Degradation Rate Of Poly Research Articles

Mechanical Properties and Degradation Rate of Poly(Sorbitol Adipate-Co-Dioladipate) Copolymers Obtained with a Catalyst-Free Melt Polycondensation Method.

A new family of polyester-based copolymers-poly(sorbitol adipate-co-ethylene glycol adipate) (PSAEG), poly(sorbitol adipate-co-1,4 butane diol adipate) (PSABD), and poly (sorbitol adipate-co-1,6 hexane diol adipate) (PSAHD)-was obtained with a catalyst-free melt polycondensation procedure using the multifunctional non-toxic monomer sorbitol, adipic acid, and diol, which are acceptable to the human metabolism. Synthesized polyesters were characterized by FTIR and 1H NMR spectroscopy. The molecular weight and thermal properties of the polymers were determined by MALDI mass spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis. The degradation rate was investigated, at 37 °C, in 0.1M NaOH (pH 13) and in phosphate-buffered solution (PBS) at pH 7.4. It was found that the polymers degraded faster in NaOH (i.e., in a day) compared to their degradation in PBS, which was much slower (in a week). The highest degradation rate was noticed for the PSAEG sample in both media, whereas PSAHD was the most stable polymer at pH 7.4 and 13. A reduced hydrophilicity of the polymers with diol length was indicated by low swelling percentage and sol content in water and DMSO. Mechanical studies prove that all the polymers are elastomers whose flexibility increases with diol length, shown by the increase in percentage of elongation at break and the decrease in tensile stress and Young's modulus. These biodegradable copolymers with adaptable physicochemical characteristics might be useful for a broad variety of biological applications by merely varying the length of the diol.

To improve the flame retardancy, mechanical properties and degradation rate of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by divinybenzene-maleic anhydride microsphere

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB), as a bio-originated and biodegradable polyester, is expected to be developed to substitute traditional petroleum-based plastics. However, its flammability restrains its application, intumescent flame retardant (IFR) has been used in P34HB. Herein, a rigid microsphere divinylbenzene-maleic anhydride (DM) copolymer was used as a synergistic agent with IFR together in P34HB. The LOI of the 83wt% P34HB/16wt% IFR/1wt% DM reached 30.0%, and the composite also passed the UL-94V-0 rating. In the cone calorimeter test, the peak heat release rate (PHRR) of the control P34HB was 727 kW/m2, which was reduced to 281 kW/m2 for the 83wt% P34HB/16wt% IFR/1wt% DM. The total smoke production (TSP) of the control P34HB was 12.1 m2, however, the TSP value of 83wt% P34HB/16wt% IFR/1wt% DM was reduced to 8.4 m2. The results showed that DM acted as an ideal synergist flame retardant. For the 75wt% P34HB/25wt% IFR, the tensile strength and impact strength were 13.7 MPa and 4.2 KJ/m2, respectively and for the 83wt% P34HB/16wt% IFR/1wt% DM, they were increased to 18.1 MPa and 9.1 KJ/m2, respectively. In the degradation process, the weight loss rate of control P34HB was 0.1 mg/h, and that was 0.56 mg/h for 83wt% P34HB/16wt% IFR/1wt% DM, which indicated that the IFR/DM accelerated the degradation of P34HB. All the work documented that DM improved the flame retardant, mechanical properties, and degradation rate of P34HB.

Synthesis, properties, and hydrolysis of bio‐based poly(butylene succinate‐co‐diethylene glycol succinate) copolyesters

AbstractMicroplastic has become the focus of environmental pollution recently, especially in seawater. Due to its high crystallinity and hydrophobicity, the degradation rate of poly(butylene succinate) (PBS) is slow. In this paper, a series of poly(butylene succinate‐co‐diethylene glycol succinate) (PBSD) copolymers were synthesized by melt‐polycondensation in order to improve the nonenzymatic hydrolysis of PBS. The contact angle and water uptake content of copolymer were increased obviously when the regular crystalline structure of chain segment was disturbed by diethylene glycol. Rheological tests revealed the microphase separation structure occurred at 130°C. The tensile strength of PBSD40 copolymer was 15 MPa and the elongation at break was more than 700%, and the decomposition temperature was above 370°C. The weight loss of PBSD60 copolymer in acid condition was 98.6% after 49 days at 50°C. However, in neutral condition and simulated seawater, the weight loss was less than 10%. Acid and alkaline catalyzed the hydrolysis of ester bonds. Some holes and cracks appeared at the surface of the samples after degradation from SEM analysis. Thus, PBSD copolymers have the potential to serve as promising water degradable materials.

