Tin 2-ethylhexanoate Research Articles

Polycondensation, Cyclization and Disproportionation of Solid Poly(L-lactide) Trifluoroethyl Esters and the Simultaneous Formation of Extended Chain Crystals and Extended Ring Crystals

Two poly(L-lactide)s (PLAs) with a degree of polymerization (DP) of 20 or 100 were prepared by trifluoroethanol-initiated ring-opening polymerization (ROP) catalyzed by tin(II) 2-ethyl hexanoate (SnOct2). These PLAs were annealed at 140 °C or at 160 °C in the presence of SnOct2, and the changes in topology and molecular weight distribution (MWD) were monitored by matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry and gel permeation chromatography (GPC). For the PLA with a DP 20, the main reaction was polycondensation combined with higher dispersities. In the case of the DP 100, PLA polycondensation was combined with disproportionation and the formation of a new MWD maximum around m/z 3 500. In addition, extensive cyclization occurred, and the resulting cyclic PLAs crystallized separately from the linear chains in the form of extended ring crystals. These results also suggest that both extended chain and extended ring crystals posses the same crystal thickness as a result of thermodynamically controlled transesterification in the solid state.

Optimizing thickness of tin oxide electron transporting layer to reduce hysteresis in carbon-based perovskite solar cells

Tin oxide (SnO2) is frequently chosen as an electron transport layer (ETL) in perovskite solar cells (PSCs) owing to its outstanding electron transport properties. Nevertheless, the thickness of the ETL significantly influences hysteresis behavior of PCSs. To address this issue, tin (II) 2-ethylhexanoate in 2-methoxyethanol (2-MOE) was employed as the precursor solution for SnO2 ETL preparation. We systematically varied its concentrations from 0.2 M to 1.0 M to optimize the film thickness. Our findings indicate that the PSC with a SnO2 film deposited from a 0.6 M precursor concentration achieved the highest power conversion efficiency (PCE) of 13.51% and the lowest hysteresis index (HI) of 0.54. Furthermore, we explored the impact of film thickness on hysteresis behaviour and provided a comprehensive analysis. Based on the experiment, it was observed that the thickness of the film has an impact on the presence of defects and interfacial charge transfer, which could contribute to the occurrence of HI. This study offers valuable insights into the development of alternative ETLs suitable for large-scale PSC production.

Highly sensitive photoelectrochemical immunosensor for detecting cancer marker CA19-9 based on a new SnSe quantum dot.

Asandwich-type photoelectrochemical (PEC) immunosensor was constructed on a screen-printed electrode (SPE) using gold-coated tin selenide quantum dots (Au-SnSe QDs) to determinethe carbohydrate antigen 19 9 (CA19-9). Water-soluble Au-SnSe QDs were prepared by coating low-cost SnSe QDs, prepared by reacting tin(II) 2-ethyl hexanoate with selenium ions (HNaSe) without needing to add an external capping agent (SnSe QDs). SnSe-based QDs were characterized using high-resolution transmission electron microscopy (HR-TEM) and dynamic light scattering (DLS). DSP (dithio-bis (succinimidyl propionate)) as a linker was attached on Au@SnSe QDs and conjugated with CA19-9 monoclonal antibodies (Ab2-DSP-Au@SnSE QD). For capture probe assembling, an Au nano-layer was electrochemically deposited on a SPE by HAuCl4 reduction using 12 cycles of cyclic voltammetry (0 to - 1.4V) at the scan rate of 50mVs-1, then covered by self-assembly of DSP and covalent conjugation of CA19-9 Ab1. Our developed PEC immunosensor showed a significant photoelectrochemical response, recorded using chronoamperometry (0.3V), for the presence of CA19-9 antigen in serum samples under light irradiation, with adetection limit (LOD) of 0.0011 U mL-1 and adynamic range of 0.005-100 U mL-1. The recovery of CA19-9 determinationfrom serum samples was 101 to 113%.

Branched Amphiphilic Polylactides as a Polymer Matrix Component for Biodegradable Implants.

