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In this study, the stereocomplexation of poly- l -lactide (PLLA) and poly- d -lactide (PDLA) was monitored in real time using fluorescence spectroscopy. To introduce fluorescence probes at the beginning (i.e., α position) of the PLLA and PDLA chains, a pyrene derivative was employed as an initiator for ring-opening polymerization of l,l -lactide (LLA) and d,d -lactide (DLA), respectively, and the post-polymerization functionalization of the hydroxyl end-groups of the PLLA were obtained by initiating LLA using the BuOH/Sn(Oct)2 system to form polylactide decorated with a pyrene moiety on the opposite polymer chain-end (i.e., ω position). Using these approaches, linear Py-PLLA-OH, Py-PDLA-OH, and Bu-PLLA-Py with molar masses equal to 3100, 3350 and 3300 g mol−1, respectively, were prepared. Next, equimolar compositions of Py-PLLA-OH/Py-PDLA-OH and Py-PDLA-OH/Bu-PLLA-Py in different solvents were prepared, and the stereocomplexation, which is related to excimer formation between the Py end-groups, was directly observed using fluorescence measurements of the excimer emission at 470 nm in both AcCN and THF solutions, respectively. The kinetic curves based on the IE/IM ratio as a function of time are complex in shape and indicate interaction of two enantiomeric chains occurred. In addition, at the beginning of the association, the PLA enantiomeric pairs form stereocomplex crystallites. The probability of parallel and antiparallel interactions of PLA enantiomers during stereocomplexation is similar and consistent with Cantow's calculations. In addition, the DSC analysis of the final PLA products confirmed that only stereocomplex crystallites were formed in these two solvents.

The spectral properties of novel pyrene-piperidine/pyrene-piperidine-1-oxyl adducts with varying linkers differing in electronic conjugation between these two functionalities were investigated in solvents of different polarity. Tuning their fluorescence efficiency via structure modification is discussed in terms of increased conjugation, solvent polarity effect, main non-radiative de-excitation pathways and static/dynamic excimer or solute-solvent exciplex fluorescence. Compared to parent pyrene molecule, the main additional non-radiative de-excitation pathways leading to significant fluorescence quenching were studied using time-resolved fluorescence spectroscopy and quantum-chemical DFT (Density Functional Theory) calculations and were identified as reductive photo-induced electron transfer and intramolecular paramagnetic quenching.

Two substituted pyrene derivatives with cholesterol ((3β)-cholest-5-en-3-ol) moiety as esters were synthetized. The spectral properties of the mono-substituted derivatives of pyrene as esters with different linkages to cholesterol via carboxy unit ( PyCACh1 ) and methylene carboxy unit ( PyMECh2 ) are compared with the mono-substituted pyrene derivatives and the parent pyrene in toluene at low concentration and doped in glassy polymer matrices of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polyvinylchloride (PVC) in the concentration range of 0.002–0.06 mol kg −1 . Fluorescence spectroscopy of the pyrene derivatives in polymer matrices reveals changes in the shape of the fluorescence spectra with increasing concentration. Two limiting cases are observed: (1) a medium or large red shift of the entire fluorescence spectrum or (2) the formation of an emission band in the excimer emission region (approx. 500 nm). These changes are less pronounced in the pyrene-cholesterol esters in the PS matrix due to higher compatibility than in PMMA and PVC matrices. Exploitation of these emissions to estimate the interactions of the components in the polymer matrix is discussed.

A series of ionic benzotristhiazolium (BTT) push–pull chromophores, with different nitrogen donor groups and different lengths of conjugated bridges, was successfully doped in polar polymer matrices (PVC and PSS). The spectral (photophysical) properties of their low concentration thin polymeric films are compared with those in solution and are discussed in terms of matrix polarity/viscosity influence, specific polymer–chromophore interaction, structure–spectral property relationship and Twisted Intramolecular Charge-Transfer (TICT) state formation. The elimination of a non-emissive phantom and TICT state formation by restricted intramolecular rotations in the polymer matrix or viscous solvent results in a relatively high ΦF of all the investigated NLO-phores; particularly for near-infrared NIR molecular rotors bearing diphenylamino and julolidine donor groups. Because of cationic characteristics, small molecular weight, calculated high second hyperpolarizability and significant emission efficiency dependence on surroundings’ viscosity (rigidochromic effect), two dyes were chosen as candidates for potential fluorescent probes for one-photon (1P) and two photon (2P) cellular imaging. The selected BTT NLO-phore with a julolidine donor is promising as a mitochondria-specific fluorescent small molecular probe for live cell super-resolution imaging with low cytotoxicity and good photostability, and is also potentially suitable for super-resolution STED imaging.

The theoretical and experimental study of ten model 2,2′-bithiophene (BT) derivatives containing carbonyl chromophoric pair in position 5 is presented. In this context, the synthesis and chemical characterization of four derivatives with substituents COCF3 (trifluoroacetyl) (H_CF), COCH3 acetyl (H_Me), COCH2CN oxopropanenitrile (H_CCN) and 5′-(9H-fluoren-9-ylidenemethyl)3-methyl,5-methylcarboxylate (FL_OMe) was described. The absorption and fluorescence spectra of prepared molecules were measured in solution (dichloromethane, methanol and acetonitrile). These selected molecules, comparing to the parental BT, exhibit in absorption spectrum the bathochromic shift about 50 nm and distinct fluorescence above 400 nm. The most intense fluorescence was observed for H_CCN and H_CF molecules and their lifetime of fluorescence was measured in the range 1.0–2.6 ns. The quantum chemical calculations were used for the investigation of the molecular electronic structure, energy diagrams of excited singlet and triplet states as well as optical properties of all selected derivatives.

The adducts of simple chromophore 4-N,N-dimethylamino benzoic acid with 2,2,6,6-tetrametyl-4-hydroxy- or 4-amino-piperidine were examined as fluorescence probes (spin double sensors) to monitor radical processes. The links in the adducts were either an ester or amide group, and the sterically hindered amines were in the form of -NH, -NO• and -NOR. The spectral properties of the three related derivatives (esters or amides) were quite similar. The maxima of the absorption spectra were in the range of 295-315 nm, and the maximum of fluorescence was located in the range of 330-360 nm, depending on the polarity of the solvent. In polar solvents, a red-shifted fluorescence band at 460-475 nm was observed. The fluorescence of these derivatives was rather weak as compared to anthracene under the same conditions. The Stokes shift was large, as high as 6,000 cm(-1), indicating the formation of a twisted intra-molecular charge transfer (TICT) state. No large differences in Stokes shifts were observed in polymer matrices of poly(methyl methacrylate), polystyrene and poly(vinyl chloride). The extent of intramolecular quenching was expressed as Φ(NX)/Φ(NO) (X = H, NOR) and was in the range of 1-3 in solution and as high as 8 in polymer matrices. The low efficiency of intramolecular quenching limits the application of these new adducts as fluorescence probes for the monitoring of radical processes in solution but favors their application in polymer matrices.

