Synthesis Of Polycaprolactone Research Articles

Living Cationic Polymerization of ε-Caprolactone Catalyzed by a Metal-free Lewis Acid of Trityl Tetrafluoroborate

Research on metal-free catalytic synthesis of polycaprolactone (PCL) is fueled by the many practical needs for biodegradable and biocompatible materials. In this regard, the pursuit of effective and economical catalysts as well as precise control over the polymerization has become the main challenge. Herein, we report a living cationic ring-opening polymerization of ε-caprolactone catalyzed by a safe, inexpensive, and metal-free Lewis acid of trityl tetrafluoroborate. The polymerization is initiated by alcohol or water, which is corroborated by the presence of initiator segments at the chain ends of PCL polymers via 1H NMR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Kinetic experiments show that polymerization is a first-order reaction to monomers. This result, together with the predictable molar mass, narrow molar-mass dispersity, and controllable chain growth and extension, confirms the synthesis to be a living polymerization. This work expands the catalytic toolbox of PCL synthesis and represents a rare example of cationic living polymerization of ε-caprolactone catalyzed by Lewis acids.

Zn-Polyacrylate Tentacles in Microporous Organic Polymers as Nanocatalysts for Polycaprolactone Synthesis

Zn-Polyacrylate Tentacles in Microporous Organic Polymers as Nanocatalysts for Polycaprolactone Synthesis

An efficient way to change surface properties of poly(l-lactic acid) by synthesis of polycaprolactone grafted fluoropolyacrylate

Macromolecules with fluoroalkyl group are promising as anti-fouling materials. In the work, a series of polycaprolactone grafted poly(octafluoropentyl methacrylate-co-hydroxyethyl methacrylate)s (PCL-PFHs) were synthesized as additives to change the surface properties of poly(l-lactic acid) (PLLA). The synthesized products were characterized with 1HNMR and GPC. PCL-PFH and PLLA were immiscible in blend, but PCL-PFH microparticles could immerse uniformly in PLLA substrate. The molar ratio of [OFPA]/[HEMA] in PFH and blend ratio of PCL-PFH/PLLA played a key role in changing the surface properties of PLLA blend. When the molar ratio and blend ratio were 4/1 and 10/90 respectively, the surface tension of PLLA blend lowered to 19.57 mN m−1, and it inhibited BSA adhesion effectively during protein adsorption process. At the same time, PLLA blend presented good hydrolytic stability. PCL-PFH also toughened PLLA, and the tensile strength and elongation at a break were 37.0 MPa and 126.1%. Then this work would built a new bridge between PLLA materials and biomedical engineering.

Comparison between Artificial Neural Networks and Support Vector Machine Modeling for Polycaprolactone Synthesis via Enzyme Catalyzed Polymerization

Comparison between Artificial Neural Networks and Support Vector Machine Modeling for Polycaprolactone Synthesis via Enzyme Catalyzed Polymerization

The synthesis of polycaprolactone (PCL) microspheres containing cerium (III) nitrate (Ce(NO3)3) self-healing agent via double emulsion evaporation method

In this study, the synthesis of polycaprolactone (PCL) microspheres containing cerium (III) nitrate (Ce(NO3)3) as a self-healing agent was performed by water-in-oil-in-water (W1/O/W2) double emulsion evaporation (DEE) method. The parameters including stirring speeds (100, 200, 400, 600, 800, and 1000 rpm) and mixing temperatures (room temperature, 50 °C, 60 °C, and 70 °C) were investigated during the DEE formation. Based on the results, an increase in stirring speeds resulted in a decrease in an average particle size of the PCL microspheres containing Ce(NO3)3; yet it did not affect the average particle size of the PCL microspheres without Ce(NO3)3 inside. The suitable temperature for synthesizing PCL microspheres containing Ce(NO3)3 as well as PCL microspheres without Ce(NO3)3 inside should not exceed 50 °C during DEE formation because the PCL compound started to melt at temperature above 50 °C. Based on the results, the conditions of DEE formation at the stirring speed of 1000 rpm and mixing temperature of 50 °C yielded the PCL microspheres containing Ce(NO3)3 with an average size of 5.48 μm.

