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2019 Volume 37 Issue 8
2019, 37(8): 729-736
doi: 10.1007/s10118-019-2286-0
Abstract:
This study presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(styrene-methyl methacrylate-acrylic acid) and poly(vinyl alcohol). The pattern was obtained by directly inkjet printing water onto the electrospun colloidal fiber. The pattern formation was attributed to the morphological transition of the colloidal fiber from the fiber aggregation to latex aggregation and the corresponding color change due to the dissolution of poly(vinyl alcohol) by water. Interestingly, a clear and clean image was successfully obtained on the ethanol-treated colloidal fibers film in comparison to a confused and blur image onto the freshly-made film. It is because the treatment process can compact the fiber structure and lower the spreading/wetting behavior of ink on the fiber structure, contributing to the formation of high-quality pattern. Various letters or quick response code were flexibly designed and printed on to colloidal fibers. Furthermore, the pattern can be easily transferred onto flexible substrate, i.e., a flexible printed bracelet. This work will be of great significance for the development of novel wearable functional materials/devices based on electrospun colloidal fibers.
This study presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(styrene-methyl methacrylate-acrylic acid) and poly(vinyl alcohol). The pattern was obtained by directly inkjet printing water onto the electrospun colloidal fiber. The pattern formation was attributed to the morphological transition of the colloidal fiber from the fiber aggregation to latex aggregation and the corresponding color change due to the dissolution of poly(vinyl alcohol) by water. Interestingly, a clear and clean image was successfully obtained on the ethanol-treated colloidal fibers film in comparison to a confused and blur image onto the freshly-made film. It is because the treatment process can compact the fiber structure and lower the spreading/wetting behavior of ink on the fiber structure, contributing to the formation of high-quality pattern. Various letters or quick response code were flexibly designed and printed on to colloidal fibers. Furthermore, the pattern can be easily transferred onto flexible substrate, i.e., a flexible printed bracelet. This work will be of great significance for the development of novel wearable functional materials/devices based on electrospun colloidal fibers.
2019, 37(8): 737-743
doi: 10.1007/s10118-019-2301-5
Abstract:
Given that conventional bulky electrochemical energy storage devices are too rigid and heavy to be considered wearable, developing fully integrated power systems is expected to accelerate the successful commercialization of smart electronic textiles. Although great achievements have been made for fiber-shaped energy storage devices, there remain key challenges pertaining to their fabrication efficiency, scalability, and stability. Herein, a general and highly efficient method is developed to continuously fabricate supercapacitor fibers with lengths of kilometers at high production rate up to 118 m/h through a simple one-step wet spinning method. Beneficial from the designed unique two-circle-in-one-circle architecture, the resulting supercapacitor fibers demonstrated high electrochemical stability even after being bended for 1 × 105 cycles. As a demonstration, these continuous supercapacitor fibers were further woven into a flexible power scarf for large-scale applications in wearable electronics. This simple and scalable fabrication process combined with the unique structure provides a general and effective paradigm to design other fiber-shaped devices like sensors, batteries, and solar cells.
Given that conventional bulky electrochemical energy storage devices are too rigid and heavy to be considered wearable, developing fully integrated power systems is expected to accelerate the successful commercialization of smart electronic textiles. Although great achievements have been made for fiber-shaped energy storage devices, there remain key challenges pertaining to their fabrication efficiency, scalability, and stability. Herein, a general and highly efficient method is developed to continuously fabricate supercapacitor fibers with lengths of kilometers at high production rate up to 118 m/h through a simple one-step wet spinning method. Beneficial from the designed unique two-circle-in-one-circle architecture, the resulting supercapacitor fibers demonstrated high electrochemical stability even after being bended for 1 × 105 cycles. As a demonstration, these continuous supercapacitor fibers were further woven into a flexible power scarf for large-scale applications in wearable electronics. This simple and scalable fabrication process combined with the unique structure provides a general and effective paradigm to design other fiber-shaped devices like sensors, batteries, and solar cells.
