Polymer Degradation Rate Research Articles

Argon nonthermal plasma etching of poly(L-lactic acid) films: Tunning the local surface degradation and hydrolytic degradation rate

Plasma technology is widely used in the industry for the surface modification of polymeric materials, improving the adhesion of paints in polymeric packaging and cellular adhesion on polymers' surfaces without using hazardous chemicals. Plasma etching is a fast way to modify polymers, creating new nanostructure surfaces and adding chemical groups for new applications like antimicrobial surfaces. Poly(L-lactic acid) (PLLA) is a biodegradable polymer with exciting properties for biomedical, tissue engineering, food packaging, and other applications. In many cases, these products must undergo plasma surface treatments to meet the technical requirements of their function. Herein, we evaluated the effects of surface modification of PLLA using Argon nonthermal plasma etching. The results from Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray Excited Photoelectron Spectroscopy (XPS), and Matrix-assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-ToF-MS) show that increasing the plasma exposure time causes an enhancement in bulk and local surface degradation, crystallization kinetics and susceptibility to hydrolytic degradation for PLLA. Atomic Force Microscopy (AFM) show that the PLLA films present the highest surface roughness after 60 s of plasma etching times. Our findings suggest that plasma etching can be a suitable tool to adjust the polymer degradation rate to design intracorporeal devices with controlled degradation kinetics.

PBAT/PLA Films and Supercritical Impregnation of Caffeine for Potential Application in Anticellulite Tools

AbstractTopical administration is the preferred route for the controlled release of active compounds since it reduces side effects typical of other administration methods. The use of polymer blends is a way to modulate drug release from a topical device. The blends ensure modulation of a wide range of properties, such as mechanical properties, water sorption, and degradation. This paper proposes blends of poly(lactide acid) (PLA), and Poly(butylene adipate‐co‐terephthalate) (PBAT), for the topical release of caffeine, a molecule with anti‐inflammatory, antioxidant, and anticellulite activities. PBAT/PLA blends are optimized for compatibility between the two polymers, mechanical properties, and drug release rate. Blends with a higher amount of PBAT show the best performance regarding polymer compatibility. The blends undergo supercritical CO2‐assisted caffeine impregnation. This process assures homogeneous dispersion of caffeine into the polymer matrix. The ratios 45/55 and 55/45 PBAT/PLA show the best performance in terms of caffeine release (complete caffeine release within 25 h). Caffeine is released into three steps: a burst effect due to the caffeine dispersed over the film surface, a slower release due to the caffeine dispersed in the polymer matrix, and a fast release due to the increase of polymer degradation rate induced by caffeine presence.

Tuning the Emulsion Properties Influences the Size of Poly(Caprolactone) Particles for Drug Delivery Applications.

Advances in drug delivery have been accelerated with the addition of polymeric drug carriers. Direct delivery to a target site is a promising step in developing effective drug and gene therapies to treat disease. The efficacy of these drug carriers heavily relies on cell uptake without compromising critical cellular processes that promote cell viability. Drug release from biodegradable polymers is mediated largely by polymer degradation, and therefore the rate of polymer degradation dictates the feasibility of drug delivery applications. Traditionally, poly(caprolactone) (PCL) has only been used in long-term biomedical applications because the degradation time is much slower than other polymers. However, the biocompatibility of this polymer and the potential for longer delivery windows renders it a promising polymer candidate for drug delivery. In this work, we outline sixteen emulsion solvent evaporation preparation methods for PCL nanoparticles and microparticles to develop particles between 300nm and 1.7μm and with zeta potentials of -1.8mV. We further investigated particles in a size range suitable for systemic tumor delivery and inhaled aerosol delivery to determine cell biocompatibility with the polymer in lung adenocarcinoma, endometrial adenocarcinoma, and human embryonic kidney cells. We determined these particles aren't detrimental to cell viability below particle monolayer coverage atop cells and therefore these formulations hold promise for the next stage of development as sustained-release drug delivery carriers.

Effect of Polymer Aging on Uptake/Release Kinetics of Metal Ions and Organic Molecules by Micro- and Nanoplastics: Implications for the Bioavailability of the Associated Compounds.

