Abstract

Abstract

Four heterocyclic hexaarylbiimidazoles, BFuTM-HABI, BThTM-HABI, BCTFu-HABI, and BCTTh-HABI, were synthesized to improve the UV-vis absorption properties of hexaarylbiimidazoles. UV-vis spectra, fluorescence spectra, ESR measurements, photo-dilatometer experiments, and photo-DSC measurements indicate that BCTFu-HABI and BCTTh-HABI exhibit better UV-vis absorption abilities and photoinitiation activities for acrylate derivatives with different functionalities than BFuTM-HABI and BThTM-HABI, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

A water-soluble supramolecular-structured photoinitiator (SSPI) was synthesized by supramolecular self-assembling between methylated β-cyclodextrin (MβCD) and hydrophobic 2,2-dimethoxy-2-phenylacetophenone (DMPA). The structure of SSPI was characterized by X-ray diffraction, FTIR, ¹H NMR, UV–vis, and fluorescence spectra. The results indicated that MβCD and DMPA had formed 1 : 1 inclusion complex in methanol solution. The binding constant (K) for the complex was 7.51 × 10²M⁻¹. SSPI could be dissolved in water easily and its water-solubility was 15.3 g/100 mL. SSPI was the more efficient photoinitiator than DMPA for the photopolymerization of acrylamide (AM) in homogeneous aqueous system. The conversion for photopolymerization of trimethylolpropane triacrylate system initiated by SSPI was similar to that initiated by DMPA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Three PU-type polymeric photoinitiators containing side-chain benzophenone and coinitiator amine, PUSBA-h, PUSBA-t and PUSBA-i, were synthesized via polycondensation of 3,5-diamino-4′-thiophenylbenzophenone, different diisocyanates and N-methyldiethanolamine. FT-IR, ¹H NMR and GPC analyses confirm the structures of all polymers. The UV-vis spectra of polymeric photoinitiators are similar and all exhibit the maximal absorption near 320 nm. ESR spectra show PUSBA-h and PUSBA-t can efficiently generate free radicals. The photopolymerization of trimethylolpropane triacrylate and the PU prepolymer, initiated by these polymeric photoinitiators, was studied by photo-DSC. The results indicate that the macromolecular structure has an important effect on photopolymerization, and different photoinitiators exhibit different behavior towards different monomers: PUSBA-t is the most efficient for TMPTA and PUSBA-h is the most efficient for PU prepolymer. The final conversion for the photopolymerization of PU prepolymer initiated by PUSBA-h is greater than 97%.

A novel chemically bonded polymerizable photoinitiator 4-[(4-maleimido)phenoxy]benzophenone (MPBP) comprising the structure of planar N-phenylmaleimide (NPMI) and benzophenone (BP), compared with the physical mixtures of NPMI/BP or NPMI/4-hydroxybenzophenone, was investigated to disclose the mutual influence between NPMI and BP. A BP derivative, 4-phenoxylbenzophenone, was selected as the model compound. Electron spin resonance spectra of such photoredox systems indicated MPBP and BP possess the same initiation mechanism. The large red-shifted π–π* absorption of MPBP should be because of the phenoxyl group in MPBP but not the maleimide group. The photopolymerization of methyl methacrylate (MMA) and 1,6-hexanediol diacrylate (HDDA) initiated by those systems, using the unsaturated tertiary amine N,N-dimethylaminoethyl methacrylate (DMAEMA) as the coinitiator (H donor), was studied through dilatometry and photo-differential scanning calorimetry. The results showed that MPBP was more efficient for the photopolymerization of MMA and HDDA than its physical mixture counterpart. The high efficiency of MPBP may be mainly because of the interaction between NPMI and BP group but not the phenoxyl group alone. A certain amount of NPMI can accelerate the photopolymerization when added to the formulations, but too much NPMI will eventually decrease the photoefficiency. Copyright © 2006 Society of Chemical Industry

