Porous biodegradable polyester blends of poly(L‐lactic acid) and poly(ε‐caprolactone): physical properties,morphology, and biodegradation

Poly(L ‐lactic acid) (PLLA), poly(ε‐caprolactone) (PCL), and their films without or blended with 50 wt% poly(ethylene glycol) (PEG) were prepared by solution casting. Porous films were obtained by water‐extraction of PEG from solution‐cast phase‐separated PLLA‐blend‐PCL‐blend‐PEG films. The effects of PLLA/PCL ratio on the morphology of the porous films and the effects of PLLA/PCL ratio and pores on the physical properties and biodegradability of the films were investigated. The pore size of the blend films decreased with increasing PLLA/PCL ratio. Polymer blending and pore formation gave biodegradable PLLA‐blend‐PCL materials with a wide variety of tensile properties with Young's modulus in the range of 0.07–1.4 GPa and elongation at break in the range 3–380%. Pore formation markedly increased the PLLA crystallinity of porous films, except for low PLLA/PCL ratio. Polymer blending as well as pore formation enhanced the enzymatic degradation of biodegradable polyester blends. Copyright © 2006 Society of Chemical Industry     

Which is more effective for protein adsorption: surface roughness,surface wettability or swelling? Case study of polyurethane films prepared from castor oil and poly(ethylene glycol)

In order to investigate the effects of surface roughness, surface wettability and swelling on protein adsorption, polyurethane films were prepared from castor oil (CO) and poly(ethylene glycol)‐3000 (PEG) using one‐shot bulk polymerization. Hexamethylene diisocyanate and 1,4‐butanediol were used as isocyanate and chain extender, respectively. The hydrophilicity of the polyurethane films was adjusted by varying the ratio of CO to PEG. The surface of the polyurethane films was treated using plasma polymerization in the presence of acrylic acid vapour. Therefore, the polyurethane films could be obtained with the same hydrophilicity but with different roughness. The hydrophilicity of untreated and treated polymer films was examined using contact angle measurements. The surface topology of the polymer films was investigated using scanning electron microscopy and atomic force microscopy. Adsorption of bovine serum albumin and bovine serum fibrinogen on treated and untreated polymer films was determined and the performance of the films was compared. After evaluation of all results it is found that surface roughness and swelling are as important as hydrophilicity for protein adsorption in the case of CO/PEG‐based polyurethanes. © 2012 Society of Chemical Industry     

Adjustable thermal property of polyethylene glycol/diatomite shape‐stabilized composite phase change material

The work involves the fabrication, characterization, and thermal properties of polyethylene glycol (PEG)/diatomite powder (DP), which can be used as a novel shape‐stabilized composite phase change material (CPCM). The maximum load of PEG in DP can reach 55% while PEG melts during solid–liquid phase transformation. Differential scanning calorimeter results indicated that the melting temperature of the new CPCMs could be adjusted from 34 to 59°C and that the solidifying temperature could be adjusted from 27 to 44°C. Corresponding latent heats of the melting and solidifying processes were 77.27–106.5 J/g and 72.07–94.93 J/g, respectively. Scanning electronic microscope, Fourier transform infrared spectroscopy, and X‐ray diffraction results indicated that PEG was well dispersed in diatomite pores and no chemical changes took place during thermal cyclic test. Thermo‐gravimetric analysis indicated that the CPCMs had good thermal and chemical stability and reliability when diatomite was immersed into melting PEG at 75°C for 90 min. Thermal conductivity of the CPCMs increased from 0.36 to 0.71 W/mK after adding 10 wt% expanded graphite (EG). POLYM. COMPOS., 37:854–860, 2016. © 2014 Society of Plastics Engineers     

Poly(ethyl glycol) assisting water sorption enhancement of poly(ε‐caprolactone) blend for drug delivery