New, Environment Friendly Approach for Synthesis of Amphiphilic PCL–PEG–PCL Triblock Copolymer: An Efficient Carrier for Fabrication of Nanomicelles

Ring opening copolymerization is the most frequently applied reaction for the synthesis of polycaprolactone–polyethylene glycol–polycaprolactone (PCL–PEG–PCL). In this reaction, a number of expensive and toxic organic solvents are being used for the purpose of purification and extraction of the prepared copolymer. Exposure to these organic solvents can cause serious issues to the human health and also impart serious environmental pollution. In the current work, a new, economical and organic solvent free approach was used for the synthesis of triblock copolymer. The results of the current studies confirmed the successful formation of triblock copolymer as revealed by Fourier transform infrared spectra, 13carbon nuclear magnetic resonance (13C-NMR) and proton nuclear magnetic resonance (1H-NMR). Gel permeation chromatography analysis ensured the homo-distribution of the prepared copolymer. The prepared copolymer was further evaluated as a carrier for the drug loading. Nanomicelles were successfully prepared by the nanoprecipitation technique and exhibited an average size distribution of 42.50 nm and an encapsulation efficiency of 90%. The prepared nanomicelles also exhibited safety at the concentration of 50 µg/ml and a long-term storage stability. All these studies suggested the success of the new simplest and economical method for the synthesis of PCL–PEG–PCL and its subsequent applications as a carrier for fabrication and efficient delivery of hydrophobic drug molecules.

Enzymatic Polymerization of PCL-PEG Co-polymers for Biomedical Applications.

Biodegradable polymers, obtained via chemical synthesis, are currently employed in a wide range of biomedical applications. However, enzymatic polymerization is an attractive alternative because it is more sustainable and safer. Many lipases can be employed in ring-opening polymerization (ROP) of biodegradable polymers. Nevertheless, the harsh conditions required in industrial context are not always compatible with their enzymatic activity. In this work, we have studied a thermophilic carboxylesterase and the commonly used Lipase B from Candida antarctica (CaLB) for tailored synthesis of amphiphilic polyesters for biomedical applications. We have conducted Molecular Dynamics (MD) and Quantum Mechanics/Molecular Mechanics (QM/MM) MD simulations of the synthesis of Polycaprolactone—Polyethylene Glycol (PCL—PEG) model co-polymers. Our insights about the reaction mechanisms are important for the design of customized enzymes capable to synthesize different polyesters for biomedical applications.

Lipase mediated synthesis of polycaprolactone and its silica nanohybrid

Abstract In this study, rice husk ash (RHA) silanized with 3-glycidyloxypropyl trimethoxysilane was used as support material to immobilize Candida antarctica lipase B. The developed biocatalyst was then utilized in the ring opening polymerization (ROP) of ε-caprolactone and in situ development of PCL/Silica nanohybrid. The silanization degree of RHA was determined as 4 % (w) by thermal gravimetric analysis (TGA). Structural investigations and calculation of molecular weights of nanohybrids were realized by proton nuclear magnetic resonance (1H NMR). Crystallinity was determined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Scanning Electron Microscopy (SEM) was used for morphological observations. Accordingly, the PCL composition in the nanohybrid was determined as 4 %, approximately. Short chained amorphous PCL was synthesized with a number average molecular weight of 4400 g/mol and crystallinity degree of 23 %. In regards to these properties, synthesized PCL/RHA composite can find use biomedical applications.

Comparison of response surface methodology and feedforward neural network modeling for polycaprolactone synthesis using enzymatic polymerization

Abstract This study highlights the optimisation of process parameters for the synthesis of a biodegradable polymer – polycaprolactone using response surface methodology and artificial neural networks. Temperature, time, mixing speed and solvent volume are the parameters considered for optimisation and polymer yield was chosen as response. The results obtained from RSM displays a good agreement with 3.4% percent deviation between predicted values and actual values. Further, feedforward neural network (FFNN) modeling is developed with five different training algorithms. Out of all, Levenberg-Marquardt training algorithm proved to be best with lowest MSE, MAE, MAPE values of 0.10, 0.18 and 0.02 respectively. Both the techniques have been successful in predicting the biopolymer yield. Coefficient of determination (R2) and Absolute average deviation (AAD) value for RSM are obtained better proving RSM superior to ANN in this study.