A novel thio-containing diamine with a benzophenone structure, 4-amino-4′-[4-aminothiophenyl]benzophenone (AATBP), was synthesized. Two kinds of polymeric photoinitiators, PUPIA and PUPI, were synthesized through the polycondensation of toluene-2,4-diisocyanate with AATBP and/or N-methyldiethanolamine (MDEA). A macroamine, PUPA, was also synthesized for comparison. Fourier transform infrared, ¹H NMR, and gel permeation chromatography analyses confirmed the structures of all the polymers. The ultraviolet–visible spectra of PUPIA, PUPI, and AATBP were similar, and all exhibited the maximal absorption above 325 nm. The photopolymerization of two monomers with different functionalities, poly(propylene glycol)diacrylate and trimethylolpropane triacrylate initiated by PUPIA, PUPI/MDEA, PUPI/PUPA, AATBP/MDEA, and AATBP/PUPA, was studied through differential scanning photocalorimetry. The results showed that both PUPIA and PUPI/MDEA had high photoefficiency, and their low-molecular-weight counterparts could hardly initiate the photopolymerization. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 576–587, 2007

A novel hexaarylbiimidazole derivative 2,2′-bis-(2-chlorophenyl)-4,4′,5,5′-tetra-[3-(2-hydroxyl-3-ethylene glycol monoethylene ether-propane-1-oxy)-phenyl]-1,2′-biimidazole (BCTE-HABI) was synthesized from 3,3′-dihydroxyl benzil. Ultraviolet spectra, fluorescence spectra, ESR measurements, photo-dilatometer experiments and photo-DSC measurements indicated its good UV-visible absorption ability, high photolysis efficiency and efficient photo-initiation for acrylates. Copyright © 2006 Society of Chemical Industry

Four kinds of polymerizable N-aromatic maleimides (MIs)—4-[(4-maleimido)phenoxy]benzophenone (MPBP), 4,4′-bis[(4-maleimido)phenoxy]benzophenone (BMPBP), 4-maleimidobenzophenone (MBP), and 4,4′-bismaleimidobenzophenone (BMBP)—were synthesized as free radical photoinitiators, by introducing directly N-phenylmaleimide groups or maleimide groups into the molecule of benzophenone (BP). Compared with BP, their UV-visible spectra have a significantly red-shifted maximum absorption. The maximum absorption of MIs containing bifunctional maleimide groups is slightly larger than the corresponding monofunctional ones. Choosing an unsaturated tertiary amine N,N-dimethylaminoethyl methacrylate (DMAEMA) as coinitiator, the photopolymerization of 1,6-hexanediol diacrylate (HDDA), initiated by these four MIs, was studied through photo-DSC. The results show that all the MIs are dramatically more efficient than BP. Among them, MPBP is the most efficient, in which the polymerization rate is almost three times as high as that of the BP system. Photoinitiators containing bifunctional maleimide groups, though having higher final conversion, are less efficient than the corresponding monofunctional ones. These polymerizable photoredox systems significantly reduced the migration of the active species, leading to their higher efficiency. Copyright © 2006 Society of Chemical Industry

Summary: Three novel polymerizable sulfur-containing benzophenone photoinitiators, MAATPBP, CMAATPBP and BMAATPBP, were synthesized. These novel photoinitiators possess strongly red-shifted maximum UV absorption and very weak fluorescence emission. The photopolymerization of two monomers with different functionality, bifunctional HDDA and trifunctional TMPTA, initiated by these three polymerizable photoinitiators, was studied by photo-DSC using the unsaturated tertiary amine DMAEMA as the coinitiator. The results show that all the polymerizable photoinitiators were highly efficient and different photoinitiators exhibited different behaviors towards different monomers: BMAATPBP was the most efficient for HDDA; MAATPBP was the most efficient for TMPTA. They could also efficiently initiate the photopolymerization without the coinitiator because of photolysis at the CS bond.

