Blends of aliphatic polyesters. VIII. Effects of poly(L‐lactide‐co‐ε‐caprolactone) on enzymatic hydrolysis of poly(L‐lactide), poly(ε‐caprolactone), and their blend films

Poly(L ‐lactide), that is, poly(L ‐lactic acid) (PLLA), poly(ε‐caprolactone) (PCL), and their blend (50/50) films containing different amounts of poly(L ‐lactide‐co‐ε‐caprolactone) (PLLA‐CL), were prepared by solution casting. The effects of added PLLA‐CL on the enzymatic hydrolysis of the films were investigated in the presence of proteinase K and Rhizopus arrhizus lipase by use of gravimetry. The addition of PLLA‐CL decreased the proteinase K–catalyzed hydrolyzabilities of the PLLA and PLLA/PCL (50/50) films as well as the Rhizopus arrhizus lipase‐catalyzed hydrolyzability of the PCL and PLLA/PCL (50/50) films. The decreased enzymatic hydrolyzabilities of the PLLA and PCL films upon addition of PLLA‐CL are attributable to the fact that the PLLA‐CL is miscible with PLLA and PCL and the dissolved PLLA‐CL must disturb the adsorption and/or scission processes of the enzymes. In addition to this effect, the decreased enzymatic hydrolyzabilities of the PLLA/PCL (50/50) films upon addition of PLLA‐CL can be explained by the enhanced compatibility between the PLLA‐rich and PCL‐rich phases arising from the dissolved PLLA‐CL. These effects result in decreased hydrolyzable interfacial area for PLLA/PCL films. The decrement in proteinase K–catalyzed hydrolyzability of the PLLA film upon addition of PLLA‐CL, which is miscible with PLLA, was in marked contrast with the enhanced proteinase K–catalyzed hydrolyzability of the PLLA film upon addition of PCL, which is immiscible with PLLA. This confirms that the miscibility of the second polymer is crucial to determine the proteinase K–catalyzed hydrolyzabilities of the PLLA‐based blend films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 412–419, 2003     

Microcomposites of Poly(ε‐caprolactone) and Poly(methyl methacrylate) Prepared by Suspension Polymerization in the Presence of Poly(ε‐caprolactone) Macromonomer

Poly(methyl methacrylate)‐poly(ε‐caprolactone) (PMMA/PCL) microparticles were synthesized by suspension polymerization of methyl methacrylate in the presence of PCL. The incorporation of a small amount of a macromonomer, methacryloyl‐terminated PCL (M‐PCL), into the reaction mixture, led to the formation of grafted systems, namely PMMA‐g‐PCL/PCL. The synthesis of the macromonomer and its characterization by nuclear magnetic spectroscopy (¹H NMR) is described. The role of M‐PCL as an effective compatibilizing agent in the composite was investigated. PMMA/PCL and PMMA‐g‐PCL/PCL composites were fully characterized by ¹H NMR, gel permeation chromatography (GPC) and thermal analysis, including thermogravimetric analysis (TGA), conventional differential scanning calorimetry (DSC), modulated DSC (MDSC) and dynamic mechanical thermal analysis (DMTA). Finally, the morphology of the prepared systems was investigated by scanning electron microscopy (SEM). The addition of compatibilizing agent led the formation of a more homogeneous microcomposite with improved mechanical properties.

SEM picture of PMMA‐g‐PCL/PCL composite surface.     

The effect of pH on the hydrolytic degradation of poly(ε‐caprolactone)‐block‐poly(ethylene glycol) copolymers

The in‐vitro hydrolytic behavior of diblock copolymer films consisting of poly(ε‐caprolactone) (PCL) and poly(ethylene glycol) (PEG) was studied at pH 7.4 and pH 9.5 at 37°C. The degradation of these films was characterized at various time intervals by mass loss measurements, GPC, ¹H‐NMR, DSC, FTIR, XRD, and SEM. A faster rate of degradation took place at pH 9.5 than at pH 7.4. Analysis of the molecular weight profile during the course of degradation revealed that random chain scission of the ester bonds in PCL predominates at the initial induction phase of polymer degradation. There was also an insignificant mass loss of the films observed. Mass spectroscopy was used to determine the nature of the water soluble products of degradation. At pH 7.4, a variety of oligomers with different numbers of repeating units were present whereas the harsher degradation conditions at pH 9.5 resulted in the formation of dimers. From the results, it can be proposed that a more complete understanding of the degradation behavior of the PCL‐b‐PEG copolymer can be monitored using a combination of physiological and accelerated hydrolytic degradation conditions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Improvement of processability of poly(ε‐caprolactone) by radiation techniques

