Fluorescence Micropatterning by the Photo‐Anilide Rearrangement of Polymer Bearing Anilide Groups

A fluorescent micropattern in a thin polymer film is fabricated via a photo‐anilide rearrangement of anilide groups in the polymer. Polymer bearing anilide groups are prepared by polymerization of N‐phenyl methacrylamide (PMA) and methyl methacrylate. The photo‐anilide rearrangement of the prepared polymer and the reaction of the produced amino groups with fluorescamine, are studied by using UV and IR absorption spectroscopy. The fluorescence spectrum of the fluorescamine‐treated irradiated polymer film shows a strong fluorescence in the range of ≈420–620 nm with a fluorescence maximum at 496 nm. The patterns exhibited very distinct fluorescence images in the colors of dark blue, sky blue, green, yellow, and red depending on the observed wavelength ranges.     

Photo‐Orientation Phenomena in Photochromic Liquid Crystalline Azobenzene‐Containing Polymethacrylates with Different Spacer Length

Synthesis and investigation of the phase behavior and photo‐optical properties of two chiral liquid‐crystalline polymers with azobenzene‐containing side groups having different spacer lengths, 6 and 10 methylene groups ( PMAzo‐6 and PMAzo‐10 , respectively) are described. Formation of different smectic phases and high‐temperature cholesteric phase is studied by polarizing optical microscope, differential scanning calorimetry, and X‐ray investigations. It is shown that UV‐irradiation induces effective reversible E –Z photoisomerization in polymer solutions and films. Atomic force microscopy (AFM) study reveals substantial changes in the surface topography of the polymer PMAzo‐6 film after UV‐irradiation, whereas PMAzo‐10 surface remains the same. Irradiation by polarized light (457 nm) results in photo‐orientation process in polymer films consequential in significant alignment of the chromophores in direction perpendicular to the polarization plane of the incident light. A significant difference is found in thermal stability of the photoinduced alignment; an annealing of PMAzo‐10 irradiated samples results in a slight decrease of dichroism values (down to 0.57); whereas the dichroism increases up to very high values (0.91) for PMAzo‐6 .

     

Radiation‐Induced Reaction of Sulfonamide‐Containing Polymers in the Film State for Color Imaging

A polysulfonamide and copolymers consisting of sulfonamides and amides underwent Fries rearrangement and scission, forming amino groups upon EB irradiation. The EB irradiation of these films with a dose of 500 µC · cm^?2, followed by the color forming reaction provided the color imaging of line/space patterns with a resolution of 300 nm.

     

Preparation of Polymeric Nanoparticles by Photo‐Crosslinking of an Acryloylated Polyaspartamide in w/o Microemulsion

Summary: Biodegradable polymeric nanoparticles have been prepared by UV irradiation of an acryloylated water soluble polymer by an inverse microemulsion. The starting polymer was a α,β‐poly(N‐2‐hydroxyethyl)‐D ,L ‐aspartamide (PHEA) partially functionalized with glycidyl methacrylate (GMA) in order to introduce reactive vinyl groups in the side chain. The PHEA‐GMA copolymer obtained (PHG) was crosslinked by UV irradiation of the inverse microemulsion prepared by mixing an aqueous solution of PHG with propylene carbonate (PC)/ethyl acetate (EtOAc) in the presence of sorbitan trioleate (SPAN 85) as surfactant. Nanoparticles obtained were characterized by FTIR spectrophotometry, transmission electron microscopy, size distribution analysis and zeta potential measurements. Nanoparticles investigated revealed spherical and homogeneous shading, the particle size having a mean diameter of 88 ± 13 nm (PDI = 0.21) and a negative surface charge in several aqueous media. Moreover, in vitro chemical and enzymatic hydrolysis studies evidenced the partial biodegradability of PHG nanoparticles, which is more evident after incubation with enzymes such as esterases. PHG nanoparticles were loaded during UV irradiation process with Cytarabine, chosen as a model drug, and Cyt‐loaded PHG nanoparticles were able to release it in a simulated physiological fluid (phosphate buffer at pH 7.4) and in blood plasma.

Transmission electron micrograph of photo‐crosslinked PHG.     