The spectral properties of a novel type of Y-shaped fluorophores consisting of an imidazole ring end-capped with two electron-donating N,N-dimethylaminophenyl groups at positions C4 and C5 and one electron-withdrawing cyano group on the imidazole moiety at position C2 were examined. The π-linker separating the 4,5-bis[4-(N,N-dimethylamino)phenyl]-1H-imidazole donor moiety and the cyano group comprises 1,4-phenylene (1), (E)-phenylethenyl (2), (E)-phenylbuta-1,3-dienyl (3), biphenyl (4), (E)-phenylethenylphenyl (5) and phenylethynylphenyl (6) conjugated paths. The absorption and fluorescence spectra were obtained in toluene, dichloromethane, acetonitrile and methanol and in polymer matrices such as polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinylchloride) (PVC). The most intense absorption bands of fluorophores 1-6 were observed within the range of 283 to 330 nm. Less intense but longer-wavelength absorption bands designated as charge-transfer bands were observed at approximately 380-430 nm depending on the medium. The fluorophores exhibited strong fluorescence in the visible region with a Stokes shift of approximately 4300-5800 cm(-1) in non-polar toluene and polystyrene, whereas very low intensity of fluorescence was observed with a Stokes shift in the 6500-7800 cm(-1) region in polar methanol and acetonitrile. The large Stokes shift indicates a large difference in the spatial arrangement of the chromophore in the absorbing and emitting states. A relatively intense fluorescence (quantum yields of 0.12-0.69) was observed only for derivative 1 in all media except methanol. The fluorophores doped in matrices yielded more intense fluorescence compared with the fluorescence in liquid media. The use of solid polymer matrices lowers the probability of forming non-emissive excited states. The fluorescence lifetimes were short (1-4 ns) for all of the fluorophores in solvents and in polymer matrices.

The absorption and fluorescence spectra of substituted coumarins (2-oxo-2H-chromenes) were investigated in solvents and in polymer matrices. The substitutions involved were: (1) by groups with varying electron donating ability such as CH₃, OCH₃ and N(CH₃)₂, mainly, but not exclusively, in positions 7 and (2), by either CHO or 4-PhNHCONHN=CH- in position 3. While the spectra of non-substituted coumarin-3-carbaldehyde has absorptions at approximately 305 and 350 nm, substitution at position 7 leads to remarkable changes in the shape of the absorption spectrum and shifts the absorption to a longer wavelength. Similarly, the replacement of the formyl group with a semicarbazide group substantially influences the shape of the absorption spectrum, and coumarins which have only N(CH₃)₂ in position 7 experience small changes. These changes are associated with the increasing intramolecular charge transfer (ICT) character and increasing conjugation length of the chromophoric system, respectively, in the studied molecules. The fluorescence is almost negligible for derivatives which have H in this position. With increasing electron donating ability, and the possibility of a positive mesomeric (+M) effect of the substituent in position 7 of the coumarin moiety, the fluorescence increases, and this increase is most intense when N(CH₃)₂ substitutes in this position, for both 3-substituted derivatives. Spectral measurements of the studied coumarins in polymer matrices revealed that the absorption and fluorescence maxima lay within the maxima for solvents, and that coumarins yield more intense fluorescence in polymer matrices than when they are in solution. The quantum yield of derivatives which have a dimethylamino group in position 7 in polymer matrices approaches 1, and the fluorescence lifetime is within the range of 0.5-4 ns. The high quantum yield of 7-dimethylamino derivatives qualifies them as laser dyes which have k(F) higher than k(nr) in the given medium. This is caused by stiffening of the coumarin structure in polar polymer matrices, such as PMMA and PVC, due to higher micro-viscosity than in solution and intermolecular dipole-dipole interaction between chromophore (dopant) and matrix.

Novel chalcones (3-phenyl-1-phenylprop-2-en-1-ones) substituted on one end (position 3) with electron donating diphenylaminophenyl substituent and on the other end (position 1) with thiophenes with variable electronic effects ( CH-1 – CH-5 ) were prepared. The spectral properties of these molecules in solvents such as chloroform, cyclohexane, acetonitrile, methanol and incorporated into polymer matrices of polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC) were compared with those of 3-[4-( N , N -dimethylamino)-phenyl]-1-phenylprop-2-en-1-one ( CH-1m ) and 3-[4-( N , N -dimethylamino)phenyl]-1-(4-nitrophenyl)prop-2-en-1-one ( CH-2m ). The longest wavelength absorption band of model chalcones CH-1m and CH-2m was in the range of 400–420 nm and did not appear to be influenced by the medium. The fluorescence increased with the addition of acetonitrile, while it was effectively quenched in methanol. The strong electron-attracting nitro group quenched the fluorescence of CH-2m in nearly all solvents. In contrast, the fluorescence became more intense when the molecule was incorporated in a polymer matrix. The longest wavelength absorption band of novel chalcones was observed in the range of 410–450 nm in all media. The fluorescence of chalcones was red-shifted to the range of 530–575 nm and was most intense in chloroform. The quantum yield of fluorecence was the highest in chloroform for the chalcone with a methyl-thiophene (0.49) and low for the chalcone with a fluorenyl-thiophene group (0.07). The fluorescence of all chalcones ( CH-1 – CH-5 ) was effectively quenched in polar acetonitrile and methanol, and was less intense relative to chloroform when incorporated into a polymer matrix and more intense relative to other solvents. The lifetime of fluorescence was in the range of 1–4 ns. The Stokes shift was in the range of 4000–5000 cm −1 in chloroform, and lower in all other media. The spectral behavior of model chalcones CH-1m and CH-2m and novel chalcones with diphenylamino substituents was similar, producing observable fluorescence in several polymer matrices. The effect of the solvent on the fluorescence is discussed in terms of negative and positive solvatokinetic effects.

Novel dyes based on a benzothioxantheneimide chromophore covalently linked with a sterically hindered amine (HAS) were prepared and their light stability was tested in polymer matrices. The following dyes: 2-(2,2,6,6-tetramethyl-4-piperidyl)-thioxantheno[2,1,9-dej]isoquinoline-1,3-dione (BTXINH) and N -alkoxy derivative 2-(1-(1′-phenylethoxy)-2,2,6,6-tetramethyl-4-piperidyl)-thioxantheno[2,1,9-dej] isoquinoline-1,3-dione (BTXINOR) were prepared. For comparison the parent dye without HAS structural unit benzothioxanthene-3,4-dicarboxylic anhydride and the N-alkyl derivative 2-(1-dodecyl)-thioxantheno[2,1,9-dej]isoquinoline-1,3-dione (BTXID) and the stable nitroxyl radical 2-(1-oxo-2,2,6,6-tetramethyl-4-piperidyl)-thioxantheno[2,1,9-dej]isoquinoline-1,3-dione (BTXINO) were also tested. Their spectral properties, absorption and fluorescence have been examined in polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC) and in isotactic polypropylene (PP). The light stability of these dyes and model compounds were examined in thin polymer films. The photolysis rate was monitored by UV spectroscopy and for all additives under study it was in the range 10 −4 –10 −3 h −1 . The rate of decomposition was the lowest for the parent amine BTXINH in PMMA, PS and PVC. The rate constants of photolysis are about 10 times higher for all adducts and the lowest rate of decomposition in PP matrix was observed for BTXINOR. A distinct stabilization effect of HAS structural unit on the dye decomposition was not observed. The light stability of the dyes was more influenced by the selection of the polymer. The photolysis proceeds rather fast in PP, and moderately in PS and PVC compared to PMMA.

