Amino acid functionalized pH- and temperature-sensitive biodegradable injectable hydrogels: synthesis,physicochemical characterization and in vivo degradation kinetics

Abstract

In recent years, injectable hydrogels that undergo sol-to-gel phase transition in response to the physiological pH- and temperature have attracted increasing attention in therapeutics delivery. In this study, we developed a biodegradable pH- and temperature-sensitive pentablock copolymers by chemical conjugation of L-cysteine oligomer to the backbone of poly(ε-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone-co-lactide) (PCLA-PEG-PCLA) copolymers. A series of pentablock copolymers with various chain lengths were prepared by tuning the reaction time and temperature. These copolymers were freely soluble in water at high pH and low temperature; whereas, they could form a stable gel at the physiological condition (pH 7.4, 37?°C). An in vivo injectable study in the back of Sprague-Dawley (SD) rats indicated that the copolymer could form an in situ gel. In addition, an in vivo biodegradation study of the hydrogels showed controlled degradation of the gel matrix without inflammation at the injection site. Overall, our results show that biodegradable pH- and temperature-responsive hydrogel prepared in this study found to be bioresorbable and could be used as a controlled therapeutics delivery vehicle.     

Synthesis and characterization of a redox‐initiated,injectable, biodegradable hydrogel

A chemically crosslinked biodegradable hydrogel was prepared via a macromer technique, and physicochemical characterizations associated with its potential application as an injectable biomaterial were carried out. The macromers were composed of poly(ethylene glycol) extended with oligomers of biodegradable polyesters such as oligolactide and end‐capped with acryloyl groups. Hydrogels were obtained through the polymerization of the macromer aqueous solutions in phosphate‐buffered saline initiated by a redox initiator system at body temperature. The initiator system was composed of ammonium persulfate as an initiator and N,N,N′,N′‐tetramethylethylene diamine as an accelerator. The modulus of this chemical gel was much higher than that of a Pluronic physical gel. In vitro biodegradation was also confirmed. The degradation rates were highly tunable by the adjustment of several factors, such as the kind of ester group, the block length of the oligoester, and even the concentration of the accelerator used in the crosslinking reaction. The gelation time could be adjusted to meet the requirements of an injectable biomaterial. The effect of the polymerization heat seemed not to be significant. This kind of biodegradable hydrogel might be in situ formed after being injected into the body and shows potential applications as a unique tissue engineering material free of porogening techniques in scaffold fabrication and less invasive in implantation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Z-protected glutamic acid-based biodegradable thermoplastic and thermosetting polyesters: Synthesis and characterization

Biodegradable polymers were formed from N-benzyloxycarbonyl-l -glutamic acid with the comonomers ethylene glycol, diglycidyl ether of 1,4-butanediol, and diglycidyl ether of bisphenol A. The three polymers were a linear and a crosslinked heterochain polyester and a crosslinked polyester that contained aromatic units within its network chains. The thermoplastic resin and the soluble fractions for the thermosetting resins were characterized by gel permeation chromatography. Conversions for carboxylic acid were determined by titrations. A quality, 22,000 molecular weight thermoplastic resin was formed. The two thermosets were cured past their gel points. Gelation analysis revealed that the relative rate constants for the sequential oxirane/acid and alcohol/acid reactions were distinct. With diglycidyl ether of 1,4-butanediol, the ratio of the respective rate constants was 3; with diglycidyl ether of bisphenol A, the ratio approached 200. The resins hydrolyzed to monomers in the presence of lipase, but in the presence of a mixed microbial culture, only the first two resins decayed to biomass, respiratory gases, and water. The third resin was inert during the period of observation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 869–879, 1999     