L‐Tyrosine Ester‐Mediated Photosensitized Charge Separation – Length Effects of Alkyl Side Chains in Polymers and Alkyl Groups in L‐Tyrosine Esters

The ruthenium(II) complex‐ and viologen‐containing partially quaternized poly(1‐vinylimidazole)s with a butyl (C₄RuVQPIm), an octyl (C₈RuVQPIm), a dodecyl (C₁₂RuVQPIm), and hexadecyl (C₁₆RuVQPIm) as alkyl side chains have been prepared. The length‐effects of the alkyl side chain in the polymers and the alkyl groups in the L ‐tyrosine esters on the L ‐tyrosine‐ester‐mediated intra‐polymer photosensitized charge‐separation reactions have been investigated in methanol. The L ‐tyrosine esters with a hexyl (C₆Tyr), an octyl (C₈Tyr), and a dodecyl (C₁₂Tyr) group were used. The luminescence intensities decreased with the addition of the L ‐tyrosine esters, and they significantly depended on the length of the alkyl side chains on the polymers, C₁₂RuVQPIm showed the smallest luminescence intensity. In contrast, the luminescence intensity of C₄RuVQPIm depended on the length of the alkyl groups in the L ‐tyrosine esters, but not for C_nRuVQPIms (n ≥ 8). These results were explained by a difference in the microdomain structure formed by the polymer structure between C₄RuVQPIm and other polymers. During the photosensitized charge separation, the reaction proceeded through a mediated process, using L ‐tyrosine esters, and a direct process (without L ‐tyrosine esters). The initial rate of the viologen radical formation was influenced by both the alkyl side chains on the polymers and alkyl groups in the L ‐tyrosine esters, particularly; particularly influenced was the back reaction in the mediated process.     

Bulk Polymerization Photo‐Initiator ZnO: Increasing of the Benzoyl Formic Acid Concentration and LED Illumination

Polymerization in volume/bulk is one of the most important processes used in science and in industry to form solid polymers used in multiple different applications. The migration and transport of molecular polymerization initiators are problematic for commercially used photo‐polymerization procedures. ZnO not only is a well‐known photo‐semiconductor but has the potential to be used as an enlarged size photo‐initiation system. A high reactivity modification, firstly systematically investigated using novel light‐emitting diode illumination and two benchmarked resins is presented here. The curing potential of layers up to 1.4 mm is proven and first indications of differences in oxygen dependencies of such initiating systems are discovered. Additionally, the optimized synthesis procedure (0.45 mol L^?1 Zn²⁺ at room temperature) is presented which allows to perform systematic variation of the ZnO surface. Starting from one approach/batch, the content of the modification is systematically increased.     

PCL‐Isocyanate: A New,Degradable Macromolecular Synthon for the Synthesis of Polymeric Bioconjugates

A new route to poly(ε‐caprolactone) (PCL) conjugates is described. It is based on successive reactions: the formation of a polycarboxylated PCL via an anionic carboxylation of PCL, the activation of the carboxylic acid group via an acyl chloride group, the conversion of the acyl chloride group to an azide group and finally the formation of an isocyanate group by the Curtius rearrangement. The various steps were monitored using FTIR spectroscopy. To exemplify the potential of the method, isocyanated poly(ε‐caprolactone) was reacted with UV–absorbing, model, alcohol‐ and amine‐bearing small molecules that were bound to the PCL skeleton via carbamate or urea bonds, respectively. FTIR spectroscopy, SEC with refractometric/photodiode‐array double detection, and ¹H NMR spectroscopy were used to assess the effective binding of the drug models on the polymeric backbone. The thermal transitions of the conjugates were characterized using DSC.

     

Novel Polymers to Study the Influence of the Azobenzene Content on the Photo‐Induced Surface Relief Grating Formation

Summary: The influence of the azobenzene concentration on the photo‐induced surface relief grating (SRG) formation in polymer films was investigated. Two series of polymers with 4‐alkoxy‐4′‐cyanoazobenzene side groups were synthesized. In series A, the degree of substitution was varied, while in series B, azobenzene and biphenyl groups were introduced in varying composition, but the concentration of non‐reacted HEMA‐groups was kept constant. Photo‐induction of the dichroism and the SRG was studied as function of the azobenzene concentration. An optimum was found for the SRG formation (76%), while the highest dichroism was induced at the lowest azobenzene concentration of 20%. The restriction of rotational and translational molecular motions observed at higher azobenzene concentration was explained by π‐π stacking of the azobenzene moieties and interaction of unreacted HEMA groups.