The combination of biocompatibility, biodegradability, and high mechanical strength has provided a steady growth in interest in the synthesis and application of lactic acid-based polyesters for the creation of implants. On the other hand, the hydrophobicity of polylactide limits the possibilities of its use in biomedical fields. The ring-opening polymerization of L-lactide, catalyzed by tin (II) 2-ethylhexanoate in the presence of 2,2-bis(hydroxymethyl)propionic acid, and an ester of polyethylene glycol monomethyl ester and 2,2-bis(hydroxymethyl)propionic acid accompanied by the introduction of a pool of hydrophilic groups, that reduce the contact angle, were considered. The structures of the synthesized amphiphilic branched pegylated copolylactides were characterized by 1H NMR spectroscopy and gel permeation chromatography. The resulting amphiphilic copolylactides, with a narrow MWD (1.14-1.22) and molecular weight of 5000-13,000, were used to prepare interpolymer mixtures with PLLA. Already, with the introduction of 10 wt% branched pegylated copolylactides, PLLA-based films had reduced brittleness, hydrophilicity, with a water contact angle of 71.9-88.5°, and increased water absorption. An additional decrease in the water contact angle, of 66.1°, was achieved by filling the mixed polylactide films with 20 wt% hydroxyapatite, which also led to a moderate decrease in strength and ultimate tensile elongation. At the same time, the PLLA modification did not have a significant effect on the melting point and the glass transition temperature; however, the filling with hydroxyapatite increased the thermal stability.

Synthesis and characterization of solution processed p-SnS and n-SnS2 thin films: Effect of starting chemicals

This study represents the investigation of earth-abundant and non-toxic SnS absorber and SnS2 buffer layer materials by using a green solution process. Some physical properties of prepared thin films were investigated for different starting chemicals and molar ratios of Sn/S. Here, by using different starting chemicals such as tin (II) 2-ethylhexanoate and tin (II) chloride dihydrate, we observed that the formation of p-SnS and n-SnS2 phases can be simply controlled. All the SnS films obtained by the tin (II) 2-ethylhexanoate showed p-type conductivity. Moreover, it has been observed that an n-type SnS2 thin film can be produced by using tin (II) chloride dihydrate as the starting chemical instead of tin (II) 2-ethylhexanoate. According to the Hall effect measurement results, the resistivity of the p-type films obtained with both starting chemicals is in the order of 106 Ωcm. The resistivity of films with n-type properties drops to the order of 101 Ωcm. The I–V characteristic of the n-SnS2/p-SnS bilayer exhibits the p-n heterojunction diode characteristic. This study paves the way for solution processed SnS and SnS2 thin films as a potential absorber and buffer layer to be used in photovoltaic devices.

Non-Covalent PS–SC–PI Triblock Terpolymers via Polylactide Stereocomplexation: Synthesis and Thermal Properties

Polylactide (PLA) stereocomplexes (SCs) containing amorphous block copolymers have gained enormous interest due to their unique properties and wide range of potential applications. In this work, we report the synthesis and properties of non-covalent triblock terpolymers: polystyrene–SCPLA–polyisoprene (PS–SC–PI) via the stereocomplexation of PS-b-PDLA with PI-b-PLLA diblock copolymers through the solution-precipitation method. The diblock copolymers were prepared by combining the anionic polymerization high-vacuum technique with ring-opening polymerization (ROP). First, several well-defined ω-hydroxyl polystyrenes and polyisoprenes (PS-OH and PI-OH) with varied molecular weights were synthesized by anionic polymerization using sec-BuLi as the initiator. PS-OH and PI-OH were used as the macroinitiators for the ROP of DLA and LLA catalyzed by tin(II) 2-ethyl hexanoate to afford PS-b-PDLA and PI-b-PLLA. PS–SC–PIs were prepared by mixing PS-b-PDLA and PI-b-PLLA solutions (in dichloromethane) and precipitated into methanol. The molecular characteristics of the block copolymers were determined by 1H NMR spectroscopy and size exclusion chromatography. The formation of PS–SC–PIs was evidenced by differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared, and circular dichroism spectroscopies. A preliminary study by atomic force microscopy reveals the thin-film phase behavior and the supramolecular organization of the PS–SC–PI.

Effect of temperature and time for the production of polylactic acid without initiator catalyst from lactide synthesized from ZnO powder catalyst

