1-pyrenylmethyl Methacrylate Research Articles

Transparent and fluorescent breath figure arrays prepared from end-functionalized copolymers

Fluorescent and transparent polymer films with exquisite micro-structures are ideal candidates for anti-counterfeiting tags. However, it is still a great challenge to embed such properties in one breath figure array due to the restriction of the film-forming ability of polymers. In this work, we designed and synthesized fluorescent copolymers from styrene and 1-pyrenylmethyl methacrylate (PYMMA) and studied their self-assembly behaviors via the breath figure method. The significance of end groups and topologies have been investigated in detail. Novel hexagonal breath figure arrays with high transparency are formed at extremely low concentration (down to 0.06 mg/mL). The breath figure arrays display blue honeycomb pattern when irradiated by ultraviolet light. Breath figure arrays with such special optical properties demonstrated an ideal solution for anti-counterfeiting tags. Besides, this work demonstrates the significance of polymer architecture on the morphology of breath figure arrays and may enlighten the polymer design for a broad range of applications. • Fluorescent copolymers were designed and synthesized for self-assembly by the breath figure method. • A highly regular breath figure array can be formed at polymer concentration of as low as 0.06 mg/mL. • Transparent and fluorescent breath figure arrays are potential for anti-counterfeiting. • Effects of end groups and topologies of polymers on the morphology of breath figure arrays were studied.

Stiffness of thin, supported polystyrene films: Free-surface, substrate, and confinement effects characterized via self-referencing fluorescence

Stiffness-confinement effects are characterized via a non-contact, self-referencing fluorescence approach in polystyrene (PS) films labeled with trace levels of 1-pyrenylmethyl methacrylate. The pyrene fluorescence measurable I1/I3 is sensitive to molecular caging, which increases with stiffness. At 140 °C, molecular caging and hence stiffness in single-layer PS films supported on silica is independent of thickness down to 240 nm and increases with decreasing thickness at 165 nm and below. In contrast, near Tg at 100 °C and in the glassy state at 60 °C, molecular caging and hence stiffness in single-layer films is independent of thickness down to 63 nm and increases with decreasing thickness at 36 nm and below. In bulk bilayer films, perturbations originating at the substrate interface (free-surface interface) cause major increases (decreases) in caging and hence stiffness in 20-nm-thick substrate-adjacent (free-surface-adjacent) layers. In contrast, in 40-nm-thick bilayer films, the 20-nm-thick substrate-adjacent and free-surface-adjacent layers exhibit little difference in caging and stiffness. Thus, the gradient in stiffness from a film interface depends significantly on confinement, which we hypothesize begins to occur when thickness becomes comparable to the combined length scales over which free-surface and substrate perturbations propagate inside the film. Bulk bilayer films were used to investigate the length scales associated with interfacial perturbations. At 100 °C and 60 °C, stiffness-gradient length scales extend ∼45–85 nm from the substrate and ∼35–85 nm from the free surface. At 140 °C, the stiffness-gradient length scales extend ∼85–200 nm from the substrate and ≲ 20 nm from the free surface.

Synthesis, morphology, and electrical memory application of oligosaccharide-based block copolymers with π-conjugated pyrene moieties and their supramolecules

Transistor memory applications of maltoheptaose-block-poly(1-pyrenylmethyl methacrylate), and their supramolecules with (4-pyridyl)-acceptor-(4-pyridyl).

Fluorescent-magnetic Janus particles prepared via seed emulsion polymerization

Anisotropic polymeric colloidal or Janus particles possessing simultaneous magnetic and fluorescent properties were successfully prepared via the swelling-diffusion or the in situ emulsion polymerization method. In the swelling-diffusion process, magnetic emulsions (an organic ferrofluid dispersed in aqueous medium) were synthesized and used for seeds of submicron magnetic Janus particles. After swelling the anisotropic particles obtained by 1-pyrene-carboxaldehyde fluorescent dye dissolved in tetrahydrofuran, well-defined fluorescent-magnetic Janus particles were produced. In the in situ emulsion polymerization, styrene monomer mixed with fluorescent dye monomers, i.e., 1-pyrenylmethyl methacrylate (PyMMA) or fluorescein dimethacrylate (FDMA), and an oil-soluble initiator (2,2′-azobis(2-isobutyronitrile)) were emulsified in the presence of magnetic seed emulsions. The confocal microscopic images showed the fluorescent-magnetic Janus particles with high fluorescent intensity when a fluorescent crosslinker monomer FDMA was employed.