The spectral properties of novel bifunctional dyes based on – coumarin and diethylamino-coumarin and piperidine parent amine and N -oxyl and N -alkoxy derivatives were compared in cyclohexane, methanol, diethylene glycol, acetonitrile and chloroform solvents and in polystyrene, poly(methyl methacrylate) and poly(vinyl chloride) polymer matrices. The fluorescence of the derivatives excited at the longest-wavelength band around 295 nm is very low for coumarin-based dyes, whereas the fluorescence of the 7-diethylamino-3-carboxy coumarin dyes excited at 420 nm is as intense as that of anthracene in comparable conditions. Intramolecular quenching on the singlet level, monitored by fluorescence and expressed as the ratio of Φ NH /Φ NO for the parent amine and N -oxyl and Φ NOR /Φ NO for N -alkyloxy and N -oxyl, is more efficient in polymer matrices than in solvents. The spectral properties of 7-diethylamino-3-carboxy coumarin fluorophores depend on the polarity and viscosity of the environment. Highest values of quantum yield ratio were observed for 7-diethylamino-3-carboxy coumarin dyes in polystyrene and poly(vinylchloride). Though the fluorescence intensity is higher in chloroform or in poly(vinyl chloride) matrices, the intramolecular quenching efficiency of a given fluorophore by nitroxide is higher in low polarity media, such as cyclohexane and polystyrene.

Spectral properties of novel type of fluorophores consist of a π-conjugated system end-capped with an electron-donating N,N-dimethylaminophenyl group and an electron-withdrawing imidazole-4,5-dicarbonitrile moiety were examined. An additional π-linker separating these two structural units comprises simple bond (B1P), phenyl (B2B), styryl (B3S) and ethynylphenyl (B4A) moieties. The absorption and fluorescence spectra were taken in cyclohexane, chloroform, acetonitrile, methanol and in polymer matrices such as polystyrene, poly(methyl methacrylate) and poly(vinylchloride). The longest-wavelength absorption band was observed in the range of 300 to 400 nm. Intense fluorescence with quantum yields of 0.2 to 1.0 was observed in cyclohexane, chloroform and in polymer matrices within the range of 380 to 500 nm. The fluorescence was strongly quenched in neat acetonitrile and methanol. The fluorescence lifetimes are in the range of 1-4 ns for all measured fluorophores. The large Stokes shift (4,000 to 8,000 cm(-1)) indicates a large difference in the spatial arrangement of the chromophore in the absorbing and the emitting states. The observed fluorescence of all fluorophores in chloroform was quenched by 1-oxo-2,2,6,6-tetramethyl-4-hydroxy piperidine by the diffusion-controlled bimolecular rate (cca 2 × 10(10) L mol(-1) s(-1)). Polar solvents such as acetonitrile and methanol quenched the fluorescence as well but probably via a different mechanism.

Spectral properties of bichromophoric pyrene probes with different linkage between pyrene units were compared in chloroform, cyclohexane and methanol, as well as in the polymer matrices polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC). The derivatives under study were pyrene, di(1-pyrenylmethyl) ether (DiPyM), 4-(1-pyrenemethoxymethyl) phenylethene (PyS) and 2,3-di(4-(1-pyrenemethoxymethyl)phenyl)butane (DiPyS). The absorption spectra of the probes exhibited well-resolved bands that were only slightly influenced by substitution and medium. Parent pyrene and PyS, exhibited well-resolved monomer fluorescence in all media, which indicated a weak solvent effect. DiPyM and DiPyS exhibited strong excimer fluorescence in solutions of low viscosity. The influence of the viscosity on the ratio of excimer and monomer emission Φ exc / Φ em of DiPyS and DiPyM in diethylene glycol was also studied. In polymer matrices, only monomer emission of DiPyM and DiPyS was observed. However, the lifetime of monomer emission was influenced by the medium.

Fluorescent probes pyrene (Py), di(1-pyrenylmethyl)ether (DiPyM) and newly synthesized 2,3-bis-[4-(1-pyrenemethoxy)methylphenyl]butane (DiPyS) were used to monitor the formation and aging of silica hydrogel prepared from poly(glyceryl silicate) (PGS) sol. The fluorescence emission spectra of these probes are sensitive to their environment and this feature is utilized for monitoring the evolution of silica hydrogels prepared in this work. The polarity of hydrogel matrix during sol–gel transition assessed by all three pyrene probes decreases in the first stage of hydrogel formation, for about 2 h, followed by a gradual increase in polarity and reaching the constant level after 24 h for at least 2 weeks. The process of crosslinking was assessed by DiPyM and DiPyS. These fluorescent probes possess two pyrene structures, which ability to form a dynamic intramolecular excimer can be used to monitor the degree of hydrogel crosslinking with time. These data support the polarity measurements that the hydrogel network is predominatly formed within the first 2 h, stabilized within the 24 h, and that there is a minor increase in the network density for about 10 days until reaching the constant level. In addition, utilizing the second-order diffraction of scattered excitation light may also be used to obtain an adequate information about the silica hydrogel evolution. In summary, this paper demonstrates that pyrene-type fluorescent probes represent simple and precise tool for characterization of formation and aging of the silica hydrogels.

Novel series of chromophore-nitroxide adducts were synthesized for the monitoring of photophysical and photochemical processes in solution as well as in a polymer matrix. These adducts were: (1) N-butyl-4-(1′-oxy-2′,2′,6′,6′-tetramethyl-4′-piperidylamino)-1,8-naphthalimide, BUNO – paramagnetic probe has been synthesized having the nitroxyl radical substituent acting as a quencher attached to the naphthalene in position 4 of 1,8-naphthalimide while imino nitrogen was substituted by n-butyl group. (2) N-(1′-oxy-2′,2′,6′,6′-tetramethyl-4′-piperidyl)-4-dimethylamino-1,8-naphthalimide – DMANO, where nitroxyl unit is on imino nitrogen of 1,8-naphthalimide while in position 4 of 1,8-naphthalimide there is dimethylamino substituent. Diamagnetic parent amine (BUNH, DMANH) were used as standard samples for comparison of the efficiency of intramolecular quenching. Absorption and fluorescence spectra of probes were taken in solution as well as in polymer films. In their absorption spectrum the longest wavelength band lies in the range from 400 up to 440 nm depending on the medium. In fluorescence spectrum the maximum lies in the range from 460 to 530 nm. When compared with less polar media the maxima of absorption and fluorescence spectra in polar media are red-shifted. The fluorescence is observed for all probes but there is distinctly much higher for parent amine and alkoxyamine than for respective mono-nitroxyl radical. The extent of intramolecular quenching, represented by the ratio of quantum yields of diamagnetic and paramagnetic forms, for both pairs BUNH/BUNO and DMANH/DMANO is in the range 2–15 depending on the medium. Intramolecular quenching in solvents for both pairs of mono-nitroxyl radical (BUNH/BUNO and DMANH/DMANO) exhibits an additive effect when compared with bi-nitroxyl radical (DINH/DINO) investigated previously.

