In vitro comparative biodegradation analysis of salt‐leached porous polymer scaffolds

This study presents a comprehensive, side‐by‐side analysis of chemical, thermal, mechanical, and morphological changes in four polymers used in tissue engineering: poly(glycerol‐sebacate) (PGS), poly(lactic acid) (PLA)/poly(ε‐caprolactone) (PCL) blend, poly(lactic‐co‐glycolic acid) (PLGA), and Texin 950, a segmented polyurethane resin (PUR). Polymer foams were created using a salt‐leaching technique and then analyzed over a 16‐week period. Biodegradation was analyzed by examining the morphology, thermal properties, molecular weight, chemical, and mechanical properties using scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, attenuated total reflectance‐Fourier transform infrared spectroscopy, thermogravimetric analysis, and compression testing. PGS underwent the most rapid degradation and was hallmarked by a decrease in compressive modulus. PLA/PCL blend and PLGA both had rapid initial decreases in compressive modulus, coupled with large decreases in molecular weight. Surface cracks were observed in the PUR samples, accompanied by a slight decrease in compressive modulus. However, as expected, the molecular weight did not decrease. These results confirm that PUR does not undergo significant degradation but may not be suitable for long‐term implants. The biodegradation rates of porous PGS, PLA/PCL blend, and PLGA found in this study can guide their use in tissue engineering and other biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Solvent‐ and thermal‐induced crystallization of poly‐L‐lactic acid in supercritical CO2 medium

The effect of different annealing treatments with supercritical carbon dioxide (SCCO₂) on the structural and mechanical properties of semicrystalline poly‐L ‐lactic acid (L ‐PLA) was investigated. 2000, 27,000, 100,000, and 350,000 g mol^?1 molecular weight L ‐PLA polymers were used in the study. The solid‐state processing of L ‐PLA at temperatures lower than the effective melting point led to solvent‐ and thermal‐induced crystallization. Solvent‐induced and isothermal crystallization mechanisms could be considered similar regarding the increase of polymer chain mobility and mass‐transfer in the amorphous region; however, quite different microstructures were obtained. SCCO₂ solvent‐induced crystallization led to polymers with high crystallinity and melting point. On the contrary, SCCO₂ thermal‐induced crystallization led to polymers with high crystallinity and low melting point. For these polymers, the hardness increased and the elasticity decreased. Finally, the effect of dissolving SCCO₂ in the molten polymer (cooling from the melt) was analyzed. Cooling from the melt led to polymers with high crystallinity, low melting point, low hardness, and low elasticity. Distinctive crystal growth and nucleation episodes were identified. This work also addressed the interaction of SCCO₂‐drug (triflusal) solution with semicrystalline L ‐PLA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Wet‐spinning of biomedical polymers: from single‐fibre production to additive manufacturing of three‐dimensional scaffolds

Wet‐spinning of polymeric materials has been widely investigated for various biomedical applications, such as extracorporeal blood treatment, controlled drug release and tissue engineering. This review is aimed at summarizing and assessing current advances in wet‐spinning of biomedical polymers to manufacture single fibres and three‐dimensional scaffolds, as well as their functionalization through loading with bioactive agents. The theoretical principles and the main technological aspects of fibre production by wet‐spinning on either a laboratory or an industrial scale are outlined. The non‐solvent‐induced phase inversion determining polymer coagulation during the wet‐spinning process is discussed by highlighting its influence on the resulting fibre morphology and how it can be exploited to induce a nano/microporosity in the solidified polymeric matrix. The versatility of wet‐spinning in material selection, bioactive agent loading and fibre morphology tuning is underlined through an overview of significant literature reporting on the processing of various naturally derived and synthetic polymers. A special focus is given to cutting‐edge advancements in the application of additive manufacturing principles to wet‐spinning for enhanced control and reproducibility of three‐dimensional polymeric scaffold morphology at different scale levels (i.e. macrostructural to micro/nanostructural features). © 2017 Society of Chemical Industry     

Reactive compatibilization of biodegradable poly(lactic acid)/poly(ε‐caprolactone) blends with reactive processing agents