Polyamide/Poly(Amino Acid) Polymers for Drug Delivery.

Polymers have always played a critical role in the development of novel drug delivery systems by providing the sustained, controlled and targeted release of both hydrophobic and hydrophilic drugs. Among the different polymers, polyamides or poly(amino acid)s exhibit distinct features such as good biocompatibility, slow degradability and flexible physicochemical modification. The degradation rates of poly(amino acid)s are influenced by the hydrophilicity of the amino acids that make up the polymer. Poly(amino acid)s are extensively used in the formulation of chemotherapeutics to achieve selective delivery for an appropriate duration of time in order to lessen the drug-related side effects and increase the anti-tumor efficacy. This review highlights various poly(amino acid) polymers used in drug delivery along with new developments in their utility. A thorough discussion on anticancer agents incorporated into poly(amino acid) micellar systems that are under clinical evaluation is included.

Influence of Degradation of PLA with High Degree of Crystallinity on Fungal Community Structure in Compost

Degradation rate of poly(lactic acid) (PLA), a compostable plastic, is affected by its physical properties and environmental conditions. Since PLA with different physical properties enter composting systems, investigation of degradation of PLA with strong physical properties in compost at different temperatures and its influence on compost fungal community structure are the main concerns of this study. To determine the effect of slow PLA degradation on fungal communities, PLA granules with high degree of crystallinity, 60%, were incubated in compost at 25 °C and 50 °C for 4 months at 0, 10, 25 and 50% (w/w) concentrations; their degradation rates were compared and impact of PLA degradation on compost fungal communities was examined by terminal restriction fragment length polymorphism (TRFLP). PLA granules in compost at 25 °C showed no physical changes but at 50 °C physical disintegration occurred after 4 months. TRFLP revealed that fungal community profiles in compost were affected by PLA, particularly at 50 °C where PLA degraded. Compost fungal communities in the presence of PLA at 50 °C had more variation, 63%, than at 25 °C (52%). Incubation time affected fungal community structure as during 2nd month, community structure changed specifically at 50 °C and at 50% (w/w) PLA, however, became similar to that in the absence of PLA at the end of 4th month at both temperatures indicating PLA with a high degree of crystallinity causes a temporal perturbation in compost fungal communities. In compost containing PLA at 50 °C, abundance of certain TRFs representing fungal populations increased to 30% which may involve in PLA utilization.

Biodegradability of poly(lactic-co-glycolic acid) irradiated with femtosecond laser pulses without material removal

The degradation rates of biodegradable polymers are necessary to be controlled for tissue scaffold applications. In this work, we demonstrate that the degradation rate of poly(lactic-co-glycolic acid) (PLGA) was accelerated by irradiating with femtosecond laser pulses under the condition where material removal, i.e., laser ablation had not occurred. Scanning electron microscopy observation showed that the degradation rate was accelerated without significant laser ablation. The analysis of Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the chemical properties of the PLGA had changed by femtosecond laser pulses irradiation. Furthermore, we have investigated the degradation of PLGA when the femtosecond laser pulses were focused inside the material. After the degradation, the PLGA showed enhanced optical scattering region in the depth of 300 µm from the surface. The results indicate that high-aspect-ratio modification and degradation are possible by changing the depth of focus of femtosecond laser pulses under the conditions where the direct removal of the material was not occurred.

Enhanced pH stability, cell viability and reduced degradation rate of poly(L-lactide)-based composite in vitro: effect of modified magnesium oxide nanoparticles

The modified MgO nanoparticles (m-MgO-NPs) by a copolymer containing the malic acid and low molecular weight poly(L-lactide) (poly(L-lactide-co-malic acid), PLMA) have been successfully prepared. MgO nanoparticles (MgO-NPs) were coated by the PLMA and m-MgO-NPs were uniformly dispersed in the PLLA matrix to a novel biocomposite material (PLLA/m-MgO-NPs) with more excellent interface bonding and uniformer dispersion, compared to the PLLA/MgO-NPs. Compared to neat PLLA and PLLA/MgO-NPs film, the m-MgO-NPs not only shown the obvious neutralization effect on the acidic solution in the degradation of the PLLA and better hydrophilicity, but also exhibited the higher cell viability and decrease the toxicity to the cell in the degradation process of PLLA in vitro. In addition, m-MgO-NPs also reduced the degradation rate of the PLLA. The mechanisms for the excellent dispersion of nanoparticles, enhanced pH stability, reduced degradation rate of the PLLA and the cell viability in vitro in the case of PLLA/m-MgO-NPs have also been proposed and discussed in detail.