The synthesis, spectral measurements and theoretical study of simple model oligothiophenes terminated symmetrically or asymmetrically by (10H-anthracen-9-one) methylene chromophore are presented. The electron absorption spectra of these novel molecules were measured in polymer matrices and chloroform solution. The absorption spectra of investigated systems measured in chloroform are characterised by a broad low energy band with partially distinguished vibrational structure. Theoretical calculations of electronic ground state structures have been performed at the density functional theory (DFT) level of the theory. The vertical excitations energies were calculated using the time-dependent version of DFT (TD-DFT) and semiempirical Zerner's Intermediate Neglect of Differential Overlap methods. The role of the termination group upon the vertical excitation was estimated from the localisation of highest and lowest occupied orbitals. This analysis showed that the excitation energy transfer upon the optical excitation leads from the thiophene chromophores into the central part of (10H-anthracen-9-one) methylene unit.

Novel probes representing connection of 1,8-naphthalimides as chromophore and two structural units of sterically hindered amine stabilizer (HAS) were synthesized. One HAS unit was situated on naphthalene ring in position 4 and second HAS created imide composition. HASes were in the form of parent amine – DINH, stable nitroxyl radical – DINO and substituted hydroxylamine DINOR. Absorption and fluorescence spectra of probes were taken in solution as well as in polymer films. In absorption spectrum the longest wavelength band was shifted from 410 nm in non-polar cyclohexane to 440 nm in polar methanol. In fluorescence spectrum the maximum of the broad band is red shifted from 460 nm in cyclohexane to 530 nm in methanol. All derivatives exhibit similar solvatochromism in absorption as well as in fluorescence spectrum. The fluorescence is observed for all probes but there is distinctly much higher fluorescence intensity for parent amine DINH and alkoxyamine DINOR than for adequate bi-radical DINO. The extent of fluorescence enhancement comparing amine and alkoxyamine derivatives with bi-radical is in the range 10–70 depending on the medium. Using laser flash photolysis the probe DINH exhibited transient absorption after 266 nm excitation in the nanosecond time scale region which is ascribed to triplet state. This transient absorption is red shifted in going from non-polar cyclohexane (460 nm) to polar methanol (520 nm). No (or extremely weak transient) absorption spectra was observed for stable nitroxyl bi-radical DINO.

The synthesis, spectral measurements and theoretical study of oligothiophenes terminated by (9H-fluoren-9-ylidene)methyl chromophores at the one (series A N ) and both (series B N ) ends are presented. The electron absorption and fluorescence spectra of prepared molecules were measured in polymer matrices and chloroform solution. The absorption and fluorescence spectra of the investigated systems are represented by broad band without vibrational structure. Well detectable fluorescence is observed for the compounds of the B N family. The experimentally observed medium large Stokes shifts (less than 5000 cm −1 ) indicate restricted geometrical changes in molecular chain upon optical excitation. Experimental lifetimes of fluorescence are shorter than 1 ns. Theoretical calculations have been performed at the semiempirical Austin Model 1 (AM1) and density functional theory (DFT) levels of the theory. The planarisation of dihedral angles between the fluorene and thiophene chromophores upon optical excitation theoretically was characterised, as well.

Maleic anhydride addition to polystyrene in diluted dioxane solutions initiated by radiation of wavelength longer than 340 nm proceeds only in the presence of sensitizers, such as benzophenone and acetophenone. The degree of addition is, however, about 17 times less than for low-molecular maleic anhydride addition to cumene under similar conditions. Due to the concentration effect, the efficiency of the bonded sensitizer exceeds that of the freely added one by up to three times in this instance. Quenching experiments showed that maleic anhydride acts as a quencher of poly (vinyl phenyl ketone) photolysis (Ksv = 31.5 1./mole) and copolystyrene/vinyl phenyl ketone (Ksv = 41.5 1./mol), although acting with only one-half of the efficiency obtained with naphthalene. A comparison of the quenching efficiency of naphthalene with that of maleic anhydride for poly (vinyl phenyl ketone) (1.43) and copolystyrene/vinyl phenyl ketone (1.32) leads to the conclusion that in diluted dioxane solution there is no interaction of maleic anhydride with aromatic nuclei in the copolymer. The sensitized photoaddition is supposed to proceed via an attack by the excited maleic anhydride in the triplet state on the aromatic nucleus and not by the excited state of the charge transfer complex between maleic anhydride and the aromatic nucleus.

The Stern-Volmer constant of 40 quenchers was determined at 366 nm for poly(vinyl phenyl ketone) photolysis in benzene and dioxane solution at room temperature. Aromatic hydrocarbons, dienes and olefins were used as quenchers. A procedure for quantitative separation of the screening effect of quenchers absorbing at irradiation wavelength was elaborated. The correctness of this procedure was checked using 2-hydroxy-5-methyl benzophenone over the concentration range 0-10−3 mole/1. The values of the Stern-Volmer constants lay within the range 0-250 1./mole, expressing changes of the rate constant of quenching. Stern-Volmer constants were found to be constant for naphthalene, its alkyl, halogen derivatives and esters at about 70 1./mole, that of 1-naphtyl amine 1- and 2-naphtol being, however, substantially higher. Electron-deficient olefins were equally effective as dienes. There has not so far been found a parameter to characterize unambiguously the quenching efficiency of the compounds investigated.

New types of combined chromophore–HAS (Hindered Amine Stabilizer) fluorescence probes were prepared and their photo-stability as well as their photo-stabilizing efficiency was tested in polypropylene film. The chromophore was benzothioxanthene and HAS was 2,2,6,6-tetramethylpiperidine. They were prepared by a one-step synthesis from benzothioxanthene-3,4-dicarboxylic anhydride (BTXA) by condensation with 4-amino-2,2,6,6-tetramethylpiperidine to obtain the probe in the form of parent amine (BTXI-NH) and 4-amino-1-oxy-2,2,6,6-tetramethylpiperidine in the case of stable nitroxyl radical form (BTXI-NO). Kinetics of BTXA photo-decomposition followed by UV spectroscopy were similar to kinetics of photo-decomposition for derivatives with covalently linked HAS i.e. BTXI-NH and BTXI-NO. It consists of two parts, slower in the beginning and very fast at the end of the process. Better stability of BTXI-NO in comparison with BTXI-NH can be explained by the presence of stable nitroxyl radical in its structure. The rate of decomposition of the fast part is similar for both additives. As soon as the decomposition starts there is no influence of NO or NH on this process. Times represented the start of the fast decomposition of probes correspond to the induction period of photo-oxidation of PP films. Possible effect of mutual interaction of chromophore and HAS coupled in one molecule (BTXI-NH or BTXI-NO) during photo-oxidation was followed by comparison with the course of photo-oxidation of PP film containing physical mixture of chromophore in the form of BTXA and HAS in the form of parent amine (4-hydroxy-2,2,6,6-tetramethylpiperidine) and stable nitroxyl radical (4-hydroxy-2,2,6,6-tetramethylpiperidin- N -oxyl).

