Second-order nonlinear optical hyperbranched polymers via facile ring-opening addition reaction of azetidine-2,4-dione

A new hyperbranched polymeric structure was chosen as a nonlinear optical material. First, a difunctional chromophore, 4-(4′-nitrophenyl-diazenyl) phenyl-1,3-diamine (NDPD) was synthesized, which was then reacted with 4-isocyanato-4′(3,3-dimethyl-2,4-dioxo-azetidino)diphenylmethane (MIA) to form NDPDMIA (A₂ type monomer). The azetidin-2,4-dione functional groups exhibit selective reactivity, which can react only with primary amines under mild conditions. The hyperbranched polymers were synthesized via ring-opening addition reaction between azetidine-2,4-dione (A₂ type monomer) and primary amine (B₃ type monomer). This synthetic scheme comes with easy purification, high yield and rapid synthesis. Chemical structures of the hyperbranched polymers were characterized by FT-IR, ¹H NMR, and elemental analysis. The inherent viscosity of hyperbranched polymers in DMSO ranged from 0.15 to 0.22 dLg⁻¹. All of the obtained polymers were soluble in DMF, DMAc, and DMSO. Using in situ contact poling, r₃₃ coefficients of 6-16 pm/V and their temporal stability at 60 °C were obtained. Optical loss measurement was also achieved by a prism coupling setup.     

Development of DSM's hybrane® hyperbranched polyesteramides

The development of DSM's Hybrane® hyperbranched poly(ester amides) is described. The monomer (1) for the hyperbranched polyester is obtained from the reaction of a cyclic anhydride with diisopropanol amine, yielding a tertiairy amide with one COOH and two OH groups. Polycondensation takes place via an oxazolinium intermediate in bulk at relatively mild conditions in the absence of catalyst. The reaction has been scaled up to ton scale. By varying and combining anhydrides, and modification with several types of end groups, a large variety of structures with concomitant properties and industrial applications has been realized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3110–3115, 2004     

Synthesis, characterization and functionalization of thermally stable hyperbranched polyamide-ethers based on 6-hydroxy-2,4-bis(4′-nitrobenzamide)pyrimidine

Thermally stable hyperbranched polyamide-ethers (HBPAEs) containing pyrimidine moieties were synthesized using new AB₂ type monomer, 6-hydroxy-2,4-bis(4′-nitrobenzamide)pyrimidine (NAL), which was prepared through amidation and its structural characterization was made by FTIR, ¹H, ¹³C NMR spectrometry and elemental analysis. Polymerization of NAL proceeded homogeneously to yield a gel-free polymer (HBPAE 1). End group derivatization of nitro-terminated HBPAE 1 yielded HBPAE 2 and 3. FTIR confirmed the structure and complete modification of ensuing polymers. DB and inherent viscosity (η_inh) of HBPAE 1 was found to be 0.41 and 0.23 dL/g, respectively. Modified HBPAE 2 and 3 were soluble in various organic solvents including NMP, DMAc and DMSO but amorphous HBPAE 1 was partially soluble in DMF. Glass transition temperature (T_g) of thermally stable HBPAEs was affected by nature of end groups as well as introduction of pyrimidine rings.     

2,4‐Di­nitro­phenyl­hydrazones of 2,4‐di­hydroxy­benz­aldehyde, 2,4‐di­hydroxy­aceto­phenone and 2,4‐di­hydroxy­benzo­phenone

In 2,4‐di­hydroxy­benz­aldehyde 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­amide solvate {or 4‐[(2,4‐di­nitro­phenyl)­hydrazono­methyl]­benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate}, C₁₃H₁₀N₄O₆·C₃H₇NO, (X), 2,4‐di­hydroxy­aceto­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­am­ide solvate (or 4‐{1‐[(2,4‐di­nitro­phenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate), C₁₄H₁₂N₄O₆·C₃H₇NO, (XI), and 2,4‐di­hydroxy­benzo­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­acet­amide solvate (or 4‐­{[(2,4‐di­nitro­phenyl)hydrazono]phenyl­methyl}benzene‐1,3‐diol N,N‐di­methyl­acet­amide solvate), C₁₉H₁₄N₄O₆·C₄H₉NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent mol­ecule.     

