Abstract The main aim of this study was to examine the potential of hydrophlilic–hydrophobic chem... more Abstract The main aim of this study was to examine the potential of hydrophlilic–hydrophobic chemically crosslinked polymers as vehicles for drug delivery. To this end, a range of polypropyleneglycol dimethacrylate/polyethyleneglycol dimethacrylate (PPGDMA/PEGDMA) and polypropyleneglycol diacrylate/polyethyleneglycol dimethacrylate (PPGDA/PEGDMA) hydrogels were photopolymerised using UV light. Thereafter, the chemical, rheological and mechanical properties were evaluated, where it was revealed that the presence of the methyl group on the PPGDMA/PEGDMA hydrogel had no statistically significant effect on the gel fraction, storage loss modulus, or tan delta. In terms of mechanical properties, the 75 wt% PPGDMA/PEGDMA and PPGDA/PEGDMA hydrogels had the highest compressive modulus, with values of 9.02 MPa and 8.47 MPa recorded respectively. Drug release was examined for two anti-inflammatory agents; dexamethasone and diclofenac sodium, where it was revealed that the concentration of the PPGDA in the PPGDA/PEGDMA had no significant effect on the release profile of dexamethasone. However, the size and interaction of the drug with the hydrogel appears to alter the release profile, as the larger, acidic dexamethasone drug was eluted faster than the smaller, ionic, basic diclofenac sodium agent.
Radiation is currently being exploited to modify polyethylene in order to improve properties for ... more Radiation is currently being exploited to modify polyethylene in order to improve properties for various applications such as hip replacements. This paper thoroughly examines the effects of high energy electron beam irradiation (10MeV) on low density polyethylene (LDPE) material. ASTM (American Society for Testing and Materials) testing specimens were manufactured from LDPE and subjected to a broad range of doses
ABSTRACT High energy electron beam irradiation of Poly (ether-block-amide) (Pebax) can induce mod... more ABSTRACT High energy electron beam irradiation of Poly (ether-block-amide) (Pebax) can induce modifications and/or degradation to transpire in the material subsequent to treatment. To minimise this, Pebax was blended with three stabilisers where each formulation was subjected to electron beam radiation at doses of 25, 50 and 75 kGy. Mechanical testing revealed that the virgin Pebax and the Pebax blended with Irganox B215 provided the best radiation resistance in terms of the tensile strength, elongation at break and Young's modulus. Upon increase in radiation dose from 25 to 75 kGy, a gradual diminution was observed for the melt flow index (MFI) of the virgin Pebax, whereas Pebax blended with Irganox B215 had a minute effect on the properties post irradiation. This study provides evidence that the stabilisers used can either promote undesirable effects or enhance the radiation resistance of Pebax material following radiation exposure.
ABSTRACT The current contribution investigates the potential use of styrene butadiene styrene (SB... more ABSTRACT The current contribution investigates the potential use of styrene butadiene styrene (SBS) block copolymer grafted with N-vinyl-2-pyrrolidinone (NVP) for use as a novel biomaterial. SBS-g-NVP was synthesised using UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR), dynamic thermal mechanical analysis (DMTA) and goniometry were used to characterise the grafted copolymers. The ATR-FTIR spectrum for grafted SBS-g-NVP copolymer exhibits a shoulder at 1714cm−1, which is associated with carbonyl stretching of NVP. DSC analysis showed the grafted copolymers had broader thermographs within the butadiene rich domain resulting in increased Tg values, suggesting that grafting occurred. Confirmation of this was established by the use of DMTA, where the Tg (−90°C) which represents the butadiene domain increased to −76°C, thus proving grafting. The surface chemistries of the grafted copolymers have also been altered which is reflected in the goniometry results which show a dramatic reduction in contact angles (113° to 7°), which is a desired property for biomedical polymers.