The photoperoxidation at λ > 400 nm of benzil (BZ) groups with the air oxygen to benzoyl peroxide (BP) groups in the polystyrene matrices was investigated in the presence of hindered amine stabilizer (HAS). HAS was used as a free molecule or was bound in combined molecule with BZ. HAS was in the form of parent amine as 2,2,6,6-tetramethyl-4-hydroxypiperidine (TMP) and in the form of stable nitroxyl radical 1-oxo-2,2,6,6-tetramethyl-4-hydroxypiperidine (NO). Both HAS forms effected the photooxidation of BZ structures. The main product of the photooxidation in the presence of parent amine TMP as well as in its absence is benzoyl peroxide (BP). The rate of BZ consumption increases in the presence of TMP. Irradiation of BZ in the presence of sufficient concentration of freely added NO results only in the formation of benzoic acid esters and benzoic acid, which are the main decomposition products of BP. The benzoic acid esters/benzoic acid ratio increases with the increasing concentration of NO. Bounding of BZ and TMP into one molecule (BZNH) results in slower dicarbonyl depletion, as compared with the case when mixture of BZ and TMP was used. Very slow depletion of BZ carbonyl absorption was observed in the case of bounded BZ and NO in one molecule (BZNO), in comparison with the mixture of free NO and BZ. In the case of BZNO, an effective intramolecular quenching of BZ excited triplet states with NO structures proceeds. Steady stay and dynamic emission (phosphorescence) measurements also show an effective quenching of BZ excited states by unbounded or bounded NO. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4420–4428, 2006

Most polymer materials are sensitive to long-term UV radiation, which induces generally unwanted chemical reactions responsible for their degradation and the modification of their properties. But light can also be utilized to promote some desired reaction, such as the polymerization of monomer or the crosslinking of a polymer. The main interest of using light to induce a chemical reaction (e.g., polymerization) lies in the high initiation rate nearly independent on temperature provided by intense radiation and precise spatial and temporal control.

Since 2000, every two years coworkers of the Institute of Macromolecular Chemistry of Academy of Sciences of the Czech Republic (CR) and the Polymer Institute of the Slovak Academy of Sciences (SAS) Slovak Republic (SR) meet for a conference devoted to the topics of actual cooperation and mutual interest. The main goal of the Conference meeting is to allow participants to meet younger coworkers—mainly Ph.D. students and post doctoral fellows—to present the latest results and find common interests for common projects on a bilateral or multilateral level in the Framework 6 or 7 of the research projects of the European Union.

Probes, composed of pyrene (Py) and piperazine (7,15-diazadispiro[5.1.5.3]hexadecane or 7,15-diazadispiro[5.1.5.3]hexadecane-14,16-dione) (PA) linked directly or through methylene group (Me) were prepared. Probe with direct link is 15-(1-pyrenyl)-7,15-diazadispiro[5.1.5.3]hexadecane (PyPA). In 15-(1-pyrenylmethyl)-7,15-diazadispiro[5.1.5.3]hexadecane-14,16-dione (PyMePAH) pyrene is connected with piperazine through methylene bridge. The parent amine of PyMePAH was oxidized to the form of stable nitroxyl radical (PyMePAO) in position 7. Oxidation of the amine PyPA did not yield any aminooxide. The deactivation processes of the probes were monitored by fluorescence (singlet excited state route) as well as by nanosecond laser flash photolysis techniques (triplet excited state route). The spectral features of the multifunctional probes were compared. Spectral measurements were performed in methanol and polymer matrices as polymethyl methacrylate (PMMA) and polystyrene (PS). The absorption and the fluorescence spectra of the probe PyPA do not exhibit vibrationally resolved bands while the probes with the methylene link PyMePAH (or PyMAPAO) have well resolved vibrational structure similar to that obtained with pyrene. Absorption spectra of the probes have got similar shape in solvent as well as in polymer matrix. The quantum yield of fluorescence of the PyPA relative to anthracene is rather high as compared with PyMePAH or PyMePAO in aerated methanol. The quantum yield of the PyMePAH or PyMePAO relative to anthracene is higher in deaerated methanol and polymer matrices except polystyrene. The lifetime of fluorescence of PyPA is rather short about 5 ns and those of PyMePAH or PyMePAO lies in the range above 10–300 ns. It is strongly dependent on the experimental conditions. The extent of intramolecular quenching expressed as the ratio of relative quantum yields of PyMePAH and PyMePAO and respective lifetimes is rather low indicating that the intramolecular quenching is not very effective. Nanosecond laser flash photolysis was also used to examine the triplet excited state route of deactivation of these novel probes. The formation of this excited state which exhibits a T–T absorption band in the range 360–550 nm, occurred at 355 nm laser excitation in these probes as well as for parent pyrene. Triplet states of pyrene chromophore of all probes were efficiently quenched by oxygen with rate constant about 2 × 10 9 dm 3 mol −1 s −1 . Intermolecular quenching of triplet states of the all probes by N -oxyl radical (1-oxo-2,2,6,6-tetramethylpiperidine, TEMPO) was rather low. The rate constant was evaluated to about 5 × 10 7 dm 3 mol −1 s −1 . The intramolecular triplet quenching expressed as the ratio of the rate constants of triplet decay of the oxidized probe PyMePAO to PyMePAH was 5 in methanol and 7.7 in cyclohexane.

Novel probes represented 4-substituted 1,8-naphtalic anhydride and 1,8-naphthalimide as a chromophore and sterically hindered amine in the form of parent amine as well as stable nitroxyl radical form were synthesized. Laser flash photolysis was used to examine the triplet route of deactivation. The formation of the triplet state occurred at 355 nm laser excitation exhibiting the absorption in the range 360–700 nm. Triplet states of 1,8-naphthalic anhydride chromophore were quenched by oxygen with rate constant about 2 × 10 9 dm 3 mol −1 cm −1 for unsubstituted and 4-bromo substituted derivatives. The 4-dimethylamino substitution of 1,8-naphthalic anhydride exhibited the triplet state, which was not quenched by oxygen or 1-oxo-2,2,6,6-tetramethylpiperidine (TEMPO). The same effect of 4-dimethylamino substitution was observed on the triplet state of N -(2,2,6,6-tetramethyl-4-piperidinyl)-1,8-naphthalimide. In the series of 4-bromo- N -(2,2,6,6-tetramethyl-4-piperidinyl)-1,8-naphthalimide derivatives, the weak transient triplet absorption was observed for 1-oxo derivative. Probably, the decay of triplet state of 1,8-naphthalimide chromophore is fast due to combination of two effects: paramagnetic effect of free N -oxyl radical and heavy atom effect of bromo substituent.

The syntheses, spectral measurements and the theoretical study of 2-((9H-fluoren-9-ylidene)methyl)thiophene (A), ((9H-fluoren-9-ylidene)methyl)-5-(thiophen-2-yl)thiophene (B), 1-(5-((9H-fluoren-9-ylidene)methyl)thiophen-2-yl)propan-1-one (C), 1- (5-((9H-fluoren-9-ylidene)methyl)thiophen-2-yl)pentan-1-one (D), 1,2-bis(1-(5-((9H-fluoren-9-ylidene) methyl)thiophen-2-yl)propylidene)hydrazine (E) and 1,2-bis(1-(5-((9H-fluoren-9-ylidene)methyl)thiophen-2-yl)pentylidene)hydrazine (F) are presented. The electron absorption and fluorescence spectra of prepared molecules are measured in polymer matrix and solution. The influence of the conformation (e.g. cis- and trans-forms in the case of E and F molecules) on electronic spectra are interpreted by ZINDO/S method. Our results indicate that the thiophene rings connected with terminal fluorene chromophores through the double bounded carbon atom seem to be suitable candidates for the subsequent preparation of the electro-optical materials.