Properties and morphologies of UV‐cured epoxy acrylate blend films containing hyperbranched polyurethane acrylate/hyperbranched polyester

The properties and morphologies of UV‐cured epoxy acrylate (EB600) blend films containing hyperbranched polyurethane acrylate (HUA)/hyperbranched polyester (HPE) were investigated. A small amount of HUA added to EB600 improved both the tensile strength and elongation at break without damaging its storage modulus (E′). The highest tensile strength of 31.9 MPa and an elongation at break around two times that of cured pure EB600 were obtained for the EB600‐based film blended with 10% HUA. Its log E′ (MPa) value was measured to be 9.48, that is, about 98% of that of the cured EB600 film. The impact strength and critical stress intensity factor (K_1c) of the blends were investigated. A 10 wt % HUA content led to a K_1c value 1.75 times that of the neat EB600 resin, and the impact strength of the EB600/HPE blends increased from 0.84 to 0.95 kJ m^?1 with only 5 wt % HPE addition. The toughening effects of HUA and HPE on EB600 were demonstrated by scanning electron microscopy photographs of the fracture surfaces of films. Moreover, for the toughening mechanism of HPE to EB600, it was suggested that the HPE particles, as a second phase in the cured EB600 film, were deformed in a cold drawing, which was caused by the difference between the elastic moduli of HPE and EB600. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3159–3170, 2005     

Bio‐based high‐performance waterborne hyperbranched polyurethane thermoset

Tannic‐acid‐based low volatile organic compound‐containing waterborne hyperbranched polyurethane was prepared. In order to improve the performance, it was modified in an aqueous medium using a glycerol‐based hyperbranched epoxy and vegetable‐oil‐based poly(amido amine) at different wt%. The combined system was cross‐linked by heating at 100°C for 45 min. Fourier transform infrared spectroscopy and swelling study were used to confirm the curing. A dose‐dependent improvement of properties was witnessed for the thermoset. Thermoset with 30 wt% epoxy showed excellent improvements in mechanical properties like tensile strength (~3.4 fold), scratch hardness (~2 fold), impact resistance (~1.3 fold), and toughness (~1.7 fold). Thermogravimetric analysis revealed enhancement of thermal properties (maximum 70°C increment of degradation temperature and 8°C increment of T_g). The modified system showed better chemical and water resistance compared with the neat polyurethane. Biodegradation study was carried out by broth culture method using Pseudomonas aeruginosa as the test organism. An adequate biodegradation was witnessed, as evidenced by weight loss profile, bacterial growth curve, and scanning electron microscope images. The work showed the way to develop environmentally benign waterborne polyurethane as a high‐performance material by incorporating a reactive modifier into the polymer network. Use of benign solvent and bio‐based materials as well as profound biodegradability justified eco‐friendliness and sustainability of the modified system. Copyright © 2015 John Wiley & Sons, Ltd.     

Single‐step synthesis of internally functionalizable hyperbranched polyethers

Radical catalyzed thiol‐ene reaction has become a useful alternative to the Hüisgen‐type azide‐yne click reaction as it helps expand the variability in reaction conditions as well as the range of clickable entities. In this study, the direct generation of a hyperbranched polyether (HBPE) having decyl units at the periphery and a pendant allyl group on every repeat unit of the polymer backbone is described; the allyl groups serve as a reactive handle for postpolymerization modifications and permits the generation of a variety of internally functionalized HBPEs. In this design, the AB₂ monomer carries two decylbenzyl ether units (B‐functionality), an aliphatic ? OH (A‐functionality) and a pendant allyl group within the spacer segment; polymerization of the monomer readily occurs at 150 °C via melt transetherification process by continuous removal of 1‐decanol under reduced pressure. The resulting HBPE has a hydrophobic periphery due to the presence of numerous decyl chains, while the allyl groups that remain unaffected during the melt polymerization provides an opportunity to install a variety of functional groups within the interior; thiol‐ene click reaction with two different thiols, namely 3‐mercaptopropionic acid and mercaptosuccinic acid, generated interesting amphiphilic structures. Preliminary field emission scanning electron microscope (FESEM) and Atomic Force Microscopy (AFM) imaging studies reveal the formation of fairly uniform spherical aggregates in water with sizes ranging from 200 to 400 nm; this suggests that these amphiphilic HBPs is able to reconfigure to generate jellyfish‐like conformations that subsequently aggregate in an alkaline medium. The internal allyl functional groups were also used to generate intramolecularly core‐crosslinked HBPEs, by the use of dithiol crosslinkers; gel permeation chromatography traces provided clear evidence for reduction in the size after crosslinking. In summary, we have developed a simple route to prepare core‐clickable HBPEs and have demonstrated the quantitative reaction of the allyl groups present within the interior of the polymers; such HB polymeric systems that carry numerous functional groups within the core could have interesting applications in analyte sequestration and possibly sensing, especially from organic media. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4125–4135     