The main driver of the potential toxicity of micro- and nanoplastics toward biota is often the release of compounds initially present in the plastic, i.e., polymer additives, as well as environmentally acquired metals and/or organic contaminants. Plastic particles degrade in the environment via various mechanisms and at different rates depending on the particle size/geometry, polymer type, and the prevailing physical and chemical conditions. The rate and extent of polymer degradation have obvious consequences for the uptake/release kinetics and, thus, the bioavailability of compounds associated with plastic particles. Herein, we develop a theoretical framework to describe the uptake and release kinetics of metal ions and organic compounds by plastic particles and apply it to the analysis of experimental data for pristine and aged micro- and nanoplastics. In particular, we elucidate the contribution of transient processes to the overall kinetics of plastic reactivity toward aquatic contaminants and demonstrate the paramount importance of intraparticulate contaminant diffusion.

Controlled Degradation of Polycaprolactone Polymers through Ultrasound Stimulation.

This study describes the development of an ultrasound-responsive polymer system that provides on-demand degradation when exposed to high-intensity focused ultrasound (HIFU). Diels-Alder cycloadducts were used to crosslink polycaprolactone (PCL) polymers and underwent a retro Diels-Alder reaction when stimulated with HIFU. Two Diels-Alder polymer compositions were explored to evaluate the link between reverse reaction energy barriers and polymer degradation rates. PCL crosslinked with isosorbide was also used as a non-Diels-Alder-based control polymer. An increase of HIFU exposure time and amplitude correlated with an increase of PCL degradation for Diels-Alder-based polymers. Ultrasound imaging during HIFU allowed for real-time visualization of the on-demand degradation through cavitation-based mechanisms. The temperature surrounding the sample was monitored with a thermocouple during HIFU stimulation; a minimal increase in temperature was observed. PCL polymers were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), optical profilometry, and mechanical testing. PCL degradation byproducts were identified by mass spectrometry, and their cytocompatibility was evaluated in vitro. Overall, this study demonstrated that HIFU is an effective image-guided, external stimulus to control the degradation of Diels-Alder-based PCL polymers on-demand.

The microstructure of polyphosphoesters controls polymer hydrolysis kinetics from minutes to years

The stability and degradation rates of polymers in aqueous media are critical factors for their biomedical applications, as they must remain intact for a specific period of time before degrading or degrading on-demand to prevent potential accumulation and harmful effects. Polyphosphoesters (PPEs) are highly compatible with biological systems, and the ester bonds in the backbone allow for hydrolytic degradation. In this study, we have demonstrated that the degradation rate of various PPEs can be precisely controlled by minor modifications to the side-chain and the binding pattern around the phosphorous center in the polymer backbone. We synthesized a systematic library of water-soluble PPEs using ring-opening polymerization, resulting in polyphosphates and in-chain or side-chain polyphosphonates. Specifically, we investigated the degradation rates of side-chain polyphosphonates with different side-chain structures (methyl, ethyl, allyl, iso- or n-propyl) at pH = 8 and pH = 11. Our results indicate that the degradation mechanism is influenced by the type and size of the side-chain, as well as the pH. At pH = 11, hydrophilicity is a key factor, while at pH = 8, electron density on the phosphorus is crucial, leading to a random chain scission or a backbiting mechanism. We also observed that changing the binding pattern of the phosphorus or incorporating additional “breaking points” allowed us to tune the half-life times of the polymer from less than a day to several years. This study highlights the versatile stability of water-soluble PPEs, making them a promising option for various applications that require different hydrolysis rates, such as tissue regrowth.

Biobased, Degradable, and Conjugated Poly(Azomethine)s.

Carotenoids are a class of biobased conjugated molecules that bear a resemblance to the substructure of polyacetylene, a well-known conductive but insoluble polymer. Solubility is an important physical attribute for processing materials using different techniques. To impart solubility in polymers, alkyl side chains are often included in the molecular design. While these design strategies are well explored in conjugated systems, they have not been implemented with carotenoids as a building block in polymers. Here, we show a series of carotenoid-based polymers with varying side chain lengths to tune solubility. Using carotenoid and p-phenylenediamine-based monomers, degradable and biobased poly(azomethine)s were synthesized via imine polycondensation. Maximum solubilities corresponding to the varying alkyl chain lengths were quantitatively determined by ultraviolet-visible (UV-vis) absorption spectroscopy. Since carotenoids are biobased with known degradation products, the effect of acidic and artificial sunlight-promoted degradation was systematically investigated using UV-vis spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, gel permeation chromatography (GPC), and high-resolution mass spectroscopy (HRMS). Our polymer system was found to have two modes of on-demand degradation, with acid hydrolysis accelerating the rate of polymer degradation and artificial sunlight generating additional degradation products. This work highlights carotenoid monomers as viable candidates in the design of biobased, degradable, and conjugated polymers.