Synthesis and characterization of hydrogels containing biodegradable polymers

BACKGROUND: Amphiphilic block and graft copolymers constitute a very interesting class of polymers with potential for biomedical applications, due to their special characteristics, which derive from the combination of properties of hydrophilic and hydrophobic moieties. In this work, the synthesis and biodegradation of poly(2‐hydroxyethyl methacrylate)‐graft‐poly(L ‐lactide) are studied. RESULTS: The graft copolymers were synthesized using the macromonomer technique. In a first step, methacryloyl‐terminated poly(L ‐lactide) macromonomers were synthesized in a wide molecular weight range using different catalysts. Subsequently, these macromonomers were copolymerized with 2‐hydroxyethyl methacrylate in order to obtain a graft copolymer. These new materials resemble hydrogel scaffolds with a biodegradable component. The biodegradation was studied in hydrolytic and enzymatic environments. The influence of different parameters (molecular weight, crystallinity, ratio between hydrophilic and hydrophobic components) on the degradation rate was investigated. CONCLUSION: Based on this study it will be possible to tailor the release properties of biodegradable materials. In addition, the materials will show good biocompatibility due to the hydrophilic poly(2‐hydroxyethyl methacrylate) hydrogel scaffold. This kind of material has potential for many applications, like controlled drug‐delivery systems or biodegradable implants. Copyright © 2008 Society of Chemical Industry     

Synthesis and evaluation of novel injectable and biodegradable polyglycolide‐based composites

Novel 3‐arm methacrylate‐endcapped biodegradable polyglycolide prepolymer was synthesized and characterized. Injectable and in situ curable composites formulated with the liquid prepolymer and bioabsorbable β‐tricalcium phosphate were prepared. The pastelike composites were cured at room temperature using a redox‐initiation system. The initial compressive strengths (CSs), curing time, exotherm, and degree of conversion of the cured composites were determined. The composites showed initial yield CS ranging from 20.1 to 92.3 MPa, modulus from 0.73 to 5.65GPa, ultimate strength from 119.9 to 310.5 MPa, and toughness from 630 to 3930 N mm. Increasing filler content increased yield strength and modulus but decreased ultimate strength and toughness. Diametral tensile strength test showed the same trend as did CS test. Increasing filler content also increased curing time but decreased exotherm and degree of conversion. During the course of degradation, all the materials showed a significant burst degradation behavior within 24 h, followed by a significant increase in strength between Day 1 and Day 3, and then continuous degradation until no strength was detected. The composites with higher filler content retained their strengths longer but those with lower filler contents lost their strengths in 45 or 60 days. The degradation rate is filler‐content dependent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2977–2984, 2007     

Novel biodegradable superabsorbent hydrogels derived from cotton cellulose and succinic anhydride: Synthesis and characterization

The synthesis of novel superabsorbent hydrogels was investigated with the reaction of cotton cellulose and succinic anhydride (SA) in the presence of 4‐dimethylaminopyridine as an esterification catalyst in a mixture of lithium chloride (LiCl) and N‐methyl‐2‐pyrrolidinone (NMP) or in a mixture of tetrabutylammonium fluoride (TBAF) and dimethyl sulfoxide (DMSO), followed by NaOH neutralization. Interestingly, a hydrogel was obtained without any crosslinking agent, and this indicated the partial formation of a diester between the cellulosic hydroxyl group and SA. The products obtained in LiCl/NMP exhibited superior absorbency to these obtained in TBAF/DMSO. The former absorbed an amount of water about 400 times its dry weight, and this was comparable to a conventional sodium polyacrylate superabsorbent hydrogel. Furthermore, in an aqueous NaCl solution, the absorbency of the product hydrogels was higher than that of the sodium polyacrylate superabsorbent hydrogel. The formed hydrogels biologically degraded almost completely after 25 days, and this showed their excellent biodegradability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3251–3256, 2006     

