True Copolymers Research Articles

Polymerization of Allyltrimethylisilane and 4-Methyl-1-Pentene by Using Metallocene Catalysts.

Polymers of higher olefin, obtained by Ziegler-type polymerization, have been used in some critical fields, e.g., as the membrane for extracorporeal membrane oxygenation (ECMO), which plays an important role in the treatment of patients with severe COVID-19. The polymer obtained by a single-site catalyst, e.g., metallocene catalysts, demonstrated a higher performance. The homo- and co-polymerization of allyltrimethylisilane (ATMS) and 4-methyl-1-pentene (4M1P) were conducted using syndiospecific (cat 1) and isospecific (cat 2) metallocene catalysts. Cat 1 showed low conversions and provided a polymer with a higher molecular weight, while cat 2 behaved oppositely. 13C-NMR spectra certified the stereotacticity of the resultant polymer, and the resonance of the carbon atom of CH2 (αα') between the two tertiary carbon atoms of the ATMS and 4M1P units were observed. This could be the evidence of the formation of a true copolymer. The crystallization of the polymer was explored using a differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD). All homopolymers and some of the copolymers showed high melting temperatures and low melting enthalpies. The WAXD patterns of the syndiotactic polymer and isotactic homopolymer or the ATMS-rich copolymer were consistent with the reported literature, but the isotactic 4M1P-rich copolymer provided the crystal form I, which is unusual for a 4M1P polymer without any pretreatment.

Copolymers of sodium 4-styrene sulphonate and vinyl derivatives of nitrogen-containing heterocycles

The formation of ion-exchange composite materials based on high molecular weight precursors appears to be an intensively developing area in the synthesis of proton-conducting membranes for fuel cells. In such membranes, proton transfer is often provided by functional polymers simultaneously containing sulphonic acid groups in their composition units along with fragments of vinyl derivatives of nitrogen-containing heterocyclic bases. Proton exchange activity in the latter is determined by the possibility of doping with inorganic acids. In the framework of this study, for the further formation of hybrid composite membranes under conditions of radical initiation, copolymers of sodium 4-styrene sulphonate (SSt) with 4-vinylpyridine (VP) and 1-vinylimidazole (VIM) were obtained. The monomodal nature of the turbidimetric titration curves for solutions of copolymerisation reaction products indicates the presence of true copolymers during the process of formation. The composition and structure of the copolymers were characterised using data from elemental analysis, as well as from IR and 13 C NMR spectroscopy. Constants of the relative activity for the monomers and the microstructure parameters of the polymer chains are calculated according to the non-linear leastsquares method using the MathCAD package. The calculated copolymerisation constant values indicate a greater reactivity of SSt in comparison with nitrogen-containing monomers. The lengths of the monomer unit blocks depend on the composition of the initial mixture and vary over a wide range from 1 to 18. The possibility of varying the length of the unit blocks in the composition of the copolymers will affect the ion-conducting properties of hybrid composites formed on their basis. The stability of the copolymers to thermal oxidative degradation by heating in air was studied using the differential scanning calorimetry (DSC) method. The copolymers demonstrated significant thermo-oxidative stability. Decomposition temperatures were 350 °С and 400 °С for SSt-VIM and SSt-VP copolymers, respectively.

Homopolymerization and copolymerization of vinyl chloride over supported metalorganic catalysts

The homopolymerization of vinyl chloride and its copolymerization with ethylene over dibutyl ether–modified SiO2-supported Ziegler–Natta catalysts based on titanium and vanadium chlorides have been studied. The supported metal complexes are sufficiently active in the polymerization of vinyl chloride. Their activity depends on the catalyst composition and conditions of formation of the catalyst on the surface of the support. The chain structure of the resulting polyvinyl chloride (PVC) has been studied by NMR spectroscopy. The thermal properties of the synthesized PVC have been investigated by differential scanning calorimetry. The PVC obtained possesses enhanced thermal stability owing to the specific features of its chain structure. Vinyl chloride polymerization over the supported metalorganic catalyst proceeds mainly via a free-radical mechanism. Process conditions have been found for conducting the copolymerization of vinyl chloride with ethylene over supported metal complexes resulting in the formation of true statistical copolymers, which is confirmed by IR and NMR spectroscopy.