Photocatalytic Synthesis of Materials for Regenerative Medicine Using Complex Oxides with β-pyrochlore Structure.

Graft copolymerization of methyl methacrylate onto cod collagen was carried out under visible light irradiation (λ = 400-700 nm) at 20-25 °C using the RbTe1.5W0.5O6, CsTeMoO6, and RbNbTeO6 complex oxides with β-pyrochlore structure as photocatalysts. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. It was also found that RbNbTeO6 with β-pyrochlore structure was not able to photocatalyze the reaction. Enzymatic hydrolysis of the obtained graft copolymers proceeds with the formation of peptides with a molecular weight (MW) of about 20 and 10 kDa. In contrast to collagen, which decomposes predominantly to peptides with MW of about 10 kDa, the ratio of fractions with MW of about 10 kDa and 20 kDa differs much less, their changes are symbatic, and the content of polymers with MW of more than 20 kDa is about 70% after 1 h in the case of graft copolymers. The data obtained indicate that synthetic fragments grafted to the collagen macromolecule do not prevent the hydrolysis of the peptide bonds but change the rate of polymer degradation. This is important for creating network matrix scaffolds based on graft copolymers by cross-linking peptides, which are products of enzymatic hydrolysis.

Acceleration of Biodegradation Using Polymer Blends and Composites

AbstractBiobased and biodegradable polymers are used in bioplastics as blends or composites of various materials to tune their physical properties but also influence their stability with respect to biodegradation. Biodegradable polymers are often not as biodegradable as they are claimed to be, especially due to different degradation conditions in soil, water, compost, or in vivo. Mixing such polymers with faster degrading polymers (blends) or fillers (composites) is a powerful strategy to adjust degradation rates. This review selects representative examples of bioplastic blends and composites in applications, such as tissue engineering, agriculture, or packaging, with a focus on controlling/accelerating the biodegradation rates. It also focuses on strategies such as hydrolysis enhancement, attraction of microbes for microbial degradation, pore forming fillers, or increase of phase separation in polymer mixtures. A basis for the prevention of microplastic formation or unwanted side effects with too slow degradation rates of biodegradable polymers is set.

Degradation kinetics of synthetic acrylamide polymers as a viscosity and filtration control additives in the low-density water – Based drilling fluid systems

The impact of synthetic polymers in water-based drilling fluids (WBDFs) along with other functional additives is a critical task to ensure wellbore stability. In this regard, three different synthetic acrylamide polymers with various degrees of sulfonation–DoS (0–30%) and molecular weight of ≈2.8–3 million DU were investigated. The sulfonic substitution was verified using NMR techniques. The thermal-stability of these polymers was quantitatively investigated using a reliable titration technique.The quantified time-temperature kinetics of polymer degradation was correlated with their respective performance in low-density WBDFs in terms of filtration and viscosity. The WBDFs were formulated using NaCl brine, synthetic polymers, bentonite and other additives. The WBDFs were hot rolled at 250 °F and 350 °F for 16 h and the viscosity and filtration control was determined.The WBDFs investigation showed that the three polymers maintained desired viscosity (AV: 35–65 cp) and reasonable filtration control (<15 ml) for the fresh and aged fluids up to 250 °F. However, at elevated temperatures, the filtration performance at 350 °F got deteriorated. The present work, for the first time, explains this impact of temperature on the WBDF performance on the basis of time-temperature kinetics of polymer degradation. It was also noted that at the elevated temperature of 350 °F, moderately sulfonated polymer (DoS = 15%) had shown significantly better filtration control and viscosity compared to the other polymers as evident from both viscosity and filtration tests. The optimum performance of the polymer with moderate sulfonation was explained using a novel approach as a competing effect of two distinct mechanisms: variation in activation energy parameter of polymer degradation rate and change in polymer length with increasing degrees of substitution. The insights gained on the time-temperature dynamics of the polymer stability in the present work could also be utilized for devising the polymer replenishment strategy for the drilling automation processes.

