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We previously reported that ABA‐type triblock copolymers with azobenzene‐containing terminal blocks can be utilized as a light‐induced reworkable adhesive that enables repeatable bonding and debonding on demand. The reworkability was based on the photoisomerization of the azobenzene moiety and concomitant softening and hardening of the azo blocks. Our aim in this study is to investigate the effect of the composition, molecular weight, and block copolymer architectures on the reworkable adhesive properties. For this purpose, we prepared AB diblock, ABA triblock, and 4‐arm (AB)4 star‐block copolymers consisting of polymethacrylates bearing an azobenzene moiety (A block) and 2‐ethylhexyl (B block) side chains and performed adhesion tests by using these block copolymers. As a result, among the ABA block copolymers with varied compositions and molecular weights, the ABA triblock copolymers with an azo block content of about 50 wt % and relatively low molecular weight could achieve an appropriate balance between high adhesion strength and low residual adhesion strength upon UV irradiation. Furthermore, the 4‐arm star‐block structure not only enhances the adhesion strength, but also maintains low residual adhesion strength when exposed to UV irradiation. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 806–813 Various types of azobenzene‐containing block copolymers, such as AB diblock, ABA triblock, and 4‐arm (AB)4 star‐block copolymers, can be utilized as reworkable adhesives that enable bonding/debonding by light irradiations. Among them, the star‐block structure enhances the adhesion strength, as well as maintaining low residual adhesion strength when exposed to UV irradiation. [ABSTRACT FROM AUTHOR]

ABSTRACT: A novel series of hard‐soft‐hard triblock azo‐copolymers (TBCs) composed of poly(2‐[2‐(4‐cyano‐azobenzene‐4‐oxy)ethylene‐oxy]ethyl methacrylate) (PCEAMA), poly(methyl methacrylate) (PMMA) and poly(p‐dodecylphenyl‐N‐acrylamide) (PDOPAM) were synthesized by employing reversible addition‐fragmentation chain transfer polymerization. Chemical structures and molecular weights were characterized by 1H nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). Thermal behavior, mesophase, photochemistry and morphology were investigated using differential scanning calorimetry (DSC), optical polarizing microscopy (OPM), ultraviolet–visible spectrophotometry (UV–vis), atomic force microscopy (AFM) and grazing‐incidence small‐angle X‐ray scattering (GISAXS). Kinetic studies confirmed characteristic of controlled/living radical polymerization with low polydispersities (≤1.40). TBCs manifested both endothermic and exothermic transition peaks assigned to smectic to nematic, nematic to smectic, and smectic‐A to smectic‐C phases. TBCs having hight azo fractions of 39 and 34 wt % revealed textures of smectic phase whereas TBC possessing 30 wt % of azo content exhibited poor texture, suggesting nematic phase. Regarding TBC with low azo ratio (25 wt %), neither mesophase texture was found. All TBCs showed photoresponsive behavior under UV–vis irradiation or thermal relaxation. TBC‐1 with PCAEMA (39 wt %), PMMA (40 wt %) and PDOPAM (21 wt %) generated a mixture of cylinder and lamellar nanostructures compared to TBC‐2 and TBC‐3 which formed lamellae. However, TBC‐4 having the highest PDOPAM fraction (50 wt %) produced hexagonal cylindrical nanostructure. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1617–1629 [ABSTRACT FROM AUTHOR]

ABSTRACT Functional polystyrene (PS) crosslinked microbeads were developed by dispersion polymerization as fluorescent molecularly imprinted polymers (MIPs) having cavities with specific recognition sites. The functional azobenzene molecule modified with pyridine was self-assembled with Pyrenebutyric acid (template molecules), and introduced during the second stage of dispersion polymerization of polystyrene. The template molecule was removed from MIP by Soxhlet using acetonitrile as solvent. Non imprinted polymer (NIP) having no template was also synthesized for comparative study. Fluorescence spectroscopy could be used as a tool to derive insight into the location of the template molecules on the MIP or NIP. The template molecules were adsorbed on the surface of the NIPs during binding studies, which was evidenced from the pyrene excimeric emission observed at 440 nm. The template binding efficiency of the NIPs were much lower compared to MIPs. Pyrene emission from MIP upon rebinding showed typical monomeric emission in the 375-395 nm range, confirming its location in isolated cavities. In rebinding studies of the template molecules, the MIPs selectively took up the template for which the cavity was designed, which demonstrated their selectivity towards template molecules. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1558-1565 [ABSTRACT FROM AUTHOR]