Polylactic acid (PLA) is a biodegradable polymer that most importance at the present due primarily to its properties as biological degradation and biocompatibility derived from renewable resources. This study investigated the role of zinc oxide powder and tin(II) 2-ethylhexanoate as the catalysts for lactide and PLA synthesis, respectively. Polylactic acid was obtained by four stages: dehydration, oligomerization, depolymerization and ring opening polymerization. The catalyst was added and water was removed at the first stage then the reactions are carried out at different temperatures and reaction time on the other stages. The ratio of lactic acid and zinc oxide powder was 1000:3 for lactide synthesis, the ratio of lactide product and tin(II) 2-ethylhexanoate was 1000:4 for PLA synthesis without any initiator. The PLA products were analysed for the yield, some chemical and physical properties such as functional group, decomposition temperature, melting temperature of synthesized PLA. It is found that at reaction temperature of 160°C and reaction time for 5 h gave the highest yield PLA of 64.5% with its decomposition temperature of 311°C and melting point temperature at 152°C. There are two main mechanisms, polymerization and depolymerisation occurring in reaction and each mechanism plays a major role with respect to the reaction condition. At higher reaction temperature and longer time, the rate of depolymerisation is higher than that of polymerization leading to the lower of decomposition and melting temperature of synthesized PLA.

One-Pot Synthesis of Block Copolymers via ATRP and ROP Using PCL Macroinitiator

Poly(lactide)-b-poly(ε-caprolactone)-b-poly(styrene) triblock copolymers were synthesized simultaneously by one-pot method using atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP) in one step. Firstly, brominated poly(ε-caprolactone) (PCL-Br) as macroinitiator was made via ROP of ε-caprolactone (ε-CL) in the existence of tin(II) 2-ethyl hexanoate at 110 °C followed by esterification with 2-bromopropionyl bromide. With the one-pot method, the simultaneously via ROP of D, Llactide in the existence of tin(II) 2-ethyl hexanoate and ATRP of styrene (St) monomer with PCL-Br macroinitiator in the presence of CuCl/PMDETA system using [I]: [CuCl]:[PMDETA]=1:1:3 molar ratios at 120 °C in toluene was performed. Thus, the block copolymers with controlled molecular weights and moderately narrow polydispersities were obtained. Principal parameters, such as monomer concentration, initiator concentration, and polymerization time, which effect the one-pot polymerization were investigated. The polymers obtained were characterized using 1H NMR, FTIR, and GPC technique.

Synthesis of Poly(Lactic Acid-co-Glycolic Acid) Copolymers with High Glycolide Ratio by Ring-Opening Polymerisation.

The rise in demand for biodegradable plastic packaging with high barrier properties has spurred interest in poly(lactic acid-co-glycolic acid) (PLGA) copolymers with a relatively high glycolide content. In this work, we examined how reaction conditions affect the synthesis of PLGA25 (L:G 25:75) through the ring-opening polymerisation of d-l-lactide (L) and glycolide (G), using tin 2-ethylhexanoate (Sn(Oct)2) as the catalyst and 1-dodecanol as the initiator. The effects of varying the initiator concentration, catalyst concentration, reaction time, and temperature on the molecular weight, monomer conversion, and thermal properties of PLGA25 were investigated. Increasing the reaction temperature from 130 to 205 °C significantly reduced the time required for high monomer conversions but caused greater polymer discolouration. Whilst increasing the [M]:[C] from 6500:1 to 50,000:1 reduced polymer discolouration, it also resulted in longer reaction times and higher reaction temperatures being required to achieve high conversions. High Mn and Mw values of 136,000 and 399,000 g mol−1 were achieved when polymerisations were performed in the solid state at 150 °C using low initiator concentrations. These copolymers were analysed using high temperature SEC at 80 °C, employing DMSO instead of HFIP as the eluent.

Curing Reaction Kinetics of the EHTPB-Based PBX Binder System and Its Mechanical Properties

In this research, differential scanning calorimetry (DSC) was employed to compare the curing reaction kinetics of the epoxidized hydroxyl terminated polybutadiene-isophorone diisocyanate (EHTPB-IPDI) and hydroxyl terminated polybutadiene-isophorone diisocyanate (HTPB-IPDI) binder systems. Glass transition temperature (Tg) and mechanical properties of the EHTPB-IPDI and HTPB-IPDI binder systems were determined using the DSC method and a universal testing machine, respectively. For the EHTPB-IPDI binder system, the change of viscosity during the curing process in the presence of dibutyltin silicate (DBTDL) and tin 2-ethylhexanoate (TECH) catalysts was studied, and the activation energy was estimated. The results show that the activation energies (Ea) of the curing reaction of the EHTPB-IPDI and HTPB-IPDI binder systems are 53.8 and 59.1 kJ·mol−1, respectively. While their average initial curing temperatures of the two systems are 178.2 and 189.5 °C, respectively. The EHTPB-IPDI binder system exhibits a higher reactivity. Compared with the HTPB-IPDI binder system, the Tg of the EHTPB-IPDI binder system is increased by 5 °C. Its tensile strength and tear strength are increased by 12% and 17%, respectively, while its elongation at break is reduced by 10%. Epoxy groups and isocyanates react to form oxazolidinones, thereby improving the mechanical properties and thermal stability of polyurethane materials. These differences indicate that the EHTPB-IPDI binder system has better thermal stability and mechanical properties. During the EHTPB-IPDI binder system’s curing process, the DBTDL catalyst may ensure a higher viscosity growth rate, indicating a better catalytic effect, consistent with the prediction results obtained using the non-isothermal kinetic analysis method.

