Compatible ternary blends of chitosan/poly(vinyl alcohol)/poly(lactic acid) produced by oil-in-water emulsion processing

Ternary compatible blends of chitosan, poly(vinyl alcohol), and poly(lactic acid) were prepared by an oil-in-water (O/W) emulsion process. Solutions of chitosan in aqueous acetic acid, poly(vinyl alcohol) (PVA) in water, and poly(lactic acid) (PLA) in chloroform were blended with a high-shear mixer. PVA was used as an emulsifier to stabilize the emulsion and to reduce the interfacial tension between the solid polymers in the blends produced. It proved to work very well because the emulsions were stable for periods of days or weeks and compatible blends were obtained when PVA was added. This effect was attributed to a synergistic effect of PVA and chitosan because the binary blends PVA/PLA and chitosan/PLA were completely incompatible. The blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), stress-strain tests, and Fourier transform infrared spectroscopy (FTIR). The results indicated that despite the fact that the system contained distinct phases some degree of molecular miscibility occurred when the three components were present in the blend.     

Wheat gluten-thiolated poly(vinyl alcohol) blends with improved mechanical properties

A multifunctional macromolecular thiol (TPVA) obtained by esterification of poly(vinyl alcohol) (PVA) with 3-mercaptopropionic acid was characterized by a combination of NMR, IR, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC), and was used as a wheat gluten (WG) reactive modifier. The effect of TPVA molecular weight (M(w) = 2000, 9500, 50 000, and 205 000) and blend composition (5, 20, and 40% w/w TPVA/WG) on the mechanical properties of compression-molded bars indicates that TPVA/WG blends increase the fracture strength by up to 76%, the elongation by 80%, and the modulus by 25% above WG. In contrast, typical WG additives such as glycerol and sorbitol improve flexibility but decrease modulus and strength. Preliminary investigations of suspension rheology, water uptake, molecular weight distribution and electron microscopy of TPVA/WG and PVA/WG blends illustrate the different protein interactions with PVA and TPVA. Further work is underway to determine whether TPVA and WG form protein conjugates or microphase-separated morphologies.     

Electrospun water-soluble carboxyethyl chitosan/poly(vinyl alcohol) nanofibrous membrane as potential wound dressing for skin regeneration

Biocompatible carboxyethyl chitosan/poly(vinyl alcohol) (CECS/PVA) nanofibers were successfully prepared by electrospinning of aqueous CECS/PVA solution. The composite nanofibrous membranes were subjected to detailed analysis by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). SEM images showed that the morphology and diameter of the nanofibers were mainly affected by the weight ratio of CECS/PVA. XRD and DSC demonstrated that there was strong intermolecular hydrogen bonding between the molecules of CECS and PVA. The crystalline microstructure of the electrospun fibers was not well developed. The potential use of the CECS/PVA electrospun fiber mats as scaffolding materials for skin regeneration was evaluated in vitro using mouse fibroblasts (L929) as reference cell lines. Indirect cytotoxicity assessment of the fiber mats indicated that the CECS/PVA electrospun mat was nontoxic to the L929 cell. Cell culture results showed that fibrous mats were good in promoting the cell attachment and proliferation. This novel electrospun matrix would be used as potential wound dressing for skin regeneration.     

Blends of poly-(epsilon-caprolactone) and polysaccharides in tissue engineering applications

