Trifunctional Monomer Research Articles

Bimodal architecture and rheological and foaming properties for gamma-irradiated long-chain branched polylactides

A series of long-chain branched polylactides (LCB-PLAs) were prepared from a linear PLA precursor by applying gamma radiation with addition of the trifunctional monomer, trimethylolpropane triacrylate (TMPTA) and their topological structures were investigated by size-exclusion chromatography coupled with a multiangle light scattering detector (SEC-MALLS) and rheology. SEC-MALLS measurements show that LCB-PLAs exhibit not only the increased weight-average molecular mass but also a bimodal architecture with a short linear chain fraction and a LCB fraction, as compared with LCB-PLA samples generated by electron-beam radiation, which only show the monomodal macromolecular structure. The introduction of LCB structure contributes to the enhancement of complex viscosity, shear-thinning and storage modulus, and the deviations of phase angle, δ from the “universal” curve of linear PLA in δ(|G*|) plots (van Gurp–Palmen plot). By the analysis of the thermorheological behaviors and determination of activation energies, the bimodal architecture is confirmed. Activation energies around 77 kJ mol−1 lead to an expectation that some linear macromolecules are still present in LCB-PLAs, while the higher activation energies at large phase angles are associated with the existence of the LCB ones. A conclusion with respect to the tree-like topography for LCB-PLAs is drawn from the molecular mass dependences of zero-shear viscosity (η0–Mw plot). An explanation to these findings is provided under the consideration of the radiation dose rate for the gamma radiation. The remarkable modification of PLA topological chain structure contributes to the improvement of the foaming properties of LCB-PLAs.

Synthesis and characterization of cross-linked polymeric nanoparticles and their composites for reinforcement of photocurable dental resin

Reactive polymeric nanoparticles were formed for reinforcement of photocurable dental resin. Cross-linked polymeric nanoparticles were synthesized by emulsion polymerization of mono- (methyl methacrylate; MMA) and trifunctional (trimethylol propane trimethacrylate; TMPTMA) monomers. The nanoparticles were dispersed in bisphenol A glycol dimethacrylate (Bis-GMA) based dental resin matrix in the range of 5–25wt% to form photocurable nanocomposites.The effect of reactive polymeric particles on the mechanical properties of photocurable dental resin was investigated. Polymerization shrinkage, polymerization shrinkage stress, viscosity, diametral tensile strength, compressive, and flexural strength of the nanocomposites have been studied.It was observed that the cross-linked nanoparticles significantly influenced the mechanical properties of the reinforced dental resin nanocomposites.

Photopolymerization behavior and phase separation effects in novel polymer dispersed liquid crystal mixture based on urethane trimethacrylate monomer

AbstractPolymer dispersed liquid crystals (PDLCs) are often formed by polymer induced phase separation, based on photopolymerization of multifunctional acrylate monomers. The emerged morphology is controlled by the interplay between polymerization rate and phase separation dynamics, which depends on different parameters such as monomer structure and functionality. In this work, a new PDLC formulation containing urethane trimethacrylate (UTMA) monomer is introduced, which has different molecular weight evolution, polymer gel point, and polymerization kinetics in comparison with some common ester acrylate (such as TMPTA and DPHPA) based PDLC compositions. UTMA is synthesized and characterized by Fourier transform infrared, 1H‐NMR, and 13C‐NMR spectroscopic techniques. Simultaneous examination of polymer evolution and LC phase separation by real‐time infrared spectroscopy shows that the UTMA based PDLC, which contains trifunctional urethane acrylate monomer, has greater amount of bond conversion, polymerization rate, and liquid crystal (LC) phase separation in comparison with TMPTA based PDLC. In spite of the acrylate monomers, which show gel point conversions as low as 1.83–5.72%, UTMA reaches to its maximum rate at 19.5% conversion, which causes higher phase separation and therefore greater LC domain size. The experimental results are explained more precisely by means of SEM and optical microscopy analyses. The results are confirmed by electro‐optics measurements. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Internal Functionalization of Three‐Dimensional Covalent Organic Frameworks

Thinking inside the COF: Internally functionalized, boroxine-linked, three-dimensional, covalent organic frameworks (COFs) can be synthesized by co-crystallizing a truncated, trifunctional monomer with the parent tetrafunctional building block. The functionalized COFs possess accessible functional groups and a distinct interior microenvironment. In the picture the orange sphere corresponds to an alkyl chain or an allyl group in the pore interior.