Poly(lactic acid) (PLA) blended with poly(ε‐caprolactone) (PCL) was prepared with various reactive processing agents. Four isocyanates‐lysine triisocyanate (LTI); lysine diisocyanate (LDI); 1,3,5‐tris(6‐isocyanatohexyl)‐1,3,5‐triazinane‐2,4,6‐trione (Duranate TPA‐100); 1,3,5‐tris(6‐isocyanatohexyl)biuret (Duranate 24A‐100)‐and an industrial epoxide‐trimethylolpropane triglycidyl ether (Epiclon 725)‐were used as reactive processing agents. PLA/PCL blended in the presence of LTI had the highest torque in a mixer test. The test specimens were prepared by injection molding. The mechanical properties, thermal properties, molecular weight, melt viscosity, phase behavior, and morphology were investigated using tensile strength, impact strength, differential scanning calorimetry, melt mass‐flow rate measurements, capillary rheometery, gel permeation chromatography, laser scanning confocal microscopy (LSCM), and visco‐elasticity atomic force microscopy (VE‐AFM). The impact strength increased considerably at 20 wt% PCL. The nominal tensile strain of PLA/PCL blended with LTI increased by 270%. The MFR values of PLA/PCL blends decreased with increasing LTI. Similar results were observed for shear viscosity. LSCM measurements showed that the diameters of PCL were dispersed about 0.4 μm in the presence of LTI. VE‐AFM showed that spherical particles with diameters of 50 nm were PCL‐rich domain. These results indicate that isocyanate groups of LTI react with both terminal hydroxyl or carboxyl groups of polymers, and the compatibility of PLA/PCL blends improves with LTI by reactive processing. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Melt electrospinning writing of three‐dimensional star poly(ϵ‐caprolactone) scaffolds

In the last decade, the melt‐electrospinning technique has gained attention for the production of highly porous microfibrous tissue engineering scaffolds. The possibility of processing polymers without the use of organic solvents is one of the main advantages over solution electrospinning. In this study, computer‐controlled melt‐electrospinning of a commercial poly(?‐caprolactone) and of two batches with different molecular weights of a three‐arm star poly(?‐caprolactone) by means of a screw‐extruder‐based additive manufacturing system is reported. Experimental parameters such as processing temperature, extrusion flow rate and applied voltage were studied and optimized in order to obtain non‐woven meshes with uniform fibre morphology. Applying the optimized parameters, three‐dimensional scaffolds were produced using a layer‐by‐layer approach (0 ? 90° lay‐down pattern). © 2013 Society of Chemical Industry     

Lipase‐catalyzed synthesis of polylactic acid: an overview of the experimental aspects

BACKGROUND: Enzymes have received increasing attention as biocatalysts. The poly(lactic) acid (PLA) has been widely employed in biomedical applications and PLA synthesis by a ‘green route’ is of particular interest. Here the aim is to prepare PLA using lipases, focusing on optimization of the procedure. The effects of the type and concentration of lipase, type of reaction, solvent, and time on the recovery of solid polyester, conversion rate and molecular weight have been explored. Pseudomonas cepacia (PCL), Porcine pancreatic lipase (PPL) and immobilized CAL‐B were used as biocatalysts. RESULTS: CAL‐B was the most effective biocatalyst, with 60% LA conversion and 55% recovered solid polymer; PCL and PPL gave rise to poor recovery of polymer. A novel thermal treatment was successfully employed to enhance the molecular weight Mn of PLA. CONCLUSIONS: This work offers a set of optimal conditions to synthesize PLA as a function of the lipase used. Information of this nature is currently not available in the literature, thus the findings here are a valuable tool for any researcher in this topic and a state‐of‐the‐art contribution in terms of the best biocatalyst and the best conditions for PLA synthesis. Copyright © 2008 Society of Chemical Industry     

Ternary blend nanofibres of poly(lactic acid), polycaprolactone and cellulose acetate butyrate for skin tissue scaffolds: influence of blend ratio and polycaprolactone molecular mass on miscibility,morphology, crystallinity and thermal properties

