Hydroxyl-terminated Hyperbranched Polyesters Research Articles

Fabrication of 5-fluorouracil-loaded tablets with hyperbranched polyester by digital light processing 3D printing technology

Three-dimensional (3D) printing technique offers the possibility of producing personalized drug products. However, the suitable printing materials for vat photopolymerization in biomedical applications are still limited. In this study, the hydroxyl-terminated hyperbranched polyester (HBPE) was synthesized by 1,1,1-trimethylolpropane as a core moiety and 2,2-bis(hydroxymethyl)propionic acid as a branched monomer. HBPE was then reacted with acrylic acid (AA) to produce acrylated hyperbranched polyester (AHBPE). NMR analysis indicated that the degree of branching and number of hydroxyl group of HBPE were 0.40 and 19.5, respectively, while the degree of acrylation of AHBPE was 84.0%. AA as a monomer, poly(ethylene glycol) dimethacrylate (PEGDMA) as a difunctional crosslinker, and AHBPE as a multifunctional crosslinker were employed as printing resins to fabricate 5-fluorouracil- (5-FU) loaded tablets by digital light processing 3D printing. A D-optimal mixture design was applied to optimize the composition of printing resins and investigate the influence of the component on the printing time and drug release. Results showed that the printing time and drug release increased with increasing AA content but they decreased with the increase of AHBPE content. Addition of AA to the printing resins was necessary to achieve more complete drug release. The premature drug release was effectively inhibited by the incorporation of AHBPE. The tablet printed with a composition of 47.5 wt% of AA, 32.5 wt% of PEGDMA and 20.0 wt% of AHBPE had the lowest drug release of 13.96% at 2 h and highest one of 53.10% at 12 h, which were close to the model predicted values of 14.64 and 55.31%, respectively. It exhibited sustained drug release over 24 h in simulated gastrointestinal fluid and followed anomalous transport mechanism. The results suggest that AHBPE is a potential crosslinker for use in vat photopolymerization 3D printing of personalized drug delivery.

The Hyperbranched Polyester Reinforced Unsaturated Polyester Resin.

We report a method of reinforcing and toughening unsaturated polyester resin (UPR) with a kind of hyperbranched polyester (HBP-1). Polyethylene glycol with different molecular weight was used as the core molecule of the preparation reaction, and the reaction product of phthalic anhydride and glycerol was used as the branching unit. The esterification reaction of polycondensation occurred, and then the hydroxyl-terminated hyperbranched polyester was prepared. The reaction product of maleic anhydride and isooctanol was added to the prepared hydroxyl-terminated hyperbranched polyester for esterification reaction. Both ends of the hyperbranched polyester had unsaturated double bond to obtain the hyperbranched polyester (HBP-1). The effects of this treatment on the morphology, mechanical properties and thermal properties of the composites were studied in detail. The HBP-1 was investigated by Fourier Transform Infrared Spectroscopy (FT-IR). The HBP-1/UPR composites were investigated by Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), mechanical properties analysis and Scanning Electron Microscope (SEM). The results showed that HBP-1 enhanced the thermostability and mechanical properties of UPR. However, DMA indicated that the addition of HBP-1 cannot effectively improve the thermodynamic properties of UPR due to the flexible chain in HBP-1 structure. The HBP-1 improves tensile strength, bending strength and impact strength compared to neat UPR.

Properties of paving epoxy asphalt with epoxy-terminated hyperbranched polyester

ABSTRACT Epoxy asphalt is a high performance pavement material, but the poor toughness of epoxy asphalt at low temperature has limited its utilisation. Hyperbranched polyester (HBP) is a spherical polymer with highly branched structures, which can effectively improve the toughness of epoxy asphalt. However, hydroxyl-terminated HBP would accelerate the reaction rate of epoxy asphalt because of the rapid reaction between hydroxyl groups of HBP and epoxy groups of resin. We modified the hydroxyl end groups of HBP as epoxy end groups to avoid its curing reaction with epoxy resin and further reduce the viscosity of epoxy asphalt. Epoxy-terminated HBP also has good compatibility with epoxy resin to improve phase structure uniformity of epoxy asphalt. Moreover, with the help of hyperbranched structure, epoxy-terminated HBP still can improve the toughness of epoxy asphalt, which can be proved by the fracture surface morphology, mechanical properties, and dynamic thermomechanical properties.