AFM topography image of surface relief grating in polymer B‐76.     

The F···H Hydrogen Bonding Effect on the Dynamic Mechanical and Shape‐Memory Properties of a Fluorine‐Containing Polybenzoxazine

A fluorine‐containing difunctional benzoxazine is synthesized by hydrosilylation of a monofunctional benzoxazine based on o‐allylphenol and p‐fluoroaniline. Besides the intramolecular and intermolecular hydrogen bonding associated with the nitrogen and oxygen atoms in the oxazine ring, specific self‐complementary intermolecular Ar F···HO hydrogen bonding is formed in the polymerization of the benzoxazine, which leads to the resultant polybenzoxazine possessing a broad glass transition temperature range and showing two not well‐separated transitions. Based on the two glass transition temperatures, the polybenzoxazine exhibits triple‐shape‐memory behaviors by manipulating temperature and strain in the shape fixing process under tensile and bending modes. The dynamic mechanical and shape‐memory properties of the polybenzoxazine are influenced by the combined effect of the cross‐linking density and the Ar F···HO hydrogen bonding.

     

Tetraalkylammonium Salts of Amino Acids and Sulfur‐Containing Amino Acids as Effective Co‐Initiators of Free Radical Polymerization in the Presence of Aromatic Ketones

Photoredox pairs, composed of xanthone or thioxanthone derivatives acting as light absorbers and tetrabutylammonium salts of amino acids or sulfur‐containing amino acids as co‐initiators, were studied as photoinitiators for free‐radical polymerization. The mechanism of free‐radical formation was established using the laser flash photolysis. Measurements of polymerization kinetics show that the photoinitiation ability of the xanthone‐ or thioxanthone‐derivative/amino acid or sulfur‐containing amino acid pairs depends on the initiator and co‐initiator properties, mostly on the triplet state lifetime of xanthone or thioxanthone derivatives.

     

Visible Light Induced Emulsion Polymerization: An Improved Photoinitiation System Based on Amphiphilic Tertiary Amine N‐Oxides

A new method for visible‐induced emulsion polymerization is successfully demonstrated. Photo­initiators are used upon irradiation with visible light to undergo sequential photodecomposition, demonstrating an effective way to generate radicals with octadecylamine ethoxylates N‐oxide (AO‐1805, EO = 5). AO‐1805, acting both as a surfactant and mediator simultaneously, is proposed for free radical generation through synergistic effects with the photoinitiator, which differs greatly from organoboron compounds, especially in emulsions. Comparative experiments are carried out with nonylphenol ethoxylates (NP‐10, EO = 5) upon irradiation with UV and visible light in order to examine the nature of the photoinitiated emulsion polymerization with AO‐1805. The laser flash photolysis method is then used to study the interaction between AO‐1805 and free radicals. The emulsion photopolymerization of styrene may be successfully mediated by AO‐1805, with good control over molecular weight. A synergistic effect between radicals and AO‐1805 is observed in the UV irradiation process that can further mediate radical polymerization. In visible light‐induced emulsion polymerization, AO‐1805 also has a novel stabilizing role because of the interaction between D1 and AO‐1805. Moreover, it is hard to see such a trend with the NP‐10/D1 combination, indicating that the functional group (N‐oxide) of AO‐1805 plays an important role in photoinitiation and has an influence on the overall polymerization rate.

     

A New Polymeric Light‐Emitting Material with Pure Green Emission: Poly(fluorene‐alt‐quinoxaline) with Benzothiadiazole Groups in the Side Chain

A new alternative copolymer composed of fluorene and quinoxaline units having benzothiadiazole groups in the side chain was prepared and used as a green emitter for polymeric light‐emitting diodes to give a device emitting pure green color at about 520 nm with a chromaticity coordinate of (x = 0.32, y = 0.59), matching the NTSC 1979 standard green color (x = 0.31, y = 0.595) very well.