Designing biodegradable alternatives to commodity polymers.

The development and widespread adoption of commodity polymers changed societal landscapes on a global scale. Without the everyday materials used in packaging, textiles, construction and medicine, our lives would be unrecognisable. Through decades of use, however, the environmental impact of waste plastics has become grimly apparent, leading to sustained pressure from environmentalists, consumers and scientists to deliver replacement materials. The need to reduce the environmental impact of commodity polymers is beyond question, yet the reality of replacing these ubiquitous materials with sustainable alternatives is complex. In this tutorial review, we will explore the concepts of sustainable design and biodegradability, as applied to the design of synthetic polymers intended for use at scale. We will provide an overview of the potential biodegradation pathways available to polymers in different environments, and highlight the importance of considering these pathways when designing new materials. We will identify gaps in our collective understanding of the production, use and fate of biodegradable polymers: from identifying appropriate feedstock materials, to considering changes needed to production and recycling practices, and to improving our understanding of the environmental fate of the materials we produce. We will discuss the current standard methods for the determination of biodegradability, where lengthy experimental timescales often frustrate the development of new materials, and highlight the need to develop better tools and models to assess the degradation rate of polymers in different environments.

Characterization of photo-oxidative degradation process of polyolefins containing oxo-biodegradable additives

The effects of oxo-biodegradable additives on the photo-oxidation of four types of polyolefin polymers, namely high-density polyethylene (HDPE), low-density PE (LDPE), linear low-density PE (LLDPE), and isotactic polypropylene (itPP) were investigated. Scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, and wide- and small-angle X-ray scattering were employed to gain insights into the chemical and structural modifications induced by the degradation process. The photo-oxidation preferentially occurred at the sample surface and was favored in the amorphous region of the polymers. The carbonyl index calculated for the neat and additive-containing samples suggested that the additives promoted the photo-oxidative degradation, particularly of the PE polymers, which are intrinsically resistant to oxidation, without altering their degradation pathways. The overall degradation rate of the additive-containing polymers was in the order of itPP > LDPE > LLDPE > HDPE.

Novel biodegradable molecularly imprinted polymer nanoparticles for drug delivery of methotrexate anti-cancer; synthesis, characterization and cellular studies.

Recently biodegradable nanoparticles are the center of attention for the development of drug delivery systems. Molecularly imprinted polymer (MIP) is an interesting candidate for designing drug nano-carriers. MIP-based nanoparticles could be used for cancer treatment and exhibited the potential to fill gaps regarding to ligand-based nanomaterials. Also, the presence of a cross-linker can play an essential role in nanoparticle stability and physicochemical properties of nanoparticles after synthesis. In this research, a biodegradable drug delivery system based on MIP nanoparticles was prepared using a biodegradable cross-linker (dimethacryloyl hydroxylamine, DMHA) for methotrexate (MTX). A hydrolysable functional group CO-O-NH-CO was added to the crosslinking agent to increase the final biodegradability of the polymer. Firstly, a biodegradable cross-linker was synthesized. Then, the non-imprinted polymers were prepared through mini-emulsion polymerization in the absence of a template; and efficient particle size distribution was determined. Finally, methotrexate was placed in imprinted polymers to achieve the desired MIP. Different types of MIPs were synthesized using different molar ratios of template, cross-linker, and functional monomer, and the optimal molar ratio was obtained at 1:4:20, respectively. HNMR successfully confirmed the chemical structure of the cross-linker. According to SEM images, nanoparticles had a spherical shape with a smooth surface. The imprinted nanoparticles showed a narrow size distribution with an average of 120nm at a high ratio of cross-linker. The drug loading and entrapment efficiency were 6.4% and 92%, respectively. The biodegradability studies indicated that the nanoparticles prepared by DMHA had a more degradability rate than ethylene glycol dimethacrylate as a conventional cross-linker. Also, the polymer degradation rate was higher in alkaline environments. Release studies in physiological and alkaline buffer showed an initial burst release of a quarter of loaded MTX during the day and a 70% release during a week. The Korsmeyer-Peppas model described the release pattern. The cytotoxicity of MTX loaded in nanoparticles was studied on the MCF-7 cell line, and the IC50 was 3.54μg/ml. It was demonstrated that nanoparticles prepared by DMHA have the potential to be used as biodegradable drug carriers for anticancer delivery. Synthesis schema of molecular imprinting of methotrexate in biodegradable polymer based on dimethacryloyl hydroxylamine cross-linker, for use as nanocarrier anticancer delivery to breast tumor.