2019, 37(8): 744-759
doi: 10.1007/s10118-019-2294-0
Abstract:
Structured block copolymer (BCP) particles have gained increasing attention due to their potential applications in separation, catalysis, controlled release, and other fields. Three-dimensional (3D) confined assembly has been proved as a facile yet robust approach for generating BCP particles with controllable shapes and internal structures. In this feature article, we summarized the preparation of structured polymeric particles through 3D confined self-assembly of BCPs. The effects of interfacial interactions, degree of confinement, and additives on the shape and internal structure of BCP microparticles were comprehensively discussed. In addition, we highlighted the recent progress in using disassembly as a route to synthesize colloidal particles with unique structures. Two strategies were introduced in this part: (a) disassembling the discrete domains resulted in mesoporous microparticles; (b) disassembling the continuous domains led to the dissociation of microparticles into micelle-like nano-objects. The applications of the structured colloidal particles in photonic crystals, controlled release, and directed growth of inorganic materials were also presented. Finally, we discussed the current challenges and future opportunities in this promising area.
Structured block copolymer (BCP) particles have gained increasing attention due to their potential applications in separation, catalysis, controlled release, and other fields. Three-dimensional (3D) confined assembly has been proved as a facile yet robust approach for generating BCP particles with controllable shapes and internal structures. In this feature article, we summarized the preparation of structured polymeric particles through 3D confined self-assembly of BCPs. The effects of interfacial interactions, degree of confinement, and additives on the shape and internal structure of BCP microparticles were comprehensively discussed. In addition, we highlighted the recent progress in using disassembly as a route to synthesize colloidal particles with unique structures. Two strategies were introduced in this part: (a) disassembling the discrete domains resulted in mesoporous microparticles; (b) disassembling the continuous domains led to the dissociation of microparticles into micelle-like nano-objects. The applications of the structured colloidal particles in photonic crystals, controlled release, and directed growth of inorganic materials were also presented. Finally, we discussed the current challenges and future opportunities in this promising area.
2019, 37(8): 760-766
doi: 10.1007/s10118-019-2257-5
Abstract:
Fabrication of flexible transparent electrodes (FTEs) is one of the core technologies in the field of flexible electronics. Among multiple choices of FTEs, poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonic acid) (PEDOT:PSS) has shown its promising application in roll-to-roll manufacturing. A simple yet effective method for substantially boosting the conductivity of these conducting polymer films without causing large-domain aggregations is by adding ethylene glycol (EG) as dopant. Herein, we investigated in detail the effects of the secondary solvent of ethylene glycol (EG) on the optical and electrical characteristics of PEDOT:PSS films. The modified PEDOT:PSS FTEs were deposited using drop-coating techniques as it had greater compatibility for large-area samples than the conventional spin-coating method did. The 6% EG-doped PEDOT:PSS FTE via drop-coating method achieved a high figure of merit (FoM) value of 47.24 and the devices fabricated using the optimal PEDOT:PSS FTE yielded a high power conversion efficiency (PCE) of 8.89%, mostly attributed to the modified PEDOT:PSS films that had excellent optical and electrical characteristics with low surface roughness. These results suggested that EG-doping could effectively boost the conductivity of PEDOT:PSS films and that the modified PEDOT:PSS FTE is suitable for roll-to-roll manufacturing in the future.
Fabrication of flexible transparent electrodes (FTEs) is one of the core technologies in the field of flexible electronics. Among multiple choices of FTEs, poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonic acid) (PEDOT:PSS) has shown its promising application in roll-to-roll manufacturing. A simple yet effective method for substantially boosting the conductivity of these conducting polymer films without causing large-domain aggregations is by adding ethylene glycol (EG) as dopant. Herein, we investigated in detail the effects of the secondary solvent of ethylene glycol (EG) on the optical and electrical characteristics of PEDOT:PSS films. The modified PEDOT:PSS FTEs were deposited using drop-coating techniques as it had greater compatibility for large-area samples than the conventional spin-coating method did. The 6% EG-doped PEDOT:PSS FTE via drop-coating method achieved a high figure of merit (FoM) value of 47.24 and the devices fabricated using the optimal PEDOT:PSS FTE yielded a high power conversion efficiency (PCE) of 8.89%, mostly attributed to the modified PEDOT:PSS films that had excellent optical and electrical characteristics with low surface roughness. These results suggested that EG-doping could effectively boost the conductivity of PEDOT:PSS films and that the modified PEDOT:PSS FTE is suitable for roll-to-roll manufacturing in the future.