Performance comparison of feedforward neural network training algorithms in modeling for synthesis of polycaprolactone via biopolymerization

This paper reports the biopolymerization of e-caprolactone, using lipase Novozyme 435 catalyst at varied impeller speeds and reactor temperatures. A multilayer feedforward neural network (FFNN) model with 11 different training algorithms is developed for the multivariable nonlinear biopolymerization of polycaprolactone (PCL). In previous works, biopolymerization carried out in scaled-up bioreactors is modeled through FFNN. No review discussed the role of different training algorithms in artificial neural network on the estimation of biopolymerization performance. This paper compares mean absolute error, mean square error, and mean absolute percentage error (MAPE) in the PCL biopolymerization process for 11 different training algorithms that belong to six classes, namely (1) additive momentum, (2) self-adaptive learning rate, (3) resilient backpropagation, (4) conjugate gradient backpropagation, (5) quasi-Newton, and (6) Bayesian regulation propagation. This paper aims to identify the most effective training method for biopolymerization. Results show that the quasi-Newton-based and Levenberg–Marquardt algorithms have the best performance with MAPE values of 4.512, 5.31, and 3.21% for the number of average molecular weight, weight average molecular weight, and polydispersity index, respectively.

Periodontal Tissues, Maxillary Jaw Bone, and Tooth Regeneration Approaches: From Animal Models Analyses to Clinical Applications.

This review encompasses different pre-clinical bioengineering approaches for periodontal tissues, maxillary jaw bone, and the entire tooth. Moreover, it sheds light on their potential clinical therapeutic applications in the field of regenerative medicine. Herein, the electrospinning method for the synthesis of polycaprolactone (PCL) membranes, that are capable of mimicking the extracellular matrix (ECM), has been described. Furthermore, their functionalization with cyclosporine A (CsA), bone morphogenetic protein-2 (BMP-2), or anti-inflammatory drugs’ nanoreservoirs has been demonstrated to induce a localized and targeted action of these molecules after implantation in the maxillary jaw bone. Firstly, periodontal wound healing has been studied in an induced periodontal lesion in mice using an ibuprofen-functionalized PCL membrane. Thereafter, the kinetics of maxillary bone regeneration in a pre-clinical mouse model of surgical bone lesion treated with BMP-2 or BMP-2/Ibuprofen functionalized PCL membranes have been analyzed by histology, immunology, and micro-computed tomography (micro-CT). Furthermore, the achievement of innervation in bioengineered teeth has also been demonstrated after the co-implantation of cultured dental cell reassociations with a trigeminal ganglia (TG) and the cyclosporine A (CsA)-loaded poly(lactic-co-glycolic acid) (PLGA) scaffold in the jaw bone. The prospective clinical applications of these different tissue engineering approaches could be instrumental in the treatment of various periodontal diseases, congenital dental or cranio-facial bone anomalies, and post-surgical complications.

PCL-Based Composite Scaffold Matrices for Tissue Engineering Applications.

Biomaterial-based scaffolds are important cues in tissue engineering (TE) applications. Recent advances in TE have led to the development of suitable scaffold architecture for various tissue defects. In this narrative review on polycaprolactone (PCL), we havediscussed in detail about the synthesis of PCL, various properties and most recent advances of using PCL and PCL blended with either natural or synthetic polymers and ceramic materials for TE applications. Further, various forms of PCL scaffolds such as porous, films and fibrous have been discussed along with the stem cells and their sources employed in various tissue repair strategies. Overall, the present review affords an insight into the properties and applications of PCL in various tissue engineering applications.

