Biodegradation Of PCL Research Articles

Comprehensive analysis reveals the differentiated influential mechanism of degradable poly (ε-caprolactone) and polybutylene succinate microplastics on nitrogen transformation in aerobic granular sludge systems

The escalating releasing of degradable microplastics (DMPs) into wastewater may pose a potential threat to biological nitrogen removal. However, whether and how different DMPs affect nitrogen transformations in aerobic granular sludge (AGS) systems remains unclear. This work therefore aimed to fill such knowledge gaps by employing poly (ε-caprolactone) (PCL) and polybutylene succinate (PBS) as the model microplastics. Results revealed that exposure to 0.5 and 5 mg/L DMPs did not remarkably affect the nitrogen removal. However, increasing DMPs concentration to 50 mg/L suppressed the nitrogen transformation, causing a significant degree of inhibition in total nitrogen removal efficiency, particularly in the PCL-exposure group (decreased by 2.0%–25.7%). The pronounced inhibitory effects were attributed to the more readily biodegradability of PCL compared to PBS, resulting in an enhanced release of microplastics that induced excessive production of reactive oxygen species and destruction of cytomembrane integrity. Consequently, the relative abundance of denitrifiers was decreased, leading to suppressed expression of the genes (e.g. narG) involved in nitrogen transformation. This was accompanied by a decline in enzyme activity (e.g. nitrate reductase) and electron transport system activity. The correlations among genes, microbes and environmental factors were reshaped by different DMPs, underlying the intrinsic mechanism for the deteriorated nitrogen removal. Overall, this study implies that compared to PBS microplastics, the accumulation of PCL microplastics in aquatic environments poses a more significant threat to biological treatment efficacy and global nitrogen cycling, thereby warranting increased attention.

Enhancement of hydrophilicity, biocompatibility and biodegradability of poly(ε-caprolactone) electrospun nanofiber scaffolds using poly(ethylene glycol) and poly(L-lactide-co-ε-caprolactone-co-glycolide) as additives for soft tissue engineering

In this study, poly(ε-caprolactone) (PCL) has been blended with a more hydrophilic poly(ethylene glycol) (PEG) and with a biocompatible block-co-polymer: poly(L-lactide-co-ε-caprolactone-co-glycolide) (PLCG) in order to improve hydrophilicity, biocompatibility and biodegradability of PCL. PCL and the blend solutions were subjected to electrospinning to produce nanofiber scaffolds by the addition of only 1 wt% of PEG and PLCG either singly or in combination in PCL to retain the mechanical properties of the scaffolds. PCL-PEG-PLCG ternary and two binary (PCL-PEG and PCL-PLCG) blend nanofiber scaffolds have been prepared for comparison. The resulting nanofibers showed a smooth and flaw-free surface and the diameter of the nanofibers displayed a normal distribution. The PCL-PEG nanofiber scaffold showed improved hydrophilicity [water contact angle (WCA) ∼84°] over pristine PCL (WCA ∼127°); while PCL-PLCG and PCL-PEG-PLCG scaffolds exhibited absolute wetting by water, likely due to high porosity. In vitro biocompatibility studies using gingival mesenchymal stem cells (gMSCs) suggested that, both the PCL and the blend scaffolds were biocompatible supporting cell-viability and growth of gMSCs following their seeding on these scaffolds. Biodegradation studies in phosphate buffer solution showed that the addition of PEG and PLCG in PCL increased the weight loss of scaffolds with time, indicating higher extent of biodegradation in the blend scaffolds and the weight loss followed the power law curve with time.

Study on Biodegradable Behavior of Polyesters in the Soil of FuJian Local

The biodegradation and biodegradable mechanism of the polyesters ,such as poly (lactic acid) (PLA), poly (butylene succinate) (PBS) and poly (caprolactone) (PCL) have been investigated; the soil of Shanxi local land and activated sludge from Ningde waste water plant played the biodegradable medium in this study. The results shown the remarkable eroded trace of the surface of the films could be found after degradation by the results of Polarized Light Microscope (PLM) and scanning electron microscope (SEM); the biodegradation of PCL is best, the PLA′s is better than that of PBS. The structures of the films determined with Fourier-Transformation Infrared Spectrum (FT-IR) after degradation.