Improvement of processability of Poly(ε‐caprolactone) (PCL) was achieved by introduction of a branch structure using gamma‐irradiation from a ⁶⁰Co source. Irradiated PCL has higher molecular weight by producting a branch structure. Hence, the irradiation at a lower dose, such as 3 Mrad, leads to a higher melt viscosity. The branched structure gave improved properties for dynamic viscoelasticity and elongational viscosity. High elongational viscosity was observed by entanglement due to branch chain formed during irradiation, and the elongational viscosity for 3 Mrad is higher than 1.5 Mrad. Due to a higher elongational viscosity, PCL foam can be produced by a molding process. Foam produced from irradiated PCL pellets at 3 Mrad has honeycomb‐like structure, and the foam showed higher enzymatic degradation compared to film samples. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1815–1820, 1999     

Isothermal crystallization kinetics of silk fibroin fiber‐reinforced poly(ε‐caprolactone) biocomposites

BACKGROUND: Poly(ε‐caprolactone) (PCL) has attracted great attention due to its wide applications for pharmaceutical controlled released systems and implanted polymer devices. In this study, silk fibroin fiber (SF) obtained from degumming treatment of silk was used to prepare novel reinforced PCL biocomposites. The isothermal crystallization behavior of these composites was investigated using differential scanning calorimetry measurements. RESULTS: With a decrease of isothermal crystallization temperature (T_c) and an increase of fiber filler, the crystallization time of the SF/PCL composites becomes shorter, the crystallization rate constant (K) increases and the Avrami exponent (n) gradually decreases (being between 1 and 2). The crystallization of PCL and SF/PCL composites occurs in the same regime. With the gradual addition of fiber, lateral surface free energy (σ) is nearly unchanged, but fold surface free energy (σ_e) decreases. CONCLUSION: Heterogeneous nucleation is dominant and different growth morphologies coexist during the isothermal crystallization process of the SF/PCL hybrid systems. Although the introduction of SF obviously increases the overall crystallization rate of PCL, the growth rate constant and nucleation constant of PCL are reduced because of the confinement effect of fiber network structures on the molecular mobility of polymer molecular chains. Copyright © 2009 Society of Chemical Industry     

Crystallization,melting behavior,and wettability of poly(ε‐caprolactone) and poly(ε‐caprolactone)/ poly(N‐vinylpyrrolidone) blends

Both wettability and crystallizability control poly(ε‐caprolactone)'s (PCL) further applications as biomaterial. The wettability is an important property that is governed by both chemical composition and surface structure. In this study, we prepared the PCL/poly(N‐vinylpyrrolidone) (PVP) blends via successive in situ polymerization steps aiming for improving the wettability and decreasing crystallizability of PCL. The isothermal crystallization of PCL/PVP at different PVP concentrations was carried out. The equilibrium melting point (T), crystallization rate, and the melting behavior after isothermal crystallization were investigated using differential scanning calorimetry (DSC). The Avrami equation was used to fit the isothermal crystallization. The DSC results showed that PVP had restraining effect on the crystallizability of PCL, and the crystallization rate of PCL decreased clearly with the increase of PVP content in the blends. The X‐ray diffraction analysis (WAXD) results agreed with that. Water absorptivity and contact angle tests showed that the hydrophilic properties were improved with the increasing content of PVP in blends. The coefficient for the water diffusion into PCL/PVP blends showed to be non‐Fickian in character. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enzymatic Degradation of Biodegradable Polyester Composites of Poly(L‐lactic acid) and Poly(ε‐caprolactone)