Graphene oxide-enriched poly(ε-caprolactone) electrospun nanocomposite scaffold for bone tissue engineering applications

Tissue engineering aims at fabricating biological substitutes to improve, repair, and regenerate failing human tissues or organs. Designing a nanocomposite scaffolds with tailored properties that enhance the development of functional tissue can be an appropriate approach to achieve this purpose. In this study, the uniform and bead-free nanofibers of poly(ε-caprolactone) composited with different graphene oxide nanosheet contents (ranging from 0.5 to 2 wt%) were successfully fabricated through electrospinning process. A decrease in the average diameter of poly(ε-caprolactone) nanofibers was observed with the addition of graphene oxide nanosheets. Moreover, the nanocomposite scaffolds containing 2 wt% of graphene oxide nanosheets exhibited superior mechanical properties compared to that of pure poly(ε-caprolactone). Compared with pure poly(ε-caprolactone) scaffold, the degradation rate of poly(ε-caprolactone)-graphene oxide nanosheet nanofibers was enhanced, while the integrity of fibers was preserved. The presence of graphene oxide nanosheets in poly(ε-caprolactone) fibers promoted in vitro biomineralization, indicating bioactive features of the nanocomposite scaffolds. Compared to the pure one, nanocomposite fibers also showed better ability in protein adsorption. The in vitro cell culture studies showed that the addition of graphene oxide nanosheets did not diminish the biocompatibility of the electrospun poly(ε-caprolactone) nanofiber. Furthermore, the adhesion and proliferation of MG63 cells were increased. Altogether, the results demonstrated that electrospun poly(ε-caprolactone)-graphene oxide nanosheet nanofiber may be a suitable candidate for tissue engineering scaffold applications.

Surfactant tuning of hydrophilicity of porous degradable copolymer scaffolds promotes cellular proliferation and enhances bone formation.

Poly(l-lactide-co-ɛ-caprolactone) (poly(LLA-co-CL)) has been blended with Tween 80 to tune the material properties and optimize cell-material interactions. Accordingly, the aims of this study were fourfold: to evaluate the effect of low concentrations of Tween 80 on the surface microstructure of 3D poly(LLA-co-CL) porous scaffolds: to determine the effect of different concentrations of Tween 80 on proliferation of bone marrow stromal cells (BMSCs) in vitro under dynamic cell culture at 7 and 21 days; to assess the influence of Tween 80 on the degradation rate of poly(LLA-co-CL) at 7 and 21 days; and in a subcutaneous rat model, to evaluate the effect on bone formation of porous scaffolds modified with 3% Tween 80 at 2 and 8 weeks. Blending 3% (w/w) Tween 80 with poly(LLA-co-CL) improves the surface wettability (p < 0.001). Poly(LLA-co-CL)/3% Tween 80 shows significantly increased cellular proliferation at days 7 and 21 (p < 0.001). Moreover, the presence of Tween 80 facilitates the degradation of poly(LLA-co-CL). Two weeks post-implantation, the poly(LLA-co-CL)/3% Tween 80 scaffolds exhibit significant mRNA expression of Runx2 (p = 0.004). After 8 weeks, poly(LLA-co-CL)/3% Tween 80 scaffolds show significantly increased de novo bone formation, demonstrated by μ-CT (p = 0.0133) and confirmed histologically. It can be concluded that blending 3% (w/w) Tween 80 with poly (LLA-co-CL) improves the hydrophilicity and osteogenic potential of the scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2049-2059, 2016.

Biodegradability, cellular compatibility and cell infiltration of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) in comparison with poly(ε-caprolactone) and poly(lactide-co-glycolide)

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(ε-caprolactone), and poly(1actide-co-glycolide) films were prepared by solution casting and electrospinning. The degradability of cast films was evaluated in vitro and in vivo by recording the weight remaining, observing the morphology, and measuring change in molecular weight and Mw/ Mn polydispersity. In addition, cell proliferation on electrospun films was tested by MTT assay, and cell infiltration into electrospun films was assessed through subcutaneous implantation in rats. By analyzing data obtained from these tests, we discovered that the degradation rates of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers were between those of poly(ε-caprolactone) and poly(1actide-co-glycolide) and could be controlled by adjusting 4-hydroxybutyrate content. Moreover, tissue responses to materials made from poly(3-hydroxybutyrate-co-4-hydroxybutyrate) were milder compared with those elicited by poly(ε-caprolactone) and poly(1actide-co-glycolide), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) films exhibited a good and moderate cell infiltration. Therefore, our data demonstrate that poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers are promising candidates for the construction of scaffolds designed for various types of tissue regeneration with special biodegradability requirements.