Bioartificial blends of poly-(epsilon-caprolactone) (PCL) with a polysaccharide (starch, S; dextran, D; or gellan, G) (PCL/S, PCL/D, PCL/G 90.9/9.1 wt ratio) were prepared by a solution-precipitation technique and widely characterized by differential scanning calorimetry analysis (DSC), Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), optical microscopy (OM), wide-angle X-ray diffraction analysis (WAXD), and thermogravimetry (TGA). DSC showed that the polysaccharide reduced the crystallinity of PCL and had a nucleation effect, which was also confirmed by OM analysis. Hoffman-Weeks analysis was performed on PCL and blend samples allowing calculation of their equilibrium melting temperatures (). WAXD showed that the crystalline unit cell type was the same for PCL and blends. FTIR-ATR did not evidence interactions between blend components. Thermal stability was affected by the type of polysaccharide. Microparticles (<125 microm) were produced from blends by cryogenical milling and characterized by scanning electron microscopy analysis (SEM). Selective laser sintering (SLS), a new rapid prototyping technology for scaffold fabrication, was applied to sinter blend microparticles according to a PC-designed two-dimensional geometry (strips and 2 x 2 mm(2) square-meshed grids). The optimal experimental conditions for sintering were established and laser beam parameters (beam speed, BS, and power, P) were found for each blend composition. Morphology of sintered objects was analyzed by SEM and found to be dependent on the morphology of the sintered powders. Sintered samples were analyzed by chemical imaging (CI), FTIR-ATR, DSC, and contact angle analysis. No evidence of the occurrence of degradation phenomena was found by FTIR-ATR for sintered samples, whereas DSC parameters of PCL and blends showed changes which could be attributed to some molecular weight decrease of PCL during sintering. CI of sintered samples showed that the polysaccharide phase was homogeneously dispersed within the PCL matrix, with the only exception being the PCL/D blend. The contact angle analysis showed that all samples were hydrophilic. Fibroblasts were then seeded on scaffolds to evaluate the rate and the extent of cell adhesion and the effect of the polysaccharides (S, D, G) on the bioactivity of the PCL-based blends.     

Studies of chitosan: II. Preparation and characterization of chitosan/poly(vinyl alcohol)/gelatin ternary blend films

Chitosan/poly(vinyl alcohol)/gelatin (CS/PVA/GA) ternary blend films were prepared by solution blending method in this study. The thermal properties of the CS/PVA/GA ternary blend films were examined by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The melting point of the CS/PVA/GA ternary blend film was increased when the amount of GA in the blend film was increased based upon the DSC thermal analysis. Results of X-ray diffraction (XRD) analyses indicated that the intensity of diffraction peak at 19 degrees of PVA became lower and broader with increasing the amount of GA in the CS/PVA/GA ternary blend film. Although CS, PVA, and GA are hydrophilic biodegradable polymers, the results of water contact angle measurements are still as high as 83 degrees, 68 degrees, and 66 degrees, respectively. A minimum water contact angle (56 degrees) was observed when the ternary blend film contains 50 wt.% GA (i.e. GA5). This behavior is primarily due to the reorientation of polar functional groups toward to the top surface of CS/PVA/GA ternary blend films.     

FT-IR imaging spectroscopy of phase separation in blends of poly(3-hydroxybutyrate) with poly(L-lactic acid) and poly(epsilon-caprolactone)

The detection of phase separation and identification of miscibility in biopolymer blends is an important aspect for the improvement of their physical properties. In this article, the phase separation in blends of poly(3-hydroxybutyrate) (PHB) with poly(L-lactic acid) (PLA) and poly(epsilon-caprolactone) (PCL), respectively, has been studied as a function of the blend composition by FT-IR imaging spectroscopy. For both polymer blend systems, a miscibility gap has been found around the 50:50% (w/w) composition of the two components. Furthermore, the separating phases have been identified as blends of the two polymer components and their compositions could be determined from calibrations based on the spectra of the blends in the compositional range of miscibility. The data derived from FT-IR spectroscopic imaging were corroborated by additional DSC analyses and mechanical stress-strain measurements of polymer blend films, which exhibited a characteristic fracture behavior as a function of PHB composition.     

Crystallization behavior and environmental biodegradability of the blend films of poly(3-hydroxybutyric acid) with chitin and chitosan

Crystallization behavior and environmental biodegradability were investigated for the films of bacterial poly(3-hydroxybutyric acid) (PHB) blends with chitin and chitosan. The blend films showed X-ray diffractive peaks that arose from the PHB crystalline component. It was suggested that the lamellar thickness of the PHB crystalline component in the blends was large enough to show detectable X-ray diffractive peaks, but this was too small to show observable melting endotherm in the DSC thermogram and the crystalline band absorption in the FT-IR spectrum. In the PHB/chitin and PHB/chitosan blends, thermal transition temperatures of PHB amorphous region observed by dynamic mechanical thermal analysis were almost the same as that of neat PHB. Both the PHB/chitin and the PHB/chitosan blend films biodegraded in an environmental medium. Several blend films showed faster biodegradation than the pure-state component polymers.     