Electrosyntheses of anthracene clicked poly(thienylpyrrole)s and investigation of their electrochromic properties

A new anthracene containing thienylpyrrole derivative (SNS-Anth) was synthesized through click reaction of 9-((prop-2-yn-1-yloxy)methyl)anthracene with 1-(2-azidoethyl)-2,5-di(thiophen-2-yl)-1H-pyrrole(SNS-N3). The chemical structure of SNS-Anth was confirmed by using 1H, 13C NMR, FT-IR, UV–Vis, Fluoresence and mass spectroscopy techniques. SNS-Anth was subjected to electrochemical polymerization and the resultant polymer (PSNS-Anth) displayed green to blue coloration in 1.40 s with a coloration efficiency of 78 cm2 C−1. The electrochemical copolymerization of SNS-Anth and 3,4-ethylenedioxythiophene (EDOT) was successfully achieved. The copolymer revealed distinct multichromic behavior where a wide pallet of esthetically pleasing colors (pinkish-red, orange, yellow, green and blue) was observed at various potentials. The objective evaluation of the colors of both PSNS-Anth and the copolymer at various potentials was performed through colorimetry studies on the basis of “Commission Internationale de l′Eclairage” (CIE) standards. The response time, optical contrast and coloration efficiency of the copolymer were calculated as 0.67 s, 28.88%, 193 cm2 C−1 (at 900 nm), respectively. Considering the explicit spectral difference between PSNS-Anth and the copolymer, enhancement of the color pallet, switching time, optical contrast safely confirms formation of a true copolymer.

SYNTHESIS OF RANDOM COPOLYMERS OF 2,6-DI(THIOPHEN-2-YL)ANILINE AND 2,2'-(THIOPHEN-2,5-DIYL)DIANILINE WITH ANILINE AND ITS EVALUATION IN ORGANIC SOLAR CELLS

The present work deals with copolymers synthesized by reacting aniline units or blocks with 2,6-di(thiophen-2-yl)aniline and 2,2'-(thiophen-2,5-diyl)dianiline monomers. Characterization by spectroscopic techniques such as FT-IR, UV-vis, 1H-NMR corroborated the formation of true copolymers. Synthesized products showed improved solubility and better photovoltaic efficiency than the respective homopolymers. The latter is due to the presence of a greater number of quinoid units, capable of promoting charge carriers generation. However, the low mobility of the charge carriers, that increases copolymers resistivity, would be responsible for an efficiency improvement of just one order of magnitude with respect to the homopolymers.

Structure, morphology and interfacial behaviour of ethylene/methacrylate copolymers

Two alpha-diimine monometallic Ni catalysts, catalyst 1 and catalyst 2, were studied in the copolymerization reaction of ethylene (E) with methyl methacrylate (MMA). The reaction products of these reactions were characterized using not only the usual techniques such as NMR, GPC and DSC but also the Langmuir balance and AFM. 1H and 13C NMR spectra revealed that both copolymers and mixtures of E and MMA (in a range of 20–70 mol% of MMA) could be obtained with these catalysts. A better insight of the products was possible with 1H DOSY NMR. Since p(E-MMA) copolymers comprising hydrophobic PE blocks and surface active PMMA blocks are amphiphilic, the Langmuir monolayer technique provided further information on the two-dimensional phase behavior of copolymer monolayers at the air-water interface. Additionally, AFM topographic images of the Langmuir-Blodgett (LB) monolayers deposited on mica substrates clearly showed that the morphology of the copolymer LB monolayer is quite different from the corresponding mixture of PE and PMMA homopolymers. These techniques together with molecular modeling calculations allowed us to conclude that with catalyst 2 it was possible to obtain a true block copolymer by a mechanism involving a cationic ester-enolate metal complex as the active species.