From Flexible to Hard Polyurethane Aerogels: The Effect of Molecular Functionality vs. Molecular Rigidity

ABSTRACTHigh performance all-polymer aerogels are not only interesting for their low thermal conductivity, but also for their mechanical strength and their conversion to porous carbons. The prevalent design rule dictates that crosslinking at the monomer level decreases solubility of the developing polymer and induces phase separation of nanoparticles with high surface to volume ratios. Hence, hyperbranched structures based on trifunctional single aromatic core monomers should have enhanced interparticle connectivity and rigidity compared to those based on either difunctional or multiple aromatic core monomers. That design rule is applied here to hyperbranched polyurethane (PU) aerogels synthesized from tris(4-isocyanatophenyl)methane (TIPM) and 1,1,1-tris(4-hydroxyphenyl)ethane (HPE) in anhydrous acetone using dibutyltin dilaurate (DBTDL) as catalyst. The resulting materials vary from highly flexible to rigid as the monomer concentration increases. FTIR and 13C solid NMR confirm formation of urethane. SEM shows that the flexible variety is macroporous with a beaded worm-like structure, while the rigid variety is mesoporous and nanoparticulate. Lower-density flexible aerogels are highly porous (92%) with surface area of 132 m2 g-1, while the rigid ones have higher surface areas, up to 256 m2 g-1. Polyurethane aerogels from other triols and diols, e.g., phloroglucinol (POL) and resorcinol (RES), respectively, have also been studied and for similar monomer concentrations shrinkage and bulk density increases.

Sulfur-containing polyurethanes as novel macro photoinitiators comprising in-chain benzophenone and coinitiator amine for photopolymerization

AbstractThree novel sulfur-containing polyurethanes (PUs) as macrophotoinitiators, hydroxyl-terminated PUa and PUb, and amino-terminated PUc, were synthesized through polycondensation of a novel diamine 4,4’-bis[(4- amino)thiophenyl]benzophenone (BATPBP), isophorone diisocyanate (IPDI) and N-methyldiethanolamine (MDEA). The beznophenone and coinitiator amine structures were successfully introduced into the backbones of PUs. FT-IR, 1H NMR, GPC and DSC analyses confirmed their structures and properties. UV-vis spectra indicate that the macromolecular structure nearly has no influence on their UV-vis absorptions. A trifunctional monomer of trimethylolpropane triacrylate (TMPTA), initiated by these macrophotoinitiators with a low-molecular-weight photoinitiator system (benzophenone/MDEA) as the reference, was studied through photo differential scanning calorimetry (photo-DSC). The results show PUa is the most efficient photoinitiator and the molar content of coinitiator amine in PUs has an important effect on their photoefficiency.

A Method of Controlling Dispersity by Monomer Feeding Protocol and Forced Gelation in Nongelling Step-Growth Branched Polymerization Systems

Changes in dispersity of step-growth linear polymer were calculated for systems where monomer was added to polymerization reactor in portions, each after the previous ones reached certain conversion or after predetermined time. For step-growth branching polymerization involving di- and trifunctional monomers used in the ratios that do not lead to gelation it was shown that the monomer mixtures can be forced to gel, when they are introduced to the reactor in several portions.

Synthesis and Characterization of Acrylated Epoxidized Soybean Oil for UV-Cured Coatings

This paper investigates the curing of biodegradable polymer films which were synthesized from soybean oil through the ultraviolet radiation and their stability against thermal degradation. In this study the epoxidation of soybean oil has been carried out via peracetic method. Further, an epoxy acrylate resin was synthesized from the epoxidized soybean oil (ESO) by using acrylic acid monomer. Triethylamine (TEA) and hydroquinone were used as a catalyst and inhibitor respectively. The acrylation of epoxidized soybean oil (AESO) is done by introducing acrylic acid, which is an unsaturated monomer into oxirane groups of the epoxidized oil (ESO). This reaction was confirmed by analytical data in terms of oxirane oxygen content, acid value, viscosity and spectral analysis. Different UV curable formulations have been investigated using synthesized acrylated resin and trifunctional acrylate monomer used as crosslinkable active diluents with photoinitiator. Monomer used was trimethylolpropane trimethacrylate (TMPTMA) while photoinitiator used was benzophenone along with an activator dimethyl ethanol amine (DEA). The mixtures were cured to make thin polymeric films under UV radiation with optimum irradiation dosing time of 20 min to produce the excellent cured coating which exhibits good thermal stability of about 473 K.