Summary: By the polycondensation of TDI with DATBP or AATBP, and different coinitiator amines, six novel thio-containing polymeric photoinitiators that contain a coinitiator amine and a side-chain or in-chain benzophenone (PUSBA or PUIBA) have been synthesized. FT-IR, ¹H NMR, and GPC analyses confirm the structures of all polymers. The UV-vis spectra indicate that the structure of the coinitiator amines has no significant influence on the maximal absorption. ESR spectra indicate that the polymeric photoinitiators that contain PDEA moieties can generate free radicals most efficiently. Three types of monomer with different functionality, EA, PPGDA, and TMPTA, are chosen to be initiated by these polymeric photoinitiators. The results show that the structure of the coinitiator amines has an important effect on the photopolymerization. For the PUSBA photoinitiators, the photoinitiator that contains N-phenyldiethanolamine as the coinitiator amine is the most efficient for EA, and that with N-butyldiethanolamine is the most efficient for both PPGDA and TMPTA. As for the PUIBA photoinitiators, that containing N-phenyldiethanolamine as the coinitiator amine is the most efficient for the polymerization of the three monomers.

Summary: A novel polyurethane-type polymeric photoinitiator (PUIOA) was synthesized through polycondensation of a novel diamine AAPBP, TDI and MDEA. The BP and coinitiator amine structures were successfully introduced into the backbones of PUIOA. A polymeric photoinitiator without the coinitiator amine in the polymer chain (PUIO) was also synthesized for comparison. FT-IR, ¹H NMR and GPC analyses confirmed the structures of polymeric photoinitiators. The UV-vis spectra of PUIOA and PUIO are similar to the parent AAPBP, and both exhibit high red-shifted maximal absorption as compared with BP. ESR spectra indicate that PUIOA can generate free radicals most efficiently. Photopolymerization of the Polyurethane prepolymer, initiated by PUIOA, PUIO/MDEA, AAPBP/MDEA and BP/MDEA, was studied by photo-DSC. The results show that PUIOA is the most efficient photoinitiator for PU prepolymer.

A new monomer 1,1-bis(4-amino-3-mercaptophenyl)-4-tert-butylcyclohexane dihydrochloride, bearing the bulky pendant 4-tert-butylcyclohexylidene group, was synthesized from 4-tert-butylcyclohexanone in three steps. Its chemical structure was characterized by ¹H NMR, ¹³C NMR, MS, FTIR, and EA. Aromatic poly(bisbenzothiazole)s (PBTs V) were prepared from the new monomer and five aromatic dicarboxylic acids by direct polycondensation. The inherent viscosities were in the range of 0.63–2.17 dL/g. These polymers exhibited good solubility and thermal stability. Most of the prepared PBTs V were soluble in various polar solvents. Thermogravimetric analysis showed the decomposition temperatures at 10% weight loss that were in the range of 495–534°C in nitrogen. All the PBTs V, characterized by X-ray diffraction, were amorphous. The UV absorption spectra of PBTs V showed a range of λ_max from 334 to 394 nm. All the PBTs V prepared had evident fluorescence emission peaks, ranging from 423 to 475 nm with different intensity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2000–2008, 2006

A novel polymerizable photoinitiator, 4-[(4-maleimido)phenoxy]benzophenone (MPBP) comprising the structure of N-phenylmaleimide and benzophenone was used for the photopolymerization with N,N-dimethylaminoethyl methacrylate (DMAEMA) as coinitiator. The ESR spectrum of this photoredox system was studied and compared with BP/DMAEMA; the results showed the same signals of them and verified that N-phenylmaleimide does not generate radicals. The kinetics for photopolymerization of methyl methacrylate (MMA) using such system was studied by dilatometer. It was found that the polymerization rate was proportional to the 0.3172th power of the MPBP concentration, the 0.7669th power and the 0.1765th power of MMA concentration and DMAEMA concentration respectively; the overall apparent activation energy obtained was 31.88 kJ/mol. The polymerization kinetics of 1,6-hexanediol diacrylate (HDDA) initiated by such system was studied by photo-DSC. It showed that the increase in the MPBP concentration, light intensity, and temperature leads to increased polymerization rate and final conversion. The apparent activation energy was 11.25 kJ/mol. This polymerizable photoredox system was significantly favorable for reducing the migration of active species but owning high efficiency. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2347–2354, 2006