Preparation and properties of waterborne polyurethane with star-shaped hyperbranched structure

The second-generation hydroxyl-terminated hyperbranched polyester (HB-20) was used as the core, and perfluorooctylethanol (PFOE), monohydroxypolyoxyethylene ether (MPEG) and n-octadecyl alcohol (C18) were grafted to the periphery of HB-20, coupled by isophorone diisocyanate (IPDI) to synthesize four star hyperbranched polymers (SHPs). The structures of the four synthesized typical SHPs were characterized by FT-IR, 1H NMR and 19F NMR. The SHPs obtained were introduced into anionic waterborne polyurethane (WPU) and waterborne polyurethanes (FWPUs) with good storage stability modified by SHPs were prepared. The particle size and morphology of FWPUs were characterized by dynamic laser light scattering and TEM. The surface chemical composition and surface hydrophilic and hydrophobic regions of FWPU film were characterized by XPS and AFM. The surface energy, mechanical properties and thermal properties of FWPU film were determined. The water absorption and moisture permeability of FWPU film were also discussed.

Robust Hyperbranched Polyester-Based Anti-Smudge Coatings for Self-Cleaning, Anti-Graffiti, and Chemical Shielding.

In this work, a novel anti-smudge coating system was developed by using hydroxyl-terminated hyperbranched polyester as a coating precursor, mono-hydroxyl-terminated poly(dimethylsiloxane) (PDMS) as an anti-smudge agent, and hexamethylene diisocyanate trimer as a curing agent. The resultant coatings with 0.5 wt % PDMS content incorporated are highly transparent and liquid repellent. They exhibit striking repellency against various liquids and display remarkable self-cleaning performance. Water, hexadecane, salt solution, strong alkali solution, strong acid solution, pump oil, and crude oil could slide off the coated surface without leaving any traces, and the dirt on the coated surface could be readily removed by water or oil. Besides, these coatings show potential application for anti-fingerprint and anti-graffiti due to the exceptional repellency of coated surface against artificial fingerprint liquid, oil-based ink, paint, and water-based smudge. Furthermore, they also possess superb chemical shielding ability and thus endow substrates with remarkable protection against exposure to harsh chemical conditions. Moreover, these coatings are mechanically robust against extensive abrasion, impact, and bending without compromising anti-smudge properties, and they also exhibit excellent adhesion to various substrates. Therefore, these newly developed coatings have tremendous potential for widespread applications.

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.

Synthesis of Novel Hyperbranched Polyurethane Acrylate Based on Pentaerythritol

To study the structure and properties of hyperbranched polyesters as well as the modified ones. Three generations of hyperbranched polyesters named HBPE-1, HBPE-2 and HBPE-3 were synthesized by the reactions from pentaerythritol and 2,2-dihydroxy-methyl-propionic acid by single-step polycondensation. They were characterized by 1H NMR, 13C NMR and the results indicated they possessed a high degree of branching. Then homemade urethane acrylate prepolymer reacted with three generations of hydroxyl-terminated hyperbranched polyesters introducing C=C contents, the product was characterized by FT-IR, DSC, TGA techniques. The results of TGA showed well thermal stability of all the products. TGA curves of the modified HBPES showed two stages, 280-350°C means pyrolysis of main chain ester section and 400-450°C means pyrolysis of urethane acrylate section. The results of DSC indicated that glass transition temperature increased with the number of the hyperbranched polyester units’ increment. What’s more, glass transition temperature of HBPE-3 was 48.13°C. HPUA-3 was semi-crystalline material, its glass transition temperature was-12.59°C, cold crystallization temperature Tc 110.92°C, melting temperature Tm 134.74°C. Since the introduction of a large number of unsaturated units to the end, the resin can be introduced into the UV-curable systems for paints, inks, adhesives and some other fields.