Preparation and characterization of electrospun,biodegradable membranes

Nonwoven, biodegradable membranes fabricated by electrospinning have recently attracted a great deal of attention for biomedical applications. In this study, microporous, nonwoven membranes of poly(L ‐lactide) and its copolymers and blends were fabricated through electrospinning. The structures and morphologies of the electrospun membranes were investigated with scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction. Different polymer membranes, incorporated with carmofur, were fabricated, and their drug release profiles were investigated. Scanning electron microscopy images showed that the fiber diameters were down to the nanometer range. The diameters and morphologies of thenanofibers depended on processing parameters such as the solution properties (concentration and polymer molecular weight), applied electric voltage, solution feeding rate, and needle diameter. Differential scanning calorimetry showed that the crystallinity of the electrospun membranes was lower than that of the cast film. For all the membranes incorporated with the drug, there was a burst release in the first 10 h of incubation in phosphate‐buffered saline at 37°C. Poly(glycolide‐co‐lactide) membranes showed faster and more complete drug release than poly(L ‐lactide), and this could be attributed to its faster degradation. The incorporation of polylactide–poly(ethylene glycol) could shorten the drug release time. A combination of suitable degradable biomaterials with an appropriate electrospinning process could be useful in the fabrication of a new kind of membrane suitable for different biomedical applications such as tissue engineering and drug delivery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of biodegradable polyurethanes with unsaturated carbon bonds based on poly(propylene fumarate)

The segmented polyurethanes synthesized from biodegradable polyesters are very promising and widely applicable because of their excellent physiochemical properties. Poly(propylene fumarate) (PPF), a kind of linear aliphatic unsaturated and biodegradable polyesters, has been well recognized in biomedical applications. Herein novel polyurethanes (PPFUs) were synthesized based on the PPF‐diol, diisocyanates such as 1,6‐diisocyanatohexane, l ‐lysine diisocyanate, and dicyclohexylmethane diisocyanate, and chain extenders such as 1,4‐butylene glycol and l ‐lysine methyl ester hydrochloride (Lys‐OMe·2HCl). By varying the types of diisocyanates, and chain extenders, and the proportion of hard segments, the PPFUs with tailored properties such as mechanical strength and degradation rate were easily obtained. The synthesized PPFUs had an amorphous structure and slight phase separation with strong hydrogen bonding between the soft segments and the hard segments. The elongation of PPFU elastomers reached over 400% with a slow deformation‐recovery ability. The PPFUs were more sensitive to alkaline (5 M, NaOH) hydrolysis than acid (2 M, HCl) and oxidative (30 vol.%, H₂O₂) erosion. The tensile strength, deformation‐recovery ability, and glass transition temperature of the PPFUs were improved with the increase of hard segment proportion, while the degradation rate was opposite because of the faster degradation of the soft segments. In vitro culture of smooth muscle cells in the extractant of the PPFUs or on the PPFUs film surface revealed low cytotoxicity and good cytocompatibility in terms of cell viability, adhesion, and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42065.     

Surface hydrophilicity and enzymatic hydrolyzability of biodegradable polyesters: 1. effects of alkaline treatment

Surface treatment using alkaline solutions was attempted to enhance the surface hydrophilicity and enzymatic hydrolyzability of hydrophobic poly(L ‐lactide) [ie poly(L ‐lactic acid) (PLLA) and poly(ε‐caprolactone) (PCL). The alkaline treatment was performed by immersing the PLLA and PCL films in 0.01 and 4 N NaOH solutions, respectively, for various periods of time. The effects of the alkaline treatment on the hydrophilicity of the films were monitored by dynamic contact angle measurements, while the enzymatic hydrolyzability of the PLLA and PCL films after the alkaline treatment were evaluated by weight losses in the presence of proteinase K and Rhizopus arrhizus lipase, respectively. With the alkaline treatment the hydrophilicity of the PLLA and PCL films was controllable in the advancing contact angle (θ_a) ranges of 84–108° and of 69–93°, respectively, by varying the alkaline treatment time. The enzymatic hydrolysis rates of the PLLA films became higher with decrease of the θ_a, irrespective of the crystallinity, strongly suggesting that the surface hydrophilicity or the surface molecular weight is crucial to determine their enzymatic hydrolyzability. In contrast, the enzymatic hydrolyzability of the PCL films remained unchanged even when the θ_a decreased from 93° to 73° by alkaline treatment for 4 h. However, prolonged alkaline treatment for periods of time exceeding 4 h, which insignificantly altered the θ_a but caused the formation of pores and cracks on the PCL film surface, accelerated the enzymatic hydrolysis of the PCL films. This indicates that the enzymatic hydrolyzability of the PCL film depends on the surface area per unit weight rather than the surface hydrophilicity. Copyright © 2003 Society of Chemical Industry     