Rheological and topological characterizations of electron beam irradiation prepared long‐chain branched polylactic acid

AbstractIn this study, a series of linear‐ and long‐chain branched polylactic acid (PLA) samples was prepared by electron beam irradiation without or with addition of a trifunctional monomer, trimethylolpropane triacrylate (TMPTA). The chain structures of the PLA samples were characterized by size‐exclusion chromatography coupled with a light scattering detector (SEC‐MALLS) and shear and extensional rheology. PLA tends to degrade while keeps linear structures with increasing irradiation dose and without addition of TMPTA, as evidenced by decreased molecular mass Mw and reductions of storage modulus G′ and the zero shear viscosity η0. Long‐chain branched PLA samples were successfully prepared with irradiation and addition of TMPTA, which shows prominent higher η0 and apparent flow activation energy, longer characteristic relaxation time τ, and pronounced strain‐hardening behaviors. With increasing amount of TMPTA, Mw dependences of η0 and the root mean square radius of gyration Rg obviously deviate from the scaling relation of linear PLA samples, which strongly indicates the increased long‐chain branching degree for the branched PLA samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Bifunctional Dendronized Cellulose Surfaces as Biosensors

Well-defined dendronized cellulose substrates displaying multiple representations of dual-functionality were constructed by taking advantage of the efficiency of the click reaction combined with traditional anhydride chemistry. First, activated cellulose surfaces were decorated with several generations of dendrons, and their peripheral reactive groups were subsequently reacted with a trifunctional orthogonal monomer. The generated substrate tool box was successfully explored by accurately tuning the surface function using a versatile orthogonal dual postfunctionalization approach. In general, the reactions were monitored by using a click-dye reagent or a quartz crystal microbalance (QCM) technique, and the resulting surfaces were well-characterized using XPS, FT-IR, and contact angle measurements. Utilizing this approach two different surfaces have been obtained; that is, triethylenglycol oligomers and amoxicillin molecules were efficiently introduced to the dendritic surface. As a second example, mannose-decorated hydroxyl functional surfaces illustrated their potential as biosensors by multivalent detection of lectin protein at concentration as low as 5 nM.

Linear polyisophthalamides from the trifunctional monomer 5-hydroxyisophthalic acid. A convenient approach towards functionalized aromatic polymers

Wholly aromatic polyisophthalamides (PIPAs) containing free hydroxylic groups were prepared from 5-hydroxyisophthalic acid and sulfonyldianiline by the condensation phosphorylation method, using triphenylphosphite as a condensing agent, in the presence of pyridine. Linear polymers were attained in high yield and high molecular weight, and the properties of the polymers were investigated in comparison with homologous polyisophthalamides without OH groups. The presence of OH groups did not much modified the solubility of hydroxyl-containing polyisophthalamides as they behaved against common solvents in a similar manner as that of reference polyisophthalamides. However, hydroxyl side groups greatly enhanced the water affinity of polyisophthalamides, which showed up to 16% water uptake in 98% relative humidity, and contact angles about 10° smaller than those of classical PIPAs. The presence of free OH groups slightly diminished the thermal resistance, as evaluated by TGA, but the glass transition temperatures were higher by 20–30°C, with a maximum of 345°C. The mechanical properties of hydroxyl-containing polyisophthalamides were reasonably acceptable, with modulus around 2000MPa and tensile strength up to 60MPa.

Controlling the evolution of polypropylene microstructure during melt free radical modification using zinc dithiocarbamate with different N-substituted groups

The effects of zinc dithiocarbamates on degradation and branching of polypropylene (PP) were studied during melt radical modification using a tri-functional monomer (trimethylol propane triacrylate (TMPTA)). High-temperature size-exclusion chromatography (HT-SEC) coupled with differential refractive index detector (DRI), light scattering detector (LSD) and viscometer detector (VD) and rotational rheometry were used to analyse the microstructure of modified PP samples. The chemical structure of the N-substituted group showed an important influence in controlling the evolution of PP microstructure during melt radical reaction. The chain cleavage of PP was controlled in the presence of zinc N, N-dimethyldithiocarbamate (ZDMC), and a substantial long chain branched (LCB) fraction was formed. Without co-agent, the molecular weight of PP decreased measurably, and only a minor LCB fraction was formed. Importantly, considerable amounts of highly branched (microgel and hyperbranched) structures were formed in this case.