Stability of poly(l‐lactic acid) in textile applications

The present paper is focused on the use of promising bio‐based thermoplastic—poly(l‐lactic acid)—in textile applications and with possible limits related to its enhanced sensitivity to (bio)degradation. Linear and planar fabrics made of staple were exposed to standard washing cycles imitating the maintenance of textile materials. The effect of temperature and pH of the washing bath on the degradation rate of poly(l‐lactic acid) was monitored by the abiotic hydrolysis test. The properties of the fabrics after carrying out the tests were evaluated from the changes of mass per areal weight, strength, and morphology of the fabrics. The changes of the structure of the polymer chains were assessed by differential scanning calorimetry, by the decrease of molar masses (determined using size exclusion chromatography) and of the viscosity of the polymer solutions, and by infrared spectroscopy. Poly(l‐lactic acid) fabric finds application for various kinds of garments, and untreated fabric reliably tolerates 60 standard washing cycles. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Effects of Surface Morphology Variation on the Degradation Rate of Poly(L-Lactic Acid) Membranes and the Behavior of Attached Cells

Effects of Surface Morphology Variation on the Degradation Rate of Poly(L-Lactic Acid) Membranes and the Behavior of Attached Cells

Degradation and compatibility behaviors of poly(glycolic acid) grafted chitosan

The films of poly(glycolic acid) grafted chitosan were prepared without using a catalyst to improve the degradable property of chitosan. The films were characterized by Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The degradation of the poly(glycolic acid) grafted chitosan films were investigated in the lysozyme solution. In vitro degradation tests revealed that the degradation rate of poly(glycolic acid) grafted chitosan films increased dramatically compared with chitosan. The degradation rate of poly(glycolic acid) grafted chitosan films gradually increased with the increasing of the molar ratio of glycolic acid to chitosan. Additionally, the poly(glycolic acid) grafted chitosan films have good biocompatibility, as demonstrated by in vitro cytotoxicity of the extraction fluids. The biocompatible and biodegradable poly(glycolic acid) grafted chitosan would be an effective material with controllable degradation rate to meet the diverse needs in biomedical fields.

Enzymatic degradation of polyester films by a cutinase-like enzyme from Pseudozyma antarctica: surface plasmon resonance and atomic force microscopy study

Enzymatic degradation of polyester films by a cutinase-like enzyme from Pseudozyma antarctica JCM10317 (PaE) was analyzed by surface plasmon resonance (SPR). The adsorption of PaE and the degradation rate for polyester films were quantitatively monitored by a positive and negative SPR signal shifts, respectively. The decrease in SPR signal and the erosion depth of amorphous poly(L-lactide) (a-PLLA) film measured by atomic force microscopy (AFM) had a linear relationship, and the weight loss was estimated from the AFM data combined with a density of a-PLLA film. Furthermore, SPR sensorgrams for various polyester films showed that degradation rate of poly(ε-caprolactone) and poly(butylene succinate-co-adipate) which contain C6 units was higher than that of other polyesters such as poly(butylene succinate) and a-PLLA. These results suggest that C6 is the preferred chain length as substrates for PaE.

Influence of Transducer Structure on Mechanical and Chemical Effects of 20 kHz Sonication

In this work, we examined the influence of transducer structure on the mechanical and chemical effects of 20 kHz sonication, where the dissipated power measured by calorimetry was kept constant (5 W). The mechanical effects were evaluated from the degradation rate of poly(ethylene oxide) in aqueous solution, and the chemical effects were measured with potassium iodide solution. The mechanical effects for a bath-type apparatus with the transducers fixed at a node with a diameter of 50 mm are nearly equal to those for a horn-type apparatus. The former transducer showed the strongest chemical effects among the transducers investigated here.