Synthesis and characterization of biodegradable low molecular weight aliphatic polyesters and their use in protein‐delivery systems

Poly(lactic acid) (PLA) and poly(lactic‐co‐GA) (PLGA) with low molecular weights were synthesized by a one‐step polycondensation of lactic acid (LA) with glycolic acid (GA) molecules using stannous octoate as a catalyst at 160°C. A high yield (>80%) of all the polymers was obtained in the study. The PLA and PLGA copolymers were characterized by ¹H‐NMR, GPC, and DSC measurements, etc. We elaborated HSA‐loaded microspheres based on PLA and PLGA copolymers with different monomer ratios (LA/GA = 85:15, 75:25, 65:35, and 50:50) by the solvent‐extraction method based on the formation of double w/o/w emulsion. Microspheres were characterized in terms of the morphology, size, and encapsulation efficiency (E.E.). The highest E.E. (69.3%) of HSA was obtained for HSA‐loaded PLGA (65/35) microspheres among all the formulations. In vitro matrix degradation and protein release of these microspheres were performed in phosphate‐buffer saline (PBS; 154 mM, pH 7.4). The degradation profiles were characterized by measuring the loss of the microsphere mass and the decrease of the polymer intrinsic viscosity. The release profiles were investigated from the measurement of the protein presented in the release medium at various intervals. It was shown that the matrix degradation and protein‐release profiles were highly LA/GA ratio‐dependent. It is suggested that these matrix polymers may be optimized as carriers in protein‐ and peptide‐delivery systems for different purposes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1848–1856, 2004     

Synthesis,characterization, and degradation of a novel L‐tyrosine‐derived polycarbonate for potential biomaterial applications

A novel class of pseudo‐poly(amino acid)s was synthesized with a cyclic dipeptide as new diphenole. Nonpeptide bonds alternating with a peptide bond structure were introduced into the backbone of the pseudo‐poly(amino acid)s. The cyclic dipeptide in this study was obtained from natural L ‐tyrosine. L ‐Tyrosine is a major nutrient amino acid with a phenolic hydroxyl group, so a polycarbonate derived from the cyclic dipeptide should possess more optimum mechanical properties, bioactivity, and biocompatibility. The hydrolytic specimen of the resulting polycarbonate was prepared by a modified solvent evaporation process. Under strongly alkaline conditions, degradation testing was performed. The tyrosine‐derived polycarbonate possessed a low glass‐transition temperature value and a high thermal decomposition temperature value, which formed a broad mean thermal processing range. The most important results of our study were the effects of the polycarbonate degradation on the local pH values, which were smaller than those of other biodegradable polymers [e.g., poly(lactic acid), poly(glycolic acid), and poly(lactic glycolic acid)]. The synthesized polymer and cyclic dipeptide were characterized with Fourier transform infrared, ¹³C‐NMR, and ¹H‐NMR spectroscopy to determine their chemical structures; by differential scanning calorimetry and thermogravimetric analysis to determine the thermal properties of the polymer; by gel permeation chromatography to determine the polymer's molecular weight; and by X‐ray diffraction to determine the polymer's morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

新型无毒可生物降解氨基酸衍生环氧树脂的合成与表征

用天然氨基酸为起始材料,合成了一种具有双酚羟基官能团的环肽,并以此环肽为联酚合成了主链包含酰胺键的可生物降解环氧树脂。用FT-IR与NMR表征了合成氨基酸衍生环肽与对应环氧树脂的化学结构,结果表明合成了预期结构。用盐酸丙酮法测定了合成环氧树脂的环氧值。     

Synthesis and characterization of cholic acid‐containing biodegradable hydrogels by photoinduced copolymerization