Poly(ε‐caprolactone) (PCL) has been thermally synthesized, and then fractionated to blend with poly(ethyl glycol) (PEG). Blend films of PCL and PEG have been prepared by solution casting. Fourier transform infrared spectrum and differential scanning calorimetry of the films have been carried out, and the results indicate some hydrogen bonding interaction between the two components, which is resulted from the carbonyl groups of PCL and the hydroxyl end‐groups of the low‐molecular‐weight PEG. Scanning electron microscope images of the blend films reveal porous network structures for their surfaces and for their inner parts and the porous structure becomes more pronounced with the increase of PEG in the blend film. Ibuprofen (IBU) was used as the model drug to test the drug release behavior for the PCL/PEG blend matrices. The results show that IBU could be released from the blend tablets rapidly, and the release rate increases with PEG content. Analysis of the release profiles indicates PCL erosion control release mechanism of pure PCL tablet, but drug diffusion control of the blend tablet, because PEG can absorb water to allow water feasible to diffuse into drug core and dissolve drug. Therefore, the interconnected channels in the blend matrices and the hydrophilic nature of PEG contribute to the improvement of the IBU release rate. The research indicates that drug release rate from PCL based material could be efficiently improved by addition of small amount of hydrophilic low‐molecular‐weight PEG. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structure and Performance of Poly(vinylidene chloride‐co‐vinyl chloride) Porous Membranes with Different Additives

Poly(vinylidene chloride‐co‐vinyl chloride) (P(VDC‐co‐VC) membranes were prepared by non‐solvent‐induced phase separation and adjusted by adding water‐soluble polyethylene glycol (PEG) and water‐insoluble silicon dioxide (SiO₂) hydrophilic nanoparticles. The structure of pores and antifouling performance were investigated to illustrate the effect of these nanoparticles. The cross section of the P(VDC‐co‐VC) membrane exhibited more macropores and the typical finger‐like pores turned into more vertically interconnected ones with increasing PEG content, while the number and size of finger‐like pores became less with increasing SiO₂ content. Considering the filtration and antifouling experiments, the presence of hydrophilic PEG and SiO2 nanoparticles in the P(VDC‐co‐VC) polymer matrix improved the membrane performance in terms of high flux, high BSA rejection ratio, and fouling resistance.     

模板组装纳米TiO2多孔膜及形成机理

以钛酸丁酯(TBTi)为原料，加入高分子表面活性剂聚乙二醇(PEG)作模板，采用溶胶-凝胶技术合成了孔径10～500nm可调的纳米TiO2多孔薄膜。扫描电镜(SEM)观察结果表明，合成过程中水含量增加形成的薄膜孔密度减小，而PEG加入量的增加，薄膜表面孔径和孔密度增大。通过红外光谱测试对溶胶-凝胶过程中发生的物理化学变化进行了系统的分析，初步探讨了薄膜多孔结构的形成机理。     

光催化多孔TiO2薄膜的表面形貌对亲水性的影响

从含聚乙二醇（ＰＥＧ）的钛醇盐溶胶前驱体中通过溶胶－凝胶工艺在普通钠钙玻表面制备了多孔锐钛矿型ＴｉＯ２纳米薄膜。用扫描电镜（ＳＥＭ）,Ｘ射线光电子能谱（ＸＰＳ）和红外光谱（ＩＲ）分析了ＴｉＯ２薄膜表面的微结构,结果表明,随着前驱物中聚乙二醇的加入量和分子量的增加,聚乙二醇热分解后的薄膜中产生的气孔就越多且孔径越大,同时ＴｉＯ２薄膜表面的羟基含量增加且表面粗糙度增大。接触角测试表明：随着薄膜中气孔数     

Formation of nanoporous poly(methyl silsesquioxane) thin films using adamantane for low‐k application

Nanoporous poly(methyl silsesquioxane) PMSSQ thin films for low‐k application have been prepared using chemically attached adamantylphenols as pore generating materials (porogen). To obtain the mechanically stable porous structure, multifunctional 1,2‐bistrimethoxysilylethane (BTMSE) was employed in addition to methyltrimethoxysilane as a main matrix material. From the decomposition of porogen, confirmed by FTIR and TGA, the nanoporous thin films containing pores less than 5 nm, which are characterized using sorption analysis, were successfully achieved. The dielectric constant was significantly decreased to 1.9, while maintaining the stable mechanical properties with the elastic modulus of 3.7 GPa measured by a nanoindenter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