Study on cast membranes and electrospun nanofibers made from keratin/fibroin blends

Keratin regenerated from wool and fibroin regenerated from silk were mixed in different proportions using formic acid as the common solvent. Both solutions were cast to obtain films and electrospun to produce nanofibers. Scanning electron microscopy investigation showed that, for all electrospun blends (except for 100% keratin where bead defects are present), the fiber diameter of the mats ranged from 900 (pure fibroin) to 160 nm (pure keratin). FTIR and DSC analysis showed that the secondary structure of the proteins was influenced by the blend ratios and the process used (casting or electrospinning). Prevalence of beta-sheet supramolecular structures was observed in the films, while proteins assembled in alpha-helix/random coil structures were observed in nanofibers. Higher solution viscosity, thinner filaments, and differences in the thermal and structural properties were observed for the 50/50 blend because of the enhanced interactions between the proteins.     

Characteristics and bending performance of electroactive polymer blend made with cellulose and poly(3-hydroxybutyrate)

This paper describes a novel cellulose/poly(3-hydroxybutyrate) blend based electroactive polymer. The fabrication process, bending actuation test and its characteristics are investigated. To prepare this new EAP, cellulose and PHB were dissolved in trifluoroacetic acid. The solution was cast to form a film followed by depositing thin gold electrode on both sides of the film. The characteristics of the cellulose/PHB film were investigated by Fourier transform infrared spectra, scanning electron microscopy, X-ray diffraction differential scanning calorimetry, tensile test and dynamic mechanical analysis. The bending performance was evaluated in terms of free bending displacement, electrical power consumption output and lifetime test under ambient conditions. Primary results show that this cellulose/PHB blend EAP is less sensitive to humidity and it shows higher bending displacement and longer lifetime than pure cellulose EAP at room humidity condition. These results indicate that this new cellulose/PHB blend EAP has potential for many biomimetic applications.     

Phase structure and enzymatic degradation of poly(L-lactide)/atactic poly(3-hydroxybutyrate) blends: an atomic force microscopy study

Phase structures and enzymatic degradation of poly(l-lactide) (PLLA)/atactic poly(3-hydroxybutyrate) (ata-PHB) blends with different compositions were characterized by using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) thermograms of PLLA/ata-PHB blends with different compositions showed two glass transition temperatures, indicating that the PLLA/ata-PHB blends are immiscible in the melt. Surface morphologies of the thin films for PLLA/ata-PHB blends were determined by AFM. Phase separated morphology was recognized from the AFM topography and phase images. The domain size of the components was dependent on the blend ratio. Enzymatic degradation of the PLLA/ata-PHB blends was performed by using both PHB depolymerase and proteinase K. Either PLLA or ata-PHB domains were eroded depending on the kinds of enzyme. Surface morphologies after enzymatic degradation have revealed the phase structure along the depth direction. Enzymatic adsorption of PHB depolymerase was examined on the surface of PLLA/ata-PHB blends. The enzyme molecules were found on both domains of the binary blends. The larger number of enzyme molecules was found on the PLLA domains relative to those on the ata-PHB domains, suggesting the higher affinity of the enzyme against PLLA domain.     

Imaging and thermal studies of wheat gluten/poly(vinyl alcohol) and wheat gluten/thiolated poly(vinyl alcohol) blends

The morphology of wheat protein (WG) blends with polyvinyl alcohol (PVA) and respectively with thiolated polyvinyl alcohol (TPVA) was investigated by atomic force (AFM) and transmission electron microscopy (TEM) as well as by modulated dynamic scanning calorimetry (MDSC). Thiolated additives based on PVA and other substrates were previously presented as effective means of improving the strength and toughness of compression molded native WG bars via disulfide-sulfhydryl exchange reactions. Consistent with our earlier results, AFM and TEM imaging clearly indicate that the addition of just a few mole percent of thiol to PVA was sufficient to dramatically change its compatibility with wheat protein. Thus, TPVA is much more compatible with WG and phase separates into much smaller domains than in the case of PVA, although there are still two phases in the blend: one WG-rich phase and another TPVA-rich phase. The WG/TPVA blend has phase domains ranging in size from 0.01 to 0.1 microm, which are roughly 10 times smaller than those of the WG/PVA blend. MDSC further illustrates the compatibilization of the protein with TPVA via the dependence of the transition temperatures on composition.     