Ternary blends of poly(lactic acid) (PLA), polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were fabricated into the form of electrospun nanofibres targeted for skin tissue scaffolds. The effects of blend ratio and molecular mass of PCL (PCL1 and PCL2) on morphology, miscibility, crystallinity, thermal properties, surface hydrophilicity and cell culture of the nanofibres were investigated. Blends with high PLA loading (80/10/10 PLA/PCL/CAB) gave fibres with a smooth surface, owing to the enhanced miscibility between the polymer chains from the presence of CAB, which acts as compatibilizer. In contrast, blends with high PCL loading were immiscible, which led to beads during the electrospinning process. The increased molecular mass of PCL2 produced smoother fibres than low‐molecular‐mass PCL1. The XRD patterns of blends of PLA/PCL1/CAB and PLA/PCL2/CAB were similar to one another, in which the high‐crystallinity peaks of PCL seen for 20/70/10 blends were very small for 50/40/10 blends and much less prevalent for 80/10/10 blends. Better fibre formation (80/10/10 > 50/40/10 > 20/70/10) with less crystallinity occurs in well‐formed fibres. Selected blends of PLA/PCL/CAB promoted growth of NIH/3T3 fibroblast cells, demonstrating that our novel biocompatible ternary blend nanofibrous scaffolds have potential in skin tissue repair applications. In addition, this work helps in the design and understanding of the factors that control the properties of nanofibrous PLA/PCL/CAB scaffolds. © 2017 Society of Chemical Industry     

Predictors of glass transition in the biodegradable poly‐lactide and poly‐lactide‐co‐glycolide polymers

The biodegradable polylactide (PLA) and polylactide‐co‐glycolides (PLGAs) are being widely investigated for use as scaffolds in bone and ligament reconstruction. The glass transition temperatures (T_g) for these polymers are generally greater than 37°C, causing PLA and PLGA devices to possess brittle characteristics in physiological conditions. To evaluate the possibility of obtaining PLGA polymers with T_g values below 37°C, we evaluated the determinants of T_g in PLA and PLGA copolymers. The T_g, changes in specific heat capacity (ΔC_p), and enthalpic relaxation (ΔH_g) in two consecutive heating cycles were correlated with lactide/glycolide content and intrinsic viscosity [η] for PLA, PLGAs 90:10, 75:25, 65:35, and 50:50. A linear correlation was observed between T_g and intrinsic viscosity, with 0.1 dL/g increase in viscosity resulting in an increase in T_g by about 3.55°C. The selection of PLA and PLGA copolymers with [η] values <0.19 dL/g, corresponding to a viscosity average molecular weight of <70 kDa, will obtain PLA/PLGA polymers with T_g values below 37°C. The lowest attainable T_g values were found to be 28–30°C. Intrinsic viscosity also correlated with ΔC_p differences between aged and rapidly cooled polymers, and is therefore important in predicting free volume changes within these polymers upon aging. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1983–1987, 2006     

Synthesis,characterization and biocompatibility of novel biodegradable poly[((R)‐3‐hydroxybutyrate)‐block‐(D,L‐lactide)‐block‐(ε‐caprolactone)] triblock copolymers

BACKGROUND: Biodegradable block copolymers have attracted particular attention in both fundamental and applied research because of their unique chain architecture, biodegradability and biocompatibility. Hence, biodegradable poly[((R )‐3 ‐hydroxybutyrate)‐block‐(D ,L ‐lactide)‐block‐(ε‐caprolactone)] (PHB‐PLA‐PCL) triblock copolymers were synthesized, characterized and evaluated for their biocompatibility. RESULTS: The results from nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis showed that the novel triblock copolymers were successfully synthesized. Differential scanning calorimetry and wide‐angle X‐ray diffraction showed that the crystallinity of PHB in the copolymers decreased compared with methyl‐PHB (LMPHB) oligomer precursor. Blood compatibility experiments showed that the blood coagulation time became longer accompanied by a reduced number of platelets adhering to films of the copolymers with decreasing PHB content in the triblocks. Murine osteoblast MC3T3‐E1 cells cultured on the triblock copolymer films spread and proliferated significantly better compared with their growth on homopolymers of PHB, PLA and PCL, respectively. CONCLUSION: For the first time, PHB‐PLA‐PCL triblock copolymers were synthesized using low molecular weight LMPHB oligomer as the macroinitiator through ring‐opening polymerization with D ,L ‐lactide and ε‐caprolactone. The triblock copolymers exhibited flexible properties with good biocompatibility; they could be developed into promising biomedical materials for in vivo applications. Copyright © 2008 Society of Chemical Industry     