Differential Drug Release Kinetics from Paclitaxel-Loaded Polydioxanone Membranes and Capsules.

Drug laden implantable systems can provide drug release over several hours to years, which eventually aid in the therapy of both acute and chronic diseases. The present study focuses on a fundamental evaluation of the influence of implant properties such as morphology, architecture, porosity, surface area, and wettability in regulating the drug release kinetics from drug-loaded polymeric matrices. For this, Polydioxanone (PDS) was selected as the polymer and Paclitaxel (Ptx) as the model drug. Two different forms of the matrix implants, viz., reservoir type capsules developed by dip coating and matrix type membranes fabricated by phase inversion and electrospinning, were utilized for the study. Drug release from all the four different matrices prepared by simple techniques was evaluated in vitro in PBS and ex vivo in peritoneal wash fluid for ~4 weeks. The drug release profiles were thereafter correlated with the physicochemical parameters of the polymeric implants. Reservoir-type capsules followed a slow and steady zero-order kinetics, while matrix-type electrospun and phase inversion membranes displayed typical biphasic kinetics. It was inferred that the slow degradation rate of PDS polymer as well as the implant properties like porosity and wettability play an important role in controlling the drug release rates.

Relationship between molecular properties and degradation mechanisms of organic solar cells based on bis-adducts of phenyl-C61 butyric acid methyl ester.

Environmental stability remains a major challenge for the commercialisation of organic solar cells and degradation pathways remain poorly understood. Designing materials for improved device stability requires an understanding of the relationship between the properties of the donor or acceptor molecule and different degradation mechanisms. Here we study the correlations between various molecular parameters of the fullerene derivative bis-PCBM and the degradation rate of polymer:bis-PCBM organic solar cells, based on the same carbazole-alt-benzothiadiazole polymer, in aerobic and anaerobic conditions. We compare eight high purity bis-PCBM isomers with different electronic, chemical and packing properties along with PCBM and the mixture of bis isomers. In the case of aerobic photodegradation, we find that device degradation rate is positively correlated to the LUMO energy of the bis-PCBM isomer and to the degree of crystallinity of the isomer, while the correlation of degradation with driving force for epoxide formation is unclear. These results support the idea that in these samples, aerobic photodegradation proceeds via superoxide formation by the photogenerated polaron on the fullerene, followed by further chemical reaction. In the absence of air, photodegradation rate is correlated with molecular structure, supporting the mechanism of microstructural degradation via fullerene dimerization. The approach and findings presented here show how control of specific molecular parameters through chemical design can serve as a strategy to enhance stability of organic solar cells.

Self-regenerating zwitterionic hyperbranched polymer with tunable degradation for anti-biofouling coatings

Regeneration of zwitterionic surfaces is a promising strategy to combat biofouling. In this study, we have prepared degradable hyperbranched anti-biofouling polymers of methyl methacrylate, tertiary carboxybetaine ester (TCB), and divinyl monomers via reversible addition-fragmentation chain transfer (RAFT) polymerization. The degradation rate of such polymers is a function of the content or type of divinyl monomers. As the content of methacrylic anhydride (MAAH) increases, the degradation rate of the polymer becomes faster; whereas, a change of the divinyl monomers causes the degradation rate to follow a descending order: N,N′-adipic bis(diacetone acrylamide hydrazone) (DAA2H) > MAAH > ethylene glycol dimethacrylate (EGDMA). Antibacterial and anti-diatom assays show that the coatings inhibit the adhesion of the marine bacteria Pseudomonas sp. and the diatom Navicula incerta. The polymeric coating is expected to be applied in marine anti-biofouling.