Pd‐mediated polymerization of diazoacetates with aromatic ester group: Synthesis and photophysical property of poly(1‐pyrenylmethoxycarbonylmethylene)

Pd-mediated polymerization of 1-pyrenylmethyl diazoacetates affords poly(1-pyrenylmethoxycarbonylmethylene) (poly4′), whose CC main chain is tightly surrounded by pyrene groups. The intensity ratio of excimer emission to monomer emission (IE/IM) of poly4′ was more than 20 times higher than that of its vinyl polymer counterpart of poly(1-pyrenylmethyl methacrylate) (polyPyrMA), clearly demonstrating much higher efficiency for excimer formation in poly4′, because of the tight arrangement of the pyrene groups around the main chain.

A novel poly[(N-vinylimidazole)-co-(1-pyrenylmethyl methacrylate)] ferric complex with fluorescence and superparamagnetism

Due to its unique physical and chemical properties, the polymer N-vinylimidazole (VI), either as a homopolymer or copolymer, has a large number of important applications. Currently, technological advances have identified further uses for it and there are practical demands for multiply functional forms of the polymer; e.g., fluorescence and magnetism in one VI-polymer material. Toward this end, a novel poly[(N-vinylimidazole)-co-(1-pyrenylmethyl methacrylate)] (VI-co-PyMMA) ferric complex prepared by complexing a VI-co-PyMMA copolymer with 1-chlorobutane and FeCl3 in succession is presented in this work. The complexed FeCl3, which predominately exists as the FeCl4− anion, endows the resultant material with superparamagnetism; while the presence of pyrene moieties allows the complex to exhibit additional fluorescence. Both the fluorescence and magnetism exhibit a strong dependence on the content of the complexed FeCl3 but in opposite manners. The preferred complex, S4, shows a balance of the properties, with a fluorescence quantum yield of 0.13 and a magnetic susceptibility of 16.1 × 10−6 emu g−1. Along with re-dispersibility, this single-component fluorescent–magnetic material may replace some corresponding multi-component nanomaterials, where the polymer component acts only as a protective coating and/or an organic fluorophore and the magnetic performance is usually provided by magnetic nanoparticles (MNPs). It may find potential applications in the booming biotechnology field.

Synthesis of photo- and pH-responsive composite nanoparticles using a two-step controlled radical polymerization method

We present a versatile synthetic method for photo- and pH-sensitive composite nanoparticles using a combined use of reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP). Crosslinked nanoparticles of a random copolymer composed of methyl methacrylate (MMA), 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) were first synthesized using RAFT miniemulsion polymerization in aqueous solution. This was followed by solvent exchange through extraction and dialysis that allowed the nanoparticles to be transferred to and highly swollen in an organic solvent (anisole or THF). By dissolving a monomer of a stimuli-responsive polymer in the solution, subsequent ATRP grafting polymerization could be initiated by halide groups on the swollen nanoparticle, resulting in larger composite nanoparticles. Photosensitive poly(1-pyrenylmethyl methacrylate) (PPyMA) and pH-sensitive poly(dimethylaminoethyl methacrylate) (PDMAEMA) were incorporated in the composite nanoparticles, and their photo- and pH-responsive behaviors were investigated. With this method, monomers soluble in organic solvents can be used in conjunction with emulsion polymerization in aqueous solution to design functional composite nanoparticles.

Preparation of highly monodisperse fluorescent polymer particles by miniemulsion polymerization of styrene with a polymerizable surfactant

Miniemulsion polymerization of styrene (St) in the presence of a hydrophobe (hexadecane:HD) using a cationic polymerizable surfactant ( N , N -dimethyl- N - n -dodecyl- N-2-methacryloyloxyethylammonium bromide:C 12Br) and a cationic initiator (2,2′-azobis(2-amidinopropane) dihydrochloride:V50), called St/C 12Br/V50 hereafter, proceeded efficiently compared with that using sodium dodecyl sulfate (SDS) and potassium persulfate (KPS), i.e., St/SDS/KPS, providing monodisperse polystyrene latex particles with a narrower particle size distribution. In St/C 12Br/AIBN, where an oil-soluble initiator, i.e., 2,2′-azobisisobutyronitrile (AIBN), was used in place of V50, little changes in polymerization kinetics or in particle size distribution were observed, while a significant drop in polymerization rate and a broad particle size distribution were observed with St/SDS/AIBN. A polymerizable pyrene derivative (1-pyrenylmethyl methacrylate: PyMMA) was quantitatively incorporated into monodisperse latex particles in St/PyMMA/C 12Br/V50 compared to pyrene (Py) in St/Py/C 12Br/V50. Contrary to our expectation, however, increased excimer emission was observed with St/PyMMA/C 12Br/V50 particles, indicating less evenly distributed pyrene chromophores in the particles. The fluorescence lifetime of pyrene chromophores in St/Py/C 12Br/V50 particles was determined to be 286 ns, which was 17 times longer than that of pyrene in THF solution.