Nanoparticle-Induced Controlled Biodegradation and Its Mechanism in Poly(ε-caprolactone)

Poly(epsilon-caprolactone) (PCL)/layered silicate nanocomposites have been prepared via solution route. Two different organically modified nanoclays were used to compare the variation in properties based on organic modifications. The nanostructures, as observed from wide-angle X-ray diffraction and transmission electron microscopy, indicate intercalated and partially exfoliated hybrids depending on the nature of organic modification in nanoclay. The nanohybrids exhibit significant improvement in thermal and mechanical properties of the matrix as compared to neat polymer. The nanoclays act as nucleating agent for the crystallization of PCL. The biodegradability of pure PCL and its nanocomposites have been studied under controlled conditions in enzyme, pure microorganism (fungi), compost, Ganges water, and alkaline buffer solution. The rate of biodegradation of PCL has enhanced dramatically in nanohybrids and depends strongly on the media used. Scanning confocal, electron, and atomic force microscopes have used to demarcate the nature of biodegradation of pristine PCL and its nanocomposites. The change in biodegradation is rationalized in terms of the crystallization behavior and organic modification in nanoclays of the nanohybrids vis-a-vis the neat polymer. The extent of compatibility was measured quantitatively through the interaction parameter for two different nanoclays to compare and establish the reason for variation in their properties in nanohybrids. A biodegradation mechanism has been revealed for PCL and its nanocomposites through enzyme activity in varying pH environment.

Preparation and characterization of poly(ε-caprolactone)/Na +-MMT nanocomposites

A two-step process has been developed to disperse sodium montmorillonite(Na +-MMT) in organic liquid N,N-dimethylformamide(DMF) and was applied in preparation of poly(ε-caprolactone)(PCL) nanocomposites. The dispersion of Na +-MMT particles in DMF was evaluated by laser diffraction and the dispersion of Na +-MMT particles in composites was investigated by transmission electron microscopy(TEM) and X-ray diffraction(XRD). TEM result indicated that the average lateral dimension of Na +-MMT particles in composites was approximately 300 nm and the thickness was less than 20 nm. The impact of Na +-MMT on the crystallization behavior and thermal resistance of PCL were determined by differential scanning calorimetry(DSC) and thermal gravimetric analysis(TGA), respectively. The impact of Na +-MMT on biodegradability of PCL was also studied.

Role of polyethylene‐graft‐glycidyl methacrylate compatibilizer on the biodegradation of poly(ε‐caprolactone)/cellulose acetate blends

AbstractBiodegradable polymers provide an attractive solution to reduce environmental pollution caused by the accumulation of plastic waste in landfills. In this study, the effect of polyethylene‐graft‐glycidyl methacrylate (PE‐g‐GMA) on the biodegradation of blends of poly(ε‐caprolactone) (PCL) and cellulose acetate (CA) (80/20, 60/40, 40/60, and 20/80 PCL/CA, w/w) was assessed by mass retention, tensile strength, and morphological properties. The principal fungal strains present in the soil after biodegradation were also identified. PCL and the blends containing 60% and 80% PCL showed greater mass loss and superficial change in simulated soil. PE‐g‐GMA increased the tensile strength retention during 3 months of aging in simulated soil. Scanning electron microscopy (SEM) indicated that pure PCL was more porous, which enhanced the hydrolysis and biodegradation of PCL. PE‐g‐GMA decreased the mass loss of the polymers, possibly by enhancing the interaction between PCL and CA, with the formation of hydrogen bonds between the carbonyl groups of PCL and the hydroxyl groups of CA. This effect was marked in blends with >40% PCL. Microbiological analysis revealed the presence of several species of fungi in the soil. Copyright © 2009 John Wiley & Sons, Ltd.