Controllable Emission via Tuning the Size of Fluorescent Nano-probes Formed by Polymeric Amphiphiles
2019, 37(8): 767-773
doi: 10.1007/s10118-019-2256-6
Abstract:
Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in labeling cells for imaging. Plenty of efforts have been made on the above direction. However, the size effect of nano-emitters has not been addressed yet mainly given the difficulties in controlling morphology and size of the assemblies. In our preceding study, we employed post-polymerization modification method for preparing amphiphilic copolymers, and obtained core-shell (the hydrophobic fluorophores are wrapped inside the nanoparticle to form the core) assemblies in aqueous solution. By this method, we are able to regulate the ratio of the hydrophilic/hydrophobic moieties, and thus alternate the size of the assemblies in a rather simple way. In this study, we synthesized a series of random copolymers by changing the ratio of poly(ethylene glycol) to tetraphenylethylene groups. Notably, the number of repeating units of the polymer was controlled constant for all the copolymers. The self-assembly of these copolymers resulted in different sizes of nanoparticles, and the size decreased with the decreasing fraction of poly(ethylene glycol). Interestingly, the emission of the nanoparticles showed size dependence, and smaller diameter corresponded to stronger emission. Being cultured with HeLa cells, either the large (diameter of ~300 nm) or the small (diameter of ~180 nm) nano-emitters allowed for very high cell viabilities up to 25 μg·mL−1. Both of them can be applied in cell imaging and provide high contrast fluorescent images.
Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in labeling cells for imaging. Plenty of efforts have been made on the above direction. However, the size effect of nano-emitters has not been addressed yet mainly given the difficulties in controlling morphology and size of the assemblies. In our preceding study, we employed post-polymerization modification method for preparing amphiphilic copolymers, and obtained core-shell (the hydrophobic fluorophores are wrapped inside the nanoparticle to form the core) assemblies in aqueous solution. By this method, we are able to regulate the ratio of the hydrophilic/hydrophobic moieties, and thus alternate the size of the assemblies in a rather simple way. In this study, we synthesized a series of random copolymers by changing the ratio of poly(ethylene glycol) to tetraphenylethylene groups. Notably, the number of repeating units of the polymer was controlled constant for all the copolymers. The self-assembly of these copolymers resulted in different sizes of nanoparticles, and the size decreased with the decreasing fraction of poly(ethylene glycol). Interestingly, the emission of the nanoparticles showed size dependence, and smaller diameter corresponded to stronger emission. Being cultured with HeLa cells, either the large (diameter of ~300 nm) or the small (diameter of ~180 nm) nano-emitters allowed for very high cell viabilities up to 25 μg·mL−1. Both of them can be applied in cell imaging and provide high contrast fluorescent images.
2019, 37(8): 774-782
doi: 10.1007/s10118-019-2261-9
Abstract:
A new soluble polymer on 2-[(2E)-1-methyl-2-buten-1-yl]aniline and its copolymers with aniline basis have been synthesized in various molar ratios. For all samples, the electrical conductivity, morphology, solubility, electrochemical properties, as well as spectral and molecular mass characteristics have been studied, and a comparative analysis with polyaniline has been carried out. The substituent introduced into the aniline aromatic ring significantly improves the solubility in typical organic solvents of a high molecular weight product. The morphology of the test compounds depends on the co-monomer ratio. As the content of the substituted aniline in the initial mixture increases, the morphology of the polymer changes from the inherent polyaniline fibrous microstructure to the globular one with irregular substituted polyaniline shapes and sizes. Electrochemical study of the samples revealed that the higher the oxidation potential, the wider the band gap (ranging from 2.00 to 2.15). The electrical conductivity decreases in proportion to the increase in the substituted aniline concentration of the initial co-monomer mixture and amounts to 12.5–35.7 × 106 nSm.
A new soluble polymer on 2-[(2E)-1-methyl-2-buten-1-yl]aniline and its copolymers with aniline basis have been synthesized in various molar ratios. For all samples, the electrical conductivity, morphology, solubility, electrochemical properties, as well as spectral and molecular mass characteristics have been studied, and a comparative analysis with polyaniline has been carried out. The substituent introduced into the aniline aromatic ring significantly improves the solubility in typical organic solvents of a high molecular weight product. The morphology of the test compounds depends on the co-monomer ratio. As the content of the substituted aniline in the initial mixture increases, the morphology of the polymer changes from the inherent polyaniline fibrous microstructure to the globular one with irregular substituted polyaniline shapes and sizes. Electrochemical study of the samples revealed that the higher the oxidation potential, the wider the band gap (ranging from 2.00 to 2.15). The electrical conductivity decreases in proportion to the increase in the substituted aniline concentration of the initial co-monomer mixture and amounts to 12.5–35.7 × 106 nSm.