On-line fractionated size exclusion chromatography–nuclear magnetic resonance of polymers with 1H and 2H nuclear magnetic resonance detection

A new approach for on-line SEC–NMR is introduced. The method combines time slicing, fractionation with adjusted loop collection and automatic stop-flow NMR analysis. It will be called on-line fractionated SEC–NMR. This technique allows the precise determination of molar mass distributions for any polymer which can be detected by NMR. It is a significant improvement of sensitivity and accuracy compared to onflow SEC–NMR and exhibits a much easier experimental setup than off-line SEC–NMR fractionation. The new method was applied to protonated and deuterated block copolymers by using 1H NMR and for the first time also 2H NMR detection. In this case block copolymers can be correctly characterized according to their block length distributions. As the consequence very precise molar mass parameters Mn and Mw can be determined. The results of the on-line fractionated SEC–NMR are in very good agreement with the multi detector analysis. The new technique also proposes a method for separating the true copolymer and low molar mass fractions in the mixture, whose structures are confirmed by HPLC–FTIR and 2D chromatography.

Fast switching, high contrast multichromic polymers from alkyl-derivatized dithienylpyrrole and 3,4-ethylenedioxythiophene

In this report we disclose the synthesis and characterization of optoelectronic properties of a novel conducting polymer based on 1-(2-ethyl-hexyl)-2,5-di-thiophen-2-yl-2,3-dihydro-1H-pyrrole, (SNS-HE). Additionally, copolymers based on SNS-HE and 3,4-ethylenedioxythiophene (EDOT) were electrochemically synthesized and characterized. Cyclic voltammetry, FTIR, spectroelectrochemistry analyses confirmed that the resulting polymers were true copolymers having distinct electrochromic properties from that of the parent homopolymers. Depending on the synthesis conditions, the SNS-HE based polymers exhibited optical band gaps ranging from 2.32 to 1.70 eV and the copolymers displayed multichromism within a wide range of the visible spectrum. The copolymers revealed shorter switching times (around 0.5 s) and higher optical contrast (around 36%). Our studies have shown that color of the copolymers could be easily tuned by controlled increase in copolymerization potential. Moreover, a prototype of the all solid state poly(SNS-HE-EDOT)/PEDOT complementary electrochromic device was fabricated in order to investigate the utilization of these polymers. These devices exhibited short switching times with reasonable open circuit memory under atmospheric conditions.

Synthesis and performance of alkyd–acrylic hybrid binders

Preparation and properties of alkyd–acrylic hybrids have been studied. Hybrids with different alkyd–acrylic ratios and acrylic parts were prepared via free radical polymerization of acrylic monomers in a presence of an unsaturated alkyd resin using emulsion polymerization technique. The binders were characterized according to their solid content, conversion, viscosity, pH and particle size. Evidence on formation of true copolymer was obtained via NMR spectroscopy and molecular weight and glass transition temperature measurements, as well as via performance studies. The performance evaluation was focused on investigation of drying, penetration and water repellency ability, as well as on film formation and surface topography studies. The binders were compared to references of an alkyd emulsion, acrylic latex and a blend made of them. The results showed that alkyd–acrylic hybrids with synergistic and improved properties can be prepared.

Solid acid clay mediated copolymerization of methyl acrylate and 1‐octene: 2D NMR substantiation of predominant alternating comonomer sequence

AbstractMontmorillionite K10 powder presence during radically initiated copolymerization of methyl acrylate (M) and 1‐octene (O) gave copolymers with higher incorporation of alkene unit. Highly viscous and transparent copolymers showed alternation irrespective of the copolymer composition. Increasing the amount of K10 powder increased the total percentage conversion, as well as 1‐octene incorporation. The monomodal curves obtained in gel permeation chromatography (GPC) substantiated that true copolymers were formed. The alternation in the copolymers was authenticated through Heteronuclear Multiple Quantum Correlation (HMQC) experiments in conjugation with Total Correlated Spectroscopy (TOCSY). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2156–2162, 2009

Electrochemical synthesis and characterization of poly(pyrrole‐co‐ε‐caprolactone) conducting copolymer

AbstractThe direct electrochemical copolymerization of pyrrole (Py) and ε‐caprolactone at various monomer ratios was carried out by potentiostatic methods in nitromethane. Characterizations of the novel copolymer were based on scanning electron microscopy, differential scanning calorimetry, thermal gravimetrical analysis, cyclic voltammetry, electrochemical impedance spectroscopy, Fourier transform infrared spectra, and elemental analysis studies. The results showed that the electrochemical oxidation of Py and ε‐caprolactone comonomers generated true copolymers rather than blends of the two homopolymers. The electrical conductivity of the copolymers increased with the amount of polypyrrole in the copolymer between the value of 8.2 S/cm and 0.6 S/cm. A probable mechanism of copolymerization was proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis of Norbornene and Methyl Methacrylate Graft Copolymers with High Norbornene Content by Using Mixed Catalytic System