Stabilizing Ion Pairs in Poly(methyl methacrylate)

Decay of ions trapped in γ-irradiated poly(methyl methacrylate) (PMMA)-containing ion scavengers was examined. Cations in PMMA migrate through diffusion and by a hopping transfer of the charge. They encounter anions, combine, and thereby decay. The diffusion of cations was confirmed by a comparison of decay of ions in PMMA-containing pyrene and that in a copolymer of methyl methacrylate and 1-pyrenylmethyl methacrylate. Cations in the former sample decay faster than those in the latter sample. The ions in the copolymer are chemically bonded to the polymer chains, preventing the diffusion of the ions. However, the dependence of the decay of the ions on the concentration of pyrenyl groups indicated that the ions decay through a hopping transfer of the charge on pyrenyl groups. The hopping transfer was suppressed by triphenylamine. The suppression is ascribed to structural difference in neutral triphenylamine and its cation. Anions in PMMA are ketyl-type anions at the side chains of the polymer. Their migrat...

SPECTRAL CHARACTERISTICS OF FREE AND LINKED PYRENE-TYPE CHROMOPHORES IN SOLUTION, POLYMER MATRICES, AND INTERPENETRATING NETWORKS

Monomers, 1-pyrenylmethyl methacrylate (PyMMA), 1-pyrenylbutyl methacrylate (PyBMA), 4-(1-pyrenyl)methoxymethyl styrene (PyMMS) and allyl-(1-pyrenylmehtyl) ether (PyMAE), with pyrene as chromophore, were prepared. Their spectral properties (absorption, emission and emission decay) in solution, and doped or bonded in polymer matrices and complex polymer systems as interpenetrating polymer networks (IPN), were investigated. Spectral properties of pyrene-containing monomers doped in polystyrene (PS), polymethylmethacrylate (PMMA), polyvinylchloride (PVC), polyethylene (PE) and grafted on PE as well as copolymerized in buthylmethacrylate-co-styrene copolymer (BMA-co-S) have been compared. Absorption and emission spectra of pyrene type probes in solution and in IPN matrices exhibit typical absorption of the pyrene moiety. For IPN with grafted probes on PE, the absorption is slightly shifted to red wavelength. For monomers, PyMMA, PyBMA and PyMAE grafted to PE, the shape of the emission spectrum depends on the wavelength of excitation. The ratio of intensity of the vibrational band, I1/I3, (I1 peak at 377 nm and I3 peak at 388 nm) has been a quite useful indicator of polarity of IPN. The relative quantum yields of fluorescence in IPN matrices are lower in comparison to polymer matrices of PE, PS, PMMA for all probes under study. The fluorescence life-times for bound and free probes have been in the range 100–200 ns, which is substiantialy shorter than for the parent pyrene chromophore under the same or similar condition. Grafted probes on PE alone, or as a part of IPN, exhibit substantially shorter life-time around 10 ns and decay is rather complex.

Picosecond excimer fluorescence spectroscopy: applications to local motions of polymers and polymerization monitoring

The local motions of α,ω-bis-(1-pyrene)alkanes and pyrene-labelled poly(methyl methacrylate) polymers in solution were characterized by picosecond excimer fluorescence spectroscopy. The experimental results showed that 1,3-bis-(1-pyrene)propane and 1,10-bis-(1-pyrene)decane have similar local motions that bring two pyrene groups together to form excimers. Further, poly(1-pyrenylmethyl methacrylate) and a copolymer of methyl methacrylate and 1-pyrenylmethyl methacrylate in solution were found to have similar local motions that lead to excimer formation. In addition, the viscosity change during the polymerization of methyl methacrylate was monitored by measuring with picosecond fluorimetry the fluorescence lifetime of a trace amount of 1,3-bis-(1-pyrene)propane dissolved in methyl methacrylate.