Recently, interest has been aroused in the synthesis and study of optical and electronic properties of π-conjugated oligomers and polymers containing transition metal complexes. The introduction of transition metal chromophores exhibiting metal to ligand charge transfer excited state (MLCT) in the π-conjugated polymer opens new possibilities in variations of electronic and optical properties. The new materials might find wide applications such as polymeric light emitting diodes (PLED), solar energy conversion devices, nonlinear optical materials (NLOs), in materials exhibiting photorefractions, in chemical sensing, electrochromism, and electrocatalysis. The reason for this increased interest is due to the fact that the electronic and optic

This International Conference took place on October 29-30, 2003, and it was organized on the occasion of the 60th anniversary of the starting of the education and training of polymer chemistry and technology at the Faculty of Chemical and Food Technology, Slovak Technical University in Bratislava. The Conference was opened by I. Hudec who was chairman of the Organizing Committee (Figure 1). He introduced as a main speaker of the opening ceremony D. Bakos, dean of Faculty of Chemical and Food Technology of STU, who reviewed the development of education in the technical sciences and technology since the foundation of the well-known Academy of Mining and Forestry in Banska Stiavnica, central Slovakia in the middle of the 18th century.

The irradiation (A > 400 nm) in air of a copolymer of phenyl vinyl ketone with 4-vinylbenzil (VBZ) containing 1.5 wt % VBZ structural units in film, followed by the thermal decomposition of the resulting pendant benzoyl peroxide groups, leads to crosslinking. The subsequent irradiation of the crosslinked polymer at 366 nm results in the cleavage of the poly(phenyl vinyl ketone) chain between the junction points of the polymer network through a Norrish type II reaction. Therefore, poly(phenyl vinyl ketone-co-4-vinylbenzil) represents a novel type of photoresist based on polymer network decrosslinking. The process involves three steps: photogeneration of peroxide, crosslinking by its thermal decomposition, and subsequent photodecrosslinking of the polymer network. This material provides positive-tone images after UV exposure (A > 330 nm) and development in an organic medium such as isopropyl methyl ketone.

A real-time monitoring of oxygen quenching of monomer fluorescence of bound probes: 1-pyrenemethyl methacrylate (PyMMA) and 1-pyrenemethyl(4-vinylbenzyl)ether (4-(1-pyrenyl)methoxymethylstyrene, PyMMS) was used for study of swelling of interpenetrating polymer network (IPN) consisting of polyethylene/poly(styrene-co-butylmethacrylate) (PE/P(S-co-BMA)) with different network density. The curves of oxygen quenching of pyrene chromophore were fitted to the monoexponential form of second Fick Law. The estimated diffusion coefficient of oxygen was in the range of 1–10 × 10 −6 cm 2 s −1 depending on the solvent and phase of IPN system. There is no dependence of fluorescence quenching by oxygen on cross-link density in this IPN systems.

The syntheses, spectral measurements and the AM1 geometries of di-furan-2-yl-ethane-1,2-dione, di-thiophen-2-yl-ethane-1,2-dione, bis-[2,2′]-bithiophen-2,5-yl-ethane-1,2-dione and bis-[2,2′; 5′,2″]-terthiophen-2,5-yl-ethane-1,2-dione are presented. The electron absorption spectra for stable conformers are obtained by ZINDO/S method and they reasonably well agree with the experimental data. The increasing chain length influences the electronic polarizability and hyperpolarizabilities as demonstrated by the finite field method in AM1 approach.

Preparation of labeled interpenetrating polymer-like network (IPN) composed of polyethylene and copolymer styrene and butylmethacrylate with polymerizable fluorescence probes based on phenanthrene and anthracene was described. This pair of fluorescence probes, namely (phenathrene-9-yl)methyl methacrylate and (anthracene-9-yl)methyl methacrylate, was used to explore the non-radiative energy transfer in this special polymer blend. It was demonstrated that the energy transfer between phenanthrene moiety attached to copolymer part of IPN and anthracene moiety attached to PE part of IPN occurred in rather limited extent due to micro-heterogeneous structure of this polymer blend. Fluorescence experiments with dyes attached solely to the copolymer S-BMA part of IPN indicated that these dyes were concentrated in this part of IPN.

Reactions of toluene-2,4-diisocyanate with different phenols and different HAS (hindered amine stabilizers) were used to prepare new combined phenol/HAS. As a phenol 2- tert -butyl-4-methoxyphenol ( I ); 2- tert -butyl-4-methylphenol ( II ); 2,4-di- tert -butyl-6-methylphenol ( III ) and 2,4-di- tert -butylphenol ( IV ) were used. HAS represented 4-hydroxy-2,2,6,6-tetramethylpiperidine ( TMP ), 4-hydroxy-1,2,2,6,6-pentamethyl-piperidine ( PMP ), 4-amino-2,2,6,6-tetramethylpiperidine (ATP), 4- N -butyl-amino-2,2,6,6-tetramethyl-piperidine ( BATP ) and 4-hydroxy-2,2,6,6-tetramethylpiperidin- N -oxyl ( TMP-NO · ). Symmetrical phenol–phenol and HAS–HAS were also prepared. The synthesized compounds were tested as light and thermo stabilizers in polypropylene (PP). Non-oxidized as well as partially oxidized PP was used. The stabilizing efficiency depends on the structure of the phenol as well as the HAS. Concerning the phenol structure the best efficiency at photo oxidation was obtained with combined phenol/HAS containing 2,6-disubstituted phenol III for all HAS used. Efficiencies of phenols with just one substituent in the ortho position in combined additives were much lower. This difference was rather small in the case of thermo oxidation. Among the HAS the best performance was obtained from derivatives of TMP and PMP in photo oxidation of non-oxidized PP matrix. PMP derivatives in contrast to TMP ones did not stabilized partially oxidized PP very well. The efficiency of combined phenol/HAS was much higher than the efficiency of symmetrical HAS/HAS despite two times higher concentration of the active part in the symmetrical molecules. All combined additives showed very good ability to stabilize PP against thermo-oxidation. The highest efficiency was reached with TMP derivatives—about 12 000 to 14 000 h to reach carbonyl absorption 0.2 at 110 °C.

Adducts of chromophore (anthracene substituted in position 9) and hindered amine stabilizers (HAS) such as 2,2,6,6-tetramethylpiperidine-4-yl 3-(9-anthracene)propanoate, 1-oxo-2,2,6,6-tetrametylpiperidine-4-yl 3-(9-anthracene)propanoate, [2,2,6,6-tetramethyl-piperidine-4-yl 3-(9-anthracene)propanoate]ium chloride as well as model compounds 3-(9-anthracene) propanoic acid and methyl 3-(9-anthracene)propanoate were investigated. The photochemical stability of the adducts was determined in photo-decomposition in polystyrene, poly(methyl methacrylate), poly(vinyl chloride), isotactic polypropylene (iPP) and low density polyethylene (LDPE). Their photo-stabilizing efficiency was determined in iPP and in LDPE. The rate of decomposition of adducts on irradiation λ> 310 nm was very fast in all matrices. Intramolecularly combined chromophore/HAS are more effective stabilizers than 1:1 mixtures of the separated components. The decomposition of anthracene produces free radicals containing HAS. These radicals are able to graft to the polymer chain of iPP and LDPE.