A vinyl-type polymer of norbornene containing a few pendant styrene groups obtained by copolymerization of norbornene and 1,4-divinylbenzene (1,4-DVB) was used as a macroinitiator in the reverse atom transfer radical polymerization (RATRP) of methyl methacrylate in conjunction with CuCl2/2,2′-bipyridine/2,2′-azobisisobutyronitrile (AIBN) as a catalyst. In the first step of the reaction, the structural characterization of the copolymers showed that norbornene and 1,4-divinylbenzene copolymerizations occur as a coordination mechanism and that true copolymers are formed by random copolymerization. With the initiation of copper dichloride and AIBN in the second step, the pendant styrene groups in the copolymers were quantitatively polymerized with methyl methacrylates, which allowed the successful synthesis of polynorbornene-based graft copolymers by RATRP mechanism. The analyses of the product by 1H-and 13C-NMR and GPC gel permeation chromatography (GPC) gave the verification of ‘true’ copolymer. Varying the monomer feed ratio controlled the thermal property of the graft copolymer.

Methyl acrylate/1‐octene copolymers: Lewis acid‐mediated polymerization

AbstractCopolymerization of methyl acrylate (MA) with 1‐octene (1‐Oct) was conducted in the presence of free radical initiator, 2,2′‐azobis(2‐methylpropionitrile) (AIBN) using heterogeneous Lewis acid, acidic alumina. The polymers obtained were transparent and highly viscous liquids. The copolymer composition calculated from 1H NMR showed alkene incorporation in the range of 10–61%. The monomodal nature of chromatographic curves corresponding to the molecular weight distribution in gel permeation chromatography (GPC) further confirmed that the polymers obtained are true copolymers. The number–average molecular weights (Mn) of the copolymers were in the range of 1.1 × 104–1.6 × 104 with polydispersity index of 1.75–2.29. The effects of varying the acidic alumina amount, time of polymerization, and monomer infeed on the incorporation of 1‐Oct in the polymer chain were studied. Increased 1‐Oct infeed led to its higher inclusion in the copolymer chain as elucidated by NMR. DEPT‐135 NMR spectral analysis was used to explicate the nature of arrangement of monomer sequences in the copolymer chain. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Influence of imidazolium‐based ionic liquids on the synthesis of amphiphilic copolymers based on n‐butylmethacrylate and a zwitterionic methacrylate

AbstractImidazolium‐based ionic liquids are used as new solvents for the synthesis of statistical copolymers from methacrylates of strongly differing polarities and solubilities, namely of n‐butylmethacrylate and 3‐(N‐2‐[methacryloyloxyethyl]‐N,N dimethyl‐3‐ammonio)propane sulfonate. Though difficult to prepare in classical solvents, true copolymers of these monomers can be obtained in ionic liquids, providing zwitterionic amphiphilic polymers. The relative reactivity of the monomers and thus the copolymer composition is influenced by the ionic liquid used. Analysis of the copolymers using 1H NMR spectroscopy, elemental analysis, and asymmetrical flow field‐flow fractionation (AF4) shows the influence of both the length of the alkyl chain bound at the nitrogen atom of the imidazolium ring and the anion of the ionic liquid on the structure of the copolymers. Furthermore, the highly polar methacrylate with a sulfobetaine moiety is only slightly preferred in copolymerization if ionic liquids are used as solvents for copolymerization. The ratio of monomer segments in the copolymer can be influenced by the selection of the ionic liquid used as a solvent for polymer synthesis and by the variation of the monomer ratio selected for copolymerization if it is carried out in an ionic liquid. This opens new possibilities for a broad variation of amphiphilic copolymer structures obtained through free radical copolymerization of differently polar monomers. Copyright © 2008 John Wiley & Sons, Ltd.