聚乙二醇对非水解溶胶-凝胶法制备TiO2薄膜结构及性能的影响

采用非水解溶胶-凝胶法制备了多孔TiO2光催化薄膜.用紫外光照甲基橙的降解实验研究了聚乙二醇(polyethylene glycol,PEG)分子量和添加量对TiO2薄膜光催化活性的影响.应用场发射扫描电镜分析了薄膜的显微结构与其光催化性能的关系.结果表明:当PEG的相对分子量为1 000,PEG与TiCl4的摩尔比为0.1时,薄膜的比表面积大,薄膜颗粒细小,薄膜中存在均匀分布的大量微小孔隙,其光催化性能最佳.PEG的分子量和加入量过高或过低均会降低薄膜的光催化性能.当PEG的分子量过小或其加入量过少时,TiO2薄膜显微结构的特点是晶粒粗、孔隙数量多和孔径大.PEG的分子量过大或加入量过多,薄膜的颗粒细小,但前者导致薄膜致密而后者又促使薄膜多孔.     

Poly(ethylene glycol)‐modulated cellular biocompatibility of polyhydroxyalkanoate films

Polyhydroxybutyrate (PHB) and its copolymer with hydroxyvalerate, P(HB‐co‐HV), are widely used biomaterials. In this study, improvements of their biological properties of degradability and compatibility were achieved by blending with low‐molecular‐weight poly(ethylene glycol) (PEG106) approved for medical use. Surface morphology and chemistry are known to support cell attachment. Attachment and proliferation of neural olfactory ensheathing cells increased by 17.0 and 32.2% for PHB and P(HB‐co‐HV) composite films. Cell attachment was facilitated by increases in surface hydrophilicity, water contact angles decreased by 26 ± 2° and water uptake increased by 23.3% depending upon biopolymer and PEG loading. Cells maintained high viability (>95%) on the composite films with no evidence of cytotoxic effects. Assays of mitochondrial function and cell leakage showed improved cell health as a consequence of PEG loading. The PEG component was readily solubilised from composite films, allowing control of degradation profiles in the cell growth medium. Promotion of biopolymer compatibility and degradability was not at the expense of material properties, with the extension to break of the composites increasing by 5.83 ± 1.06%. Similarly, crystallinity decreased by 36%. The results show that blending of common polyhydroxyalkanoate biomaterials with low‐molecular‐weight PEG can be used to promote biocompatibility and manipulate physiochemical and material properties as well as degradation.© 2013 Society of Chemical Industry     

Studies on thermal activities of fabrics treated by polyethylene glycol

In this study, the special adjusting‐temperature function of polyethylene glycol (PEG) with low molecular weight was introduced. PEGs and a two‐group mixing system of PEGs of different molecular weights were added to fabrics, respectively, and the thermal activities of modified fabrics were studied. In addition, the thermal stability of PEG and fabric at a higher curing temperature was also discussed in detail. The results showed that the thermal properties of PEG decreased after being crosslinked to fabrics and the thermal activity parameters of treated fabrics could be changed and adjusted by selecting an appropriate two‐group mixing system. Some thermolysis and thermooxidative degradation of PEG and fabric used in the investigations might take place at higher curing temperatures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2288–2292, 2003     

Fabrication of superhydrophobic silica‐based surfaces with high transmittance by using polypropylene and tetraeyhoxysilane precursors

Preparation of superhydrophobic silica‐based surfaces via sol–gel process by adding polyethylene glycol (PEG) polymer into the precursor solution has been developed. Surface roughness of the films was obtained by removing the organic polymer at 500°C and then the hydrophobic groups bonded onto the films were obtained by self‐assembly modification with a monolayer. Characteristic properties of the as‐prepared films were analyzed by contact angle measurements, scanning electron microscopy, atomic force microscopy, UV–vis scanning spectrophotometer, and X‐ray photoelectron spectrophotometer. The experimental parameters were varied by the type of silane species, the R ratio, the hydrolysis time of the precursor solution, the molecular weight of PEG, the pH value of mixing solution, and the different reagents for modification. The results showed that optimum ratio of TEOS/H₂O/ethanol in the sol–gel process for precursor solution was set to 1/10/4. The better contact angles of the films can be obtained by the acid catalyst reaction, especially the pH value of mixing solution was adjusted to 0. When the as‐prepared rough films were modified with (tridecafluoro‐1,1,2,2‐tetrahydrooctyl) dimethylchlorosilane (TFCS), the contact angle of the film can be promoted to 150.4°, and the transmittance of the films in the visible light region was greater than 94.5%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Environmental degradation of biodegradable polyesters. IV. The effects of pores and surface hydrophilicity on the biodegradation of poly(ϵ‐caprolactone) and poly[(R)‐3‐hydroxybutyrate] films in controlled seawater