Preparation of the stimuli-responsive ZnS/PNIPAM hollow spheres

Novel quantum dots ZnS/poly(N-isopropylacrylamide) (PNIPAM) hybrid hollow spheres were obtained by localizing free radical polymerization of NIPAM and crosslinker (MBA) at the peripheral of PCL nanoparticles, followed by biodegradation of PCL with an enzyme of the Lipase PS. The formation of ZnS/PNIPAM hollow spherical structures and the thermo-sensitive reversible properties was systematically investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The ZnS/PNIPAM hollow spheres possess the photoluminescence properties and a swelling and de-swelling at about 32°C, which agrees well with the slight red shift in photoluminescence spectra.

Structure and mechanical properties of blends of poly(ε‐caprolactone) with a poly(amino ether)

AbstractPoly(ε‐caprolactone) (PCL)/poly(amino ether) (PAE) blends were obtained by injection molding without any previous extrusion step in an attempt to (i) contribute to the knowledge of the relation between structure and mechanical properties in these type of blends composed of a rubbery and a glassy polymer and (ii) to find out to which extent are the PCL/PAE blends compatible, and therefore whether the biodegradability of PCL can be added as a characteristic of PAE‐based applications. PCL/PAE blends are composed of a crystalline PCL phase, a pure amorphous PCL phase, and a PAE‐rich phase where some PCL is present. The presence of some dissolved and probably unreacted PCL in the PAE‐rich phase led to a low interfacial tension as observed by the small size of the dispersed particles and the large interfacial area. The dependence on composition of both the modulus of elasticity and the yield stress of the blends was parallel to that of the orientation level. The elongation at break showed values similar to those of PAE in PAE‐rich blends, and was slightly synergistic in very rich PCL compositions; this behavior reflects a change in the nature of the matrix, from glassy to rubbery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Novel Differential Refractometry Study of the Enzymatic Degradation Kinetics of Poly(ethylene oxide)-b-poly(ε-caprolactone) Particles Dispersed in Water

A poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) diblock copolymer was micronized into small micelle-like particles (approximately 80 nm) via dialysis-induced microphase inversion. The enzymatic biodegradation of the PCL portion of these particles in water was in situ investigated inside a recently developed novel differential refractometer. Using this refractometry method, we were able to monitor the real-time biodegradation via the refractive index change (Deltan) of the dispersion because Deltan is directly proportional to the particle mass concentration. We found that the degradation rate is proportional to either the polymer or enzyme concentration. Our results directly support previous speculation on the basis of the light-scattering data that the biodegradation follows the first-order kinetics for a given enzyme concentration. This study not only leads to a better understanding of the enzymatic biodegradation of PCL, but also demonstrates a novel, rapid, noninvasive, and convenient way to test the degradability of polymers.

Mechanical Behavior and Biodegradation of Poly(ε-caprolactone)/Starch Blends with and without Expansor

The use of biodegradable polymers has provided an alternative to the problem of polymer-based products discarded in the environment. Poly(e-caprolactone) (PCL) is a biodegradable polymer that has been used industrially, but it is very expensive. Starch is a potentially useful material for biodegradable plastics because of its natural abundance and low cost. The aim of this work was to examine the effect of adding azodicarbonomide (ADC) as an expansor to blends of PCL with corn starch. Different proportions, of ADC (0.1%, 0.2% and 0.3%, w/w) were added to pure PCL and to PCL/starch (50/50) blends and their properties were studied. Biodegradable blends of PCL with starch had a higher density than PCL alone and the addition of ADC reduced the density of the materials. The incorporation of starch increased the water absorption and ADC did not significantly alter this property. The incorporation of starch into PCL reduced the tensile strength and the elongation at break; ADC enhanced these reductions and also decreased the Young’s modulus of PCL. SEM showed that blends prepared with starch were immiscible, had a homogeneous dispersion of starch, and poor interfacial adhesion. The addition of ADC resulted in cells in the interior of the polymers. The 50/50 PCL/starch blends biodegraded faster than PCL, and ADC had no significant influence on the biodegradation of the blends but inhibited the biodegradation of PCL.

