Amino-terminated Hyperbranched Polymer Research Articles

Preparation of efficient heavy metal adsorbent based on walnut shell and adsorption for Pb(II) ions from aqueous solution

An efficient heavy metal absorbent, amino-terminated hyperbranched polymer modified walnut shell (FWNS) was prepared. The adsorption behavior for Pb(II) ions from aqueous solution was also discussed. The FWNS was prepared using an amino-terminated hyperbranched polymer (ATHBP) as modifying agent and glycidyl methacrylate(GMA) as the grafting bridge. The FWNS was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscope (SEM). The adsorption capacity of FWNS for Pb(II) was investigated at different adsorbent dosages (0.25–2.5gL−1) and pH (from 2.0 to 6.0). The result indicated that the absorbent had good adsorption capacity over a wide pH range (2.0–6.0). The maximum Pb(II) ions adsorption capacity (Qm) obtained by a Langmuir fitting model was 1250.00 mg/g at 293 K. The adsorption kinetics fitted the pseudo-second-order equation. The adsorption of FWNS for Pb(II) ions was an endothermic reaction and spontaneous process. Furthermore, the result shows FWNS has excellent regeneration.

Study on the adsorption properties of multiple-generation hyperbranched collagen fibers towards isolan-series acid dyes.

In the present study, collagen fibers derived from leather solid wastes were used and modified as insoluble vectors and successfully employed as adsorbents for the removal of acid dyes. A “one-step” method was applied to synthesis effective adsorbents, which provided a sustainable way to reuse leather solid wastes via multifunctional modification. The adsorption properties of amino-terminated hyperbranched polymer (HBPN)-modified collagen fibers for the removal of different kinds of acid dyestuff from aqueous solutions were studied. The adsorption capacities of the second generation of modified collagen fibers (CF-HBPN-II) toward Isolan Black 2S-LD, Supralan Yellow, Isolan Grey K-PBL 02, Isolan Dark Blue 2S-GL 03, and Isolan Brown NHF-S were determined to be 224.87, 340.14, 287.36, 317.80, and 251.25 mg g−1, respectively. Three kinetic models, namely, pseudo-first-order, pseudo-second-order and intraparticle diffusion, were used to analyze the kinetic data. The fitting result indicated that the adsorption process of Isolan Black 2S-LD on CF-HBPN-II followed a pseudo-second-order rate model. The adsorption equilibrium of amino-terminated hyperbranched polymer-modified collagen fibers (CF-HBPN) was analyzed using the Langmuir, Freundlich and Temkin isotherm models. The Langmuir isotherm was suitable to describe the adsorption process of Isolan Black 2S-LD. RL was observed to be in the range of 0–1. The values of ΔH, ΔS and ΔG suggest that adsorption is an endothermic and spontaneous process. The adsorbed dye from the modified collagen fiber was successfully desorbed by 0.1 M NaOH. This research provides theoretical guidance for the engineering and recycling application of bio-based adsorbents.

Improvement of hydrothermal stability and chrome uptake of leather: Amino-terminated hyper-branched polymer as high exhausted tanning auxiliary

Carboxyl-terminated hyper-branched polyester is extensively used as high exhaustion chrome tanning auxiliary owing to its strong coordination ability with trivalent chrome. Owing to lower electronegativity of N than O, the coordination ability with trivalent chrome for hyper-branched polyamide is stronger than polyester. Herein, in this paper, an amino-terminated hyper-branched polyamide (HBPN) is synthesized and used as high exhaustion chrome in tanning of pickling pigskin (HBPN–Cr). The effects of utilization of HBPN in denaturation temperature, shrinkage temperature, chrome uptake, and microstructure structure of wet-blue leather are studied. Moreover, the anti-oxidation stability of wet-blue leather is preliminary studied by heat treatment. The results show that incorporation of 1% HBPN in pickling process can significantly improve chrome uptake to 83.32%. The hydrothermal stability of wet-blue leather is improved due to the formation of higher crosslinking degree of collagen fibers. In addition, for the wet-blue leather without unsaturated fatliquoring agent, through heat treatment, hexavalent chrome does not appear after 24 ​h heat treatment. On the contrary, the chrome complex changes from hydroxyl copolymerization to more stable oxygen copolymerization or chrome oxide for C–Cr and HBPN-Cr tanned leather, respectively. These results will build a data support for the further study of hyper-branched polymer chrome tanning auxiliaries.