ABSTRACT Two photosensitive chiral liquid crystalline azobenzene-containing polymethacrylates having different length of flexible spacer connecting chromophores with backbone were synthesized and their phase behavior and photo-optical properties were studied. Both polymers consist of lateral methyl substituents in ortho-position of azobenzene chromophores providing high photosensitivity even in red spectral region as well as high thermal stability of photoinduced Z-form of azobenzene chromophores. It is shown, that smectic phase (SmA*) formation in films of polymer with longer spacer predetermines its quite unusual spectral response to UV and subsequent visible light actions. The SmA* phase promotes spontaneous homeotropic alignment of azobenzene chromophores in polymer films. UV-irradiation induces not only E-Z isomerization but also results in disruption of homeotropic alignment, whereas subsequent visible light action enables to obtain films with the low degree of chromophores orientation. The photo-orientation phenomena under the action of polarized light of different wavelength on polymer films were studied. The possibility of using red polarized light of moderate intensity for optical photorecording on polymer films is demonstrated. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2962-2970 [ABSTRACT FROM AUTHOR]

ABSTRACT We report novel liquid crystalline (LC) polymers containing pendant azobenzene moieties with n-dodecyl substituents and ethyleneoxy spacers of different lengths and describe their selective detection behaviors to alkali metal ions. The new azopolymers produce homogenous smectic phases with a typical fan-shaped texture. UV-Vis and 1H NMR studies confirm that the azopolymers selectively bind to Li+ and Na+, but do not complex with K+, Ba2+, Mg2+, or Ca2+. Both the ethyleneoxy spacer and azobenzene units participate in binding to Li+ and Na+ cations in solution. Interestingly, after formation of the complexed structure, the ratio of cis to trans conformer is considerably increased suggesting stronger interactions of the cis conformer with alkali metal ions. Irradiation of the complexed structure with 365 nm UV induces conversion of the uncomplexed trans to the cis. These findings suggest a great potential of the LC azopolymers as selective sensors or separation membranes for alkali metal ions. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1713-1723 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel visible light responsive random copolymer consisting of hydrophobic azobenzene-containing acrylate units and hydrophilic acrylic acid units has been prepared. The azobenzene molecule bearing methoxy groups at all four ortho positions is readily synthesized by one-step conversion of diazotization. The as-prepared polymer can self-assemble into nanoparticles in water due to its amphiphilic nature. The tetra- o-methoxy-substituted azobenzene-functionalized polymer can exhibit the trans-to- cis photoswitching under the irradiation with green light of 520 nm and the cis-to- trans photoswitching under the irradiation with blue light of 420 nm in both solution and aggregate state. The morphologies of the self-assembled nanoparticles are revealed by TEM and DLS. The controlled release of loaded molecules from the nanoparticles can be realized by adjusting pH value since the copolymer possesses pH responsive acrylic acid groups. The fluorescence of loaded Nile Red in the nanoparticles can be tuned upon the visible light irradiation. The reversible photoswitching of the azobenzene-functionalized polymer under visible light may endow the polymer with wide applications without using ultraviolet light at all. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2768-2775 [ABSTRACT FROM AUTHOR]

ABSTRACT Three main chain thermotropic liquid crystalline (LC) azobenzene polymers were synthesized using the azobenzene twin molecule (P4P) having the structure Phenylazobenzene-tetraethyleneglycol-Phenylazobenzene as the AA monomer and diols like diethylene glycol, tetraethylene glycol (TEG), and hexaethylene glycol as the BB comonomer. Terminal C(O)OMe units on P4P facilitated transesterification with diols to form polyesters. All polymers exhibited stable smectic mesophases. One of the polymers, Poly(P4PTEG) was chosen to prepare composite polymer electrolytes with LiCF3SO3 and ionic conductivity was measured by ac impedance spectroscopy. The polymer/0.3 Li salt complex exhibited a maximum ionic conductivity in the range of 10−5 S cm−1 at room temperature (25 °C), which increased to 10−4 S cm−1 above 65 °C. The temperature dependence of ionic conductivity was compared with the phase transitions occurring in the sample and it was observed that the glass transition had a higher influence on the ionic conductivity compared to the ordered LC phase. Reversible ionic conductivity switching was observed upon irradiation of the polymer/0.3 Li salt complex with alternate UV and visible irradiation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 629-641 [ABSTRACT FROM AUTHOR]