Synthesis and characterization of N‐substituted hyperbranched polyureas

N,N′‐disubstituted hyperbranched polyureas with methyl, benzyl, and allyl substitutents were synthesized starting from AB₂ monomers based on 3,5‐diamino benzoic acid. Carbonyl azide approach, which generates isocyanate group in situ on thermal decomposition, was used for the protection of isocyanate functional groups. The N‐substituted hyperbranched polymers can be considered as the new class of internally functionalized hyperbranched polyureas wherein the substituent can function either as receptor or as a chemical entity for selective transformations as a tool to tailor the properties. The chain‐ends were also modified by attaching long chain aliphatic groups to fully realize the interior functionalization. This approach opens up a possible synthetic route wherein different functional substituents can be used to generate a library of internally functionalized hyperbranched polymers. All the hyperbranched polyureas were characterized by FTIR, ¹H‐NMR, DSC, TGA, and size exclusion chromatography. Degree of branching in these N,N′‐disubstituted hyperbranched polyureas, as calculated by ¹H‐NMR spectroscopy using model compounds, was found to be lower than the unsubstituted hyperbranched polyurea and is attributed to the lower reactivity of N‐substituted amines compared to that of unsubstituted amines. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5134–5145, 2004     

Cyclopentadecanone 2,4‐dinitrophenylhydrazone

In the title compound, C₂₁H₃₂N₄O₄, no disorder is present in the 15‐membered hydrocarbon ring, which exists in an unsymmetrical quinquangular [12345] conformation. The 2,4‐dinitrophenylhydrazone group is approximately perpendicular to the C₁₅ ring, with a dihedral angle of 84.66 (1)° between their best planes.     

A hyperbranched,rotaxane‐type mechanically interlocked polymer

Based on the dibenzo‐24‐crown‐8/1,2‐bis(pyridinium)ethane recognition motif, a hyperbranched mechanically interlocked polymer was prepared by polyesterification of an easily available dynamic trifunctional AB₂ pseudorotaxane monomer. It was characterized by various techniques including ¹H NMR, COSY, NOESY, GPC, viscosity, TGA, dynamic laser light scattering, AFM, and SEM. Its GPC M_n was determined to be 191 kDa with polydispersity 1.7 and its hydrodynamic diameter in a dilute solution in acetone was about 70 nm. This measured M_n value corresponds to about 93 repeating units. The study reported here presents not only a new polymer topology but also a novel and convenient way to prepare mechanically interlocked polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4067–4073, 2010     

Functional,hyperbranched polyesters via baylis–hillman polymerization

Hyperbranched polyesters are among the most common hyperbranched polymers. One of the interesting features of hyperbranched polyesters is that they contain unreacted hydroxyl and carboxylic acid groups at the linear and terminal structural units, which can be postmodified to adjust thermal, solubility, or mechanical properties, or to prepare core–shell type architectures. This article reports on the synthesis of a novel class of hyperbranched polyesters via an A₂ + B₃ type Baylis–Hillman polymerization of 2,6‐pyridinedicarboxaldehyde and trimethylolpropane triacrylate. Baylis–Hillman polymerization generates highly functional polyesters that contain not only unreacted aldehyde and/or acrylate groups at the linear and terminal structural units but also chemically orthogonal vinyl and hydroxyl groups along the polymer backbone. Using 3‐hydroxyquinuclidine as the catalyst, hyperbranched polymers with number‐average molecular weights up to 7500 g/mol and degrees of branching up to 0.81 were obtained. To demonstrate the versatility of these hyperbranched polyesters to act as platforms for further derivatization, the orthogonal postpolymerization modification of the hydroxyl, vinyl, and pyridine functional moieties with phenyl isocyanate, methyl‐3‐mercaptopropionate, and methyl iodide is presented. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.     