Polymer-plastics Technology and Engineering, Mar 1, 2016
ABSTRACT Poly (lactic acid) is considered to be a promising alternative to petroleum-based polyme... more ABSTRACT Poly (lactic acid) is considered to be a promising alternative to petroleum-based polymers due to its renewability, biodegradability, biocompatibility, and good mechanical properties. Because of the high cost, the applications of poly (lactic acid) were limited to the medical field. Over the past decade, improvements in polymerization allow the economical mass production of high molecular weight poly (lactic acid). Therefore, the applications of poly (lactic acid) have recently spread to domestic, commercial packaging, and textile applications. This review outlines the chemical, thermal characteristics of poly (lactic acid) and discusses the use of poly (lactic acid) in medical applications such as sutures, stents, drug carrier, orthopaedic devices, scaffolds, as well as commercial applications in textile and packaging fields with superior properties such as high wicking performance, good dyeability, antibacterial feature, good ultraviolet resistance, high water vapor transmission rates, shrink wrapping, and dead fold property. While the drawbacks of poly (lactic acid) utilized in these fields are also discussed. It is clear that the advantages of using poly (lactic acid) outlined in this review will ensure that the market for poly (lactic acid) products will continue to expand. GRAPHICAL ABSTRACT
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The development of systems which can release active pharmaceutical ingredients in response to phy... more The development of systems which can release active pharmaceutical ingredients in response to physiological variation has been to the forefront of drug delivery research recently. The development of negative temperature sensitive hydrogels has gained most attention in recent times. This book focuses on the development of novel amphiphilic hydrogels synthesised using photopolymerisation, a fabrication technique commonly used in industrial settings. Hydrogel development especially when pertaining to drug delivery is an area that encapsulates a wide array of scientific backgrounds including polymer chemistry, biomedical engineering and pharmaceutics but to name a few. This work should therefore be ideally suited to professionals in Biomedical and Pharmaceutical fields involved in hydrogel synthesis and characterisation, and would be of particular interest to researchers engaged in ‘smart’ temperature controlled drug delivery applications.
Calcium carbonate (CaCO3) is often treated with stearic acid (SA) to decrease its polarity. Howev... more Calcium carbonate (CaCO3) is often treated with stearic acid (SA) to decrease its polarity. However, the method of application of the SA treatments has a strong influence on CaCO3 thermoplastic composite’s interfacial structure and distribution. Several of papers describe the promising effects of SA surface treatment, but few compare the treatment process and its effect on the properties of the final thermoplastic composite. In the current study, we assessed a new SA treatment method, namely, complex treatment for polymer composite fabrication with HDPE. Subsequently, a comparative study was performed between the “complex” process and the other existing methods. The composites were assessed using different experiments included scanning electron microscopy (SEM), void content, density, wettability, differential scanning calorimetry (DSC), and tensile tests. It was observed that the “complex” surface treatment yielded composites with a significantly lower voids content and higher density compared to other surface treatments. This indicates that after the “complex” treatment process, the CaCO3 particles and HDPE matrix are more tightly packed than other methods. DSC and wettability results suggest that the “wet” and “complex” treated CaCO3 composites had a significantly higher heat of fusion and moisture resistance compared to the “dry” treated CaCO3 composites. Furthermore, “wet” and “complex” treated CaCO3 composites have a significantly higher tensile strength than the composites containing untreated and “dry” treated CaCO3. This is mainly because the “wet” and “complex” treatment processes have increased adsorption density of stearate, which enhances the interfacial interaction between matrix and filler. These results confirm that the chemical adsorption of the surfactant ions at the solid-liquid interface is higher than at other interface. From this study, it was concluded that the utilization of the “complex” method minimised the negative effects of void coalescence provides key information for the improvement of existing processes.
ABSTRACT Biodegradable polymers—polyethylene oxide and poly (ϵ-caprolactone)—were melt extruded w... more ABSTRACT Biodegradable polymers—polyethylene oxide and poly (ϵ-caprolactone)—were melt extruded with β-tricalcium phosphate. Breakdown analysis revealed that the percentage increase in bioceramic caused a prolonged degradation rate, with samples containing 20 wt% β-tricalcium phosphate losing significantly less weight over time in comparison to the control sample. Compression testing of samples following submission in aqueous environments revealed the composites exhibited enhanced strength with increasing bioceramic loading. The mechanical properties were significantly reduced over a period of 5 weeks. It was found that hot-melt extrusion of β-tricalcium phosphate is a viable and effective method of producing novel composite scaffolds with potential for regenerative medicine applications. GRAPHICAL ABSTRACT
A computer vision system for measuring the displacement and bending angle of ionic polymer–metal ... more A computer vision system for measuring the displacement and bending angle of ionic polymer–metal composites (IPMC) was proposed in this study. The logical progression of measuring IPMC displacement and bending angle was laid out. This study used Python (version 3.10) in conjunction with OpenCV (version 4.5.5.64) for the development of the vision system. The coding functions and the mathematical formulas used were elaborated on. IPMC contour detection was discussed in detail, along with appropriate camera and lighting setups. Measurements generated from the vision system were compared to approximated values via a manual calculation method. Good agreement was found between the results produced by the two methods. The mean absolute error (MAE) and root mean squared error (RMSE) for the displacement values are 0.068080668 and 0.088160652, respectively, and 0.081544205 and 0.103880163, respectively, for the bending angle values. The proposed vision system can accurately approximate the d...