Polymerization of methyl acrylate and as comonomer with ethylene using a bis(imino)pyridine iron(II) chloride/methylaluminoxane catalyst

This article describes the homopolymerization of methyl acrylate (MA) and its attempted copolymerization with ethylene using three single-site catalysts. The primary catalyst under investigation is formed from a bis(imino)pyridine iron(II) chloride with methylaluminoxane (1), which is compared with bis(4,5,6,7-tetrahydro-1-indenyl)zirconium dimethyl/tris(pentafluorenyl)borane) (2), and a P,O-chelated nickel(II) enolate catalyst (3). Catalyst (1) leads to the highest activities exceeding those of catalyst (2) by a magnitude, whereas catalyst (3) results in formation of no polymer. The kinetics of the polymerizations and the effect of the Al/Fe-ratio and temperature on the activity and molecular weight of the polymers have been determined. In the ethylene/MA copolymerization trials, catalyst (1) produces a blend of the two homopolymers, polymethyl acrylate (PMA) and polyethylene. Remarkably, using catalyst (1) it is possible to produce polymer blends with up to 52% PMA at relatively high activities. The polymerization kinetics has been determined based on the directly measured uptake of ethylene during the runs. NMR spectroscopy, DSC and GPC measurements have been used as efficient methods to prove that polymer blends instead of true copolymers were formed. Finally, some conclusions about the polymerization mechanism will be drawn. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5542–5558, 2008

Microstructure of copolymers of polyhydroxyalkanoates produced by glycogen accumulating organisms with acetate as the sole carbon source

The so-called glycogen accumulating organisms (GAOs), found in mixed culture anaerobic–aerobic wastewater treatment processes, are used to produce polyhydroxyalkanoates (PHAs) copolymers from a single, simple carbon source—acetate. These polymers consist of 3-hydroxybutyrate (HB), 3-hydroxyvalerate (HV), 3-hydroxy-2-methylvalerate (HmV) and 3-hydroxy-2-methylbutyrate (HmB) with a non-HB fraction of up to 37%. A detailed characterisation using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy demonstrates that these products are true copolymers if produced under anaerobic conditions. The HmV and HmB monomers are identified and their incorporation in the polymer verified via two-dimensional (2D) NMR spectroscopy. The monomer sequence distribution analysis using a known polymer characterisation model suggests that these polyesters are mixtures of random copolymers and thus likely possess desirable properties for practical use. This assessment is supported by the polymers’ physical characteristics. It was further revealed from the study that the inclusion of aerobic periods into the process could improve the overall polymer yields but resulted in production of HB monomers only, likely in the form of separate homopolymer blocks. The study for the first time investigated the microstructure of GAO-produced biopolymers and shows that GAOs have a potential for producing high-quality polymers from a simple carbon source.

Allyl ansa‐Lanthanidocenes: Single‐Component, Single‐Site Catalysts for Controlled Syndiospecific Styrene and Styrene–Ethylene (Co)Polymerization

A series of new neutral allyl Group 3 metal complexes bearing ansa-bridged fluorenyl/cyclopentadienyl ligands [[Flu-EMe(2)-(3-R-Cp)]Ln(eta(3)-C(3)H(5))(THF)] (E=C, R=H, Ln=Y (2), La (3), Nd (4), Sm (5); R=tBu, Ln=Y (8), Nd (9); E=Si, R=H, Ln=Y (12), Nd (13)) were synthesized in good yields via salt metathesis protocols. The complexes were characterized by elemental analysis, NMR spectroscopy for diamagnetic complexes, and single-crystal X-ray diffraction studies for 2, 4, 9 and 12. Some of the allyl ansa-lanthanidocenes, especially 4, are effective single-component catalysts for the polymerization of styrene, giving pure syndiotactic polystyrenes (rrrr > 99 %) with low to high molecular weights (M(n)=6000-135,000 g mol(-1)) and narrow polydispersities (M(w)/M(n)=1.2-2.6). The catalyst systems are remarkably stable, capable of polymerizing styrene up to 120 degrees C with high activities, while maintaining high syndiotacticity via chain-end control as established by a Bernoullian analysis. Highly effective copolymerization of styrene with ethylene was achieved using neodymium complex 4 (activity up to 2530 kg PS-PE mol(-1) h(-1)) to give true copolymers void of homopolymers with M(n)=9000-152,000 g mol(-1) and narrow polydispersities (M(w)/M(n)=1.2-2.5). The nature of the resultant P(S-co-E) copolymers was ascertained by NMR, size-exclusion chromatography/refractive index/UV, temperature rising elusion fractionation, and differential scanning calorimetry. It is shown that, regardless the amount of ethylene incorporated (1-50 mol %), P(S-co-E) copolymers have a microstructure predominantly made of long highly syndiotactic PS sequences separated by single or few ethylene units. Co-monomers feed and polymerization temperature can be used straightforwardly to manipulate with the physical and mechanical characteristics of the P(S-co-E) copolymers (molecular weights and distributions, co-monomer content, microstructure, T(m), T(g), T(c)).