New probes, esters of 3-(9-anthracene)propionic acid with 2,2,6,6-tetramethyl-4-hydroxypiperidine and its oxidized and protonized form, were prepared and spectrally characterized. Spectral measurements were performed in solution and in polymer matrices as polyethylene, isotactic polypropylene, polystyrene, polymethyl methacrylate and polyvinylchloride. Absorption spectra of these derivatives were shifted about 10 nm bathochromically in comparison with anthracene. The longest wavelength absorption band of the parent amine (probe III ) and its derivatives exhibited the fine vibrational structure in solution and in all polymer matrices. Fluorescence spectra of the probes were red-shifted as compared to anthracene. The vibrational structure of this emission is well preserved in all media. Quantum yield of fluorescence of parent amine is slightly higher than anthracene in methanol. The range of values of quantum yield relative to anthracene of parent amine is rather large (0.3–11) in polymer matrices. The lifetime of fluorescence of parent amine is 3.8 ns in methanol and 4.1 ns in cyclohexane but it is larger in polymer matrices. Both quantum yield and lifetime of oxidized form were smaller in comparison with parent amine. The quantities Φ NH / Φ NO and τ NH / τ NO expressing the extent of intramolecular quenching (electronic energy transfer) are low for this type of probes in methanol solution. In all polymer matrices these values are higher (2–7.5) but there are some differences between ratio calculated from quantum yields and from lifetimes. The photolytical stability of the novel probes is low in polymer matrices at 366 nm irradiation. 2,2,6,6-Tetramethylpiperidine structural unit as parent amine or as stable nitroxyl radical does not exhibit any stabilization effect.

The syntheses, spectral measurements and the AM1 (Austin model 1) geometry optimisation of N , N ′-bis-thiophen-2-ylmethylene-hydrazine ( IIIa ), N , N ′-bis-(3-methyl-thiophen-2-ylmethylene)-hydrazine ( IIIb ), N -[2,2′]-bithiophen-5-ylmethylene- N ′-thiophen-2-ylmethylene-hydrazine ( IIIc ), N , N ′-bis-[2,2′]-bithiophen-5-ylmethylene-hydrazine ( IIId ), N -[2,2′; 5′,2″]-terthiophen-5-ylmethylene- N ′-thiophene-2-ylmethylene-hydrazine ( IIIe ), N -[2,2′]-bithiophen-5-ylmethylene- N ′-[2,2′; 5′,2″]-terthiophen-5-ylmethylene-hydrazine ( IIIf ) and N , N ′-bis-[2,2′; 5′,2″]-terthiophen-5-ylmethylene-hydrazine ( IIIg ) are elaborated. The electron absorption spectra for all- trans conformers are obtained by ZINDO/S method and compared with the experimental data. The influence of the chain length on the electronic polarisability and second-order hyperpolarisability is investigated using the time-dependent Hartree–Fock method in AM1 approach.

Spectral characteristics of derivatives of thiophene substituted on hetoroaromatic cycle as pyrazine was compared with terthiophene linked with cyano and hydrazo groups. The absorption, fluorescence and its lifetime were measured in solution (methanol, cyclohexane) and in polymer matrices (polystyrene, PS; polymethyl methacrylate, PMMA; and polyvinyl chloride, PVC). Derivatives with two thiophene units substitute on pyrazine exhibit the lowest wavenumber band in the region 26,320–25,600 cm −1 and log e ∼4.0, which is not influenced by the medium. Derivatives with benzene and pyridine ring annealed to pyrazine (2,3-bis-(2′-thienyl)quinoxaline ( I ), 2,3-bis-(2′-thienyl)pyrido[2,3-b]pyrazine ( III )) exhibit fluorescence in polar methanol with maximum at 22,200 cm −1 and quantum yield of about 0.2 which is blue-shifted in going to non-polar solvent. The maximum fluorescence is slightly blue-shifted in polymer matrices as compared to methanol. Derivatives with annealed thiophene to pyrazine or substituted with two cyano groups (2,3-bis-(2′-thienyl)thieno[3,4-b]pyrazine ( II ), 2,3-dicyano-5,6-bis(2′-thienyl)pyrazine ( IV )) do not yield any emission. Derivatives with terthiophene structural units ([2,2′,5′,2″]-terthiophene-[2]-thienylacrylonitrile ( V ) [2,2′,5′,2″]-terthiophene-5-carbaldehydehydrazone ( VI )) exhibit fluorescence with maximum around 20,000 cm −1 . The lifetime of fluorescence of all thiophene was 1 ns or shorter. The polymer matrices increase the intensity of fluorescence to some extent and prolong the lifetime of thiophene derivatives. Derivative VI exhibits some tendency to an aggregation at higher concentration above 0.01 mol kg −1 in polymer matrices.

The conformational analysis of 2,3-bis(2′-thienyl)pyrazine (A), 2,3-dicyano-5,6-bis(2′-thienyl)pyrazine (B), 2,3-difluoro-5,6-bis(2′-thienyl)pyrazine (C), 2,3-bis(2′-thienyl)furo[3,4-b]pyrazine (D), 2,3-bis(2′-thienyl)pyrrolo[3,4-b]pyrazine (E), 2,3-bis(2′-thienyl)thieno[3,4-b]pyrazine (F), 2,3-bis(2′-thienyl)quinoxaline (G), 2,3-bis(2′-thienyl)pyrido[3,4-b]pyrazine (H) and 2,3-bis(2′-thienyl)pyrido[2,3-b]pyrazine (I) is elaborated using semiempirical Austin Model 1 (AM1) method. The electron absorption spectra for stable conformers are calculated by ZINDO/S method. The influence of the bridge variations on the electronic polarisability and second hyperpolarisability is investigated using the time-dependent Hartree–Fock method in AM1 approach. The synthesis and spectral measurements of the most promising B, F, G and I compounds are presented. Our results indicate that the G and I ones seem to be suitable candidates for the subsequent preparation of the electro-optical materials.

Spectral properties of four types of bifunctional probes based on pyrene and sterically hindered amines (HAS) were compared in solution of cyclohexane and methanol and in polymer matrices as isotactic polypropylene (iPP), polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC). Absorption spectra of these probes strongly depend on the type of linkage. When the carbonyl group in the linkage is in α-position to pyrene ring, the absorption bands are broader with rather poor vibrational resolution. The carbonyl group in α-position influences the emission spectra as well. For derivatives of 4-oxo-4-(1-pyrene)butanoic acid (I), the broad emission band was observed. Some vibrational resolution was observed for probes based on 1-pyrenecarboxylic acid (IV). Lifetime of these probes is in the range 1–10 ns. When methylene group instead of carbonyl is attached to pyrene and forms the link, the absorption spectra are the same as that of alkyl-substituted pyrene. This behaviour was shown for derivatives of 1-pyreneacetic acid (III) and 4-(1-pyrene)butyric acid (II). The emission spectra of these probes are similar as parent alkyl pyrene. The lifetime is in the range above 100 ns. The influence of solvent polarity and polymer matrix on spectra was not very pronounced for probe of parent amine types Ic–IVc. The decay of fluorescence of probes of this type was satisfactorily fitted to monoexponential function. The efficiency of intramolecular quenching observed for oxidised probes Id–IVd is in the range from about 1.5 for derivative Id to value of about 10 for IIId. It was influenced by type of linkage and medium. The decay of fluorescence of linked pyrene chromophore of probes Id–IVd is better fitted by biexponential function.