2019, 37(8): 783-789
doi: 10.1007/s10118-019-2266-4
Abstract:
As an essential elastomer used in edge technologies, fluorosilicone rubber (FSR) suffers serious oxidative ageing problem when serving at high temperature. Cerium oxide is generally used as an antioxidant additive but remains unsatisfactory. In order to obtain better antioxidant effect on improving the thermal stability of FSR, a kind of cerium-containing polymethylphenyl silicone (PSI-Ce) was synthesized and the structure was verified by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Due to the homogeneous dispersion on molecular scale, PSI-Ce imposed much better antioxidant effect than the commercial CeO2 did, no matter from isothermal degradation at 320 °C or thermal-oxidative ageing test at 230 °C. In particular, after ageing for 72 h, FSR/PSI-Ce (2 phr) maintained 82% of tensile strength and 63% of elongation at break, in comparison to the corresponding values of 48% and 42% for FSR/CeO2 (2 phr). Moreover, 2 phr PSI-Ce was equivalent to 0.046 phr CeO2 according to cerium element conservation.
As an essential elastomer used in edge technologies, fluorosilicone rubber (FSR) suffers serious oxidative ageing problem when serving at high temperature. Cerium oxide is generally used as an antioxidant additive but remains unsatisfactory. In order to obtain better antioxidant effect on improving the thermal stability of FSR, a kind of cerium-containing polymethylphenyl silicone (PSI-Ce) was synthesized and the structure was verified by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Due to the homogeneous dispersion on molecular scale, PSI-Ce imposed much better antioxidant effect than the commercial CeO2 did, no matter from isothermal degradation at 320 °C or thermal-oxidative ageing test at 230 °C. In particular, after ageing for 72 h, FSR/PSI-Ce (2 phr) maintained 82% of tensile strength and 63% of elongation at break, in comparison to the corresponding values of 48% and 42% for FSR/CeO2 (2 phr). Moreover, 2 phr PSI-Ce was equivalent to 0.046 phr CeO2 according to cerium element conservation.
2019, 37(8): 790-796
doi: 10.1007/s10118-019-2253-9
Abstract:
In these years, the encapsulation of proteins for protection and delivery purpose has attracted great interest. In this research, W/O emulsion droplets were used as soft templates and bovine serum albumin (BSA) encapsulated hollow capsules were prepared by liquid-liquid interfacial thiol-disulfide exchange reaction. Block copolymer chains with pendant pyridyl disulfide groups are located at liquid-liquid interface, and upon addition of a macromolecular crosslinking agent with multiple pendant thiol groups into an emulsion, thiol-disulfide interfacial crosslinking reactions lead to the formation of BSA encapsulated hollow capsules. The cleavage of disulfides on the membranes results in the degradation of hollow structures and the release of encapsulated protein molecules. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and confocal laser scanning microscopy were employed to characterize the hollow capsules. In comparison with native BSA, BSA molecules encapsulated in the hollow structures show higher catalytic efficiency due to higher local concentration of reactants in the structures. The membranes of the hollow capsules can efficiently protect the encapsulated BSA from hydrolysis by trypsin.
In these years, the encapsulation of proteins for protection and delivery purpose has attracted great interest. In this research, W/O emulsion droplets were used as soft templates and bovine serum albumin (BSA) encapsulated hollow capsules were prepared by liquid-liquid interfacial thiol-disulfide exchange reaction. Block copolymer chains with pendant pyridyl disulfide groups are located at liquid-liquid interface, and upon addition of a macromolecular crosslinking agent with multiple pendant thiol groups into an emulsion, thiol-disulfide interfacial crosslinking reactions lead to the formation of BSA encapsulated hollow capsules. The cleavage of disulfides on the membranes results in the degradation of hollow structures and the release of encapsulated protein molecules. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and confocal laser scanning microscopy were employed to characterize the hollow capsules. In comparison with native BSA, BSA molecules encapsulated in the hollow structures show higher catalytic efficiency due to higher local concentration of reactants in the structures. The membranes of the hollow capsules can efficiently protect the encapsulated BSA from hydrolysis by trypsin.