Supercritical CO2 deposition and foaming process for fabrication of biopolyester–ZnO bone scaffolds

Subsequent supercritical CO₂‐assisted deposition and foaming process followed by in situ synthesis was used to fabricate functional polylactide (PLA) and polylactide–poly(?‐caprolactone) (PLA–PCL) bone scaffolds. Deposition of zinc bis(2‐thenoyltrifluoroacetonate) as a ZnO precursor onto biopolyester substrates (30 MPa; 110 °C) was followed by fast depressurization to create cellular structure. Contact time was optimized regarding the deposition yield (2 h), while PCL content in PLA was varied (1–10 wt %). Scaffolds impregnated with the precursor were treated with hydrazine alcoholic solution to obtain biopolyester–ZnO composites. Precursor synthesis and deposition onto the scaffolds was confirmed by Fourier‐transform infrared. Processed scaffolds had micron‐sized pores (d₅₀ ～ 20 μm). High open porosity (69–77%) and compressive strength values (2.8–8.3 MPa) corresponded to those reported for trabecular bone. PLA blending with PCL positively affected precursor deposition, crystallization rate, and compressive strength of the scaffolds. It also improved PLA surface roughness and wettability which are relevant for cell adhesion. ZnO improved compressive strength of the PLA scaffolds without significant effect on thermal stability. Analysis of structural, thermal, and mechanical properties of biopolyester–ZnO scaffolds testified a great potential of the obtained platforms as bone scaffolds. Proposed processing route is straightforward and ecofriendly, fast, easy to control, and suitable for processing of thermosensitive polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45824.     

含氧配体螯合铝络合物催化环酯聚合研究进展

聚己内酯及聚交酯是可供生物降解的高分子材料,具有良好的生物相容性和优异的力学性能,广泛应用在生物医学领域,可应用于骨骼固定材料、手术缝合线、药物载体和组织修复材料等。本文综述了不同类型含氧配体螯合金属铝络合物以配位-插入机理引发环酯开环聚合近年来的研究成果。     

Synthesis of biodegradable and flexible,polylactic acid based,thermoplastic polyurethane with high gas barrier properties

Polylactic acid (PLA) has the beneficial properties of good mechanical strength, biodegradability and biocompatibility, and these properties make it suitable for use as an environmentally friendly packaging material. However, its use has been limited by its brittleness and poor stability. In this work, we successfully developed an efficient synthesis scheme to improve the mechanical properties, flexibility and gas barrier properties of PLA‐based polymers. Four different PLA‐based thermoplastic polyurethane (PLAPU) polymers were synthesized through the reaction of PLA diol with hexamethylene diisocyanate, followed by chain extension with polycaprolactone (PCL) diol. The relative compositions of the hard PLA and the soft PCL diols in the PLAPU polymers were controlled systematically to optimize the physical properties of the polymers. For example, increasing the content of PCL resulted in higher molecular weight PLAPU polymers that had increased tensile strengths and elongations at break, but their moduli were decreased. At the optimized PLA:PCL ratio of 1:3, the PLAPU polymer had an excellent elongation at break of 1053% with a relatively high Young's modulus of 51.8 MPa. In addition, the gas barrier properties of the PLAPUs were significantly enhanced depending on the molecular weight and PCL content of the polymers. To demonstrate the feasibility of using PLAPU polymers for biodegradable packaging materials, hydrolytic degradation tests were performed in phosphate buffer solution, and the PLAPU polymers were degraded gradually at rates that depended on the content of PCL in the polymers. This optimized PLAPU polymer exhibited excellent flexibility and gas barrier property, as well as high elongation, demonstrating its potential utility as packaging materials. © 2013 Society of Chemical Industry     

Fabrication of co‐continuous poly(ε‐caprolactone)/polyglycolide blend scaffolds for tissue engineering

