The synthesis of poly(N‐vinylcarbazole)‐based block copolymers functionalized with rhenium diimine complexes or pendant terpyridine ligands is reported. The copolymers are synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization, and they exhibit interesting morphological properties as a result of the phase separation between different blocks. The rhenium complex polymer block may function as a photosensitizer, while the terpyridine‐containing polymer block can be used as the template for nanofabrication by selective deposition of zinc complexes.
Random copolymers of poly(9,9‐di‐n‐octylfluorene) (PF8) incorporating 0, 8, 12, 15, and 20% dibenzothiophene (DBT), and copolymers with 2, 5, 8, 12, and 15% dibenzothiophene‐S,S‐dioxide (S‐unit) were synthesised. Absorption and emission spectra of thin films indicate that the DBT system shows a linear decrease of toluene vapour induced β phase with increasing DBT content to a 20% cutoff, whilst in the S‐unit copolymers the β phase is present up to 12% co‐monomer content, and at 15% the characteristic absorption peak is absent or masked. These results demonstrate the limits, in thin films, at which the β phase can be formed in widely used PF8 copolymer systems for device applications and clearly show that it is practical to use copolymers having electron or hole transport units in the polyfluorene backbone and still be able to form efficient β phase emission sites.
Well‐defined PEO‐b‐PMMA was prepared, initiated by macroinitiator PEO‐Br, by means of ATRP, where esterification of the terminal hydroxyl group of PEO with 2‐bromoisobutyryl bromide yielded a macroinitiator PEO‐Br. Highly ordered microporous films (hexagonal pattern) were constructed by emulsion micelles of such amphiphilic diblock copolymer formed from a solution with CHCl3/H2O/THF = 100:5:10 (v/v). We also constructed the microporous films using diblock copolymer by the current water‐assisted method.
Blue‐light‐emitting 2,7‐carbazole‐based conjugated copolymers have been prepared by Yamamoto or Suzuki cross‐coupling reactions. By introducing highly substituted aromatic comonomers, fully soluble high‐molecular‐weight copolymers have been obtained. Moreover, these amorphous polymeric materials exhibit good thermal stability and interesting redox properties. All these features make these new conjugated polymers highly promising for the development of single‐polymer‐layer blue‐light‐emitting diodes.
The effects of addition of poly(ethylene oxide) (PEO) to poly(ethylene oxide)16‐block‐poly(butylene oxide)22 (EB1) polymersome dispersions has been studied. Aggregation and membrane fusion between polymersomes were observed with great control of the outcome by varying PEO molecular weight. Small‐scale fusion of 2 to 3 polymersomes was seen with low‐molecular‐weight PEO, whilst large‐scale aggregation occurred above a critical PEO molecular weight of 4 000 Da. The resulting highly porous EB1‐PEO aggregate shows great promise for applications in cell entrapment for transport and delivery, and as a three‐dimensional scaffold for use in tissue engineering.
Two novel monovinyl β‐cyclodextrin (β‐CD) monomers are synthesized. Their chemical compositions are characterized by means of element analysis, NMR and FT‐IR spectroscopy. The results show that the synthesis techniques used are convenient and efficient. Using N‐isopropylacrylamide as a comonomer, two novel linear copolymers can also be synthesized.
Enzyme‐loaded magnetic polyelectrolyte multilayer nanotubes prepared by layer‐by‐layer assembly combined with the porous template could be used as biomimetic nanoreactors. It is demonstrated that calcium carbonate can be biomimetically synthesized inside the cavities of the polyelectrolyte nanotubes by the catalysis of urease, and the size of the calcium carbonate precipitates was controlled by the cavity dimensions. The metastable structure of the calcium carbonate precipitates inside the nanotubes was protected by the outer shell of the polyelectrolyte multilayers. These features may allow polyelectrolyte nanotubes to be applied in the fields of nanomaterials synthesis, controlled release, and drug delivery.