Attaching SiO2 nanoparticles to GO sheets via amino-terminated hyperbranched polymer for epoxy composites: Extraordinary improvement in thermal and mechanical properties

The deposition of nano-silica (SiO2) on graphene oxide (GO) surface via amino-terminated hyperbranched polymer (HBP) was designed to improve the dispersion and interfacial interaction between GO and epoxy resin. The structures and morphologies of GO and GO-SiO2 sheets were characterized by FT-IR, XRD, XPS, TG, SEM and TEM. Epoxy composites containing GO and GO-SiO2 with 0.1 wt% loadings were prepared and systemically investigated. It was indicated that the GO-SiO2/epoxy composites displayed higher mechanical and thermal properties than that of GO or SiO2 composites. For epoxy composites containing 0.1 wt% GO-SiO2, the flexural strength increased by 20.57% and 23.58% compared to that of individual GO composites and individual SiO2 composites, respectively. Furthermore, the reinforcing mechanisms have been also illuminated. This work is expected to be beneficial to the designing of adhesive-bonded composite structures or components.

Glutaraldehyde cross-linked CDA/HBP-NH2 nanofiber membrane for adsorption of heavy metal ions in wastewater.

A new type of nanofiber membrane was prepared by mixed electrospinning of cellulose diacetate and amino-terminated hyperbranched polymer (HBP-NH2), and glutaraldehyde (GA) crosslinking was used to improve its water resistance and shape retention. pH, adsorption time, and initial solution concentration on Cu(ii) and Cr(vi) ions were studied. Results showed that the prepared GA-CDA/HBP-NH2 nanofiber had good spinning uniformity, hydrophilicity, and adsorption effect on Cu(ii) and Cr(vi) ions compared with the pure CDA nanofiber. The maximum adsorption capacity of GA-CDA/HBP-NH2 for Cu(ii) and Cr(vi) was 50.2 and 176.6 mg g−1, respectively.

Fabrication of Ag Np-coated wetlace nonwoven fabric based on amino-terminated hyperbranched polymer

Abstract To prepare antibacterial fabrics with simple approach, wood pulp/viscose fibers and amino-capped silver nanoparticles (Ag NPs) solution were utilized to form Ag Nps-coated wetlace nonwove fabric. Characterization of the Ag Nps and prepared wetlace nonwoven fabric was performed in virtue of TEM, UV-vis, XRD, ICP-AES, FESEM, EDS mapping and antibacterial test. FESEM and EDS characterizations demonstrated the hierarchical and uniform coating of high-density Ag NPs on wood pulp fibers, and antibacterial test indicated the excellent antibacterial activity of prepared wetlace nonwoven fabric.

Synthesis and characterization of cellulose-based adsorbent for removal of anionic and cationic dyes

Synthetic dyes are widely used in textile, paper, plastic, and other industries, which are toxic and harmful to environment and human. Adsorption is an efficient method to control wastewater. Cellulose is an abundant, renewable, and eco-friendly polymer produced by plants and trees. An adsorbent for removal of dyes was successfully prepared by grafting amino-terminated hyperbranched polymer (NH2-HBP) and beta-cyclodextrin (β-CD) onto cotton fibers in this study. The adsorbent were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis. The influences of adsorption parameters in a batch mode including initial solution pH, contact time, and dye initial concentration were evaluated in the experiments. The experiment results showed that the adsorption equilibrium was reached within 6 h for Congo red and within 4 h for methylene blue. Both the adsorption isotherms and kinetic studies showed that the behaviors of Congo red and methylene blue removal by the adsorbent based on cotton fibers conformed with Freundlich model and fitted pseudo-second-order model, respectively.

