reaction conditions became more favorable as the concentration of PEG 4000 increased. The SDs of valdecoxib with PEG 4000 were prepared at 1:1, 1:2, 1:5, and 1:10 (valdecoxib: PEG 4000) ratio by melting method. Evaluation of the properties of the SDs was performed by using dissolution, Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM) studies. The SDs of valdecoxib with PEG 4000 exhibited enhanced dissolution rate of valdecoxib, and the rate increased with increasing concentration of PEG 4000 in SDs. Mean dissolution time (MDT) of valdecoxib decreased significantly after preparation of SDs and physical mixture with PEG 4000. The FTIR spectroscopic studies showed the stability of valdecoxib and absence of well-defined valdecoxib-PEG 4000 interaction. The DSC and XRD studies indicated the amorphous state of valdecoxib in SDs of valdecoxib with PEG 4000. The SEM pictures showed the formation of effective SDs of valdecoxib with PEG 4000, since well-defined changes in the surface nature of valdecoxib, SDs, and physical mixture were observed.     

纳米磁性壳聚糖载药体的制备与体外释药评价

以自制Fe3O4磁性纳米为磁性靶向核,在乳液体系中制备壳聚糖／三聚磷酸钠／5-Fu磁性壳聚糖纳米载药体（TCF）,经一定比例的PHB和PEG混合外包覆,得到载药率为16．56％的磁性纳米微囊（PTCF）,通过红外光谱、x-射线粉末衍射、透射电镜和振动磁强计表征,结果显示,TCF、PTCF分别为粒径15nm和20nm均匀颗粒,25℃时的矫顽力和剩磁均趋于零,表现出超顺磁性;体外释药行为显示,PTCF无突释现象,释药速率随PHB和PEG用量可控,具备磁靶向控释药物的潜在性质。     

不同相对分子质量聚乙二醇增塑聚乳酸共混物的制备与性能

文中探究不同相对分子质量聚乙二醇(PEG)对聚乳酸(PLA)增塑改性的影响。采用转矩流变仪、万能试验机、差示扫描量热分析、动态力学、热重分析、旋转流变仪等测试表征方法对共混材料的增塑效果、力学性能、热行为、流变行为进行分析。实验结果表明,PEG可有效增塑PLA,PEG相对分子质量越低增塑效果越好,可以使PLA的塑化时间从250 s降低到128 s;加入PEG后,共混物的拉伸强度下降,断裂伸长率提高,PEG相对分子质量越低,拉伸强度下降越明显;PEG的加入使PLA的T_g和T_(cc)降低20℃左右,而T_m有所提高,其中低相对分子质量PEG可以更好地促进PLA结晶,但是随着PEG的加入共混体系的热分解温度降低,相对分子质量越低,热分解温度降低越明显;流变实验表明共混体系的复数黏度(η*)、储能模量(G')及损耗模量(G')的变化随PEG相对分子质量的减小下降越明显。