The apparent inability of a single biomaterial to meet all the requirements for tissue engineering scaffolds has led to continual research in novel engineered biomaterials. One method to provide new materials and fine‐tune their properties is via mixing materials. In this study, a biodegradable powder blend of poly(ε‐caprolactone) (PCL), polyglycolide (PGA), and poly(ethylene oxide) (PEO) was prepared and three‐dimensional interconnected porous PCL/PGA scaffolds were fabricated by combining cryomilling and compression molding/polymer leaching techniques. The resultant porous scaffolds exhibited co‐continuous morphologies with ～50% porosity. Mean pore sizes of 24 and 56 μm were achieved by varying milling time. The scaffolds displayed high mechanical properties and water uptake, in addition to a remarkably fast degradation rate. The results demonstrate the potential of this fabrication approach to obtain PCL/PGA blend scaffolds with interconnected porosity. In general, these results provide significant insight into an approach that will lead to the development of new composites and blends in scaffold manufacturing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42471.     

Process study,development and degradation behavior of different size scale electrospun poly(caprolactone) and poly(lactic acid) fibers

This study describes the preparation of electrospun poly(caprolactone) (PCL) and poly(lactic acid) (PLA) fibrous scaffolds with and without nano-hydroxyapatite (nHAp) having nanoscale, microscale and combined micro/nano (multiscale) architecture. Processing parameters such as polymer concentration, voltage, flow rate and solvent compositions were varied in wide range to display the effect of each one in determining the diameter and morphology of fibers. The effect of each regulating parameter on fiber morphology and diameter was evaluated and characterized using scanning electron microscope (SEM). Degradability of the selected fibrous scaffolds was verified by phosphate buffered saline immersion and its morphology was analyzed through SEM, after 5 and 12 months. Quantitative measurement in degradation was further evaluated through pH analysis of the medium. Both studies revealed that PLA had faster degradation compared to PCL irrespective of the size scale nature of fibers. Structural stability evaluation of the degraded fibers in comparison with pristine fibers by thermogravimetric analysis further confirmed faster degradability of PLA compared to PCL fibers. The results indicate that PLA showed faster degradation than PCL irrespective of the size-scale nature of fibrous scaffolds, and therefore, could be applied in a variety of biomedical applications including tissue engineering.     

Fused deposition processing polycaprolactone of composites for biomedical applications

The polycaprolactone (PCL)-engineered scaffolds demonstrate cell viability, which is useful for bone tissue applications. The FDA-approved PCL can be engineered with various transition metals, polymers, and nanomaterials, for biomimicking of extracellular matrix via fabrication of its scaffolds. Fused deposition modeling (FDM) is an innovative technique for processing of biopolymers via biologically functionalized nanoparticles, leveraging design of stacked architecture at microlevel resolution. Present review gives progress on PCL biomaterials processed via FDM, for bioactive scaffolds and bone tissue applications. Finally, review concludes with benefits of PCL biomaterials processed via FDM and their applicability for biomedical applications.     

Interfacially compatibilized poly(lactic acid) and poly(lactic acid)/polycaprolactone/organoclay nanocomposites with improved biodegradability and barrier properties: Effects of the compatibilizer structural parameters and feeding route

Nanocomposites with enhanced biodegradability and reduced oxygen permeability were fabricated via melt hybridization of organomodified clay and poly (lactic acid) (PLA) as well as a PLA/polycaprolactone (PCL) blend. The nanocomposite microstructure was engineered via interfacial compatibilization with maleated polypropylene (PP‐g‐MA). Effects of the compatibilizer structural parameters and feeding route on the dispersion state of the nanolayers and their partitioning between the PLA and PCL phases were evaluated with X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Although highly functionalized PP‐g‐MA with a low molecular weight was shown to be much more effective in the intercalation of PLA and the PLA/PCL blend into the clay gallery spaces, composite samples compatibilized by high‐molecular‐weight PP‐g‐MA with a lower degree of maleation exhibited lower oxygen permeability as well as a higher rate of biodegradation, which indicated the accelerating role of the dispersed nanolayers and their interfaces in the enzymatic degradation of PLA and PLA/PCL matrices. This evidenced a correlation between the nanocomposite structure and rate of biodegradation. The size of the PCL droplets in the PLA matrix was reduced by nanoclay incorporation, and this revealed that the nanolayers were preferentially wetted by PCL in the blend. However, PCL appeared as fine and elongated particles in the microstructure of the PLA/PCL/organoclay hybrids compatibilized by higher molecular weight and less functionalized PP‐g‐MA. All the PLA/organoclay and PLA/PCL/organoclay hybrids compatibilized with high‐molecular‐weight PP‐g‐MA displayed a higher dynamic melt viscosity with more pseudo solid‐like melt rheological responses, and this indicated the formation of a strong network structure by the dispersed clay layers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of poly(L‐lactide)/ poly(ϵ‐caprolactone) fibrous scaffolds for cartilage tissue engineering