Synthesis and Characterization of Carboxyl-Terminated Hyperbranched Polyester

In order to prepare carboxyl-terminated hyperbranched polyester (HBP-COOH), succinic anhydride was used to modify hydroxyl-terminated hyperbranched polyester (HBP-OH), and the influences of the solvents, catalysts and time on the product’s structure were investigated. When THF is used as the solvent, sodium acetate as the catalyst, the molar ratio of succinic anhydride and hydroxyl groups is 3:1, and the reaction time is 6 h at 65°C, the modification extent of the hydroxyl groups is about 99% with about 95% yield. HBP-COOH has much lower glass transition temperature than that of HBP-OH due to its long and flexible end-groups.

Synthesis and Characterization of A<sub>2</sub>+B<sub>4</sub> Hyperbranched Polyesters with Hydroxyl End Groups

Hydroxyl-terminated hyperbranched polyesters (HBPET) with aromatic-aliphatic structure were synthesized by melt polycondensation of isophthalic acid and pentaerythritol via A2+ B4 approach, at three different monomer mole ratios (A2/B4 =1:1, 1.5:1, 2:1, respectively). Fourier transform infrared (FTIR) spectroscopy indicated that the expected HBPET. The degree of branching of the HBPET was estimated to be between 0.39–0.45 by 1H-NMR and 13C-NMR measurement. The thermogravimetric analysis ( TGA ) measurement revealed that HBPET had a 10 % weight-loss at 350°C in N2.

Formulation and Characterization of epoxidized hydroxyl-terminated hyperbranched polyester and its application in waterborne epoxy resin

A novel epoxidized hydroxyl-terminated hyperbranched polymer (HPEEX) was formulated from epichlorohydrin and hydroxy-terminated hyperbranched polyester (HPE) based on trimethylol propane (TMP) and AB2 monomer. The obtained HPEEX was characterized with FT-IR, 1HNMR spectroscopy, TG, WAXD and GPC analysis. Results showed that the HPEEX was formulated as expected and its molecular weight and intrinsic viscosity were 3,789 g/mol and 3.96 mL/g, respectively. Meanwhile, the HPEEX was used as cross-linking agent in the preparation of waterborne epoxy resins. Performance of the HPEEX modified epoxy resin aqueous (EP-H) dispersions and their films was evaluated by various tests. It was found that with incorporation of hyperbranched polymer into the epoxy macromolecular chain, the EP-H films exhibited excellent hardness and water-proof performance: the hardness was as high as 96 (Shore A), and the contact angle of water on the surface of this kind of film was as high as 71°, resulting from branched structure, higher functionality of HPEEX, better cross-linking density and large number of hydrogen bonding in this epoxy system.

Preparation and Properties of Waterborne Polyurethane Containing Hyperbranched Polyester Linkages

Different generations of hydroxyl-terminated hyperbranched polyesters (HBPEs) were synthesized in sequence, all of the HBPEs based on methyl methacrylate (MMA) and diethanolamine (DEA) as AB2 monomer and trimethylolpropane (TMP) as core molecule. Then a series of hyperbranched waterborne polyurethane dispersions (HPUs) were prepared with the 3rd generation hyperbranched polyester (HBPE-3) used as an original cross-linking agent in this article. The intrinsic viscosity of each HBPE vs temperature and properties of HPUs was studied. The experimental data indicated that, compared with the linear one, the hyperbranched HPU aqueous dispersion exhibited larger particle size and higher surface tension, when the hydroxyl-ratio was 1:6, the HPU achieved maximum particle size of 78.0 nm and surface tension of 52.48 mN/m, respectively. For the hyperbranched HPU films, the thermal stability and mechanical properties increased, resulting from the effects of the cross-linking structures in the HPU system.

Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique

Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO3H) nanoparticles and their biomedical application. The H30-SO3H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy (1H NMR). The good hemocompatibility of H30-SO3H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO3H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO3H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2–20mM), a low detection limit 1.2×10−5M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood.

Investigation of Hyperbranced Polyesters with Different Generation and their Application in Waterborne Polyurethanes

The 1st, 2nd and 3rd generations of hydroxyl-terminated hyperbranched polyesters (HBPE-1, HBPE-2, and HBPE-3) were synthesized. A3rd generation hyperbranched polyester (HBPE-3) was used as original crosslinking agent to prepared hyperbranched waterborne polyurethane dispersions (HPU). FTIR spectra confirmed that this reaction really took place. The experimental data indicated that, compared with the linear one, the hyperbranched HPU aqueous dispersions exhibited lower viscosity, and larger particle size. For the hyperbranched HPU films, mechanical properties were obviously enhanced.

Synthesis and Characterization of Hyperbranched Polyesters Based on Isophthalic Acid and Trimethylolpropane

Hydroxyl-terminated hyperbranched polyesters (HBPEs) with aromatic/aliphatic structure were synthesized at three different monomer mole ratios (A2/B3=1, 0.9, and 0.6, respectively) by melt polycondensation of isophthalic acid and trimethylolpropane via A2+ B3 approach. Fourier transform infrared (FTIR) spectroscopy indicated that the expected HBPEs, which showed excellent solubility in a variety of polar solvents such as N, N-dimethyl formamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and terahydrofuran (THF), were produced without gelation during the polymerization. The weight-average molecular weight of HBPEs ranged from 7014 to 8306 and their inherent viscosities were varied from 0.17 to 0.34 dL/g. The degree of branching of the HBPEs was estimated to be 0.39–0.49 by1H-NMR and 13C-NMR measurement. Their glass transition temperature measured by differential scanning calorimetry (DSC) was between 64 and 86°C. The thermogravimetric analysis (TGA) measurement revealed that HBPEs had ca 8.5% weight-loss at 300°C in N2.

Local Dynamics and Hydrogen Bonding in Hyperbranched Aliphatic Polyesters

We report results from fully atomistic molecular dynamics simulations of commercially available aliphatic hydroxyl-terminated hyperbranched polyesters of two different architectures/sizes in the bulk, exploring dynamic mechanisms associated with their physical behavior as it has been described by pertinent experimental techniques. Particular emphasis is given on the role of the hydrogen-bonding capabilities of the examined systems and the impact on their local dynamic response. Analysis of the simulation results reveals that certain key aspects of their unique behavior, such as the molecular weight dependence of local group reorientation as well as the more restricted motion of these moieties in low-generation polyesters, can be explained by considering the distinct hydrogen-bonding pattern, which is realized at the intra- and intermolecular levels. This interconnection is shown to be realized through a coupling mechanism of local bond relaxation with the time scale pertinent to the formed hydrogen bond network. Quantitative accounts are provided for the relative percentage of the different kinds of hydrogen bonds as well as for their corresponding lifetimes. The detail afforded by the present work provides new insight into the structure/properties relation of such molecules and offers new ground for the interpretation of relevant experimental findings.

Synthesis and Characterization of Hyperbranched Polyurethane Hybrids Using Tetraethoxysilane (TEOS) As Cross-Linker

Organic−inorganic hybrid coatings were derived from a hydroxyl-terminated hyperbranched polyester, 3-isocyanatopropyl triethoxysilane (ISPTES), and then cross-linked with various percentages of SiO2. This system was able to cross-link by hydrolysis of a tetraethoxysilane group in room temperature and humid conditions and then at 120 °C for 12−14 h, forming a three-dimensional hybrid structure, where the organic and inorganic phases were bonded covalently. The main focus of this work was to study the change of properties of the coating with SiO2 modification. These hybrid coatings were also characterized by using NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamical mechanical thermal analyzer (DMTA), thermal analysis (TGA), and tensile strength.