Summary: Two different types of biodegradable polyester composites, PLLA fiber‐reinforced PCL and PCL/PLLA blend films were prepared at PCL/PLLA ratio of 88/12 (w/w), together with pure PCL and PLLA films. Their enzymatic degradation was investigated by the use of Rhizopus arrhizus lipase and proteinase K as degradation enzymes for PCL and PLLA chains, respectively. In the FRP film, the presence of PLLA fibers accelerated the lipase‐catalyzed enzymatic degradation of PCL matrix compared with that in the pure PCL film, whereas in the blend film, the presence of PLLA chains dissolved in the continuous PCL‐rich domain retarded the lipase‐catalyzed enzymatic degradation of PCL chains. In contrast, in the FRP film, the proteinase K‐catalyzed enzymatic degradation of PLLA fibers was disturbed compared with that of the pure PLLA film, whereas in the blend film, the proteinase K‐catalyzed enzymatic degradation rate of particulate PLLA‐rich domains was higher than that of pure PLLA film. The reasons for aforementioned enhanced and disturbed enzymatic degradation are discussed.

Normalized PCL weight loss of pure PCL, FRP, and blend films as a function of Rhizopus arrhizus lipase‐catalyzed enzymatic degradation time.     

Preparation and characterization of electrospun poly(ε‐caprolactone)–pluronic–poly(ε‐caprolactone)‐based polyurethane nanofibers

In this study, amphiphilic poly(ε‐caprolactone)–pluronic–poly(ε‐caprolactone) (PCL–pluronic–PCL, PCFC) copolymers were synthesized by ring‐opening copolymerization and then reacted with isophorone diisocyanate to form polyurethane (PU) copolymers. The molecular weight of the PU copolymers was measured by gel permeation chromatography, and the chemical structure was analyzed by ¹H‐nuclear magnetic resonance and Fourier transform infrared spectra. Then, the PU copolymers were processed into fibrous scaffolds by the electrospinning technology. The morphology, surface wettability, mechanical strength, and cytotoxicity of the obtained PU fibrous mats were investigated by scanning electron microscopy, water contact angle analysis, tensile test, and MTT analysis. The results show that the molecular weights of PCFC and PU copolymers significantly affected the physicochemical properties of electrospun PU nanofibers. Moreover, their good in vitro biocompatibility showed that the as‐prepared PU nanofibers have great potential for applications in tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43643.     

Biodegradable supramolecular composites of poly(ε‐caprolactone) and low‐molecular‐weight organic gelators

When a homogeneous hot liquid of poly(ε‐caprolactone) (PCL) with (R)‐12‐hydroxystearic acid (HSA) or N‐carbobenzyloxy‐L ‐isoleucylaminooctadecane (CIA) was gradually cooled to room temperature, the mixture became gelatinous material and then solidified to give a PCL/HSA or PCL/CIA composite. The rheological measurements of the mixtures of PCL with HSA and CIA revealed that the organogels are formed at around 70–50°C and 100–73°C during the cooling process, respectively. Furthermore, the formation of supramolecular fibrillar networks was confirmed by the microscopic and differential scanning calorimetric analyses. The tensile moduli of both the composites were improved by the addition of CIA and HSA. Both the composites showed so high biodegradability as PCL. The fibrillar networks of the composites were also regenerated during the repeated cooling process from the isotropic liquid. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of starch predrying on the mechanical properties of starch/poly(ε‐caprolactone) composites

This study describes the effect of predrying sago starch, a tropical starch, on the resultant mechanical properties of starch/poly(ε‐caprolactone) composite materials. Sago starch was dried to less than a 1% moisture level in a vacuum oven and dispersed into a polycaprolactone matrix with an internal mixer at 90°C. The mechanical properties of the composite were studied according to methods of the Association for Standards, Testing, and Measurement, whereas the morphology was monitored with scanning electron microscopy. The properties were compared with a composite obtained with native starch containing 12% moisture. The results indicated that predrying the starch led to a lower property drop rate in the composite as the starch content increased. The elastic modulus, tensile strength, and elongation at break were higher than those obtained when starch was used without predrying. The morphology observed during scanning electron microscopy studies was used to explain the observed trends in the mechanical properties. In this way, a relatively simple and cost‐effective method was devised to increase the starch loading in the polycaprolactone matrix to obtain properties within the useful range of mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 877–884, 2003     