     

Green Synthesis of a Bio‐Based Epoxy Curing Agent from Isosorbide in Aqueous Condition and Shape Memory Properties Investigation of the Cured Resin

The bio‐based diamine and epoxy monomer derived from isosorbide are synthesized. Especially, the diamine is obtained using microwave assistant thiol‐ene coupling reaction in the aqueous media and the influence of reaction parameters, such as initiator content and reaction time, are investigated. After curing the synthesized epoxy monomer together with the diamine, properties of the cured resins are studied by differential sscanning calorimetry, dynamic mechanical analysis, and thermogravimetric analyzer. Results demonstrate that the cured resin has good shape fixity, good shape recovery, and satisfied thermal stability despite the presence of heteroatoms. This bio‐based epoxy resin shows great potential to be used as a candidate for shape memory material. Considering the bio‐based feedstock and environmental friendly synthetic process, a “green + green” strategy to prepare thermosetting resins with advanced properties is provided in this paper.

     

Pressure Effects on the Thermodynamics of trans‐Decahydronaphthalene/Polystyrene Polymer Solutions: Application of the Sanchez‐Lacombe Lattice Fluid Theory

The cloud‐point temperatures (T_cl's) of trans‐decahydronaphthalene(TD)/polystyrene (PS, M _w = 270 000) solutions were determined by light scattering measurements over a range of temperatures (1–16 °C), pressures (100–900 bar), and compositions (4.2–21.6 vol.‐% polymer). The system phase separates upon cooling and T_cl was found to increase with rising pressure for constant composition. In the absence of special effects, this finding indicates positive excess volume for the mixing. Special attention was paid to the demixing temperatures as a function of pressure for different polymer solutions and the plots in the T‐? plane (where ? signifies volume fractions). The cloud‐point curves of polymer solutions under different pressures were observed for different compositions, which demonstrated that pressure has a greater effect on the TD/PS solutions when far from the critical point as opposed to near the critical point. The Sanchez‐Lacombe lattice fluid theory (SLLFT) was used to calculate the spinodals, the binodals, the Flory‐Huggins (FH) interaction parameter, the enthalpy of mixing, and the volume changes of mixing. The calculated results show that modified PS scaling parameters can describe the thermodynamics of the TD/PS system well. Moreover the SLLFT describes the experimental results well.

Pressure dependence of the phase transition temperature for the TD/PS polymer solutions at the indicated compositions (In SI units: 1 bar = 10⁵ N · m^?2).     

The Effect of Additive on the Performance and Phase Separation of Benzo[1,2‐b:3,4‐b′]dithiophene‐Based Polymer Heterojunction Photovoltaic Devices

An alternating copolymer (PBDTC₁₀DBT) of benzo[1,2‐b:3,4‐b′]dithiophene (BDT) as donor and 4,7‐di(3‐decylthiophen‐2‐yl)‐2,1,3‐benzothiadiazole (C₁₀DBT) as acceptor is designed and synthesized. In order to investigate the effect of the 1,8‐diiodooctane (DIO) additive on the morphology and photovoltaic performance, polymer solar cells (PSCs) based on PBDTC₁₀DBT:[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) are fabricated. The morphology of blend films and the interpenetrating network between the donor and the acceptor is examined using atomic force microscopy and scanning electron microscopy. This work shows that the PBDTC₁₀DBT:PC₆₁BM blend films with added DIO (3%, v/v) have improved absorption and controlled phase separation. Morphology with a domain size of 20–30 nm that forms in the DIO system is proposed to facilitate charge transport and minimize charge carrier recombination, which are the main reasons why the power conversion efficiency of the PSCs is improved from 1.93% (without DIO) to 2.23% (with DIO).

     

Improving the Stability in Aqueous Media of Polymer Brushes Grafted from Silicon Oxide Substrates by Surface‐Initiated Atom Transfer Radical Polymerization

Hydrophilic polymer brushes grown via surface‐initiated ATRP from silicon oxide surfaces are susceptible to detachment via hydrolytic cleavage of the anchoring siloxane bond. This paper investigates the influence of the structure of the ATRP initiator on the stability of these brushes and seeks for strategies to further enhance their stability. It is found that increasing the hydrophobicity of the organosilane modified ATRP initiator reduces the susceptibility of the brushes toward cleavage. Robust, hydrophilic polymer brushes are prepared, which are obtained by introducing a short, hydrophobic PMMA or PEHMA block between the silicon oxide substrate and the hydrophilic polymer brush.