Synthesis, characterization and mechanical properties of polyester-based aliphatic polyurethane elastomers containing hyperbranched polyester segments

Aliphatic polyester-based polyurethane (PU) elastomers with hyperbranched polyester segments were synthesized from polyester diol, hydroxyl-terminated hyperbranched polyester (HB-20), isophorone diisocyanate (PDI) and 1,4-butanediol. The crosslinking density of the PU elastomer was calculated by using Flory–Rehner equation. The degree of hydrogen bonding, the microstructure and the morphologies of these PU materials were characterized by means of FT-IR, WAXD and DSC, respectively. The experimental results showed that the PU elastomers containing small amount of HB-20 exhibited the enhanced hydrogen bonding and mechanical properties. As compared with the comparable PU specimen, the tensile strength of the polyester-based aliphatic PU containing 6 wt% HB-20 increased by 71.2 times, up to 36.1 MPa, and the elongation at break was still as high as 333.1%, resulting from the dual effects of the hydrogen bonding and the crosslinking density in the PU system.

New aliphatic hyperbranched polyester polyols based on 1,3,5‐tris(2‐hydroxyethyl) cyanuric acid as a core

Different generations of new hyperbranched polyester polyols were synthesized by the polycondensation of stoichiometric amounts of the monomer 2,2-bis (hydroxymethyl) propionic acid (bisMPA) corresponding to each generation with one mole of 1,3,5-tris(2-hydroxyethyl) cyanuric acid (THECA) as a trifunctional core. The monomer to core ratio was varied between 3 and 45. The degree of branching (DB) was found to be 0.45 according to the method described by Frechet and 0.35 according to the definition introduced by Frey et al. and independent of the stoichiometric ratio between core molecule and repeating monomer. The molecular weights, calculated from 1H NMR spectra, increase on going from G1 to G4 and represent 97, 90, 72, and 58% from their theoretical molar masses, respectively. In view of the obtained results, it may be argued that the higher generations of the hyperbranched polyesters possess actually lower molecular weights and hydroxyl functionality than their theoretical ones due to some side reactions, e.g., cyclization and or self-condensation of bisMPA that occurred during the synthesis. The thermal stability and glass transition temperatures of the hydroxyl-terminated hyperbranched polyesters were determined. Two hyperbranched urethane methacrylates were synthesized by modifying 100 and 50% of the hydroxyl groups of G1 and G3, respectively. Their molecular structures were identified using IR and 1H NMR spectroscopy, and their thermal properties were also investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5568–5579, 2008

Influence of hyperbranched polyesters on the surface tension of polyols.

The influence of hyperbranched polyesters with different functional end groups on the surface tension of mixtures with an oligo(ester diol) was investigated. The temperature dependence of the surface tension of the pure components and of the mixtures was measured by a modified Wilhelmy balance technique. The results indicate that the surface tension of the pure hyperbranched polyesters strongly depends on the functionality of the end groups. The functionalization of the hydroxyl end groups by short alkyl chains (methyl, tert-butyl) reduced the surface tension depending on the degree of substitution. The surface tension of the mixtures with the hydroxyl-terminated hyperbranched polyester was slightly increased at higher concentrations of the hyperbranched polymer compared to the surface tension of the pure ester diol. On the other hand, the surface tension of mixtures could be considerably decreased using 1% of hyperbranched polyester polyols partially substituted with short alkyl chains. In that case, the modified hyperbranched polyesters act as surface active agents. On the molecular level, the enrichment of the modified hyperbranched polyester in the surface region was proven by X-ray photoelectron spectroscopy measurements.