Bagasse Cellulose Grafted with an Amino-Terminated Hyperbranched Polymer for the Removal of Cr(VI) from Aqueous Solution.

A novel bio-adsorbent was fabricated via grafting an amino-terminated hyperbranched polymer (HBP-NH2) onto bagasse cellulose. The morphology and microstructure of the HBP-NH2-grafted bagasse cellulose (HBP-g-BC) were characterized and its adsorption capacity for Cr(VI) ions in aqueous solutions was investigated. The rough surface structure of HBP-g-BC that is beneficial for improving the adsorption capacity was observed by scanning electron microscopy (SEM). The grafting reaction was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. The adsorbent performance was shown to be better with a lower pH value, a higher adsorbent dosage, or a higher initial Cr(VI) concentration. Moreover, the kinetics study revealed that the adsorption behavior followed a pseudo-second-order model. The isotherm results showed that the adsorption data could be well-fitted by the Langmuir, Freundlich, or Temkin models. Moreover, HBP-g-BC could maintain 74.4% of the initial removal rate even after five cycles of regeneration. Thus, the high potential of HBP-g-BC as a bio-adsorbent for heavy metal removal has been demonstrated.

Synthesis of TiO2NWS@AuNPS Composite Catalyst for Methylene Blue Removal.

In this article, HBP-NH2-modified titania nanowire (TiO2NWS)-decorated Au nanoparticles (TiO2NWS@AuNPS) were synthesized by one-step method. The role of HBP-NH2 concentration in the formation of TiO2NWS was investigated. The fineness and uniformity of pure TiO2NWS were enhanced by absorbed amino groups from amino-terminated hyperbranched polymer (HBP-NH2). The morphology and crystal structure of TiO2NWS and TiO2NWS@AuNPS were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fournier transform infrared (FTIR) spectroscopy. The chemical states of gold, titanium and oxygen were analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that at the concentration of HBP-NH2 100 g/L, the mean diameter of TiO2NWS was nearly 72 nm and Au nanoparticles were uniformly distributed on the surface of TiO2NWS. The presence of AuNPS improved the photocatalytic properties of TiO2NWS under UV light irradiation. The Au load was believed to improve the utilization rate of the photoelectron and activated the adsorbed oxygen. The obtained TiO2NWS@AuNPS decomposed 99.6% methylene blue (MB) after 300 min when subjected to UV light irradiation. After five cycles of the catalyzing process, the TiO2NWS@AuNPS still retained over 90% of its catalytic ability for MB. The Au deposition was found responsible for the high catalytic activity of TiO2NWS@AuNPS.

Self-healing Supramolecular Polymer Composites by Hydrogen Bonding Interactions between Hyperbranched Polymer and Graphene Oxide

A self-healing supramolecular polymer composite (HSP-GO) was designed and prepared via incorporation of modified graphene oxide to hyperbranched polymer by hydrogen-bonding interactions. The polymer matrix based on amino-terminated hyperbranched polymer (HSP-NH2) was synthesized by carboxylation, Curtius rearrangement, and amination of hydroxyl-terminated hyperbranched polyester (HP-OH), while the modified graphene oxide was prepared by transformation of hydroxyl to isocyanate and further to carbamate ester. Spectroscopic methods were utilized to characterize the obtained polymer composites. Stress-strain test was selected to carefully study the self-healing property of HSP-GO. It is found that a small amount of modified graphene oxide (up to 2 wt%) improves the glass transition temperature (Tg), tensile strength, Young’s modulus, and self-healing efficiency of the polymer composites. After healed at room temperature for 10 min, the addition of modified graphene oxide improves the self-healing efficiency to 37% of its original tensile strength. The experiment result shows that the self-healing efficiency is related to the density of hydrogen bonding site and the molecular movement.

Impact Resistance Enhancement by Adding Core-Shell Particle to Epoxy Resin Modified with Hyperbranched Polymer.