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 ...

Dynamic and static photophysical and spectroscopic measurements have been used to analyze the microdomains of interpenetrating network (IPN) films consisting of 1:1 polyethylene:(7:3)poly(butyl methacrylate)-co-polystyrene. The primary probe, fluorescence from pyrenyl groups covalently attached selectively to the different elements of the IPN, has been monitored under a variety of conditions, including in the absence and presence of a fluorescence quencher, diethyl oxalate (DEO), which is not able to enter domains of polyethylene. It has been possible to discern the parts of the IPN that are accessible to molecules of DEO and the rates at which DEO is able to enter them. Two diffusion coefficients, indicating parallel diffusion pathways, are necessary to account for DEO entry into several of the films. The IPN consists of largely segregated domains, but there are extensive interactions between domains at their interfaces. Conclusions are derived from comparisons of results from the IPN and films of their ...

Laser flash photolysis was used to study formation and decay of triplet states of bifunctional probes of type chromophore (naphthalene, 1,8-naphthaleneimide, pyrene)-sterically hindered amine (HAS). For all types of probes, the formation of the triplet state with absorption in the range 400–500 nm occurred after 266 nm excitation. The same triplet was formed at 355 nm excitation for probes extending absorption to this region. Triplet states of all probes were quenched by oxygen with rate constant 1–5×10 9 dm 3 mol −1 cm −1 . Intermolecular quenching of triplet states of the parent probes by N -oxyl (1-oxo-2,2,6,6-tetramethyl-4-hydroxypiperidine) was effective for naphthalene type probes and practically no effective for pyrene ones. The efficiency of intramolecular quenching in oxidised probes was determined by type of chromophore. The most effective intramolecular quenching was observed for N -(1-oxo-2,2,6,6-tetramethyl-4-piperidinyl)-1,8-naphthaleneimide in methanol.

Spectral properties of monosubstituted derivatives of pyrene were compared in low viscosity solvents such as cyclohexane, chloroform, and methanol, in high viscosity solvents such as heptadecane and polybutene oil, in glassy polymer matrices above T g (atactic polypropylene) and below T g (polystyrene polymethyl methacrylate, polyvinylchloride), and in semi-crystalline low density polyethylene. The derivatives under study were: 1-pyrenylmethanol (I), benzyl-(1-pyrenylmethyl) ether (II), di(1-pyrenylmethyl) ether (III) and 4-(1-pyrenyl)butyl-(1-pyrenylmethyl) ether (IV). Absorption spectra of these probes were not influenced by environment. Emission spectra of III exhibited exclusively excimer emission in low viscosity solvents. Probe IV yielded mainly monomer emission. In viscous solvents and glassy polymer matrices above and below T g , as well as in semi-crystalline polyethylene, monomer emission was exclusively observed for all probes. Distinct differences were observed in emission decay curves. Probes derived from pyrene with a bulky substituent exhibited biexponential decays with a short component (∼10 ns) in viscose solvents and polymer matrices. In semi-crystalline polyethylene, the decay of monomer emission of all probes was monoexponential with a lifetime around 200 ns.

Spectral properties of coumarin derivatives (2H-1-benzopyran-2-one), substituted with a bulky group in position 3, were investigated in solvents and in polymer matrices. The bulky electron donating groups in position 3 were phenyl-, phenyltio-, 2-methylphenyltio-, 2,6-dimethylphenyltio-, benzyl-, phenoxy-, dimethylamino- and benzoylamino-. The absorption spectra of all the derivatives are dominated by a broad band with a maximum at 340 nm (log e∼4.0), which were not influenced by the polarity or viscosity of the environment. The fluorescence of these derivatives is strongly influenced by the polarity of the solvent and viscosity of the surroundings. In high viscosity solvents and in polymer matrices, the quantum yields of around 0.1 and a lifetime of around 2 ns was observed. In low viscosity non-polar solvents such as cyclohexane, the quantum yields lower than 0.01 were observed. The fluorescence of coumarin probes was quenched by polar methanol with a bimolecular rate constant, k q , larger than diffusion controlled limit indicating static quenching. The increased polarity of the mixed solvent introduces processes such as intramolecular charge transfer or twisted intramolecular charge transfer which effectively compete with fluorescence. The dependence of quantum yield of fluorescence on temperature was determined in viscose solvents and polymer matrices. The activation energy of radiation-less process ( E a ) increased in going from phenyl to more the bulky 2,6-dimethylphenyltio group in non-polar high viscosity polybutene oil and polar glycerol supporting the idea that the radiation-less process is related to rotation of the group in position 3. The E a value is lower in rubbery matrices such as polyoctenamer or atactic polypropylene than in glassy polymers such as polystyrene, poly(methyl methacrylate) or polyvinyl chloride. 3-Phenylcoumarin, due to its spectral properties, seems to be the most suitable probe for monitoring microviscosity in polymers.

The photostabilising efficiency of compounds containing pyrene as chromophore linked to hindered amine stabiliser (HAS) has been evaluated in photo-oxidation of isotactic polypropylene. Four series of compounds were prepared which have bridges formed either by methylene groups of different length or carbonyl group in α-position to pyrene ring. All derivatives of this type exhibited some efficiency. The most effective was 1-oxo-2,2,6,6-tetramethyl-4-piperidinyl-1-pyrenylacetate (IId) which exhibited an induction period about half the length at 2×10−3 mol kg−1 compared with 2,2,6,6-tetramethyl-4-piperidinol or 1-oxo-2,2,6,6-tetramethyl-4-piperidinol under the similar conditions, monitored by IR spectroscopy. Emission spectroscopy revealed that the chromophore (pyrene) decomposes rapidly when it is used alone or when is linked to HAS in the form of parent amine or N-oxyl radicals. The decomposition rate is slower in the case of N-oxyl radicals. The increase of emission in the case of N-oxyl radicals at the beginning of irradiation indicates the reaction of this radical with other radicals formed during photo-oxidation. These reactions result in non-radical products and consequently in increase of emission due to switching off the intramolecular quenching.

A series of terpolymers containing structural units of hindered amine stabilizer (HAS), antioxidant of diphenylamine type and octadecyl alkyl chain has been prepared by radical oligomerization initiated by AIBN. Monomers bearing HAS represented acrylate, methacrylate or acrylamide of 2,2,6,6-tetramethyl and 1,2,2,6,6-penta-methylpiperidine respectively. Second monomer in terpolymers was 4-amino-diphenylamine acrylamide or methacrylamide and the third one n-octadecyl acrylate. Molecular weights of oligomers lay in the region 4000–6500. The molar ratio of monomers in oligomers was approximately the same as in the mixtures of monomers before oligomerization (1:1:1). Oligomeric stabilizers were tested as photostabilizers in polyoctenamer and polypropylene (PP) and as thermostabilizers in PP at 130°C. Stabilizing efficiency for all oligomeric stabilizers was roughly the same in photooxidation of PP. In the case of thermooxidation, the oligomer TMPA/DPA/ODA showed several times better efficiency than other oligomers.