Effect of thermal aging on the biodegradation of PCL, PHB‐V, and their blends with starch in soil compost

AbstractDifferent proportions of starch were blended with poly(β‐hydroxybutyrate)‐co‐poly(β‐hydroxyvalerate) (PHB‐V) or poly(ε‐caprolactone) (PCL) by extrusion, and the mechanical (maximum tensile strength, elongation at break and Young's modulus) and thermal properties (by differential scanning calorimetry) were determined. The biodegradability of the blends in soil compost was also assessed after thermal aging for 192, 425, and 600 h at different temperatures. The maximum tensile strength of the PCL50 blend (containing 50% starch) was 35% lower than that of PCL and that of the PHB‐V50 blend was 60% lower than that of PHB‐V without thermal aging. PHB‐V blends were more biodegradable than PCL blends. For the blends prepared, only the biodegradation of PHB‐V25 was affected by thermal aging. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3539–3546, 2003

Enzymatic degradation of poly ( ε-caprolactone), poly (vinyl acetate) and their blends by lipases

Poly ( ε-caprolactone) (PCL) and poly (vinyl acetate) (PVAc) and their blends were degraded in toluene by two lipases (Novozym 435 and Candida Rugosa) at 60°C. The degradation of PCL and side-chain hydrolysis of PVAc yielded specific products of molecular weight ∼500 and ∼700, respectively. FTIR analysis of the polymer before and after enzyme treatment and the specific products show that there is large reduction of ester linkages and generation of –OH, –COO (−), –COOH groups in the broken chains. The optimal temperature for the side-chain hydrolysis of PVAc was 60 and 65°C and the optimal temperature for the biodegradation of PCL was 55 and 60°C for Candida Rugosa and Novozym 435, respectively. Continuous distribution kinetics was proposed for determining the rate coefficients of the polymers and deactivation of the enzyme. Enzymatic degradation studies of PCL–PVAc blends showed that there is a drastic reduction in the degradation of PCL in the blends. This was modeled by the interaction between polymers.

Anaerobic Biodegradation of Aliphatic Polyesters: Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) and Poly(ε-caprolactone)

Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), PHBO, represents a class of PHA copolymers that contain both short-chain-length and medium-chain-length repeat units. Radiolabeled and cold PHBO, containing 90 mol % 3-hydroxybutyrate and 10 mol % 3-hydroxyoctanoate were chemically synthesized using a new difunctional alkoxyzinc initiator. (14)C-PHBO was incubated with samples of anaerobic digester sludge, septage, freshwater sediment, and marine sediment under conditions resembling those in situ. In addition, it was incubated in laboratory-scale landfill reactors. (14)C-PCL (poly-epsilon-caprolactone) was incubated with anaerobic digester sludge and in landfill reactors. Biodegradation was determined by measuring generation of (14)CO(2) and (14)CH(4) resulting from mineralization of the radiolabeled polymers. PHBO was extensively mineralized in digester sludge, septage sediments, and the landfill reactors, with half-lives less than 30 days. PCL was not significantly mineralized in digester sludge over 122 days. In the landfill reactors, PCL mineralization was slow and was preceded by a long lag period (>200 days), suggesting that PCL mineralization is limited by its rate of hydrolysis. The results indicate that PHBO is practically biodegradable in the major anaerobic habitats that it may enter. In contrast, anaerobic biodegradation of PCL is less ubiquitous and much slower.