A cholic acid (CA)‐containing biodegradable hydrogel (PLA‐PEG‐PLA‐co‐MACAH) was synthesized from the photoinduced copolymerization of a CA‐modified methacrylate monomer (MACAH), bearing a spacer of hexane‐1,6‐diol spacer between the methacryloyl and the cholanoate moieties, and a macromonomer (PLA‐PEG‐PLA‐DA), bearing two acryloyl end groups derived from a poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid) triblock copolymer. The structure of MACAH was confirmed by FTIR, ¹H‐NMR, and MS. The hydrogel PLA‐PEG‐PLA‐co‐MACAH was characterized by scanning electron microscopy and X‐ray diffraction. The experiment results showed that the swelling ratios of the hydrogels decreased with the increase of the CA fraction. The investigation on the in vitro degradation of the hydrogel showed that the CA‐containing hydrogels degraded much slower than the hydrogels without CA component. The bioactivity of the synthesized hydrogels was assessed by the simulated body fluid method. The observed formation of hydroxyapatite on the scaffold of the hydrogels indicated that the hydrogels possess good bioactivity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Environmental degradation of biodegradable polyesters. IV. The effects of pores and surface hydrophilicity on the biodegradation of poly(ϵ‐caprolactone) and poly[(R)‐3‐hydroxybutyrate] films in controlled seawater

Poly(?‐caprolactone) (PCL) and poly[(R)‐3‐hydroxybutyrate] (R‐PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as‐cast blend films (1:1) and by the alkali treatment of as‐cast nonporous films, respectively. These films, as well as as‐cast nonporous PCL and R‐PHB films, were biodegraded in static seawater kept at 25°C, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R‐PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 587–593, 2003     

Development and long-term in vivo evaluation of a biodegradable urethane-doped polyester elastomer

We have recently reported upon the development of crosslinked urethane-doped polyester (CUPE) network elastomers, which was motivated by the desire to overcome the drawbacks presented by crosslinked network polyesters and biodegradable polyurethanes for soft tissue engineering applications. Although the effect of the isocyanate content and post-polymerization conditions on the material structure-property relationship was examined in detail, the ability of the diol component to modulate the material properties was only studied briefly. Herein, we present a detailed report on the development of CUPE polymers synthesized using diols 4, 6, 8, 10, or 12 methylene units in length in order to investigate what role the diol component plays on the resulting material's physical properties, and assess their long-term biological performance in vivo. An increase in the diol length was shown to affect the physical properties of the CUPE polymers primarily through lowered polymeric crosslinking densities and elevated material hydrophobicity. The use of longer chain diols resulted in CUPE polymers with increased molecular weights resulting in higher tensile strength and elasticity, while also increasing the material hydrophobicity to lower bulk swelling and prolong the polymer degradation rates. Although the number of methylene units largely affected the physical properties of CUPE, the choice of diol did not affect the overall polymer cell/tissue-compatibility both in vitro and in vivo. In conclusion, we have established the diol component as an important parameter in controlling the structure-property relationship of the polymer in addition to diisocyanate concentration and post-polymerization conditions. Expanding the family of CUPE polymers increases the choices of biodegradable elastomers for tissue engineering applications.     

Synthesis and characterization of novel biodegradable poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s

Poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s were successfully synthesized by the ring‐opening copolymerization of p‐dioxanone and ethyl ethylene phosphate with triisobutyl aluminum as an initiator; this was confirmed by ¹H‐NMR and infrared spectra. The effects of the reaction conditions, such as the feeding ratio of the monomers and the reaction temperature and time, on the molecular weight of the copolymers were also studied. The in vitro degradation results showed that the introduction of phosphate segments into the backbone chains of the copolymers led to an enhancement of the degradation rate of the copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5507–5511, 2006     

Synthesis and characterization of thermosensitive poly(organophosphazene) gels with an amino functional group