Laboratory investigation on rheological, chemical and morphological evolution of high content polymer modified bitumen under long-term thermal oxidative aging

High content polymer modified bitumen (HCPMB) is now mostly used in porous asphalt pavement, and the developed polymer system causes it exhibit more complex characteristics than conventional bitumen. However, the research on the aging behavior of HCPMB is still very limited due to its high polymer content and severe aging degree. In this paper, four types of binders were selected for different time-course aging tests to simulate the aging of the actual pavement. Then, Dynamic Shear Rheometer (DSR), Fluorescence Microscopy (FM), Fourier Transform Infrared (FTIR) Spectroscopy, and Gel Permeation Chromatography (GPC) were conducted to track the rheological, chemical and morphological evolution of the four bitumens during aging. The multiple stress creep recovery (MSCR) test index can capture the decrease of elasticity due to polymer degradation, reflecting the better elastic sensitivity than rutting factor. The black diagram and master curve can better analyze the influence of polymer modification and aging on the viscoelastic properties, and polymer modified bitumen (PMB) showed obvious two-stage characteristics in the graph. The shear stress relaxation (SSR) test showed that aging could weaken the relaxation property of bitumen, which makes it easy to accumulate larger stress and lead to cracking. The micro-chemical test results more intuitively proved that the degradation of the polymer mainly occurs in the early stage of aging, and the oxidation of the bitumen phase is the dominant process of long-term aging. And the more developed the initial polymer network is, the slower the degradation rate of polymer is, thus prolonging the early stage of aging. Principal component analysis (PCA) showed that the complicated relationship between the 12 parameters analyzed in this study could be explained by SBS content and bitumen aging degree. This study can provide insights for exploring the macro and micro change characteristics of binders during the long-term aging process and better understanding the aging mechanism of HCPMB.

Drug Release Kinetics from Nondegradable Hydrophobic Polymers Can Be Modulated and Predicted by the Glass Transition Temperature.

Controlling drug release kinetics within a desired therapeutic window is the central task when designing polymeric drug delivery systems. Complex polymer chemistries have often been explored to control water penetration, polymer degradation rate, or the mesh network size of delivery systems. Here, a simple parameter for controlling the release rate and duration of nondegradable hydrophobic polymers is discovered. A systematic study involving 59 polymers and multiple drugs demonstrates that the glass transition temperature, Tg , is a critical factor that dictates drug release kinetics from nondegradable hydrophobic polymers. Drug release rate exhibits a unique and simple linear correlation of (T - Tg )0.5 despite variability of polymer structure and type. An empirical model established based on the special correlation can accurately simulate and predict drug release kinetics from polymers saving substantial time typically required to test long-acting drug delivery systems.

Controlled drug release from electrospun PCL non-woven scaffolds via multi-layering and e-beam treatment

Currently, electrospun synthetic bioresorbable polymer scaffolds are applied in regenerative medicine and tissue engineering as targeted drug delivery devices because of their mechanical and physico-chemical properties. To control the rate of polymer degradation and drug release from polymer scaffolds, surface modification techniques are widely used. In this study, paracetamol-loaded poly (ε-caprolactone) electrospun fibrous scaffolds were treated by the pulsed electron beam irradiation. Pure control PCL scaffold, as well as scaffolds with four paracetamol concentrations (2 wt./wt. %, 8 wt./wt. %, 16 wt./wt. %, and 32 wt./wt.%) were modified. The mechanical and chemical properties and morphology of modified materials were examined. The sustained release of the model drug over a period of one hour for both non-treated and treated samples was demonstrated. It was shown that treatment leads to an increase in drug release rate and does not change surface morphology of scaffolds and fibers diameter distribution.

In-vitro Degradation Behaviors of Poly(L-lactide-co-glycolide-co-ε-caprolactone) Microspheres

Among drug delivery systems, polymer microspheres have been proved to be the most promising carriers during the past several years. In this paper we describe the preparation of poly(L-lactide-co-glycolide-co-ε-caprolactone) (PLLGC) random terpolymer microspheres; their in-vitro degradation behaviors, including the changes of pH value, mass loss, molecular mass and surface morphology, were investigated during various degradation periods and compared with poly(lactic-co-glycolic acid) (PLGA) microspheres. The results showed that the introduction of the ε-caprolactone (ε-CL) unit reduced the degradation rate of the PLGA polymers. Therefore, we suggest the PLLGC microspheres with controllable degradation rate could supply a wider application future in drug delivery field than pure PLGA microspheres.