Poly(?‐caprolactone) (PCL) and poly[(R)‐3‐hydroxybutyrate] (R‐PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as‐cast blend films (1:1) and by the alkali treatment of as‐cast nonporous films, respectively. These films, as well as as‐cast nonporous PCL and R‐PHB films, were biodegraded in static seawater kept at 25°C, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R‐PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 587–593, 2003     

凝胶热处理方式对Fe-TiO2薄膜表面形态及亲水性能的影响

实验采用溶胶-凝胶法,以聚乙二醇（PEG）为致孔剂制备了仿生的Fe3+掺杂TiO2（Fe- TiO2）多孔薄膜。应用TG-DSC分析了凝胶薄膜的热分解行为,采用SEM、XRD及接触角测定仪等分析测试手段分别考察了两种热处理方式对形成薄膜的表面形态、相态以及亲水性的影响。结果表明：由恒温方式处理得到的薄膜连续无裂纹,其表面形成了分布均匀的、直径2～5 μm的球面形气孔,而升温方式得到的薄膜其表面形成了分布均匀的、直径约100 μm的葵花状斑块;溶胶不经陈化得到的薄膜为无定形,而经80 ℃、8 h陈化后制备的薄膜为锐钛型;采用Fe3+掺杂及在薄膜表面形成气孔,能显著提高TiO2薄膜的亲水性,并且恒温热处理方式得到的薄膜其亲水性优于升温方式得到的薄膜样品。     

Preparation of silk fibroin–poly(ethylene glycol) conjugate films through click chemistry

Azide silk fibroin (azido SF) and alkyne terminal poly(ethylene glycol) (PEG) 2000 (acetylene‐terminal PEG 2000) were synthesized. Azido SF was reacted with acetylene‐terminal PEG 2000 to produce films via a copper‐mediated 1,3‐cycloaddition (‘click’ chemistry) generating a triazole linkage as the networking forming reaction. Through click chemistry, novel silk‐based films with various weight ratios were prepared and investigated. Fourier transform infrared, X‐ray diffraction and differential scanning calorimetry analyses showed that the ordered association of the PEG molecules is strongly constrained by the presence of the SF molecules and crosslinking and that the presence of acetylene‐terminal PEG 2000 in the films induced crystallization to a β‐sheet of SF chains. Water content and contact angle measurements indicated that the hydrophilicity of the films increased compared with SF. SF–PEG films exhibited smooth and rough structures, depending on degree of crosslinking and on the weight ratio of SF and PEG, as shown by scanning electron microscopy. Copyright © 2011 Society of Chemical Industry     

Preparation and characterization of poly(ethylene glycol) crosslinked chitosan films

Poly(ethylene glycol) (PEG) crosslinked chitosan films with various PEG to chitosan ratio and PEG molecular weight were successfully prepared via the epoxy‐amine reaction between chitosan and PEG‐epoxy. The thermal and mechanical properties and swelling behavior were studied for the PEG crosslinked chitosan films. The mechanical strength of chitosan films were greatly enforced by the introduction of PEG‐epoxy, achieving an elongation of about 80%. It was found that the crosslinked chitosan films form hydrogel in water, achieving a swelling ratio higher than 20 times of original weight. The swelling behavior of chitosan films relied greatly on the molecular weight of the crosslinker PEG‐epoxy and the weight percent of PEG‐epoxy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Improvement of Permeability of Poly(vinyl alcohol) Hydrogel by Using Poly(ethylene glycol) as Porogen

The porous structure of PVA hydrogel achieved with varying content and varying molecular weight of PEG was investigated. It was found that with increasing content or molecular weight of PEG, the diffusion coefficient D _e and UV transmission of ink solution increased, indicating that the permeability and mass transfer capability of the gel beads were enhanced. The swelling rate constant k and equilibrium swelling rate of the gel were significantly improved by addition of PEG, and many pores formed inside the gel to provide channels for microbial metabolites. With increasing molecular weight of PEG, the size of pores became increasingly large.     