Summary: A polymeric photoinitiator (PTXP) containing in-chain thioxanthone (TX) and coinitiator amines was synthesized by step-growth polymerization, as well as low-molecular-weight model compounds. Photopolymerizations of methyl methacrylate (MMA) initiated by these photoinitiator systems were studied. Compared with corresponding low-molecular-weight model compounds, PTXP has a similar UV-vis spectrum with a red-shifted maximum absorption, and weaker fluorescence emission, and can photoinitiate the polymerization of MMA more effectively.

Two kinds of copolymeric macromolecular photoinitiator, PTXPM and PTXPC, were prepared by introducing methylacryloyl or cinnamoyl groups to the side chain of PTXP. The photopolymerizations of poly(propylene glycol)diacrylate (PPGDA) and trimethylolpropane triacrylate (TMPTA), using PTXPM and PTXPC as photoinitiators, were studied by photo-DSC. PTXPM and PTXPC have UV–vis spectra similar to that of PTXP with blue-shift absorption maxima. The photopolymerization behavior of TMPTA, initiated by three photoinitiators, appears similar to that of PPGDA. Compared with PTXP and PTXPC, PTXPM gives higher polymerization rate and final conversion, in photopolymerization of PPGDA and TMPTA, which shows that the introduction of methyl acrylate to the PTXP chain has a greater effect on photopolymerization of PPGDA and TMPTA than that of cinnamoyl acrylate. The polymerization rate and final conversion, for photopolymerization of PPDGA initiated by PTXP, can be more effectively increased by the introduction of methyl acrylate group to the PTXP chain, than are those for TMPTA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2395–2400, 2004

Two kinds of polyvinyl chloride (PVC)/montmorillonite (MMT) nanocomposites were prepared by the melt intercalation method based on a thermally stable, rigid-rod aromatic amine modifier and a commonly used 1-hexadecylamine. The information on morphological structure of PVC/MMT nanocomposites was obtained using XRD and TEM. The mechanical, thermal, and flame retardant properties of the nanocomposites were characterized by universal tester, DMA, TGA, and cone calorimeter. The degree of degradation of PVC was studied by ¹H-NMR. MMT treated by the aromatic amine exhibited better dispersibility than that treated by 1-hexadecylamine. The nanocomposites, based on this MMT, consequently exhibited better mechanical, thermal, and flame retardant properties and lower degradation degree than those based on 1-hexadecylamine-treated MMT. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 567–575, 2004

A series of photosensitive hyperbranched polyimides (HB-PIs) were prepared through facile end-group modifications of the fully imidized polymer. A triamine, 1,3,5-tris(4-aminophenoxy)benzene, and a dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, were condensed with a dropwise addition method in a molar ratio of 1/2 to afford an anhydride-terminated poly(amic acid) precursor, which was then end-capped by 4-aminophenol and chemically imidized to yield a phenol-terminated HB-PI. The modifications of the terminal phenol groups of the polyimide by acyl chloride compounds (acryloyl chloride, methylacryloyl chloride, and cinnamoyl chloride) gave the target polymers. The photosensitive HB-PIs showed good thermal properties and excellent solubility even in low-boiling-point solvents at room temperature, such as acetone, 1,1,2-trichloroethane, tetrahydrofuran, and chloroform. Photosensitive property studies revealed good photolithographic properties with a resolution greater than 3 μm and a sensitivity of 650–680 mJ/cm². © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1735–1744, 2004