Fabrication,Characterization and Cellular Compatibility of Poly(Hydroxy Alkanoate) Composite Nanofibrous Scaffolds for Nerve Tissue Engineering

Tissue engineering techniques using a combination of polymeric scaffolds and cells represent a promising approach for nerve regeneration. We fabricated electrospun scaffolds by blending of Poly (3-hydroxybutyrate) (PHB) and Poly (3-hydroxy butyrate-co-3- hydroxyvalerate) (PHBV) in different compositions in order to investigate their potential for the regeneration of the myelinic membrane. The thermal properties of the nanofibrous blends was analyzed by differential scanning calorimetry (DSC), which indicated that the melting and glass temperatures, and crystallization degree of the blends decreased as the PHBV weight ratio increased. Raman spectroscopy also revealed that the full width at half height of the band centered at 1725 cm⁻¹ can be used to estimate the crystalline degree of the electrospun meshes. Random and aligned nanofibrous scaffolds were also fabricated by electrospinning of PHB and PHBV with or without type I collagen. The influence of blend composition, fiber alignment and collagen incorporation on Schwann cell (SCs) organization and function was investigated. SCs attached and proliferated over all scaffolds formulations up to 14 days. SCs grown on aligned PHB/PHBV/collagen fibers exhibited a bipolar morphology that oriented along the fiber direction, while SCs grown on the randomly oriented fibers had a multipolar morphology. Incorporation of collagen within nanofibers increased SCs proliferation on day 14, GDNF gene expression on day 7 and NGF secretion on day 6. The results of this study demonstrate that aligned PHB/PHBV electrospun nanofibers could find potential use as scaffolds for nerve tissue engineering applications and that the presence of type I collagen in the nanofibers improves cell differentiation.     

Uniaxial drawing and mechanical properties of poly[(R)-3-hydroxybutyrate]/poly(L-lactic acid) blends

Blends of poly(L-lactic acid) (PLLA) with two kinds of poly[(R)-3-hydroxybutyrate] (PHB) having different molecular weights, commercial-grade bacterial PHB (bacterial-PHB) and ultrahigh molecular weight PHB (UHMW-PHB), were prepared by the solvent-casting method and uniaxially drawn at two drawing temperatures, around PHB's T(g) (2 degrees C) for PHB-rich blends and around PLLA's T(g) (60 degrees C) for PLLA-rich blends. Differential scanning calorimetry analysis showed that this system was immiscible over the entire composition range. Mechanical properties of all of the samples were improved in proportion to the draw ratio. Although PLLA domains in bacterial-PHB-rich blends remained almost unstretched during cold drawing, a good interfacial adhesion between two polymers and the reinforcing role of PLLA components led to enhanced mechanical properties proportionally to the PLLA content at the same draw ratio. On the contrary, in the case of UHMW-PHB-rich blends, the minor component PLLA was found to be also oriented by cold drawing in ice water due to an increase in the interfacial entanglements caused by the very long chain length of the matrix polymer. As a result, their mechanical properties were considerably improved with increasing PLLA content compared with the bacterial-PHB system. Scanning electron microscopy observations on the surface and cross-section revealed that a layered structure with uniformly oriented microporous in the interior was obtained by selectively removal of PLLA component after simple alkaline treatment.     

Lipase-catalyzed biodegradation of poly(epsilon-caprolactone) blended with various polylactide-based polymers

Poly(epsilon-caprolactone) was blended with various polylactide-based polymers and processed to films by the solution casting method. Blends of 25/75, 50/50, 75/25, 90/10, and 95/5 (w/w) poly(epsilon-caprolactone)/poly(l-lactide), a 95/5 (w/w) blend of poly(epsilon-caprolactone) with a poly(d-lactide), a 50/50 (w/w) poly(l-lactide)-poly(d-lactide) mixture, and a poly(l-lactide-co-epsilon-caprolactone) copolymer were considered comparatively. The various phase-separated films were allowed to degrade in the presence of Pseudomonas lipase, biodegradation being monitored by proton nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, X-ray diffraction, and environmental scanning electron microscopy. The formation of separated phases during solvent evaporation and their morphologies are discussed. The introduction of poly(l-lactide) dramatically decreased the degradation rate of poly(epsilon-caprolactone)/poly(l-lactide) blends. The higher the percentage of poly(l-lactide), the slower the degradation, while the presence of cracks and increasing the lipase concentration acted in favor of the enzymatic degradation. Long-term enzymatic degradation of the various 95/5 blends was investigated over 480 h. The poly(epsilon-caprolactone) phase was enzymatically degraded by the lipase regardless of the blend type, the degradation rate depending on the nature of the co-components.     