Electrochemical synthesis and characterization of poly(pyrrole-co-tetrahydrofuran) conducting copolymer

The direct electrochemical copolymerization of pyrrole and tetrahydrofuran in various monomer ratios was carried out by potentiostatic methods in nitromethane solution. The copolymer has been characterized using FT-IR, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetrical analysis (TGA), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and elemental analysis. The results showed that the electrochemical oxidation of pyrrole and tetrahydrofuran comonomers generated true copolymers rather than blends of the two homopolymers. The copolymer showed a better flexibility than pure polypyrrole. The electrical conductivity of the copolymers increases with the amount of polypyrrole in the copolymer between the value of 1.69 S/cm and 0.71 S/cm.

Sequencing Microbial Copolymers of 3-Hydroxybutyric and 3-Mercaptoalkanoic Acids by NMR, Electrospray Ionization Mass Spectrometry, and Size Exclusion Chromatography NMR

Copolymers of 3-hydroxybutyrate (3HB) and 3-mercaptopropionate (3MP) or 3-mercaptobutyrate (3MB) units and minor amounts of 3-hydroxypropionate (3HP), 3-hydroxyvalerate (3HV), or 3-mercaptovalerate (3MV) were investigated regarding their microstructure by NMR, electrospray ionization mass spectrometry, and size exclusion chromatography NMR. These copolymers were produced by Ralstonia eutropha strain H16 when cells were cultivated in a mineral salts medium with gluconate as a carbon source for growth and 3MP or 3MB as precursor substrates for incorporation of 3-mercaptoalkanoates. Mass spectrometry analysis of partially methanolyzed or pyrolyzed samples proved the presence of true copolymers or terpolymers. (13)C NMR spectroscopy of intact polymer samples, with values of average block length and degree of randomness deviating from a random sequence model, suggested microblock structures; however, composition analysis by (1)H NMR of fractions obtained by size exclusion chromatography showed significant variations with molecular weight, revealing the presence of blends of poly(3HB-co-3MP-co-3HP) or poly(3HB-co-3MB) with poly(3HB). The experimental NMR carbonyl dyad signal intensities were satisfactorily matched by a random sequence model when the presence of poly(3HB) was taken into account.

Synthesis and characterization of novel functionalized polylactides with pendent hydroxyl arms

A class of polyesters have been synthesized by the ring-opening copolymerization of dl-lactide (DLLA) and RS-benzyloxyethyl-β-malolactonate (MABE) using different monomer feeding doses. The compositions and structures of poly( dl-lactide- co- RS-benzyloxyethyl-β-malolactonate) (poly(DLLA- co-MABE)) were determined by 1H and 13C NMR measurements. GPC measurement showed that the molecular weight of the copolymers decreased as the MABE content increases. After catalytic hydrogenation of the benzyl ether functions, the desired copolymers with pendent hydroxyl arms, poly( dl-lactide- co- RS-hydroxyethyl-β-malolactonate) (poly(DLLA- co-MAHE)), were recovered. Thermal properties of poly(DLLA- co-MABE) and poly(DLLA- co-MAHE) copolymers were examined by differential scanning calorimetry (DSC) measurement. Single glass transition temperature appeared in the DSC spectra, which confirmed that the copolymers were true copolymers and not blends. The hydrophilicity of poly(DLLA- co-MAHE) copolymer was tunable, which increased with the increase in MAHE content. Furthermore, the hydrolytic degradation of poly(DLLA- co-MAHE) material was investigated and the results showed that faster degradation was observed in the copolymer film containing more MAHE content.