     

High‐risk cytogenetics in multiple myeloma: Further scrutiny of deletions within the IGH gene region enhances risk stratification

Multiple myeloma is a clonal malignancy of plasma cells in the bone marrow. Risk stratification is partly based on cytogenetic findings that include abnormalities of the IGH locus as determined by fluorescence in situ hybridization (FISH), such as rearrangements that result in either standard‐risk or high‐risk gene fusions. IGH deletions have been evaluated as a group in multiple myeloma patients with respect to cumulative outcomes but have provided limited guidance. Whether these deletions have the potential to result in gene fusions and thus further stratify patients is unknown. We identified 229 IGH deletions in patients referred for plasma cell dyscrasia genetic testing over 5.5 years. Follow‐up was conducted on 208 of the deletions with dual fusion FISH probes for standard‐risk (IGH‐CCND1) and high‐risk IGH gene fusions (IGH‐FGFR3, IGH‐MAF, IGH‐MAFB). Of all deletions identified with follow‐up, 44 (21%) resulted in a gene fusion as detected by FISH, 15 (7%) of which were fusion partners associated with high‐risk multiple myeloma. All fusion‐positive 3′‐IGH deletions (6 fusions) resulted in high‐risk IGH‐FGFR3 fusions. Of the 15 high‐risk fusion‐positive cases, eight were without other high‐risk cytogenetic findings. This study is the first to evaluate the presence of IGH gene fusions upon identification of IGH deletions and to characterize the deletion locus. Importantly, these findings indicate that follow‐up FISH studies with dual fusion probes should be standard of care when IGH deletions are identified in multiple myeloma.     

A Novel Thermo‐Polymerizable Aromatic Diamine: Synthesis and Application in Enhancement of the Properties of Conventional Polyimides

Owing to their important application in the production of high performance materials, aromatic diamines have received interest in many areas for several years. However, most of the polymers derivated from diamines show poor processability due to their rigid backbone. Although much effort has been made, a balance between the solvent (or heat)‐resistance and processability of the polymers still needs to be achieved. In this contribution, a new aromatic diamine is reported, which has both reactive amine groups and thermo‐polymerizable benzocyclobutene moieties. Starting from the diamine can not only give the corresponding polymers, such as polyamides, polyimides, and polyurethanes, but can also provide new structural materials through the post‐polymerization of the polymers. It is found that adding diamine into a conventional polyimide system can greatly improve the properties of the polyimide, such as T_g, coefficient of thermal expansion, tensile strength, and storage modulus. When the content of the diamine is in the range ≈ 5–10 mol%, the tensile strength of the conventional polyimide is increased by up to 30%. The highest T_g (> 400 °C) is observed when the content of the diamine is 40 mol%.

     

Macromolecular Crystal Engineering Based on Segmented Polymers: Influence of Heteroatoms on the Thermal Properties and Crystallization of m,n‐Polyurethanes Derived from Long‐Chain,Heteroatom‐Containing,Monodisperse α,ω‐Diols

Long‐chain heteroatom‐containing telechelic diols with 29–32 atoms in the backbone were synthesized by a one‐step, free‐radical telomerization of 10‐undecene‐1‐ol with commercially available α,ω‐dithiols. The oxygen and sulfur atoms caused a decrease in the melting point and enthalpy of the diols, compared to the corresponding purely aliphatic diols. The heteroatom‐containing α,ω‐diols HO? (CH₂)₁₁? S? (CH₂)₂? X? (CH₂)₂? S? (CH₂)₁₁? OH, where X = CH₂, O, or O? (CH₂)₂? O, were reacted in the melt with 1,6‐diisocyanatohexane O?C?N? (CH₂)₆? N?C?O, producing a series of polyurethanes containing an increasing amount of heteroatoms. Characterization by differential scanning calorimetry, infra‐red spectroscopy, thermogravimetric analysis, and wide angle x‐ray scattering of the m,n‐polyurethane series showed that, like the telechelic diols they were synthesized from, the heteroatoms caused a decrease in the melting point and enthalpy. However, they did not affect either the decomposition temperature or the crystal structure/packing.

Typical decomposition behavior of all the heteroatom‐containing m,6‐polyurethane.