Microencapsulation of an acrylate monomer in silica particles by sol–gel process

The sol–gel synthesis strategies combined with the templated growth of organic–inorganic hybrid networks provide access to an immense new area of innovative multi-functional advanced materials. One possible way to prepare such new advanced materials is to encapsulate liquid active agents (such as monomers, dyes, catalysts and hardeners) in microcapsules. Silica microcapsules of tetraethylortosilicate (TEOS) and 3-(trimethoxysilyl)propyl methacrylate (MPTS) were prepared in a precursor-monomer/NH4OH water microemulsion system. Trimethylolpropane triacrylate (TMPTA)—a trifunctional monomer useful in manufacturing of coatings, inks and adhesives—and a corresponding photoinitiator (DAROCUR 1173) were entrapped inside the obtained microcapsules. MPTS was used to increase compatibility between TMPTA and the sol–gel precursors. As stability agent we added a “home made” product resulted from functionalization of poly (ethylene glycol) methyl ether (MPEG) with (3-isocyanatopropyl) triethoxysilane (NCOTEOS). Were obtained microcapsules containing incorporated monomer and having average particle size in range of 0.5–50 μm. Thermal analysis, morphology study and the increase of the silica microcapsules average diameter, measured by DLS technique confirm the monomer encapsulation.

Characteristic Behaviors of Trifunctional Vinyl Ether Urethane Monomer in Protic and Aprotic Polymer Matrices

Characteristic Behaviors of Trifunctional Vinyl Ether Urethane Monomer in Protic and Aprotic Polymer Matrices

A hyperbranched, rotaxane‐type mechanically interlocked polymer

AbstractBased 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 Mn 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 Mn 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

Synthesis and characterization of hyperbranched aromatic polyester-imides with good thermal properties based on 1,3,5-tris(3′,4′-carboxyphenyl)benzene trianhydride

A new trifunctional monomer, 1 , 3 , 5-tris ( 3 ′, 4 ′ -carboxyphenyl ) benzene trianhydride ( TAn ), was synthesized and characterized by elemental analysis, FTIR, 1 H and 13 C NMR spectroscopy. Subsequently, one-step high-temperature polymerization of TAn and a series of commercially available diamine monomers such as p -phenylenediamine (PDA, 1), 4,4′-oxydianiline (ODA, 2), and 1,5-diaminonaphthalene (DAN, 3) successfully yielded wholly aromatic anhydride-terminated hyperbranched poly(ester-imide)s HBPEI 1, 2, and 3, respectively. Gelation was effectively avoided by controlling 1:1 M ratio of A 2 and B 3 monomers and maintaining total solid content 10 mmol, thereby, producing a novel family of aromatic HBPEIs with inherent viscosities ( η inh ) of 0.17–0.28 dL/g. As-prepared HBPEIs were fully characterized by FTIR spectroscopy and were soluble in DMAc, DMSO and NMP. Degree of branching (DB) by 1 H NMR analysis of the HBPEIs was estimated to be 0.52–0.56. Differential scanning calorimetry (DSC) showed glass transition temperatures ( T g ) between 198 and 208 °C and the synthesized polymers were thermally stable. Furthermore, crystallinity of the polymers was evaluated by means of X-ray diffraction patterns.