Dimedone and phenylazo dimedone chelates of europium as emitters in polymers

Transparent polymers when incorporated with strongly fluorescent europium chelates were found to be responding to excitation with UV radiation. In this work, two novel europium chelates have been synthesized using the β‐diketones dimedone and phenylazo dimedone along with 1,10‐phenanthroline. These chelates were characterized by elemental analyses, magnetic susceptibility measurements, UV, IR, and ESI mass spectral techniques. The chelates synthesized with metal : β‐diketone : 1,10‐phenanthroline ratio 1 : 3 : 1 were incorporated into polymer matrices. Four polymers, polyethylene vinyl acetate or acetate (EVA), polystyrene (PS), poly methyl methacryalate (PMMA), and polyethylene glycol (PEG) were used for the studies. All these, except the liquid oligomer PEG were cast into thin films. PEG was used as such for the studies. The photoluminescence spectra of the plain polymers were found to be having peaks very close to the absorption peaks of the polymers doped with europium chelate. This observation can be used in optical devices. Thermal analyses like TG/DTG/DTA of the polymer films were conducted to ascertain the thermal stability of the material. The SEM analyses of the films indicated a smooth surface with uniform distribution of the doped chelate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhancing hydrophilicity of polyethylene terephthalate surface through melt blending

In many industrial sectors, the surface properties of polymers are of particular importance. This applies, for instance, to painting, printing, and any coating on surface of polymeric objects. Hydrophilicity and wettability characteristics are known to be determined by the chemical makeup of the polymer surface. Blending with an additive or a polymer containing high‐energy functional groups is widely recognized as a potential technique to overcome disadvantages of low surface energy of polymers due to its convenient processing. Surface migration of polyethylene glycol (PEG) in Polyethylene Terephthalate (PET) host was investigated using a low‐molecular‐weight PEG (8 kDa) because of its good hydrophilicity, low toxicity, biocompatibility, and chain mobility. A twin‐screw extruder was used to blend the materials and prepare the polymer blend films. The results of surface characterizations showed that PEG renders the PET surface more hydrophilic, but not high enough for many applications. In a second approach, the addition of a third component, polystyrene (PS), to the blend in a small amount resulted in a remarkable surface enrichment of PEG at the polymer/air interface for the ternary polymer blend (PET‐PEG‐PS). Surface analysis revealed that the surface concentration of PEG in the ternary polymer blend film was significantly larger than that of the binary one. POLYM. ENG. SCI., 55:349–358, 2015. © 2014 Society of Plastics Engineers     

Rheological characterization of chitosan matrices: Influence of biopolymer concentration

Viscoelastic properties of chitosan (CH), chitosan‐poly(ethylene glycol) 400 (CH‐PEG), and chitosan‐poly(ethylene glycol) 400 with glyoxal as crosslinking agent (CH‐PEG‐Gly) systems were studied to analyze the effect of chitosan concentration (from 0.83 to 1.67%). Dynamic moduli increase as chitosan concentration increases for all systems. For CH and CH‐PEG systems the loss modulus (G″) is greater than the storage modulus (G′) with predominance of the viscous over the elastic behavior. This corresponds to the characteristic behavior of solutions (nonstructured systems). The presence of PEG 400 induces a complementary reinforcement of the mechanical properties of the system. Except for the lowest chitosan concentration, when glyoxal was added to the CH‐PEG systems, a gelled matrix was obtained. In this case, G′ is greater than G″, and practically independent of frequency. This behavior is typical of three‐dimensional networks and indicates true gel formation, showing clear elastic behavior (tan δ < 1). In creep and recovery analysis, CH‐PEG‐Gly systems exhibited distinct regions that were mathematically modeled using Burger's model. This analysis shows that the CH‐PEG‐Gly matrices (from 1.25 to 1.67%) recover almost totally (100%). Therefore, these matrices could be useful as systems for the development of films for topical hydrophilic drug delivery, and the levels of the residual viscosity (η₀) or the complex viscosity (η*) could be used to control drug release. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007