ABSTRACT A new methacrylate containing a 2,6-diacylaminopyridine (DAP) group was synthesized and polymerized via RAFT polymerization to prepare homopolymethacrylates (PDAP) and diblock copolymers combined with a poly(methyl methacrylate) block (PMMA- b-PDAP). These polymers can be easily complexed with azobenzene chromophores having thymine (tAZO) or carboxylic groups with a dendritic structure (dAZO), which can form either three or two hydrogen bonds with the DAP groups, respectively. The supramolecular polymers were characterized by spectroscopic techniques, optical microscopy, TGA, and DSC. The supramolecular polymers and block copolymers with dAZO exhibited mesomorphic properties meanwhile with tAZO are amorphous materials. The response of the supramolecular polymers to irradiation with linearly polarized light was also investigated founding that stable optical anisotropy can be photoinduced in all the materials although higher values of birefringence and dichroism were obtained in polymers containing the dendrimeric chromophore dAZO. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3173-3184 [ABSTRACT FROM AUTHOR]

ABSTRACT Triple stimuli (temperature/pH/photo)-responsive amphiphilic glycopolymer, poly(2-(dimethylamino)ethyl methacrylate- co-6- O-methacryloyl-1,2,3,4-di- O-isopropylidene-D-galactopyranose)- b-poly(4-(4-methoxyphenylazo)phenoxy methacrylate) [P(DMAEMA- co-MAIpGP)- b-PMAZO] was synthesized by atom transfer radical polymerization, followed by the hydrolysis of MAIpGP groups, resulting in the target product poly(2-(dimethylamino)ethyl methacrylate- co-6- O-methacryloyl-D-galactopyranose)- b-poly(4-(4-methoxyphenylazo)phenoxy methacrylate) [P(DMAEMA- co-MAGP)- b-PMAZO]. The composition, moleculer weight, and moleculer weight distribution of the resultant polymers were characterized by 1H NMR and gel permeation chromatography. The micelles formed in aqueous solutions were simulated by various chemical and physical stimuli and characterized by dynamic light scattering, transmission electron microscopy, and UV-vis spectroscopy. It was found that the glycopolymer is responsive to three different types of stimulus (light, temperature, and pH). The poly(2-(dimethylamino) ethyl methacrylate) segments give thermo- and pH-responsiveness. The presence of the azobenzene moiety endows the block copolymer to exhibit light-responsiveness due to its reversible trans-cis isomerization conversion. The triple stimuli-responsive glycopolymer micelles can simulate biomacromolecues in vivo/ in vitro environment and can be expected to open up new applications in various fields. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2131-2138 [ABSTRACT FROM AUTHOR]

ABSTRACT A facile, general, and highly efficient one-pot approach to obtain azobenzene (azo)-containing molecularly imprinted polymer (MIP) nanoparticles with photoresponsive template binding and release properties in aqueous media is described, which involves the combined use of hydrophilic macromolecular chain transfer agent-mediated reversible addition-fragmentation chain transfer precipitation polymerization and easily available water-insoluble azo functional monomers. The resulting azo-containing MIPs were characterized with dynamic laser scattering (DLS), SEM, FTIR, static contact angle and water dispersion studies, and equilibrium binding experiments. They have proven to be nanoparticles (their diameters being around 104-397 nm, as determined by DLS in methanol) with surface-grafted hydrophilic polymer brushes and exhibit excellent pure water-compatible template binding properties. Moreover, obvious photoregulated template binding behaviors were observed for such azo-containing MIP nanoparticles, which led to their largely accelerated template release in the aqueous media under the UV light irradiation. Furthermore, the general applicability of the strategy was also demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1941-1952 [ABSTRACT FROM AUTHOR]