High molar mass cyclic poly(l-lactide) obtained by means of neat tin(ii) 2-ethylhexanoate

l-Lactide was polymerized in bulk at 120, 140, 160 and 180 °C with neat tin(ii) 2-ethylhexanoate (SnOct2) as the catalyst and a cyclic topology was detected.

New synthetic route for polyricinoleic acid with Tin (II) 2-ethylhexanoate

Polyricinoleic acid (PRA) is a biodegradable polymer of ricinoleic acid, a hydroxy fatty acid present in castor oil. Depending upon the chain length, this homopolymer finds varied applications in oleochemical and allied industries. In the current research, we have first demonstrated synthesis route for PRA using Tin (II) 2-ethylhexanoate as a catalyst. The multiple operational variables such as the effect of the reaction time, temperature, catalyst loading, water condensation and recuperation of polymer were studied systemically. Under the optimized conditions, PRA with a molecular weight of ∼4kD was synthesized at 150 °C within 14 hrs. Using solvent extraction, the unreacted monomer and catalyst were recycled back to the next round of polymerization. The final PRA product was characterized as a single molecule with superior functional properties and suggesting to its use as an environmentally friendly biopolymer.

Synthesis and colloidal characterization of folic acid-modified PEG-b-PCL Micelles for methotrexate delivery.

Hydrophobic drugs, such as methotrexate, are not easily delivered into the human body. Therefore, the use of amphiphilic nanoplatforms to the transport of these drugs through the bloodstream is a challenge. While the hydrophobic region interacts with the drug, the hydrophilic outer layer enhances its bioavailability and circulation time. Poly (ethylene glycol)-block-poly(ε-caprolactone) PEG-b-PCL micelles are biodegradable and biocompatible, allowing its use as a nanocarrier for drug delivery systems. The stealth property of PEG that composes the outer layer of nanoplatforms, makes the micelle unperceivable to phagocytic cells, increasing the circulation time in the human body. In addition, folic acid functionalization enables micelle selectively targeting to cancer cells, improving treatment efficiency and reducing side effects. In this work, PEG-b-PCL copolymer was synthesized by ring opening polymerization (ROP) of the ε-caprolactone with Poly(ethylene glycol) as a macroinitiator and tin(II) 2-ethyl hexanoate as a catalyst. Functionalization of such micelles with folic acid occurred through the modification of the PEG terminal group. The surface modification of the copolymer micelles resulted in higher critical micellar concentration (CMC), increasing approximately 100 times. The synthesis of the copolymers resulted in molecular weight around 3000 g mol-1 with low polydispersity. The polymer micelles have a hydrodynamic diameter in the range of 100-200 nm and the functionalized sample doesn't show aggregation in the considered pH range. High incorporation efficiency was obtained with a minimum percentage of 85%. The drug release profile and linearization from the Peppas model confirmed the interaction of methotrexate with the hydrophobic segment of the copolymer and its release mechanism by relaxation and/or degradation of the chains, making PEG-b-PCL micelles suitable candidates for hydrophobic drug delivery systems.

Sustainable polycondensation of multifunctional fatty acids from tomato pomace agro-waste catalyzed by tin (II) 2-ethylhexanoate

Bioplastics were prepared from the fatty fraction (i.e., unsaturated and polyhydroxylated fatty acids) of tomato pomace agro-wastes. Aliphatic polyesters were synthesized at different temperatures (125, 150, and 175 °C), reaction times (0.25, 0.5, 0.75, 1, 3, 5, and 7 h), and amounts of tin (II) 2-ethylhexanoate (0, 0.02, 0.05, and 0.10 mmol) used as a catalyst. The rate constants and activation energies were calculated from infrared spectra. The right combination of reaction temperature and amount of catalyst improved the reaction kinetics (apparent k from ∼1 to ∼8.5 h−1), whereas the activation energy was reduced from ∼39 without catalyst to ∼28 kJ/mol when tin (II) 2-ethylhexanoate was present. Glass transitions between ca. −25 and ∼0 °C were measured by differential scanning calorimetry, strictly depending on the degree of polymerization. The amorphous character of the samples was confirmed by X-ray diffraction. Young's modulus and hardness were calculated from indentation tests and were typical of soft materials, although increased as the polycondensation reaction progressed. High water-contact angles (maximum value ∼109°) and low water uptakes (minimum value ∼2.1%) were determined. Physical properties were compared with those of common man-made plastics and polymers, finding that these tomato pomace bioplastics could be their realistic alternatives.