Backbone-thermoresponsive hyperbranched polyethers

A new type of materials, the backbone-thermoresponsive hyperbranched polyether, was successfully synthesized by proton-transfer polymerization of 1,4-butanediol diglycidyl ether and various triols, and the lower critical solution temperature (LCST) values can be readily adjusted from 19.0 to 40.3 degrees C by changing the hydrophilic/hydrophobic balance of BDE and triols.     

Cyclotridecanone 2,4‐dinitrophenylhydrazone

In cyclotridecanone 2,4‐dinitrophenylhydrazone, C₁₉H₂₈N₄O₄, the 13‐membered carbocycle exists in the triangular [337] conformation. The 2,4‐dinitrophenylhydrazone group is almost perpendicular to the 13‐membered ring, with a dihedral angle of 82.66 (2)° between the mean planes. The dinitrophenylhydrazone rings are packed parallel to each other and separated by 3.28 (1) Å. The NH group forms an intramolecular hydrogen bond to a nitro O atom, and there is a weaker C—H...O interaction between a cyclotridecane CH group and a symmetry‐related 4‐nitro O atom, with a C...O distance of 3.436 (2) Å and a 150° angle about the H atom. The structure, in combination with additional evidence, indicates that [337] is the preferred conformation of cyclotridecane and other simple 13‐membered rings.     

Assembling hyperbranched polymerics

A condensed overview discusses the existing grafting approaches and the surface behavior of various hyperbranched polymers. We focus on the recent strategies and corresponding characterization of the resulting surface morphologies and structures with a number of relevant recent results from the authors' own research and existing literature. Some results discussed here are important for prospective applications of hyperbranched polymers in biomedical fields, for resistive coatings, tough blends, and reinforced nanocomposites are briefly summarized as well. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 83–100, 2012     

End‐capped AB3‐type hyperbranched carbosilane macromolecules

End‐capped carbosilane macromolecules were prepared via the hydrosilation and continual addition of phenylethynyl, amine, bis(trimethylsilyl)amine, and cholesterol groups on the AB₃‐type hyperbranched carbosilane polymer. The matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopic views of the end‐capped hyperbranched carbosilanes agreed with the expected mass distribution, in close regularity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3287–3293, 2001     

Multistimuli‐responsive hyperbranched poly(ether amine)s

Multistimuli‐responsive hyperbranched poly(ether amine)s (hPEAs) were successfully synthesized through nucleophilic addition/ring‐opening reaction of commercial diglycidyl ether and amine via one‐pot synthesis. In aqueous solution, these hPEAs exhibited very sharp response to temperature, pH, and ionic strength, with well‐tunable cloud point (CP). Through changing the poly(ethylene oxide) (PEO) chain content of hPEAs, pH, and ionic strength, the CP could be adjustable from 35 to 100 °C, and increased with the increasing of PEO content, the decreasing of pH and ionic strength. The CP of hPEAs aqueous solution presents a linear relationship to the PEO content in pH range from 6.6 to 8.0. Dynamic light scattering (DLS) investigation indicated that these hPEAs dispersed in aqueous solution to form the stable nanomicelles, whose aggregation can be controlled by temperature, pH, and ionic strength. Moreover, the obtained hPEAs contain reactive amino groups in periphery and hydroxyl groups inside, which can be further functionalized. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4252–4261, 2010     