ABSTRACT The photomechanical response and photochemistry of a conventional, unsubstituted azobenzene-functionalized liquid crystalline polymer network (azo-LCN) is contrasted to that of an analogous material prepared with meta-fluorinated azobenzene chromophores. The polydomain azo-LCN materials exhibit nearly identical thermomechanical and optical properties. Photomechanical characterization indicates that the fluorination of the azobenzene chromophore reduces the deflection of cantilevers composed of the materials by 50%, which spectroscopic analysis reveals is due to a reduction in the ability of this material to isomerize and potentially reorient. This work is further confirmation that the underlying photochemistry of azobenzene is a primary contributor to the generation of photomechanical work in these materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 876-882 [ABSTRACT FROM AUTHOR]

ABSTRACT A new approach to the synthesis of photoactive comb-shaped homo- and copolyamides containing azobenzene, cinnamate, and coumarin side groups for photoalignment of liquid crystals was elaborated. Photooptical properties and photoorientational ability of these polymers with respect to liquid crystals were studied. It was shown that polarized UV irradiation of all spin-coated polyamides leads to orientation of liquid crystalline molecules deposited on the polyamide thin films. The synthesized polymers containing cinnamate and coumarin side groups as well as azobenzene-containing cyano- and nitro-substituted polymers demonstrated good orientation ability in relation to liquid crystals displaying photoinduced planar orientation with high dichroism values within the range of 0.68-0.72. Contrary to the above-mentioned polyamides, azobenzene-containing fluorosubstituted polymers induced a homeotropic orientation of liquid crystals. It was shown that the synthesized photoactive polyamides can be considered as promising photoalignment materials for application in display technology, photonics, and other 'smart' optical devices. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4031-4041 [ABSTRACT FROM AUTHOR]

ABSTRACT Azobenzene-containing polymers offer tremendous advantages and opportunities over other stimuli-responsive materials to interface with biology. Azobenzene's fast, reversible, and innocuous cis- trans geometrical isomerization can be leveraged into dramatic intra- and inter-molecular changes when incorporated in polymeric materials. Azobenzene use has grown from a colorant, through to optical storage materials, and most recently in a variety of biologically themed applications. This review highlights the broad impact this photo-switch has had in recent years and offers a snapshot of the research landscape at the interface between photochemistry and biology. From photo-reversible micelles and peptides to controlled drug release and sensing, the versatility of azobenzene makes it a favored photo-switch found in many emerging applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3058-3070 [ABSTRACT FROM AUTHOR]

We have demonstrated the preparation of a series of photoaddressable supramolecular block copolymers by mixing a carboxy-terminated azobenzene derivative, 6-[4-(4′-cyanophenylazo)phenyloxy]hexanoic acid (AZO), and two polystyrene- b-poly(4-vinylpiridine) (PS- b-P4VP) block copolymers. AZO can be selectively attached to the P4VP block of PS- b-P4VP through hydrogen bonding interactions. The assembly of AZO with vinylpyridine group-containing polymers was initially investigated on a model system composed of P4VP homopolymer and AZO. Homogeneous liquid crystalline materials were obtained for ratios of AZO to vinylpyridine repeating unit, x, lower or equal to 0.50. Mixtures with higher x resulted in heterogeneous materials showing clear macrophase separation. Accordingly, a series of hydrogen-bonded complexes of PS- b-P4VP and AZO, PS- b-P4VP(AZO) x, with x = 0.25 and x = 0.50 were prepared. Lamellar and spherical morphologies were observed for the complexes based on PS24- b-P4VP9.5 ( Mn,PS = 24,000, Mn,P4VP = 9500) and PS24- b-P4VP1.9 ( Mn,PS = 24,000, Mn,P4VP = 1900), respectively. Photoinduced orientation of the azobenzene units was obtained in films of P4VP(AZO) x and PS- b-P4VP(AZO) x with x = 0.25 and 0.50 by using 488 nm linearly polarized light and characterized through birefringence and dichroism measurements. This investigation shows a versatile and less laborious approach to azobenzene-containing polymer materials with low chromophore content, of interest in optical application. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Well-defined azobenzene-containing side-chain liquid crystalline diblock copolymers composed of poly[6-(4-methoxy-azobenzene-4′-oxy) hexyl methacrylate] (PMMAZO) and poly(γ-benzyl- L-glutamate) (PBLG) were synthesized by click reaction from alkyne- and azide-functionalized homopolymers. The alkyne-terminated PMMAZO homopolymers were synthesized by copper-mediated atom transfer radical polymerization with a bromine-containing alkyne bifunctional initiator, and the azido-terminated PBLG homopolymers were synthesized by ring-opening polymerization of γ-benzyl- L-glutamate- N-carboxyanhydride in DMF at room temperature using an amine-containing azide initiator. The thermotropic phase behavior of PMMAZO- b-PBLG diblock copolymers in bulk were investigated using differential scanning calorimetry and polarized light microscopy. The PMMAZO- b-PBLG diblock copolymers exhibited a smectic phase and a nematic phase when the weight fraction of PMMAZO block was more than 50%. Photoisomerization behavior of PMMAZO- b-PBLG diblock copolymers and the corresponding PMMAZO homopolymers in solid film and in solution were investigated using UV-vis. In solution, trans-cis isomerization of diblock copolymers was slower than that of the corresponding PMMAZO homopolymers. These results may provide guidelines for the design of effective photoresponsive anisotropic materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