L'invention porte sur un enrobage pour substrats presentant des radicaux hydrogene extrayable... more L'invention porte sur un enrobage pour substrats presentant des radicaux hydrogene extrayable comportant: un groupe polymere hydrophile compose d'au moins deux polymeres de poids moleculaires differents; un monomere hydrophile non sature capable de polariser les radicaux libres en presence d'un radical; un composant activable par les UV pouvant extraire les radicaux hydrogene de la surface a revetir et d'un des polymere du polymere hydrophile, de maniere a amorcer et promouvoir la reticulation du monomere sur la surface, et celle du monomere ou d'une chaine de propagation du monomere sur l'un des polymere du groupe polymere; et un solvant choisi pour conferer a la preparation la viscosite voulue.
Abstract The main aim of this study was to examine the potential of hydrophlilic–hydrophobic chem... more Abstract The main aim of this study was to examine the potential of hydrophlilic–hydrophobic chemically crosslinked polymers as vehicles for drug delivery. To this end, a range of polypropyleneglycol dimethacrylate/polyethyleneglycol dimethacrylate (PPGDMA/PEGDMA) and polypropyleneglycol diacrylate/polyethyleneglycol dimethacrylate (PPGDA/PEGDMA) hydrogels were photopolymerised using UV light. Thereafter, the chemical, rheological and mechanical properties were evaluated, where it was revealed that the presence of the methyl group on the PPGDMA/PEGDMA hydrogel had no statistically significant effect on the gel fraction, storage loss modulus, or tan delta. In terms of mechanical properties, the 75 wt% PPGDMA/PEGDMA and PPGDA/PEGDMA hydrogels had the highest compressive modulus, with values of 9.02 MPa and 8.47 MPa recorded respectively. Drug release was examined for two anti-inflammatory agents; dexamethasone and diclofenac sodium, where it was revealed that the concentration of the PPGDA in the PPGDA/PEGDMA had no significant effect on the release profile of dexamethasone. However, the size and interaction of the drug with the hydrogel appears to alter the release profile, as the larger, acidic dexamethasone drug was eluted faster than the smaller, ionic, basic diclofenac sodium agent.
Radiation is currently being exploited to modify polyethylene in order to improve properties for ... more Radiation is currently being exploited to modify polyethylene in order to improve properties for various applications such as hip replacements. This paper thoroughly examines the effects of high energy electron beam irradiation (10MeV) on low density polyethylene (LDPE) material. ASTM (American Society for Testing and Materials) testing specimens were manufactured from LDPE and subjected to a broad range of doses
ABSTRACT High energy electron beam irradiation of Poly (ether-block-amide) (Pebax) can induce mod... more ABSTRACT High energy electron beam irradiation of Poly (ether-block-amide) (Pebax) can induce modifications and/or degradation to transpire in the material subsequent to treatment. To minimise this, Pebax was blended with three stabilisers where each formulation was subjected to electron beam radiation at doses of 25, 50 and 75 kGy. Mechanical testing revealed that the virgin Pebax and the Pebax blended with Irganox B215 provided the best radiation resistance in terms of the tensile strength, elongation at break and Young's modulus. Upon increase in radiation dose from 25 to 75 kGy, a gradual diminution was observed for the melt flow index (MFI) of the virgin Pebax, whereas Pebax blended with Irganox B215 had a minute effect on the properties post irradiation. This study provides evidence that the stabilisers used can either promote undesirable effects or enhance the radiation resistance of Pebax material following radiation exposure.