Electrospun PVA/HAp nanocomposite nanofibers: biomimetics of mineralized hard tissues at a lower level of complexity

Based on the biomimetic approaches the present work describes a straightforward technique to mimic not only the architecture (the morphology) but also the chemistry (the composition) of the lowest level of the hierarchical organization of bone. This technique uses an electrospinning (ES) process with polyvinyl alcohol (PVA) and hydroxyapatite (HAp) nanoparticles. To determine morphology, crystalline structures and thermal properties of the resulting electrospun fibers with the pure PVA and PVA/HAp nanocomposite (NC) before electrospinning various techniques were employed, including transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, FT-IR spectroscopy was carried out to analyze the complex structural changes upon undergoing electrospinning as well as interactions between HAp and PVA. The morphological and crystallographic investigations revealed that the rod-like HAp nanoparticles exhibit a nanoporous morphology and are embedded within the electrospun fibers. A large number of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers, which closely resemble the naturally mineralized hard tissues of bones. Due to abundant OH groups present in PVA and HAp nanorods, they strongly interact via hydrogen bonding within the electrospun PVA/HAp NC fibers, which results in improved thermal properties. The unique physiochemical features of the electrospun PVA/HAp NC nanofibers prepared by the ES process will open up a wide variety of future applications related to hard tissue replacement and regeneration (bone and dentin), not limited to coating implants.     

Biodegradability studies of polyhydroxyalkanoate (PHA) film produced by a marine bacteria using Jatropha biodiesel byproduct as a substrate

Polyhydroxyalkanoates are water-insoluble, hydrophobic polymers and can be degraded by microorganisms that produce extracellular PHA depolymerase. The present work was aimed to evaluate the degradability of Polyhydroxyalkanoate film produced by Halomonas hydrothermalis using Jatropha biodiesel byproduct as a substrate. PHB films were subjected to degradation in soil and compared with the synthetic polymer (acrylate) and blend prepared using the synthetic polymer (acrylate) and PHB. After 50 days, 60% of weight loss in PHB film and after 180 days 10% of blended film was degraded while no degradation was found in the synthetic film. Scanning electron microscopy and confocal microscopy revealed that after 50 days the PHB film and the blended film became more porous after degradation while synthetic film was not porous. The degradative process was biologically mediated which was evident by the control in which the PHB films were kept in sterile soil and the films showed inherent integrity over time. The TGA and DSC analysis shows that the melting temperatures were changed after degradation indicating physical changes in the polymer during degradation.     

Optimization of conditions for production of sago starch-based foam

Production of sago starch-based foam involved mixing of sago starch with polyvinyl alcohol (PVA) or polyvinyl pyrrolidone (PVP) followed by preparation of electron beam irradiated sago starch/PVA and sago starch/PVP sheets and expanding them in a microwave. The results revealed that good foams with high linear expansion and closed cell structure can be produced from 25:15 of sago starch:PVA and 30:10 of sago starch:PVA blends prepared at 80 °C and electron beam irradiated at 15 kGy or 10 kGy for the cross-linking process. An increment of sago starch in the blends enhanced the linear expansion of the foams produced. Change in the blend morphology was observed when it was exposed to higher irradiation doses as electron beam irradiation induced the cross-linking in PVA and PVP, and leaching of amylose and amylopectin from the starch granules. Sago starch/PVA blend is more suitable for foam production because it produced flexible and glossy foam as compared to sago starch/PVP blend which produced very rigid foam.     