Surface Modification of Nanoclay for the Synthesis of Polycaprolactone (PCL) – Clay Nanocomposite

This paper presents a new modification method to modify the surface of nanoclay (Na-MMT) to increase its d-spacing using Aminopropylisooctyl Polyhedral Oligomeric Silsesquioxane (AP-POSS) and the fabrication of Polycaprolactone (PCL) nanocomposite through solution intercalation technique. The structure and morphology of pure nanoclay, modified nanoclay (POSS-MMT) and the PCL nanocomposite were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). XRD revealed that the d-spacing of the POSS-MMT is increased by 0.64 nm as compared to pure nanoclay. FTIR and FESEM results also showed that AP-POSS were well dispersed and intercalated throughout the interlayer space of Na-MMT. An exfoliated structure was also observed for PCL/POSS-MMT nanocomposite. Thermal properties of the nanocomposite were investigated using Thermal Gravimetry Analysis (TGA) which recorded highest degradation temperature for PCL/POSS-MMT 1% nanocomposite which is 394.1°C at 50% weight loss (T50%) but a decrease in degradation temperature when POSS-MMT content is increased and Differential Scanning Calorimetry (DSC) analysis which showed highest melting and crystallization temperature for PCL/POSS-MMT 5% nanocomposite which is 56.6°C and 32.7°C respectively whereas a decrease in degree of crystallinity for PCL/POSS-MMT nanocomposite as compared to PCL/Na-MMT nanocomposite. This study affords an efficient modification method to obtain organoclay with larger interlayer d-spacing to enhance the properties of polymer nanocomposite.

Optimisation of process parameters using D-optimal for enzymatic synthesis of polycaprolactone

This work emphasizes on reactor scale synthesis of polycaprolactone using e-caprolactone as monomer and Candida antarctica lipase B enzyme as catalyst. The bio-polymerization was performed in 2 L thermostatic reactor by the conventional method with constant stirring. Optimisation of process parameters such as reactor temperature, reaction time, and mixing speed was carried out using response surface methodology based on D-optimal design. Molecular weight of the bio-polymer was chosen as the response for optimization, which is later characterised by gel permeation chromatography. The results show good agreement between predicted values and actual values obtained through the experiments.

Continuous enzymatic synthesis of polycaprolactone in packed bed reactor using pressurized fluids

Continuous processing of reagents allows high reaction yields and better operational process control, allied with cost reduction compared to batch mode. In this work, a packed-bed reactor (PBR) system using Novozym 435 for enzymatic ring-opening polymerization (e-ROP) of ɛ-caprolactone (ɛ-CL) with dichloromethane asa cosolvent in supercritical CO2 (scCO2) or in n-butane media, was investigated. The reactions carried out in scCO2 reached yields above 93wt%, average molecular weight (Mn) of up to 31.2kDa and polydispersity (Đ) from 1.4 to 1.6 for only 15min processing. The apparent monomer conversion rate constant (kapp) ranged from 0.094 to 0.180min−1. Otherwise, reactions performed with n-butane provided yields above 80wt%, Mn values of 25.4kDa and Đ in the range of 1.4–1.6, also obtained for 15min of reaction. The maintenance of high yields and molecular weights for up to 6 enzymatic reuses were obtained for both systems studied.

Research on the New Polymeric Plasticizer for the Food Industry

Aiming at researching on the new polymeric plasticizer for the food Industry, this study attempts polycaprolactone synthesis and study its optimal synthesis conditions. Polycaprolactone is a type of polyester plasticizer, it has good compatibility with the polymer properties and has excellent flexibility, processability and thermal stability. So it has been widely used in various fields of biodegradable materials and food industrial materials such as plasticizers. Through a single factor test to determine the synthesis of polycaprolactone optimum conditions are: 0.2% zinc acetate catalyst in the reaction system, the reaction 4 hours 120°C. Infrared, gel chromatography and a series of characterization methods are carried to figure out the structure and molecular characterization of polycaprolactone. The results show that the synthesized product is indeed the target product polycaprolactone.

Policaprolactone/polyvinylpyrrolidone/siloxane hybrid materials: Synthesis and in vitro delivery of diclofenac and biocompatibility with periodontal ligament fibroblasts.