Wplyw modyfikacji poli(e-kaprolaktonu) na jego biodegradacje w warunkach naturalnych

Effect of various modifiers and processing additives on poly(E-caprolactone) (PCL) biodegradation rate under natural conditions (in compost with activated sludge and in seawater) was investigated. Tests included starch, chalk or processing additives (i.e. poly(ethyl-butyl acrylate) with oxidant (EBA), or Master Batch (MB) system consisting of PE-LD and erucic and oleic acid amides) modified PCL. Characteristic parameters of both environments were controlled throughout the biodegradation (Tables 1 and 2). Biodegradation of PCL was assessed based on changes in weight, intrinsic viscosity, tensile strength, surface morphology and crystallinity characteristics (Tables 3-6, Fig. 1). Susceptibility of PCL to biological degradation caused by macro- and micro-organisms present in the natural environment was confirmed. Biodegradation of unmodified PCL lasts 6 weeks in compost and 7 weeks in seawater. Chalk does not affect PCL biodegradability rate, whereas introduction of starch accelerates the process. Modification of PCL using processing additives reduced its susceptibility to attack by microorganisms present in the natural environment, thus, prolonging the biodegradation. Microscopic observations and DSC measurements confirmed two-stage enzymatic degradation of PCL, whereby the amorphous phase is degraded first, with the polymer crystalline phase following.

Environmental degradation of biodegradable polyesters 1. Poly(ε-caprolactone), poly[(R)-3-hydroxybutyrate], and poly(L-lactide) films in controlled static seawater

Films of biodegradable aliphatic polyesters, poly(ε-caprolactone) (PCL), poly[(R)-3-hydroxybutyrate] (R-PHB), and poly(L-lactide) (PLLA) were prepared by solution-casting and annealing from the melt. Their biodegradation in static seawater controlled at 25 °C was investigated using polarizing optical microscopy, gravimetry, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and tensile testing. The change in weight loss, tensile strength, and Young's modulus revealed that the biodegradabilities of the aliphatic polyesters in the controlled seawater decreased in the order: PCL>R-PHB>PLLA. The results of gravimetry, GPC, and DSC showed that the biodegradation of PCL and R-PHB films proceeds via surface erosion mechanisms. The polarizing optical microscopy indicated that the PCL and R-PHB films were biodegraded inhomogeneously on the film surface where the marine microbes attached, resulting in pore formation. The crystalline residues of PCL and R-PHB films could not be traced by GPC even when large weight losses occurred. Polarizing optical microscopy and GPC indicated that the decreased tensile strength and Young's modulus of the PCL and R-PHB films are attributed to the formation of pores and cracks during biodegradation. The biodegradation of the PLLA films was insignificant even after immersion in the controlled seawater for 10 weeks and the initial crystallinity had no significant effects on the biodegradability of the PLLA films, excluding the tensile properties change. The biodegradation of these aliphatic polyester films in the controlled static seawater could not be traced by GPC and DSC measurements.

Biodegradation of [(3)H]poly(epsilon-caprolactone) in the presence of active sludge extracts.

Poly(epsilon-caprolactone), PCL, is a commercial biodegradable and biocompatible polyester that can be bioassimilated by outdoor microorganisms. For biomedical and environmental applications, monitoring the fate of degradation products in vivo or under environmental conditions is one of the critical steps to evaluate degradation characteristics. [(3)H] radiolabeling is the best method to monitor the fate of degradable polymer chains in contact with complex living systems and to show bioassimilation. Therefore, tritiated PCL was synthesized by chemical modification using anionic activation by reaction with lithium diisopropylamide. The resulting radioactive polymer was characterized and allowed to degrade at 37 degrees C under aerobic conditions in the presence of active sludge. Comparison was made with abiotic hydrolytic degradation in pH = 7.4, 0.13 M phosphate buffer at 37 degrees C. Water-soluble degradation products were assessed by measuring radioactivity in the solution phase. It was shown that biodegradation of PCL started after a few hours and proceeded up to the ultimate stage over ca. 72 days, giving tritiated water (80-90%) and biomass. Radioactivity detection appeared much more sensitive than measurement of CO(2) production or consumption to monitor degradation phenomena. In particular, it showed that the onset of biodegradation occurs earlier than that reported using respirometry.