The use of poly (ε‐caprolactone) to enhance the mechanical strength of porous Si‐substituted carbonate apatite

Poly(ε‐caprolactone) (PCL)/silicon‐substituted carbonate apatite (Si‐CO3Ap) composite derived from the interconnected porous Si‐CO3Ap reinforced with molten PCL was prepared. PCL was used to improve the mechanical properties of a porous apatite by a simple polymer infiltration method, in which the molten PCL was deposited through the interconnected channel of porous Si‐CO3Ap. The PCL covered and penetrated into the pores of the Si‐CO3Ap to form an excellent physical interaction with Si‐CO3Ap leading to a significant increase in diametral tensile strength from 0.23 MPa to a maximum of 2.04 MPa. The Si‐CO3Ap/PCL composite has a porosity of about 50–60% and an interconnected porous structure, with pore sizes of 50–150 μm which are necessary for bone tissue formation. These results could pave the way for producing a porous, structured biocomposite which could be used for bone replacement. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Anomalous impact strength for layered double hydroxide‐palmitate/poly(ε‐caprolactone) nanocomposites

Inherent physical properties and commercial availability makes poly(ε‐caprolactone) (PCL) very attractive as a potential substitute material for nondegradable polymers for commodity applications. However, a balance of toughness and stiffness is needed in order to transfer this potential into reality, particularly for short‐term packaging applications. In this context, layered double hydroxide modified with palmitic acid (LDH‐palmitate), was used as a nanoadditive to enhance the mechanical properties of PCL. Composites from PCL were prepared by melt‐blending with LDH‐palmitate loadings in the 1?10 wt % range. Scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction were used to study the structure and morphology of the composites. The results showed homogeneous dispersion of clay particles in composites, but the degree of stacking of clay platelets was related to the LDH‐palmitate loadings. Charpy impact test measurements revealed an anomalous toughness improvement in the case of composite containing 5 wt % LDH‐palmitate, attributed to a combination of microcavitation and changes in crystallite sizes in the composite. The addition of LDH‐palmitate improved the water vapor barrier permeation of neat PCL film. In summary, LDH‐palmitate was shown to have potential as a nanoadditive to obtain tougher LDH‐PCL composite with improved barrier property. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41109.     

The ageing of poly(ϵ‐caprolactone)

Partially crystallized poly(?‐caprolactone) has been stored for up to 6 months at various temperatures from ?18 to 50 °C and the change in tensile properties, crystallinity and melting behaviour followed with storage time. The Young modulus, yield and drawing stress were observed to increase with time and at a rate which increased with storage temperature. These changes in tensile properties could be accounted for by the increase in crystallinity and were attributed to a thickening of the lamellae which reinforced the morphology and increased the stiffness of the polymer. The thickening of the lamellae accounted for the shift of the melting endotherms to higher temperatures with time. The stem lengths increased with the square root of the storage time and the rate increased with temperature corresponding to an activation energy of 40 ± 5 kJ mol^?1. It is considered that ageing occurred by a process of secondary crystallization by extension of the ‘fold surface’ into the adjacent melt and the thickening of the lamellae. The time dependence of growth can only be explained by small segments of the chain being incorporated onto the crystal on the time scale of the local segmental mobility which is independent of chain entanglements. This does not have the characteristics of a nucleation controlled process but is a thermally activated diffusion process the rate of which increases with temperature. © 2015 Society of Chemical Industry     

Thermal degradation of ternary blends of poly(ε‐caprolactone)/poly(vinyl acetate)/poly(vinyl chloride)