New class of photo and electrically switchable azobenzene containing pendant bent-core liquid crystalline monomers ( AZBM 1, 2, and 3) and their polymers ( AZBP 1, 2, and 3) are reported. The synthesized precursors, monomers, and polymers were characterized by FT-IR, 1H, and 13C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis and revealed stable up to 260 °C. The mesophase transition of monomers and polymers are observed through polarized optical microscopy (POM) and further confirmed by differential scanning calorimetry (DSC). The electrically switching property of monomers and their polymers were studied by electro-optical method. Among the three monomers AZBM 1, 2, and 3, AZBM 1 and 2 exhibit antiferroelectric (AF) switching and AZBM 3 exhibits ferroelectric (F) switching behavior. On the other hand, low molecular weight polymers ( AZMP 1, 2, and 3) show weak AF and F switching behavior. The photo-switching properties of bent-core azo polymers are investigated using UV-vis spectroscopy, trans to cis isomerization occurs around 25 s for AZBP-1 and 30 s for AZBP-2 and 3 in chloroform, whereas reverse processes take place around 80 and 90 s. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Three types of bi-functionalized copolymers ( P1FAz, P2FAz, and P3FAz) with different numbers of fluorene units and an azobenzene unit were synthesized and characterized using UV-vis and polarized absorption spectroanalysis. The trans-cis photoisomerization was conformed under 400 nm light irradiation for all copolymers in chloroform. However, in the film state, only the trans- cis photoisomerization occurred by mono-fluorene attached copolymer poly[(9,9-di- n-octylfluorenyl-2,7-diyl)- alt-4,4′-azobenzene)] ( P1FAz). Photo-induced alignment was achieved using the P1FAz film after irradiation with linear polarized 400 nm light and subsequent annealing at 60 °C. Surface orientation of a spin-coating film of poly(9,9-didodecylfluorene) ( F12) was achieved using the photo-induced alignment layer of the P1FAz film after annealing at 90 °C. The photo-induced alignment layer of P1FAz has potential application to the surface orientation technique for appropriate polymers, which will be useful for the fabrication of optoelectronics devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

The synthesis and polymerizability of imine CN monomers is surveyed. The investigated imines were either far more reactive than similarly substituted CC or CO monomers, or too stable to polymerize. Imines with electron-attracting substituents on N favor polymerization by anionic mechanism, but led only to low molecular weight polymers. Imines with a donor substituent on N, such as N-arylmethyleneimines, polymerized by cationic or anionic mechanism. 1- and 2-Aza-1,3-butadienes were also rather unstable and polymerized to oligomers. The symmetrically substituted 2,3-diaza-1,3-butadienes could be purified and polymerized successfully using anionic initiators, resulting in both 1,4- and 1,2-structures in the polymer backbone, depending on the substituents. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