Collagen-based biomimetic nanofibrous scaffolds: preparation and characterization of collagen/silk fibroin bicomponent nanofibrous structures

Electrospinning of collagen (COL)/silk fibroin (SF) blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated for fabrication of a biocompatible and biomimetic nanostructured scaffold for tissue engineering. The morphology of the electrospun COL/SF blend nanofibers was observed by scanning electron microscopy. The average diameters of COL/SF blend fibers ranged from 320 to 360 nm, irrespective of SF content in the blends. Both COL and SF components in the as-spun COL/SF blend matrices were stabilized by glutaraldehyde and water vapor, respectively, under the saturated glutaraldehyde aqueous solution at 25 degrees C. The glutaraldehyde vapor chemically stabilized the COL component via cross-linking, whereas the water vapor physically stabilized the SF component via crystallization to the beta-sheet structure. These structural changes of after-treated COL/SF blend matrices were examined using ATR-IR and CP/MAS (13)C NMR spectroscopy. To assay the cytocompatibility and cellular behavior of the COL/SF blend nanofibrous scaffolds, cell attachment and the spreading of normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF) seeded on the scaffolds were studied. In addition, both morphological changes and cellular responses of COL/SF blend nanofibrous matrices were also compared with COL/SF hybrid nanofibrous matrices. Generally similar levels of cell attachment and spreading of NHEF were shown in the COL/SF blend nanofibrous matrix compared with those of the pure COL and pure SF matrices; the cellular responses of NHEK were, however, markedly decreased in the COL/SF blend nanofibrous matrix as compared to the pure matrices. In contrast, cell attachment and spreading of NHEK on the COL/SF hybrid nanofibrous matrix were significantly higher than that of the COL/SF blend nanofibrous matrix. Our results indicate that a COL/SF hybrid nanofibrous matrix may be a better candidate than a COL/SF blend nanofibrous matrix for biomedical applications such as wound dressing and scaffolds for tissue engineering.     

Electrospinning of poly(vinyl alcohol)-water-soluble quaternized chitosan derivative blend

Defect free mats containing a cationic polysaccharide, chitosan derivative such as N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (HTCC), have been prepared using electrospinning of an aqueous solution of poly(vinyl alcohol) (PVA)-HTCC blends. HTCC, a water-soluble derivative of chitosan, was synthesized via the reaction between glycidyl-trimethylammonium chloride and chitosan. Solutions of PVA-HTCC Blends were electrospun. The morphology, diameter and structure of the produced electrospun nanofibres were examined by scanning electron microscopy (SEM). The average fibre diameter was in the range of 200-600 nm. SEM images showed that the morphology and diameter of the nanofibres were mainly affected by weight ratio of the blend and applied voltage. The results revealed that increasing HTCC content in the blends decreases the average fibre diameter. These observations were discussed on the basis of shear viscosities and conductivities of the spinning solutions. Microbiological assessment showed that the PVA-HTCC mats have a good antibacterial activity against Gram-positive bacteria, Staphylococcus aureus, and Gram-negative bacteria, Escherichia coli.     

Synthesis, characterization, and morphology studies of biodegradable amphiphilic poly[(R)-3-hydroxybutyrate]-alt-poly(ethylene glycol) multiblock copolymers

Novel biodegradable amphiphilic alternating block copolymers based on poly[(R)-3-hydroxybutyrate] (PHB) as biodegradable and hydrophobic block and poly(ethylene glycol) (PEG) as hydrophilic block (PHB-alt-PEG) were successfully synthesized through coupling reaction. Their chemical structures have been characterized by using gel permeation chromatography, (1)H nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) analysis revealed that both PHB and PEG blocks in PHB-alt-PEG block copolymers can crystallize to form separate crystalline phase except in those with a short PEG block (M(n) 600) only PHB crystalline phase has been observed. However, due to the mutual interference from each other, the melting transition of both PHB and PEG crystalline phases shifted to lower temperature with lower crystallinity in comparison with corresponding pure PHB and PEG. The crystallization behavior of PHB block and PEG block has also been studied by X-ray diffraction, and the results were in good agreement with those deduced from DSC study. The surface morphologies of PHB-alt-PEG block copolymer thin films spin-coated on mica have been visualized by atomic force microscopy with tapping mode, indicating formation of laterally regular lamellar surface patterns. Static water contact angle measurement revealed that surface hydrophilicity of these spin-coated thin films increases with increasing PEG block content.