A core-shell particle was fabricated by grafting amino-terminated hyperbranched polymer to the surface of silica nanoparticles. The influences of core-shell particle contents on the tensile and impact strength of the epoxy thermosets modified with amino-terminated hyperbranched polymer were discussed in detail. For comparison, core-shell particle was added into the epoxy/polyamide system for toughness improvement. Results from tensile and impact tests are provided. The introduction of core-shell particle into the epoxy/polyamide systems just slightly enhanced the tensile and impact strength. The incorporation of 3 wt % core-shell particle could substantially improve the tensile and impact strength of epoxy/amino-terminated hyperbranched polymer thermosets. Field emission-scanning electron microscope images of the impact fracture surfaces showed that the excellent impact resistance of epoxy/amino-terminated hyperbranched polymer/core-shell particle thermosets may be attributed to the synergistic effect of shearing deformation and crack pinning/propagation, which is induced by the good compatibility between epoxy matrix and core-shell particle in the presence of amino-terminated hyperbranched polymer.

Preparation of adsorbent based on cotton fiber for removal of dyes

Synthetic dyes are used extensively in modern industries, which are toxic and harmful to environment and human. Cotton fiber is a kind of abundant, renewable and eco-friendly cellulose fiber in nature, however, the adsorption capacity of raw cellulose for pollutants was often low. Therefore, an efficient adsorbent for removal of dyes was successfully prepared by grafting beta-cyclodextrin (β-CD) and amino-terminated hyperbranched polymer (NH2-HBP) onto cotton fibers in this study, which was effective to anionic dyes and cationic dyes. The adsorbent were characterized using FTIR, SEM and XPS analysis. The results of adsorption experiments showed that the adsorbent based on cotton fiber exhibited better adsorption performance for Congo red(CR) and methylene blue(MB). The experimental results revealed that the pH value had a great influence on the adsorption capacity.

Preparation of partially end-capped amino-terminated hyperbranched polymer and dyeing properties enhancement to polyurethane membrane

In this study, a series of products with different water solubility, which were named as partial end-capped amino-terminated hyperbranched polymers (HBPs) 1–6, were obtained by changing the mass ratio of raw materials. The structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The polyurethane was respectively mixed with partial end-capped amino-terminated HBPs to prepare different blend membranes by the drying method. The results showed that the water solubility of partial end-capped amino-terminated HBPs had obvious effects on the dyeing properties of blend membranes. When the mass ratio of amino-terminated HBP and single-blocked isophorone diisocyanate was 3:2, the performance of prepared partial end-capped amino-terminated HBP 4 was the best. The structures of blend membranes were characterized by FTIR spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). When the mass fraction of partial end-capped amino-terminated HBP 4 was 2%, dye uptake improved from 12% to 85%. The dry-rub fastness and wet-rub fastness reached 4.5 and 3, respectively. The K/S values indicated that the surface chroma also deepened. The results indicated that partial end-capped amino-terminated HBP and polyurethane had hydrogen-bond interaction and certain phase separation.

Amino-terminated hyper-branched polyamidoamine polymer grafted magnetic graphene oxide nanosheets as an efficient sorbent for the extraction of selective serotonin reuptake inhibitors from plasma samples

In this study, third generation dendrimers covalently bonded to magnetic graphene oxide nanosheets (DMGO) were prepared.

Investigations on mechanical characteristics of glass fiber reinforced epoxy composite modified with amino-terminated hyperbranched polymer

Glass fiber, GF, which was first hydroxylated and silanized, was incorporated into epoxy resin modified with amino-terminated hyperbranched polymer (ATHBP) to obtain high performance composite. The effects of GFs content on the mechanical properties of composites were investigated, discussing the results from flexural, tensile, and impact tests. The composites revealed noticeable improvement in flexural strength, tensile strength as well as impact strength but slow decrease in elongation at break, compared to the epoxy/ATHBP thermoset. FESEM morphology results indicated the good compatibility between epoxy matrix and GF in the appearance of ATHBP and showed that the toughening mechanism was mainly attributed to the stress transfer mechanism.