The thermal degradation of ternary blends of poly(ε‐caprolactone) (PCL), poly(vinyl acetate) (PVAC), and poly(vinyl chloride) (PVC) was studied using a thermogravimetry analyzer under dynamic heating in flowing nitrogen atmosphere. PCL degraded in a single stage, whereas the PVAC and PVC degraded in two stages during which acid is released in the first stage followed by backbone breakage in the second stage. The addition of PVC to either PCL or PVAC affected the thermal stability of the blend, whereas the addition of PVAC to PCL did not alter the thermal stability of the blend. In ternary blends, the addition of PVC affected the degradation of PVAC but did not influence the degradation of PCL in the range investigated. The increased addition of PCL to the binary blends of PVC/PVAC decreased the extent of thermal instability of PVAC because of the addition of PVC. The addition of even 10% PVAC to the PCL/PVC blend removed the thermal instability of PCL resulting from the addition of PVC and can be attributed to the ease of chlorine or hydrogen chloride capture of PVAC over PCL. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1378–1383, 2004     

Paper‐sheet biocomposites based on wood pulp grafted with poly(ε‐caprolactone)

Kraft pulp fibers were used as substrates for the grafting of poly(ε‐caprolactone) (PCL) from available hydroxyl groups through ring‐opening polymerization, targeting three different chain lengths (degree of polymerization): 120, 240, and 480. In a paper‐making process, paper‐sheet biocomposites composed of grafted fibers and neat pulp fibers were prepared. The paper sheets possessed both the appearance and the tactility of ordinary paper sheets. Additionally, the sheets were homogenous, suggesting that PCL‐grafted fibers and neat fibers were compatible, as demonstrated by both Fourier transform infrared spectroscopy microscopy and through dye‐labeling of the PCL‐grafted fibers. Finally, it was shown that the paper‐sheet biocomposites could be hot‐pressed into laminate structures without the addition of any matrix polymer; the adhesive joint produced could even be stronger than the papers themselves. This apparent and sufficient adhesion between the layers was thought to be due to chain entanglements and/or co‐crystallization of adjacent grafted PCL chains within the different paper sheets. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42039.     

Biodegradation study on poly(ε‐caprolactone) with bimodal molecular weight distribution

Poly(ε‐caprolactone) (PCL) of bimodal molecular weight distribution was exposed to the action of enzymes‐lipases from Aspergillus oryzae in phosphate buffer at pH 7 and 37°C, and those produced in situ by Bacillus subtilis in nutrient medium at 30°C for 42 days. The occurrence of biodegradation is proved on the basis of the weight loss, decrease of molecular weight, carbonyl index, crystallinity, and development of cracks on the PCL surfaces. In the case of Bacillus subtilis, the degradation (10 wt % loss of PCL) proceeds faster in comparison with lipase from Aspergillus oryzae (2.6 wt % loss of PCL), where the degradation process seems to stop during 14 days of experiment. The gel permeation chromatography results reveal that preferential degradation of lower molecular portion did not occur but it is assumed that PCL chains were cleaved in accordance with particular degradation mechanism that depends significantly on biological agent. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

γ‐Butyrolactone‐processable high‐modulus poly(ester imide)s

γ‐Butyrolactone (GBL)‐processable high modulus heat‐resistant materials were developed in this work. The polyaddition of an ester‐containing tetracarboxylic dianhydride, i.e. hydroquinone bis(trimellitate anhydride) (TAHQ), and 2,2′‐bis(trifluoromethyl)benzidine (TFMB) in GBL resulted in gelation in the initial reaction stage. The incorporation of a methyl group to TAHQ (M‐TAHQ) allowed polymerization with TFMB in GBL and led to a homogeneous poly(ester imide) (PEsI) precursor solution with a short pot life of 3 days, whereas a simple copolymerization approach using bulky/flexible comonomers to TAHQ/TFMB was less effective. PEsI precursors (PEsAAs) were prepared from TFMB, M‐TAHQ and a minor fraction of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or a fluorene‐containing tetracarboxylic dianhydride. These PEsAA systems showed drastically improved GBL solution stability. In particular, the M‐TAHQ(80);6FDA(20)/TFMB copolymer system provided a PEsAA film with a very high light transmittance at 365 nm (>70%). A photosensitive film composed of this matrix resin and diazonaphthoquinone provided a clear positive‐tone pattern by development in a 2.38 wt% tetramethylammonium hydroxide aqueous solution at room temperature with a high dissolution contrast. The thermally cured PEsI film achieved a very high tensile modulus (>5 GPa) as the present target with other desirable properties, i.e. sufficient film flexibility, a relatively low coefficient of thermal expansion, a high T_g and low water absorption. The present materials can be promising candidates as novel buffer coat films in semiconductor applications. Copyright © 2011 Society of Chemical Industry     