We report systematic studies on a homologous series of twin liquid crystalline (LC) molecules based on phenyl and naphthyl azobenzene ( PnP and NpnNp) as well as segmented copolyesters based on them. The twin series had the structure azobenzene-oligooxyethylene-azobenzene, where the ethyleneoxy length was varied from 2 to 6 units. The LC properties of the twin series depended on the chemical structure of the azochromophore and also the length of the central oligooxyethylene segment. The PnP series exhibited smectic LC properties for n > three oligooxyethylene units. Conversely, NpnNp series exhibited spherulitic phases only for the shortest member - Np2Np. One non-LC short spacer twin ( P2P) and one LC long spacer twin ( P6P) were incorporated as part of a main chain polyester composed of fully aliphatic segments of sebacate and di or tetraethylene glycol (DEG/TEG) units by melt polycondensation. Non-LC P2P formed LC polymers even at low (5 mol %) incorporation in DEG-based copolymers, whereas the LC- P6P could do so only at 30 mol % incorporation. The LC properties of the twin molecules as well as copolymers were studied using differential scanning calorimetry, polarized light microscopy (PLM) along with variable temperature wide angle X-ray diffraction. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Three new types of hyperbranched photoactive liquid crystalline siloxane polymers containing azo moieties were synthesized using click chemistry methodology. The polymers were soluble in most of the polar solvents like chloroform, tetrahydrofuran, dimethylformamide, dimethyl sulphoxide and dichloromethane. The molecular weights of the polymers were in the range of 9000-12,000 g mol−1. The trans-cis photoisomerization of the polymer were studied both under UV radiation and dark. The isomerization rate constants were found to be in the range of 0.7-1.4 × 10−2 sec−1 and 7.0 × −2.5 × 10−5 sec−1. The thermotropic behavior of the polymers was studied by using polarizing optical microscopy and differential scanning calorimetry, respectively. The polymers P1 and P2 showed liquid crystalline texture characteristic of nematic phase. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

End-capped and intramolecular azofunctional oligocaprolactones were characterized at molecular level by liquid chromatography electrospray ionization mass spectrometry (ESI MS) and NMR spectroscopy. The Disperse Red 19 (DR19) azofunctional oligomers, DC, were synthesized by ring-opening oligomerization of ε-caprolactone (ε-CL) initiated by the hydroxyl groups of DR19 azo dye. The reaction products consist of a minor fraction of end-capped azo functional oligocaprolactone (α-DC), that is, a single CL arm oligomer, and a major fraction of intramolecular azo functional oligocaprolactone (β-DC), that is, a two CL arms oligomer. The chromatographic separation was used to discriminate between α-DC and β-DC, and the results were confirmed by MS/MS performed on an ESI ion trap instrument. The results supported by accurate mass data obtained for product ions using an ESI quadrupole time of flight instrument demonstrate the qualitative discrimination at the molecular level between intramolecular and end-capped azofunctional oligoesters isomers through a relatively simple multistage mass spectrometry experiment. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Copolymer containing new thermally reversible click chemistry‐assisted triazole‐substituted azobenzene and fulgimide units in the pendant F‐co‐A was prepared by free‐radical solution addition polymerization technique. The F and A were also prepared for comparison. The DSC analysis of F indicates that the polymer possessing the C‐form of fulgimide unit exhibited higher Tm than that of E‐form of the same polymer and revealed that the C‐form of fulgimide unit in F is highly ordered. The cis‐trans back isomerization behavior of the click chemistry‐assisted triazole‐substituted azobenzene unit in film A has thermal irreversibility, while in F‐co‐A it exhibited thermal reversibility. The UV‐exposed film of F‐co‐A heated around Tg leads to cis‐trans back isomerization of azobenzene unit and thermally stable C‐form of fulgimide which retains its conjugated structure where both the photochromic units are converted into planar conformations and exhibit high fluorescence properties. The fluorescence maxima of C‐form in F‐co‐A red shifted compared with F, because the substituted triazole ring in the azobenzene unit stabilized the C‐form of fulgimide unit. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7843–7860, 2008 [ABSTRACT FROM AUTHOR]