Polymer Side-Chain Conjugates를 위한 전구체인 Polydiacetone Acrylamide

Polydiacetone acrylamide (PDAAM), a reactive polymer containing pendant ketone groups was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Kinetic studies indicated a well-controlled behavior of this RAFT polymerization. The characteristics of this RAFT polymerization was also confirmed by a wellcontrolled chain-extending RAFT polymerization using the above-synthesized PDAAM as a macromolecular chain transfer agent. Acid-catalyzed ketalization of PDAAM with trimethylol propane (TMP) was carried out to obtain the polymer containing pendant cyclic ketal groups and hydroxyl groups, PDAAM-TMP. PCL was grafted from PDAAM-TMP by ring-opening polymerization (ROP) in the presence of tin 2-ethylhexanoate as a catalyst to obtain graft copolymer. Basecatalyzed aldol condensation of PDAAM with benzaldehyde was also used to obtain poly[N-(1,1-dimethyl-3-oxo-5-phenyl-pent-4-enyl)-acrylamide] (PDMOPPEAM) having cinnamoyl groups, and the photoreactivity of polymer with cinnamoyl group was studied by UV-visible and IR absorption spectroscopy. Both of these two polymers prepared from PDAAM were characterized by FTIR and 1H NMR spectroscopy. PDAAM can be a multifunctional platform that can undergo further polymerization by ketalization and aldol condensation.

The Influence of Activating Agents on the Controlled Synthesis of Poly(methyl methacrylate) in the Presence of Ruthenacarboranes

The radical polymerization of methyl methacrylate catalyzed by systems based on the carborane complexes of ruthenium(III) is studied in the presence of a number of activating agents: tin 2-ethyl hexanoate, aluminum isopropoxide, isopropylamine, and AIBN. It is shown that in the presence of the systems under consideration, polymerization proceeds in a controlled mode via the ATRP mechanism (AGET or ICAR ATRP) at catalyst concentrations with ppm level relative to that of the monomer. As the degree of monomer conversion grows, the molecular weight of the polymer increases linearly while its polydispersity coefficients decrease linearly. The role of the mentioned agents is to transfer the catalyst to the active form containing a metal atom in the oxidation number +2 and able to interact with halogen-terminated dormant polymer chains. It is first shown that the carborane complexes of ruthenium(II) are applicable for the catalysis of controlled radical polymerization.

Ring-opening copolymerization thermodynamics and kinetics of γ-valerolactone/ϵ-caprolactone.

The general misconception that γ-lactones are not thermodynamically polymerizable has limited the development of all γ-lactone-based copolymers. A few studies have reported copolymerization of these five-membered cyclic esters with more reactive monomers, yet a systematic investigation of kinetics and thermodynamics is still lacking. To explore the feasibility of the reaction, we combined equilibrium and non-isothermal syntheses for the copolymerization of γ-valerolactone with ϵ-caprolactone, initiated with methoxy polyethyleneglycol and catalyzed by Tin(II) 2-ethylhexanoate. Here, we present the polymerization kinetic and thermodynamic parameters for different monomer ratios in the reaction feed. We observed the dependency of enthalpy and entropy of polymerization upon monomer ratio changes, and estimated a linear increase in the activation energy by increasing the γ-valerolactone fraction in the starting monomer mixture. Our data demonstrate that γ-valerolactone can copolymerize with ϵ-caprolactone, but only under specific conditions. The reaction parameters determined in this study will enable preparation of additional γ-valerolactone-based copolymers and development of a family of degradable materials with improved properties in respect to commonly used polyesters.