Effects of Sunshine Duration and Precipitation on the Degradation Rate of Poly (L-Lactic Acid)

Effects of Sunshine Duration and Precipitation on the Degradation Rate of Poly (L-Lactic Acid)

Biodegradable bio-based polyesters with controllable photo-crosslinkability, thermal and hydrolytic stability

Biodegradable poly{3,4-dihydroxycinnamic acid (DHCA, coffeic acid)-co-lithocholic acid (LCA)} polyester was synthesized by polycondensation of DHCA and LCA. The molecular structure of poly(DHCA-co-LCA) copolymers was characterized by FT-IR and 1H-NMR measurement. The photo-crosslinkability of poly(DHCA-co-LCA) depended on their compositions and could be tuned by varying the monomer ratio. The presence of LCA in the copolymers enhanced the solubility and thermal stability. In addition, poly(DHCA-co-LCA) and PDHCA exhibited higher fluorescence emission intensity than DHCA monomer. Accelerated hydrolysis experiments revealed that the degradation rate of poly(DHCA-co-LCA) was slower than that of PDHCA.

The effect of chemistry on the polymerization, thermo-mechanical properties and degradation rate of poly(β-amino ester) networks

Poly(β-amino ester) networks are gaining attention as a scaffold material for tissue engineering applications where it is important to have tailorable degradation rate and elastic modulus. The objective of this work is to characterize and understand the relationships between chemical structure, polymerization, thermo-mechanical properties, and degradation in poly(β-amino esters) networks. The networks were synthesized from a primary amine with systematically varied molar ratios and chemical structures of diacrylates. Fundamental trends were established between the chemical structure, conversion during polymerization, macromer molecular weight, rubbery modulus, and degradation rate. The thermo-mechanical properties were dependent upon both polymerization steps. The rubbery modulus was tailorable over a range of several MPa by changing molar ratio and diacrylate molecular weight. The degradation rate ranged from hours to months depending upon the composition. Select chemical structures showed degradation rate independent of modulus. This work provides a basis for designing poly(β-amino esters) networks with specific thermo-mechanical properties and degradation rates for biomedical scaffolds.

Formulation and release characteristics of poly(lactic-co-glycolic acid) microspheres containing chemically modified protein

Chemical modification of proteins may influence their formulation into and release from polymeric microspheres. Three chemical modifications of rat serum albumin (RSA) were effected on the amine groups of this protein: conjugation with a polyanion using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, intermolecular cross-linking using glutaraldehyde, and reductive alkylation using propyl aldehyde. The modified proteins had different physicochemical properties as well as improved encapsulation efficiencies compared with native RSA microspheres. The microspheres were incubated at 37 degrees C for over one month to investigate the influence of protein modification on the release profiles. Microsphere degradation accelerated from the ninth day of the release studies and this coincided with an increase in the release rates. The degradation rates of poly(lactic-co-glycolic acid) microspheres containing either native or cross-linked RSA were more rapid than those containing either heparin conjugated or propylated RSA. This was in agreement with the release data, since the release of the native and cross-linked RSA were more rapid than those of the other modified proteins. The release profiles of the RSA-heparin conjugates and the propylated RSA were approximately zero rather than first order between the tenth and thirtieth day of study. Chemical modification of protein may be a useful method to increase encapsulation efficiency and to decrease release rates of proteins that are to be used in microsphere formulations of potent therapeutic proteins.

Effect of Oxidizers on Microwave-Assisted Oxidative Degradation of Poly(alkyl acrylates)

The effect of oxidizers on the microwave-assisted oxidative degradation kinetics of poly(alkyl acrylates), namely, poly(methyl acrylate) (PMA), poly(ethyl acrylate) (PEA), and poly(butyl acrylate) (PBA), was studied. The molecular weight distributions were measured by gel permeation chromatography, and continuous distribution kinetic models were used to determine the degradation rate coefficients. The effect of alkyl group substituents on the microwave-assisted oxidative degradation of poly(alkyl acrylates) was also investigated. The degradation rate of poly(alkyl acrylates) decreased with an increase in the number of carbon atoms of the alkyl substituents and thus followed the order PMA > PEA > PBA, while the activation energy increased with the length of alkyl group substituents. The rate coefficients of hydrogen abstraction and oxidative random chain scission were found to be independent of the oxidizer and dependent only on the nature of the polymer. The differences in the overall degradation rate of poly(ethyl acrylate) in the presence of different oxidizing agents were only dependent on the rate of oxidizer dissociation. This is the first study that shows that the degradation rate of the polymer in the presence of any oxidizer can be predicted by knowing only the thermal dissociation rate constant values of the oxidizer, which can be easily obtained from existing literature.