Synthesis and characterization of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) triblock copolymers with dibutylmagnesium as catalyst

Two series of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) triblock copolymers were prepared by the ring opening polymerization of ε‐caprolactone in the presence of poly(ethylene glycol) and dibutylmagnesium in 1,4‐dioxane solution at 70°C. The triblock structure and molecular weight of the copolymers were analyzed and confirmed by ¹H NMR, ¹³C NMR, FTIR, and gel permeation chromatography. The crystallization and thermal properties of the copolymers were investigated by wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The results illustrated that the crystallization and melting behaviors of the copolymers were depended on the copolymer composition and the relative length of each block in copolymers. Crystallization exothermal peaks (T_c) and melting endothermic peaks (T_m) of PEG block were significantly influenced by the relative length of PCL blocks, due to the hindrance of the lateral PCL blocks. With increasing of the length of PCL blocks, the diffraction and the melting peak of PEG block disappeared gradually in the WAXD patterns and DSC curves, respectively. In contrast, the crystallization of PCL blocks was not suppressed by the middle PEG block. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biodegradable studies of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone), poly(dioxanone), and poly(glycolide‐ε‐caprolactone) (Monocryl®) monofilaments

The aim of the study was to investigate the mechanical properties and biodegradability of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone) [P(TMC‐ε‐CL)‐block‐PDO] in comparison with poly(p‐dioxanone) and poly(glycolide‐ε‐caprolactone) (Monocryl®) monofilaments in vivo and in vitro. P(TMC‐ε‐CL)‐block‐PDO copolymer and poly(p‐dioxanone) were prepared by using ring‐opening polymerization reaction. The monofilament fibers were obtained using conventional melt spun methods. The physicochemical and mechanical properties, such as viscosity, molecular weight, crystallinity, and knot security, were studied. Tensile strength, breaking strength retention, and surface morphology of P(TMC‐ε‐CL)‐block‐PDO, poly(p‐dioxanone), and Monocryl monofilament fibers were studied by immersion in phosphate‐buffered distilled water (pH 7.2) at 37°C and in vivo. The implantation studies of absorbable suture strands were performed in gluteal muscle of rats. The polymers, P(TMC‐ε‐CL)‐block‐PDO, poly(p‐dioxanone), and Monocryl, were semicrystalline and showed 27, 32, and 34% crystallinity, respectively. Those mechanical properties of P(TMC‐ε‐CL)‐block‐PDO were comparatively lower than other polymers. The biodegradability of poly(dioxanone) homopolymer is much slower compared with that of two copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 737–743, 2006     

Transport Properties of Modified Montmorillonite‐Poly(ε‐caprolactone) Nanocomposites

A series of montmorillonite‐poly(ε‐caprolactone) nanocomposites were prepared according to a two‐stage procedure. In the first step Na‐type silicate clay was cation exchanged with protonated 12‐aminolauric acid. In the second step ε‐caprolactone was intercalated in the modified clay and ring‐opening polymerized. The clay content was varied regularly from 0 to 44 wt.‐%, with exfoliation of the silicate layers being detected by X‐ray diffraction in the nanocomposites dispersing up to at least 16 wt.‐% clay. Crystallization of poly(ε‐caprolactone) was not prevented in the nanocomposites, although it proceeded to a lower extent/order than in a homopolymer sample. The transport properties were investigated using water or dichloromethane as vapor permeants. In each case, a dual sorption behavior was observed as a function of the vapor activity because of the occurrence of different sorption mechanisms. The permeability of the nanocomposites to either permeant decreased with increasing clay content. In particular, the permeability behavior to water was largely dominated by the diffusion parameter.