2019, 37(8): 797-805
doi: 10.1007/s10118-019-2262-8
Abstract:
Nanoparticle-polymer composites exhibit unusual mechanical properties and chain dynamics when the nanoparticle size is smaller than the entanglement mesh size of the matrix polymer chains, corresponding to the ultrasmall regime defined by de Gennes. However, the mechanism is still ambiguous due to the lack of suitable model systems. Here, we develop an ultrasmall nanoparticle system by using a bimodal grafting strategy to graft both short alkyl chains and long polystyrene chains onto the polyoxometalate molecular nanoparticles with a tunable repulsive potential between the nanoparticles, thus facilitating their uniform dispersion in polystyrene matrices. Linear viscoelasticity of the resultant nanocomposites changes with increasing the filler content, which shows a decrease in both plateau modulus and terminal relaxation time, indicative of a dilution effect of the nanoparticles. Namely, the entanglement network becomes sparser with increasing the filler content.
Nanoparticle-polymer composites exhibit unusual mechanical properties and chain dynamics when the nanoparticle size is smaller than the entanglement mesh size of the matrix polymer chains, corresponding to the ultrasmall regime defined by de Gennes. However, the mechanism is still ambiguous due to the lack of suitable model systems. Here, we develop an ultrasmall nanoparticle system by using a bimodal grafting strategy to graft both short alkyl chains and long polystyrene chains onto the polyoxometalate molecular nanoparticles with a tunable repulsive potential between the nanoparticles, thus facilitating their uniform dispersion in polystyrene matrices. Linear viscoelasticity of the resultant nanocomposites changes with increasing the filler content, which shows a decrease in both plateau modulus and terminal relaxation time, indicative of a dilution effect of the nanoparticles. Namely, the entanglement network becomes sparser with increasing the filler content.
2019, 37(8): 806-814
doi: 10.1007/s10118-019-2264-6
Abstract:
Expanded graphite (EG) films exhibit potential use in a wide field including thermal management, conductive applications, and electromagnetic interference (EMI) shielding. However, their poor tensile strength and brittleness are crucial deficiencies for commercial applications. To address these defects, in our work, natural rubber (NR) is employed to improve EG films for better mechanical strength and flexibility. The origin of the strengthening effect of EG films by the addition of natural rubber mainly arises from the formation of a simulate shell structure. Compared to the neat EG films, the addition of merely 2 wt% NR can give rise to superior ductility. Further, the loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., 2.4 and 11.4 times increase in tensile strength and elongation at break, respectively. Besides, EG/NR films containing 10 wt% NR can still sustain excellent thermal and electric conductivities of 173 W·m−1·K−1 and 75 S·cm−1, respectively. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. Thus, the lightweight EG/NR films with comprehensive performance as well as their virtue of green and simple large-scale preparation endow them with the possibility of designing next-generation flexible electronics.
Expanded graphite (EG) films exhibit potential use in a wide field including thermal management, conductive applications, and electromagnetic interference (EMI) shielding. However, their poor tensile strength and brittleness are crucial deficiencies for commercial applications. To address these defects, in our work, natural rubber (NR) is employed to improve EG films for better mechanical strength and flexibility. The origin of the strengthening effect of EG films by the addition of natural rubber mainly arises from the formation of a simulate shell structure. Compared to the neat EG films, the addition of merely 2 wt% NR can give rise to superior ductility. Further, the loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., 2.4 and 11.4 times increase in tensile strength and elongation at break, respectively. Besides, EG/NR films containing 10 wt% NR can still sustain excellent thermal and electric conductivities of 173 W·m−1·K−1 and 75 S·cm−1, respectively. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. Thus, the lightweight EG/NR films with comprehensive performance as well as their virtue of green and simple large-scale preparation endow them with the possibility of designing next-generation flexible electronics.