A novel laser light-scattering study of enzymatic biodegradation of poly(ε-caprolactone) nanoparticles

A successful micronization of water-insoluble poly(ε-caprolactone) (PCL) into narrowly distributed nanoparticles stable in water has not only enabled us to study the enzymatic biodegradation of PCL in water at 25°C by a combination of static and dynamic laser light scattering (LLS), but also to shorten the biodegradation time by a factor of more than 10 3 compared with using a thin PCL film, i.e. a 1 week conventional experiment becomes a 4 min one. The time-average scattering intensity decreased linearly. It was interesting to find that the decrease of the scattering intensity was not accompanied by a decrease of the average size of the PCL nanoparticles, indicating that the enzyme, Lipase Pseudomonas (PS), “eats” the PCL nanoparticles one-by-one, so that the biodegradation rate is determined mainly by the enzyme concentration. Moreover, we found that using anionic sodium lauryl sulphate instead of cationic hexadecyltrimethylammonium bromide as surfactant in the micronization can prevent the biodegradation, suggesting that the biodegradation involves two essential steps: the adsorption of slightly negatively charged Lipase PS onto the PCL nanoparticles and the interaction between Lipase PS and PCL.

Blends of aliphatic polyesters. III. Biodegradation of solution-cast blends from poly(L-lactide) and poly(?-caprolactone)

Phase-separated blend films were prepared with the solution casting method from poly(L-lactide) (PLLA) and poly(e-caprolactone) (PCL) with different PLLA contents [XPLLA (w/w) = PLLA/(PCL + PLLA)] and their biodegradation was investigated in soil up to 20 months by gravimetry, gel permeation chromatography, tensile testing, differential scanning calorimetry, and scanning electron microscopy. The nonblended PCL film and the blend film with XPLLA = 0.25 disappeared in 4 and 12 months, respectively, while most of the initial mass remained for the blend film of XPLLA = 0.75 and the nonblended PLLA film. The decrease in weight remaining, molecular weight, tensile strength, and elongation-at-break was higher for blend films of low XPLLA. The melting temperature of PLLA in blend films of XPLLA = 0.5 and 0.75, and of nonblended film, remained around 179°C upon biodegradation in soil for 20 months. The preferred biodegradation of PCL in blend films resulted in formation of microspheres of a PLLA-rich phase at the surface for the blend film of XPLLA = 0.25 and the porous structure for blend films of XPLLA = 0.5 and 0.75. Comparison of the weight loss of blend films in biodegradation in soil with that of the nonenzymatic hydrolysis in phosphate-buffered solution revealed preferred enzymatic degradation of PCL and insignificant attack to PLLA in the blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2259–2268, 1998

A novel method of studying polymer biodegradation

A novel combination of laser light scattering (LLS) and the micronization of a water-insoluble polymer into narrowly distributed nanoparticles stable in water has provided not only an accurate, reliable and microscopic method to study polymer biodegradation, but also a novel and fast way to evaluate the biodegradability of a given polymer. Using poly(ε-caprolactone) (PCL) as a typical example, we have shown that its biodegradation time can be shortened by a factor of more than 10 3 times in comparison with the time required to biodegrade a thin film (10 × 10 × 0.1 mm 3). Moreover, the biodegradation kinetics can be in-situ monitored in terms of the decrease of the time-average scattering intensity and the particle number. A comparison of static and dynamic LLS results revealed that the enzyme, Lipase Pseudomonas, “eats” the PCL nanoparticles in an one-by-one manner and the enzymatic biodegradation of PCL follows a zero-order kinetics.

A review of the biodegradability and utility of poly(caprolactone)

Since the early 1970s, it has been known that exposure of poly(caprolactone) (PCL) to a variety of microorganisms results in biodegradation of this polymer. Besides the ability of PCL to be utilized as a carbon source for microorganisms, it has been demonstrated that, during degradation, carbon dioxide is generated. Soil burial and compost experiments have shown that chain scission of the PCL backbone occurs, mechanical properties of articles prepared from PCL are reduced rapidly, and significant weight loss occurs in a short time period. This inherent biodegradability of PCL, in combination with its ability to be converted by conventional extrusion equipment, allows for the preparation of biodegradable articles that have utility.