Thermosensitive poly(organophosphazene) gels have been synthesized with a host of side groups, including α‐amino‐ω‐methoxy‐poly(ethylene glycol), hydrophobic amino acid esters (PheOEt, LeuOEt, and IleuOEt), depsipeptide ethyl ester (GlyGlycOEt), and lysine ethyl ester (lysOEt). The fraction of the last side group, lysOEt, which possesses two amine functional groups, was designed to be in the range of 0.1–0.3 mol per polymer unit. The poly(organophosphazenes) have been characterized via ¹H‐ and ³¹P‐NMR spectroscopies, GPC, and elemental analysis. The phase transition behavior of the poly(organophosphazenes) in aqueous solution has been determined via viscometry. Some of the poly(organophosphazenes) with amino functional groups exhibit reversible sol–gel transitions at temperatures near those of the human body, when in aqueous solution. These polymers form a sol at lower temperatures, and become gels at higher temperatures. Also, these polymer solutions have been found to behave generally like Newtonian fluids in the sol state, but appear to exhibit pseudoplastic qualities in the gel state. The polymers possessing depsipeptide ethyl esters (ethyl‐2‐(O‐glycyl)glycolate) as a side group tend to exhibit much higher degradation rates under physiological conditions than do those which lack the depsipeptide ethyl ester group. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:998–1005, 2011     

Synthesis and characterization of poly(ε-caprolactone)-containing amino acid-based poly(ether ester amide)s

A new family of biodegradable amino acid-based poly(ether ester amide)s (AA-PEEAs) consisting of three building blocks [poly(ε-caprolactone) (PCL), L -phenylalanine (Phe), and aliphatic acid dichloride] were synthesized by a solution polycondensation. Using DMA as the solvent, these PCL-containing Phe-PEEA polymers were obtained with fair to very good yields with weight average molecular weight (M_w) ranging from 6.9 kg/mol to 31.0 kg/mol, depending on the original molecular weight of PCL. The chemical structures of the PCL-containing Phe-PEEA polymers were confirmed by IR and NMR spectra. These PCL-containing Phe-PEEAs had lower T_g than most of the oligoethylene glycol (OEG) based AA-PEEAs due to the more molecular flexibility of the PCL block in the backbones, but had higher T_g than non-amino acid based PEEA. The solubility of the PCL-containing Phe-PEEA polymers in a wide range of common organic solvents, such as THF and chloroform, was significantly improved when comparing with aliphatic diol based poly(ester amide)s and OEG based AA-PEEAs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

酚酞烯丙胺型苯并噁嗪树脂的合成、表征及其聚合物的热分解动力学

以酚酞、烯丙胺、多聚甲醛为原料,合成了具有烯丙基的新型酚酞型苯并嗪树脂(PT-ala)。用FT-IR、¹H NMR和DSC表征了其结构和固化特性,并用TG-DTG方法对其聚合物在氮气中的热分解过程动力学进行了详细的研究。结果表明:用Kissinger法和Ozawa法求得的聚合物热分解活化能分别为189.65 kJ·mol^-1和215.11 kJ·mol^-1;用Coats-Redfern法证实了酚酞烯丙胺型聚苯并嗪的热分解反应为一级反应;在氮气氛中维持60 s寿命的最高使用温度为285℃。     

Blends of poly(d,l‐lactide) with polyhedral oligomeric silsesquioxanes‐based biodegradable polyester: Synthesis,morphology, miscibility,and mechanical property

A highly branched hybrid copolymer based on polyhedral oligomeric silsesquioxane (POSS) was designed to improve the brittleness of poly(d,l‐lactide) (PDLLA). The toughening material was synthesized using POSS‐OH as the core, which initiated the ring‐opening polymerization of ε‐caprolactone and d,l‐lactide sequentially to form the highly branched POSS‐g‐poly (ε‐caprolactone)‐b‐poly(d,l‐lactide) (POSS‐g‐PCL‐b‐PLA) copolymer with eight PCL‐b‐PLA arms. The POSS‐g‐PCL‐b‐PLA copolymer had a very good dispersion in the PDLLA matrix with the size of microdomains smaller than 1 µm when added at a low content below 10 wt %. In related to the nano‐scale size of microdomains in the blends, the crystallinity of PCL blocks was significantly suppressed. Thus, the addition of POSS‐g‐PCL‐b‐PLA is very effective to improve the roughness of the matrix polymer when added at a low content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40776.