ABSTRACT The current contribution investigates the potential use of styrene butadiene styrene (SB... more ABSTRACT The current contribution investigates the potential use of styrene butadiene styrene (SBS) block copolymer grafted with N-vinyl-2-pyrrolidinone (NVP) for use as a novel biomaterial. SBS-g-NVP was synthesised using UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR), dynamic thermal mechanical analysis (DMTA) and goniometry were used to characterise the grafted copolymers. The ATR-FTIR spectrum for grafted SBS-g-NVP copolymer exhibits a shoulder at 1714cm−1, which is associated with carbonyl stretching of NVP. DSC analysis showed the grafted copolymers had broader thermographs within the butadiene rich domain resulting in increased Tg values, suggesting that grafting occurred. Confirmation of this was established by the use of DMTA, where the Tg (−90°C) which represents the butadiene domain increased to −76°C, thus proving grafting. The surface chemistries of the grafted copolymers have also been altered which is reflected in the goniometry results which show a dramatic reduction in contact angles (113° to 7°), which is a desired property for biomedical polymers.
Polymer-plastics Technology and Engineering, Mar 1, 2016
ABSTRACT Poly (lactic acid) is considered to be a promising alternative to petroleum-based polyme... more ABSTRACT Poly (lactic acid) is considered to be a promising alternative to petroleum-based polymers due to its renewability, biodegradability, biocompatibility, and good mechanical properties. Because of the high cost, the applications of poly (lactic acid) were limited to the medical field. Over the past decade, improvements in polymerization allow the economical mass production of high molecular weight poly (lactic acid). Therefore, the applications of poly (lactic acid) have recently spread to domestic, commercial packaging, and textile applications. This review outlines the chemical, thermal characteristics of poly (lactic acid) and discusses the use of poly (lactic acid) in medical applications such as sutures, stents, drug carrier, orthopaedic devices, scaffolds, as well as commercial applications in textile and packaging fields with superior properties such as high wicking performance, good dyeability, antibacterial feature, good ultraviolet resistance, high water vapor transmission rates, shrink wrapping, and dead fold property. While the drawbacks of poly (lactic acid) utilized in these fields are also discussed. It is clear that the advantages of using poly (lactic acid) outlined in this review will ensure that the market for poly (lactic acid) products will continue to expand. GRAPHICAL ABSTRACT
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The development of systems which can release active pharmaceutical ingredients in response to phy... more The development of systems which can release active pharmaceutical ingredients in response to physiological variation has been to the forefront of drug delivery research recently. The development of negative temperature sensitive hydrogels has gained most attention in recent times. This book focuses on the development of novel amphiphilic hydrogels synthesised using photopolymerisation, a fabrication technique commonly used in industrial settings. Hydrogel development especially when pertaining to drug delivery is an area that encapsulates a wide array of scientific backgrounds including polymer chemistry, biomedical engineering and pharmaceutics but to name a few. This work should therefore be ideally suited to professionals in Biomedical and Pharmaceutical fields involved in hydrogel synthesis and characterisation, and would be of particular interest to researchers engaged in ‘smart’ temperature controlled drug delivery applications.
Calcium carbonate (CaCO3) is often treated with stearic acid (SA) to decrease its polarity. Howev... more Calcium carbonate (CaCO3) is often treated with stearic acid (SA) to decrease its polarity. However, the method of application of the SA treatments has a strong influence on CaCO3 thermoplastic composite’s interfacial structure and distribution. Several of papers describe the promising effects of SA surface treatment, but few compare the treatment process and its effect on the properties of the final thermoplastic composite. In the current study, we assessed a new SA treatment method, namely, complex treatment for polymer composite fabrication with HDPE. Subsequently, a comparative study was performed between the “complex” process and the other existing methods. The composites were assessed using different experiments included scanning electron microscopy (SEM), void content, density, wettability, differential scanning calorimetry (DSC), and tensile tests. It was observed that the “complex” surface treatment yielded composites with a significantly lower voids content and higher density compared to other surface treatments. This indicates that after the “complex” treatment process, the CaCO3 particles and HDPE matrix are more tightly packed than other methods. DSC and wettability results suggest that the “wet” and “complex” treated CaCO3 composites had a significantly higher heat of fusion and moisture resistance compared to the “dry” treated CaCO3 composites. Furthermore, “wet” and “complex” treated CaCO3 composites have a significantly higher tensile strength than the composites containing untreated and “dry” treated CaCO3. This is mainly because the “wet” and “complex” treatment processes have increased adsorption density of stearate, which enhances the interfacial interaction between matrix and filler. These results confirm that the chemical adsorption of the surfactant ions at the solid-liquid interface is higher than at other interface. From this study, it was concluded that the utilization of the “complex” method minimised the negative effects of void coalescence provides key information for the improvement of existing processes.