Structure design of a hyperbranched polyamine adsorbent for CO2 adsorption

A CO2-imprinted adsorbent was synthesized by crosslinking the CO2 pre-adsorbed amino-terminated hyperbranched polymer, which was prepared through the Michael addition reaction between amines and methyl acrylate (MA) at 0 °C, followed by self-condensation of the addition reaction products at 100 °C and 140 °C.

The effect of amino-terminated hyperbranched polymers on the impact resistance of epoxy resins

A novel amino-terminated hyperbranched polymer (ATHBP) was synthesized through the end-capping reaction between hyperbranched polymer with hydroxyl group (HBPH) and diethylenetriamine. The chemical structure of ATHBP was characterized by attenuated total internal reflectance infrared spectroscopy (ATR-IR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The effect of ATHBP content (0–30 wt%) on the impact resistance and glass transition temperature (Tg) of diglycidyl ether of bisphenol-A epoxy resin was studied. The toughness mechanism was discussed by observing the fracture surface morphologies of epoxy thermosets using field emission scanning electron microscopy (FESEM). The results showed that the degree of branching of ATHBP was 0.56. And the introduction of ATHBP could favorably improve the impact strength but not sacrifice the Tg of epoxy resin. For example, the impact strength of 25 wt% formulation was 60.7 % higher than that of the neat epoxy thermoset. FESEM analysis indicated that the toughening mechanism may be attributed to plastic deformation mechanism.

Enhancing the mechanical properties of epoxy resin by addition of an amino-terminated hyperbranched polymer grown on glass fiber

In this study, glass fiber (GF) was grafted by an amino-terminated hyperbranched polymer (ATHBP). The structure of GF-ATHBP was characterized by attenuated total internal reflectance infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, thermal gravimetric analysis, and field emission scanning electron microscopy (FESEM). The modified GFs were used to produce high-performance epoxy composites. The effects of GF-ATHBPs on the mechanical properties of composites were investigated, discussing the results from tensile, flexural, and impact tests. The results showed that the grafting ratio of ATHBP on GF was 7.6 %, and the thickness of ATHBP layer was about 1.9 μm. And the incorporation of GF-ATHBPs could favorably improve the mechanical properties of epoxy resins. FESEM morphologies showed that the excellent compatibility and interaction may be associated with the great enhancement of mechanical properties of epoxy/GF-ATHBP composites.

Amino-terminated hyperbranched polymer for toughness improvement of epoxy/clay nanocomposites

Amino-terminated hyperbranched poly(ester-amine) (HP) was prepared and used as a toughening agent for epoxy resin in presence of Montmorillonite organoclay (OMMT) as a reinforcing filler. Several parameters which affect the physico-mechanical properties of epoxy/clay nanocomposites were studied including HP content, clay concentration, and intercalation/exfoliation and degree of dispersion of OMMT clay within the epoxy matrix. The results showed a significant improvement in toughness, physico-mechanical properties and enhancement in thermal stability of epoxy/clay nanocomposites upon using HP (20 wt%) as a toughening agent at low OMMT clay loading (1 wt%). These promising results could open the way for epoxy resins to be used in more high-impact resistance applications.

Synthesis and characterization of amino-terminated hyperbranched polymer and its effect on impact resistance of epoxy resin thermosets

Amino-terminated hyperbranched polymer (HBP-NH2) was synthesized from diethylenetriamine (DETA) and methyl acrylate (MA) by melt polycondensation through AB3 and AB2 route, and its chemical structure was characterized by attenuated total internal reflectance infrared spectroscopy (ATR-IR) and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. Then, the influence of HBP-NH2 content on the toughness improvement and fractural surface morphology of diglycidyl ether of bisphenol A (DGEBA) cured systems was investigated through impact resistance test and field emission scanning electron microscopy (FESEM), respectively. The results indicated that HBP-NH2 can enhance the toughness of epoxy cured system near 61 % than the neat DGEBA cured thermosets. FESEM images show that the toughness enhancement of epoxy system should be based on shearing deformation mechanism (the thermosets modified with low content of HBP-NH2) and the second phase toughening mechanism (the thermosets modified with high content of HBP-NH2).