A novel aromatic amine organo-modifier synthesized in our previous work was used to treat montmorillonite (MMT) and the organo-modified MMT was used to prepare poly(etherimide) (PEI)/MMT nanocomposites by a melt intercalation method. MMT treated by this amine exhibited large layer-to-layer spacing and a high ion-exchange ratio (>95%). The nanocomposites were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical analysis, a universal tester, thermogravimetric analysis, and by differential scanning calorimetry. The results of XRD and TEM showed that the nanocomposites formed exfoliated structures even when the MMT content was 10 wt %. When the MMT content was below 3 wt %, the PEI/MMT nanocomposites were strengthened and toughened at the same time. The nanocomposites also showed marked decreases in coefficient of thermal expansion and solvent uptake. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1857–1863, 2003

Benzophenone-containing, anhydride-terminated hyperbranched poly(amic acid)s were end-capped by ortho-alkyl aniline in situ and then chemically imidized, yielding autophotosensitive hyperbranched polyimides. The polyimides were soluble in strong polar solvents, such as N-methyl-2-pyrrolidone, N-dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Thermogravimetric analysis revealed their excellent thermal stability, with a 5 wt % thermal loss temperature in the range of 527–548 °C and a10 wt % thermal loss temperature in the range of 562–583 °C. The strong absorption of the polyimide films in ultraviolet–visible spectra at 365 nm indicated that the hyperbranched polyimides were patternable. Highly resolved images with a line width of 6 μm were developed by ultraviolet exposure of the polymer films. A well-defined image with lines as thin as 3 μm was also patterned, but the lines were rounded at the edges. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2026–2035, 2003

A series of photocrosslinkable, side-chain, second-order nonlinear optical (NLO) poly(ester imide)s (PEIs) based on a chromophore-containing dianhydride, 2,2′-{4-[(4-nitrophenyl)-azo]phenyl}iminobis(ethyl benzene-1,2-dicarboxylic acid anhydride-4-carboxylate), benzophenone-3,3′,4,4′-tetracarboxylic dianhydride, and 4,4′-diamino-3,3′-dimethyl diphenylmethane were prepared. The resulting PEIs exhibited many useful physical characteristics, such as good organosolubility, excellent film-forming properties, high glass-transition temperatures (186–229 °C), and high thermal decomposition temperatures. The electrooptic coefficient value of PEI3 at 650 nm was 11.5 pm/V, and high long-term stability of the NLO chromophore alignment in the poled PEI3 film at 120 °C was observed. The temporal stability of the dipole orientation at 150 °C was further enhanced by ultraviolet irradiation because of photocrosslinking. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 303–312, 2003

A triamine monomer, 1,3,5-tris(4-aminophenoxy)benzene (TAPOB), was synthesized from phloroglucinol and 4-chloronitrobenzene, and it was successfully polymerized into soluble hyperbranched polyimides (HB PIs) with commercially available dianhydrides: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′-oxydiphthalic anhydride (ODPA), and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA). Different monomer addition methods and different monomer molar ratios resulted in HB PIs with amino or anhydride end groups. From ¹H NMR spectra, the degrees of branching of the amino-terminated polymers were estimated to be 0.65, 0.62, and 0.67 for 6FDA–TAPOB, ODPA–TAPOB, and BTDA–TAPOB, respectively. All polymers showed good thermal properties with 10% weight-loss temperatures (T₁₀'s) above 505 °C and glass-transition temperatures (T_g's) of 208–282 °C for various dianhydrides. The anhydride-terminated HB PIs showed lower T₁₀ and T_g values than their amino-terminated counterparts. The chemical conversion of the terminal amino or anhydride groups of the 6FDA-based polyimides into an aromatic imido structure improved their thermal stability, decreased their T_g, and improved their solubility. The HB PIs had moderate molecular weights with broad distributions. The 6FDA-based HB PIs exhibited good solubility even in common low-boiling-point solvents such as chloroform, tetrahydrofuran, and acetone. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3804–3814, 2002