One‐pot synthesis of hyperbranched glycopolymers by RAFT polymerization

Soluble hyperbranched glycopolymers were prepared by copolymerization of glycan monomers with reversible addition‐fragmentation chain transfer polymerization (RAFT) inimers in a simple one‐pot reaction. Two novel RAFT inimers, 2‐(methacryloyloxy)ethyl 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoate (MAE‐CPP) and 2‐(3‐(benzylthiocarbonothioylthio)propanoyloxy)ethyl acrylate (BCP‐EA) were synthesized and used to prepare hyperbranched glycopolymers. Two types of galactose‐based saccharide monomers, 6‐O‐methacryloyl‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose (proGal‐M) and 6‐O‐(2′‐acrylamido‐2′‐methylpropanoate)‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose (proGal‐A), containing a methacrylate and an acrylamide group, respectively, were also synthesized and polymerized under the mediation of the MAE‐CPP and BCP‐EA inimers, respectively. In addition, hyperbranched poly(proGal‐M), linear poly(proGal‐A), and hyperbranched poly(proGal‐A) were generated and their polymerization kinetics were studied and compared. An unexpected difference was observed in the kinetics between the two monomers during polymerization: the relationship between polymerization rate and concentration of inimer was totally opposite in the two monomer–inimer systems. Branching analysis was conducted by using degree of branching (DB) as the measurement parameter. As expected, a higher DB occurred with increased inimer content. Furthermore, these polymers were readily deprotected by hydrolysis in trifluoroacetic acid solution resulting in water‐soluble polymers. The resulting branched glycopolymers have potential as biomimetics of polysaccharides. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Graft copolymers from star‐shaped and hyperbranched polystyrene macromonomers

Branched polystyrene macromonomers were synthesized by the slow addition of a stoichiometric amount of either 4‐(chlorodimethylsilyl)styrene or vinylbenzyl chloride as a coupling agent to living polystyryllithium. Star‐shaped macromonomers were produced by the addition of the coupling agent alone, and hyperbranched macromonomers resulted from the addition of the coupling agent along with styrene monomer. Star and hyperbranched graft copolymers were produced by the copolymerization of the macromonomers with styrene and methyl methacrylate. The copolymers were characterized by gel permeation chromatography coupled with multi‐angle laser light scattering, ¹H NMR spectroscopy, and Soxhlet extraction to determine that the macromonomers were incorporated in high yields into the copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3547–3555, 2001     

Synthesis and characterization of bi‐functional photorefractive hyperbranched polyisophthalesters

A series of novel bi‐functional photorefractive (PR) hyperbranched polyisophthalesters (HPIPEs) with pendant end carbazolyl and azo groups, acting as photoconductors and electro‐optic (EO) chromophores, respectively, were synthesized by modifying the HPIPE with N‐hydroxyethyl carbazole and 4‐(p‐nitrophenylazo) (N‐ethoxyl‐N‐methyl)aniline. These obtained PR polymers were then characterized by UV‐vis and IR spectrum, ¹H‐NMR, elemental analysis, gel permeation chromatography (GPC) measurements and thermal analysis. As expected, due to their three‐dimension molecular structures, the lower glass transition temperatures (21–49°C) were obtained in the absence of plasticizers, which provide a necessary free volume for the EO chromophores reorientation. The acceptable thermal stability, as well as the degradation temperatures of 205–260°C, was also determined by thermogravimetric analysis (TGA). The two‐beam coupling experiments of HPIPE‐25Azo theoretically containing 25% azo end groups showed that a high gain coefficient of 59 cm^?1 was obtained at the applied electric field of 80 V μm^?1. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and characterization of end‐group modified hyperbranched polyetherimides

End‐group modified hyperbranched polyetherimides were prepared by a one‐pot, two‐step reaction sequence. General synthetic techniques were developed to prepare both monofunctional terminating segments and the corresponding modified polyetherimide hyperbranched polymers. Monofunctional groups were used to terminate an AB₂‐type polycondensation reaction, generating capped hyperbranched polymers (HBPs). The composition and constitution of the end groups controlled the solubility and thermal properties of the HBPs. For the same polymer backbone, different end groups were able to shift the glass‐transition temperature nearly 100 °C. End‐group modification greatly influenced the film‐forming ability of the HBPs. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 936–946, 2002