Polyblend fibrous scaffolds in mass ratios of 100/0, 90/10, 80/20, and 70/30 from poly(L ‐lactide) (PLLA) and poly(?‐caprolactone) (PCL) for cartilage tissue engineering were prepared in three steps: gelation, solvent exchanging, and freeze‐drying. Effects of the blend ratio, the exchange medium, and the operating temperature on the morphology of scaffolds were investigated by SEM. PLLA/PCL scaffolds presented an ultrafine fibrous network with the addition of a “small block” structure. Smooth and regular fibrous networks were formed when ethanol was used as the exchange medium. Properties of the scaffolds, such as thermal and mechanical properties, were also studied. The results suggested that the compressive modulus declined as PCL amount increased. The incorporation of PCL effectively contributed to reduce the rigidity of PLLA. Bovine chondrocytes were seeded onto PLLA/PCL scaffold. Cells attached onto the fibrous network and their morphology was satisfactory. This polyblend fibrous scaffold will be a potential scaffold for cartilage tissue engineering. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1676–1684, 2004     

Reinforcement of electrospun poly(ε‐caprolactone) scaffold using diopside nanopowder to promote biological and physical properties

Considerable efforts have been devoted toward the development of electrospun scaffolds based on poly(ε‐caprolactone) (PCL) for bone tissue engineering. However, most of previous scaffolds have lacked the structural and mechanical strength to engineer bone tissue constructs with suitable biological functions. Here, we developed bioactive and relatively robust hybrid scaffolds composed of diopside nanopowder embedded PCL electrospun nanofibers. Incorporation of various concentrations of diopside nanopowder from 0 to 3 wt % within the PCL scaffolds notably improved tensile strength (eight‐fold) and elastic modulus (two‐fold). Moreover, the addition of diopside nanopowder significantly improved bioactivity and degradation rate compared to pure PCL scaffold which might be due to their superior hydrophilicity. We investigated the proliferation and spreading of SAOS‐II cells on electrospun scaffolds. Notably, electrospun PCL‐diopside scaffolds induced significantly enhanced cell proliferation and spreading. Overall, we concluded that PCL‐diopside scaffold could potentially be used to develop clinically relevant constructs for bone tissue engineering. However, the extended in vivo studies are essential to evaluate the role of PCL‐diopside fibrous scaffolds on the new bone growth and regeneration. Therefore, in vivo studies will be the subject of our future work. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44433.     

Controlled degradation of polylactic acid grafting N‐vinyl pyrrolidone induced by gamma ray radiation

Polylactic acid (PLA) films were surface modified by gamma ray irradiation‐induced grafting of N‐vinyl pyrrolidone (NVP). The in vitro degradation behavior of polylactic acid grafting N‐vinyl pyrrolidone (PLA‐g‐PVP) copolymer was analyzed in terms of weight loss, molecular weight, and thermal properties. Grafting NVP significantly accelerated the degradation of PLA. The mass losses of the copolymers, which were less than that of pure PLA at the beginning of the degradation period, sharply accelerated with increasing degradation time. Moreover, the crystallization temperature decreased with increasing degradation time in the same graft ratio, and the degree of crystallinity increased. Cytotoxicity experiments and animal experiments in vivo were carried out to evaluate the biocompatibility of PLA‐g‐PVP copolymer. Varying graft ratios of PVP could control the degradation rate of copolymers, and thus broadening the applications of this material, such as in tissue engineering scaffolds, drug delivery, and prevention of postsurgical adhesion. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013