ABSTRACT Biodegradable polymers—polyethylene oxide and poly (ϵ-caprolactone)—were melt extruded w... more ABSTRACT Biodegradable polymers—polyethylene oxide and poly (ϵ-caprolactone)—were melt extruded with β-tricalcium phosphate. Breakdown analysis revealed that the percentage increase in bioceramic caused a prolonged degradation rate, with samples containing 20 wt% β-tricalcium phosphate losing significantly less weight over time in comparison to the control sample. Compression testing of samples following submission in aqueous environments revealed the composites exhibited enhanced strength with increasing bioceramic loading. The mechanical properties were significantly reduced over a period of 5 weeks. It was found that hot-melt extrusion of β-tricalcium phosphate is a viable and effective method of producing novel composite scaffolds with potential for regenerative medicine applications. GRAPHICAL ABSTRACT
A computer vision system for measuring the displacement and bending angle of ionic polymer–metal ... more A computer vision system for measuring the displacement and bending angle of ionic polymer–metal composites (IPMC) was proposed in this study. The logical progression of measuring IPMC displacement and bending angle was laid out. This study used Python (version 3.10) in conjunction with OpenCV (version 4.5.5.64) for the development of the vision system. The coding functions and the mathematical formulas used were elaborated on. IPMC contour detection was discussed in detail, along with appropriate camera and lighting setups. Measurements generated from the vision system were compared to approximated values via a manual calculation method. Good agreement was found between the results produced by the two methods. The mean absolute error (MAE) and root mean squared error (RMSE) for the displacement values are 0.068080668 and 0.088160652, respectively, and 0.081544205 and 0.103880163, respectively, for the bending angle values. The proposed vision system can accurately approximate the d...
L'invention porte sur un enrobage pour substrats presentant des radicaux hydrogene extrayable... more L'invention porte sur un enrobage pour substrats presentant des radicaux hydrogene extrayable comportant: un groupe polymere hydrophile compose d'au moins deux polymeres de poids moleculaires differents; un monomere hydrophile non sature capable de polariser les radicaux libres en presence d'un radical; un composant activable par les UV pouvant extraire les radicaux hydrogene de la surface a revetir et d'un des polymere du polymere hydrophile, de maniere a amorcer et promouvoir la reticulation du monomere sur la surface, et celle du monomere ou d'une chaine de propagation du monomere sur l'un des polymere du groupe polymere; et un solvant choisi pour conferer a la preparation la viscosite voulue.
The success of any implant, dental or orthopaedic, is driven by the interaction of implant materi... more The success of any implant, dental or orthopaedic, is driven by the interaction of implant material with the surrounding tissue. In this context, the nature of the implant surface plays a direct role in determining the long term stability as physico-chemical properties of the surface affect cellular attachment, expression of proteins, and finally osseointegration. Thus to enhance the degree of integration of the implant into the host tissue, various surface modification techniques are employed. In this work, laser surface melting of titanium alloy Ti–6Al–4V was carried out using a CO2 laser with an argon gas atmosphere. Investigations were carried out to study the influence of laser surface modification on the biocompatibility of Ti–6Al–4V alloy implant material. Surface roughness, microhardness, and phase development were recorded. Initial knowledge of these effects on biocompatibility was gained from examination of the response of fibroblast cell lines, which was followed by examination of the response of osteoblast cell lines which is relevant to the applications of this material in bone repair. Biocompatibility with these cell lines was analysed via Resazurin cell viability assay, DNA cell attachment assay, and alamarBlue metabolic activity assay. Laser treated surfaces were found to preferentially promote cell attachment, higher levels of proliferation, and enhanced bioactivity when compared to untreated control samples. These results demonstrate the tremendous potential of this laser surface melting treatment to significantly improve the biocompatibility of titanium implants in vivo.
Uploads
on biocompatibility was gained from examination of the response of fibroblast cell lines, which was followed by examination of the response of osteoblast cell lines which is relevant to the applications of this material in bone repair. Biocompatibility with these cell lines was analysed via Resazurin cell viability assay, DNA cell attachment assay, and alamarBlue metabolic activity assay. Laser treated surfaces were found to preferentially promote cell attachment, higher levels of proliferation, and enhanced bioactivity when compared to untreated control samples. These results demonstrate
the tremendous potential of this laser surface melting treatment to significantly improve the biocompatibility of titanium implants in vivo.