In this paper, we report the synthesis of polycaprolactone (PCL) based hybrid materials containing hydrophilic domains composed of N-vinylpyrrolidone (VP), and γ-methacryloxypropyltrimethoxysilane (MPS). The hybrid materials were obtained by RAFT copolymerization of N-vinylpyrrolidone and MPS using a pre-formed dixanthate-end-functionalized PCL as macro-chain transfer agent, followed by a post-reaction crosslinking step. The composition of the samples was determined by elemental and thermogravimetric analyses. Differential scanning calorimetry and X-ray diffraction indicated that the crystallinity of PCL decreases in the presence of the hydrophilic domains. Scanning electron microscopy images revealed that the samples present an interconnected porous structure on the swelling. Compared to PCL, the hybrid materials presented low water contact angle values and higher elastic modulus. These materials showed controlled release of diclofenac, and biocompatibility with human periodontal ligament fibroblasts.

Enzymatic synthesis of poly(ɛ-caprolactone) in liquified petroleum gas and carbon dioxide

Polycaprolactone (PCL) is a biodegradable, bioresorbable and biocompatible polymer widely used in biomedical applications. Unlike the classical polymerization methods that include the use of a metallic catalyst in organic solvent medium, the main goal of this work is to report the synthesis of polycaprolactone using a commercial enzyme, Novozym 435, as catalyst, together with liquefied petroleum gas (LPG) and carbon dioxide (CO2) as solvent medium in order to establish a clean-technology process. The enzymatic production of PCL was carried out in pressurized LPG medium trough a set of experiments assessing the influence of pressure (120–280bar), solvent/monomer ratio (2:1–1:2 mass ratio) and enzyme content (by monomer weight, 5–15 wt%) on the reaction yield, number-average molecular weight (Mn), weight-average molecular weight (Mw) and polidispersity index (PI). Kinetic experiments were also conducted in batch using LPG as solvent to evaluate the influence of catalyst content and pressure on reaction yield, Mn, Mw, PI with the reaction time. Furthermore, the enzyme reuse was also evaluated in order to reduce the impact of enzyme cost on the process. Continuous mode polymerizations using CO2 as solvent were also carried out for reactions at 120 and 200bar, 65°C and solvent/monomer mass ratios of 2:1 and 1:2. Results from ANOVA statistical analysis for the first set of experiments show that the pressure has no significant influence over the parameters evaluated, while the solvent/monomer mass ratio and enzyme content presented significant effect on reaction yield. Polymerization results for the kinetic assays indicated reaction yields up to 81 wt% with Mn up to 15,000Da and Mw up to 23,000Da for 20h of reaction, and PI ranging from 1.2 to 1.7 for the batch reactions and reaction yields up to 60.1 wt% with Mn 21,700Da and Mw up to 36,800Da for 10.7min of reaction, and PI ranging from 1.7 to 2.1 for the PBR (Packed Bed Reactor) reactions. The condition of 25bar, 2:1 solvent/monomer mass ratio, 3 wt% of enzyme, 65°C and 8h of reaction was selected for the enzyme batch reuse experiments, which indicate technical feasibility of enzyme reuse. Finally, future directions and some perspectives on the field of enzyme-catalyzed biopolymer production in compressed or supercritical fluid media are addressed.

Lipase catalyzed synthesis of polycaprolactone and clay-based nanohybrids

This study presents the use of original systems based on Candida antarctica lipase B (CALB) immobilized on montmorillonite and sepiolite nanoclays as efficient catalysts for the enzymatic polymerization of ε-caprolactone (ε-CL) and the in situ elaboration of nanohybrids.The kinetic studies showed that the most efficient system was obtained with CALB immobilized on organo-modified montmorillonite. Polycaprolactone (PCL) characterization demonstrated that the hydroxyl groups from the clay organo-modifier participate to the reaction as co-initiators. This allowed the successful in situ elaboration of organic/inorganic nanohybrids by promoting the PCL chains grafting and growth from the hydroxyl groups present at the clay surface.Selective extraction procedures carried out on the nanohybrids and the performed thermogravimetric analyses evidenced the effective grafting of PCL chains from the clay surface. Observations by electronic microscopy further confirmed such PCL chain grafting and demonstrated its positive effect for the elaboration of nanohybrids with finely dispersed clay nanoparticles in the polymer matrix.

Neural Network Based Modeling for Polycaprolactone Synthesis by Bio-Polymerization of ε-caprolactone

Neural Network Based Modeling for Polycaprolactone Synthesis by Bio-Polymerization of ε-caprolactone