2019, 37(8): 815-826
doi: 10.1007/s10118-019-2255-7
Abstract:
In this work, poly(amide acid) solution, the precursor of polyimide, was synthesized by the reaction of 4,4′-(hexafluoroisopropylidene)diphthalicanhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropanane in the solvent of N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF). Then, hollow fiber membranes for high flux gas separation were prepared by dry-jet wet spinning using the precursor solution of poly(amide acid) as the spinning dope and a subsequent imidization process. Silicone rubber was further coated outside the obtained hollow fiber membranes to repair the defects on the denser layer. The effects of internal, external coagulation bath ratios with air gap, and coating solution concentrations on the morphologies, structures, and separation performance of the membranes were studied. Results showed that the sponge-like support layer was formed when the content of NMP was increased from 50% to 90% in the internal coagulation bath. The outer surface of the membrane became denser when the water content in the external coagulation bath increased from 40% to 100%, and the separation coefficient of CO2/CH4 increased by 2 times. This value could reach up to 1.4 when the air gap was 6 cm. With tuning the mass fraction of silicone rubber as 5%, hollow fiber composite membranes with uniform coating layer and an improved separation coefficient of 5.4 could be obtained.
In this work, poly(amide acid) solution, the precursor of polyimide, was synthesized by the reaction of 4,4′-(hexafluoroisopropylidene)diphthalicanhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropanane in the solvent of N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF). Then, hollow fiber membranes for high flux gas separation were prepared by dry-jet wet spinning using the precursor solution of poly(amide acid) as the spinning dope and a subsequent imidization process. Silicone rubber was further coated outside the obtained hollow fiber membranes to repair the defects on the denser layer. The effects of internal, external coagulation bath ratios with air gap, and coating solution concentrations on the morphologies, structures, and separation performance of the membranes were studied. Results showed that the sponge-like support layer was formed when the content of NMP was increased from 50% to 90% in the internal coagulation bath. The outer surface of the membrane became denser when the water content in the external coagulation bath increased from 40% to 100%, and the separation coefficient of CO2/CH4 increased by 2 times. This value could reach up to 1.4 when the air gap was 6 cm. With tuning the mass fraction of silicone rubber as 5%, hollow fiber composite membranes with uniform coating layer and an improved separation coefficient of 5.4 could be obtained.
2019, 37(8): 827-833
doi: 10.1007/s10118-019-2260-x
Abstract:
Dimer impurity in the solution of a generation five (G5) polyamidoamine (PAMAM) dendrimer has been investigated by small-angle neutron scattering (SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform (IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.
Dimer impurity in the solution of a generation five (G5) polyamidoamine (PAMAM) dendrimer has been investigated by small-angle neutron scattering (SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform (IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.
2019, 37(8): 834-840
doi: 10.1007/s10118-019-2249-5
Abstract:
To effectively improve the performance and expand the applications of polymers, molecular dynamics (MD) simulations with the COMPASS force field have been applied to predict the miscibility, glass transition temperature (Tg), and mechanical properties of poly(vinyl chloride)/dioctyl phthalate (PVC/DOP) blends. The solubility parameter values obtained are in good agreement with the reference data and the little difference (|Δδ| < 2.0 MPa0.5) between two components indicates that PVC/DOP is a miscible system. Tg is predicted by the slope of the free volume and density versus temperature simulation data based on density and free volume theory which is agree well with the experimental data. In addition, the analyses of mechanical properties results indicate that the values of Young’s modulus (E), bulk modulus (K), and shear modulus (G) decrease with the addition of DOP, demonstrating that the rigidity of material is weakened and the ductility is improved. The mechanical properties can also be effectively improved by increasing the temperature, which may provide a more flexible mixture, with lower E, K, G but an increased ductility.
To effectively improve the performance and expand the applications of polymers, molecular dynamics (MD) simulations with the COMPASS force field have been applied to predict the miscibility, glass transition temperature (Tg), and mechanical properties of poly(vinyl chloride)/dioctyl phthalate (PVC/DOP) blends. The solubility parameter values obtained are in good agreement with the reference data and the little difference (|Δδ| < 2.0 MPa0.5) between two components indicates that PVC/DOP is a miscible system. Tg is predicted by the slope of the free volume and density versus temperature simulation data based on density and free volume theory which is agree well with the experimental data. In addition, the analyses of mechanical properties results indicate that the values of Young’s modulus (E), bulk modulus (K), and shear modulus (G) decrease with the addition of DOP, demonstrating that the rigidity of material is weakened and the ductility is improved. The mechanical properties can also be effectively improved by increasing the temperature, which may provide a more flexible mixture, with lower E, K, G but an increased ductility.