Electrochemical sensor for folic acid based on a hyperbranched molecularly imprinted polymer-immobilized sol–gel-modified pencil graphite electrode

Contrary to the ‘substructure imprinting approach’ of larger molecule like folic acid, which often leads molecular recognition for both folic acid and structural analogues containing pteridine and glutamic acid substructures, a molecularly imprinted polymer capable of binding specifically folic acid has been prepared by stoichiometric imprinting process (template/monomer molar ratio, 1:3) creating multiple binding sites within the cross-linked hyperbranched polymer. Dendrimer-like chains were obtained by an ‘initiator-fragment incorporation radical polymerization’ technique involving a new trifunctional monomer, 2,4,6-trisacrylamido-1,3,5-triazine. An electrochemical sensor was developed for the selective and quantitative recognition of folic acid, using a preanodized sol–gel coated pencil graphite (grade 2B) electrode with imprinted polymer immobilized to its exterior surface. During preconcentration step at +0.8 V (with respect to Ag/AgCl), the analyte recapture at pH 2.5 in aqueous environment simultaneously involved mixed hydrophobically driven hydrogen bondings and ionic interactions with pteridine substructure and purely hydrogen bonding interactions with glutamic acid residue of folic acid. The encapsulated analyte was instantly oxidized and then cathodically stripped off responding differential pulse cathodic stripping voltammetric signal. The folic acid was selectively detected with a limit of detection of 0.002 μg mL −1(3 σ, RSD ≤3.0%), without any cross-reactivities and real matrix complications.

Synthesis and photoinitiating behavior of hyperbranched polymeric photoinitiators bearing coinitiator amine

A series of benzophenone (BP)-terminated hyperbranched polyester (BoltornTM P1000), bearing amine moieties as synergists by reacting with piperidine, were synthesized as yellowish liquids with low viscosity, and used as polymeric photoinitiators (HPPIs). For comparison, acrylate groups were introduced to the terminals of hyperbranched polyester for obtaining a polymerizable photoinitiator. The chemical structures were characterized by FTIR and 1H NMR spectroscopy. HPPIs and BP exhibited the similar absorptions by UV–vis spectroscopy. The photoinitiating behavior of HPPIs with trimethylolpropane triacrylate (TMPTA) as a trifunctional monomer was investigated by using photo-DSC analysis. The results indicated that the maximum photopolymerization rate and unsaturation conversion of TMPTA initiated by HPPIs were both lower than that by BP. Among them, the HPPI with double tertiary amine moiety of BP moiety was found to be the most efficient photoinitiator. Additionally, the films cured with bisphenol A epoxy acrylate EB605 initiated by HPPIs were uniform and possessed high Tg from DMTA. Copyright © 2010 John Wiley & Sons, Ltd.

Electrically and thermally modulated optical properties of polymer dispersed chiral liquid crystal

The polymer dispersed chiral liquid crystals (PDCLCs) film was fabricated by photopolymerization induced phase separation (PIPS) of chiral liquid crystal (CLC)/polymerizable monomers/photoinitiator composites. The effects of the electrical and thermal modulation on optical rotation properties of PDCLCs film were investigated. The microsized liquid crystal droplets were resulted from the rapid polymerization of trifunctional monomers. The effects of the electrically and thermally modulated on realignment of liquid crystal director were investigated. It was found that the intensity of electric and thermal field influenced the alignment of liquid crystal droplets' director on PDCLCs film, and the electro-optical properties of the composites were affected accordingly. The principle of free energy minimum was used for explaining the change of optical rotation and transmittance of PDCLCs film with applying the voltage to the film. The dispersion and sizes of liquid crystal droplets were described by polarizing optical microscope (POM). POLYM. COMPOS., 31:1535–1540, 2010. © 2009 Society of Plastics Engineers

Preparation and characterization of hyperbranched polyimides based on 4,4’,4’’-triaminotriphenyl-methane

AbstractThis work focuses on the preparation and characterization of novel hyperbranched polyimides based on commercially available 4,4,’4’’- triaminotriphenylmethane and pyromellitic dianhydride or 4,4’-oxydiphthalic anhydride. The bi- and trifunctional monomers were reacted in a molar ratio of 1:1 or 2:1 to prepare polyimide precursors (hyperbranched polyamic acids) endcapped with either amino or anhydride groups. The precursors were then transformed into hyperbranched polyimides using thermal imidization. The final products were self-standing films, whose thermal behaviour was characterized by having no weight loss up to 250 ºC and by having glass transition temperatures above 200 ºC. We monitored the permeability of carbon dioxide, organic vapours and water vapour through these membranes. We also compared the properties of these materials with linear polyimides based on 4,4’-methylenedianiline combined with either pyromellitic dianhydride or 4,4’-oxydiphthalic anhydride.