Synthesis and characterization of divinyl-fumarate poly-ε-caprolactone for scaffolds with controlled architectures

A vinyl-terminated polycaprolactone has been developed for tissue engineering applications using a one-step synthesis and functionalization method based on ring opening polymerization (ROP) of ε-Caprolactone, with hydroxyl ethyl vinyl ether (HEVE) acting both as the initiator of ROP and as photo-curable functional group. The proposed method employs a catalyst based on aluminium, instead of the most popular Tin(II) 2-ethylhexanoate, to reduce the cytotoxicity. Following the synthesis of the vinyl-terminated polycaprolactone, its reaction with fumaryl chloride (FuCl) results in a divinyl-fumarate polycaprolactone (VPCLF). The polymers obtained were thoroughly characterized using Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) techniques. The polymer has been successfully employed, in combination with N-vinyl pyrrolidone (NVP), to fabricate films and computer-designed porous scaffolds by micro-stereolithography (μ-SL) with gyroid and diamond architectures. Characterization of the networks indicated the influence of NVP content on the network properties. Human mesenchymal stem cells adhered and spread onto VPCLF/NVP networks showing good biological properties and no cytotoxic effect. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis and properties of poly(L-lactide-co-glycolide)-b-Poly(ɛ-caprolactone) multiblock copolymers formed by self-polycondensation of diblock macromonomers

Poly(L-lactide-co-glycolide)-b-poly(ɛ-caprolactone) multiblock copolymers (PLGA-PCL MBCs) were synthesized via the self-polycondensation of PLGA-PCL diblock copolymers (PLGA-PCL DBCs) in the presence of condensation agents. PLGA-PCL DBCs were synthesized via the ring-opening copolymerization of lactide and glycolide initiated by benzyl-protected PCL in the presence of tin 2-ethylhexanoate (Sn(Oct)2) or organic catalysts (N-cyclohexyl-N’-[3,5-(trifluoromethyl)phenyl]thiourea (TU) and Tris[2-(dimethylamino)ethyl]amine (Me6TREN)). The introduction of glycolide segments hampered the formation of poly(L-lactide) (PLLA) crystals in PLGA-PCL MBCs, which was confirmed by wide-angle X-ray diffraction (WAXD) measurements. Despite the loss of crystallinity, PLGA-PCL MBCs showed better tensile strength and modulus than the PLLA-PCL random copolymer. The phase-segregated PLGA domains observed by small-angle X-ray scattering (SAXS) measurements acted as hard domains improving the tensile properties. The hydrolytic degradation of PLGA-PCL MBC in phosphate-buffered saline (PBS: pH=7.4) proceeded much faster than that of PLLA-PCL MBC. Both the loss of PLLA crystallinity and the presence of glycolide–glycolide and glycolide–lactide bonds contributed to the enhanced hydrolysis behavior of PLGA-PCL MBCs. The good tensile properties and degradation behavior in PBS expand the applicability of PLGA-PCL MBCs in biomedical applications, particularly for elastic implanting materials. Poly(L-lactide-co-glycolide)-b-poly(ɛ-caprolactone) multiblock copolymers (PLGA-PCL MBCs) were synthesized by the self-polycondensation of PLGA-PCL diblock copolymers (PLGA-PCL DBCs) in the presence of condensation agents. The phase-segregated PLGA domains acted as hard domains, improving the tensile properties. The hydrolytic degradation of PLGA-PCL MBC films in phosphate-buffered saline (PBS: pH=7.4) proceeded much faster than that of poly(L-lactide) (PLLA)-PCL MBC.

End Functionalization by Ring Opening Polymerization: Influence of Reaction Conditions on the Synthesis of End Functionalized Poly(lactic Acid)

In this paper, chemical functionalization of poly(lactic acid) (PLA) was carried out by using of salicyl aldehyde (SAl) and salicylic acid (SAc) as co-initiators of ring opening polymerization (ROP). Two factorial designs (22) were performed to evaluate the effects of the lactide/catalyst and co-initiator/catalyst molar ratios on the content of aldehyde or carboxylic acid end groups, thermal properties and molecular weight (Mw) of PLA. Tin(II) 2-ethylhexanoate was used as a catalyst. The co-initiator/catalyst molar ratio has a statistically significant influence on the polymer functionalization. The highest co-initiator/catalyst molar ratio of 12/1 allows the best aldehyde or carboxylic acid functionalization, independent on the lactide/catalyst molar ratio. On the other hand, the used lactide/catalyst and co-initiator/catalyst molar ratios did not show a statistically significant influence on the polymer thermal properties. Besides, co-initiator/catalyst molar ratio has a statistically significant influence on the polymer molecular weight. So, the highest co-initiator/catalyst molar ratio used (12/1) in combination with the highest lactide/catalyst ratio (125/1) produced functionalized PLA with higher molecular weights.