Well‐defined amphiphilic PCL‐b‐PDMAEMA block copolymers were successfully synthesized by a combination of ATRP and “click” chemistry following either a commutative two‐step procedure or a straightforward one‐pot process using CuBr · 3Bpy as the sole catalyst. Compared to the traditional coupling method, combining ATRP and click chemistry even in a “one‐pot” process allows the preparation of PCL‐b‐PDMAEMA diblock copolymers characterized by a narrow molecular weight distribution and quantitative conversion of azides and alkynes into triazole functions. Moreover, the amphiphilic character of these copolymers was demonstrated by surface tension measurements and critical micellization concentration was calculated.
Summary: Amphiphilic triblock copolymers (PEOx‐b‐PDMSy‐b‐PEOx) with different block lengths were synthesized and multi‐morphological complex crew‐cut, star‐like, and short‐chain aggregates were prepared by self‐assembly of the given copolymers. The morphologies and dimensions of the aggregates can be well controlled by variation of the preparation conditions. TEM, SEM, FFR‐TEM, and LLS studies show the resulting morphologies range from LCMs, unilamellar or multilayer vesicles, LCVs, porous spheres to nanorods.
TEM images of the vesicles formed from PEO‐b‐PDMS‐b‐PEO. 相似文献
Summary: A water‐soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono‐6‐thio‐β‐cyclodextrin with poly(propylene glycol) bis(2‐aminopropyl ether) ( ≈ 2 000) in the presence of sodium borohydride in N,N‐dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA‐cleavage reagent.
A typical TEM image of gold nanoparticle aggregate 2 . 相似文献
This study reports the first PEO‐coated polymer nanoparticles synthesis by miniemulsion polymerization of nano‐emulsions prepared by the low‐energy emulsification method called EIP. The surfactant used was Brij 98, a PEO based non ionic commercial surfactant. The partial phase diagram of the system water/Brij 98/styrene was first determined. The Emulsion Inversion Point technique was then used on the water/Brij 98/styrene system to the formation of styrene‐in‐water nano‐emulsions. After miniemulsion polymerization, particle sizes as low as 36 nm were obtained. To the best of our knowledge, this method had not been used for polymerizable system up to now.
A series of novel biodegradable random copolymers of 5‐benzyloxy‐1,3‐dioxan‐2‐one (5‐benzyloxy‐trimethylene carbonate, BTMC) and glycolide were synthesized by ring‐opening polymerization. The copolymers were characterized by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The incorporation of BTMC units into the copolymer chains results in good solubility of the polymers in common solvents. The in vitro degradation rate can be tailored by adjusting the composition of the copolymers.
The in vitro degradation of the homopolymers and poly(BTMC‐co‐GA) copolymers. 相似文献
Poly(ethylene glycol) (PEG)‐based films, nanotubes, and nanotube arrays were successfully made using layer‐by‐layer (LbL) assembly ion‐containing PEO derivatives on porous templates and planar substrates. PEG nanotubes are challenging to produce because PEG dissolves into solutions and solvents used during nanotube processing, but our techniques circumvent the issue. Nanotube dimensions were verified using microscopy and the average observed diameter was 155 nm. The PEG‐based structures showed remarkable stability in water, salt water, and sodium hydroxide solution.
The 3‐miktoarm star‐shaped ABC copolymers of polystyrene–poly(ethylene oxide)–poly(ethoxyethyl glycidyl ether) (PS‐PEO‐PEEGE) and polystyrene–poly(ethylene oxide)–polyglycidol (PS‐PEO‐PG) with low polydispersity indices (PDI ≤ 1.12) and controlled molecular weight were synthesized by a combination of anionic polymerization with ring‐opening polymerization. The polystyryl lithium (PS−Li+) was capped by EEGE firstly to form the functionalized polystyrene (PSA) with both an active ω‐hydroxyl group and an ω′‐ethoxyethyl‐protected hydroxyl group, and then the PS‐b‐PEO block copolymers, star(PS‐PEO‐PEEGE) and star(PS‐PEO‐PG) copolymers were obtained by the ring‐opening polymerization of EO and EEGE respectively via the variation of the functional end group, and then the hydrolysis of the ethoxyethyl group on the PEEGE arm. The obtained star copolymers and intermediates were characterized by 1H NMR spectroscopy and SEC.
Novel poly[(fluorene)‐co‐(2,8‐dioctyldibenzothiophene‐S,S‐dioxide‐3,7‐diyl)]s were synthesized. The octyl group on the 2,8‐dioctyldibenzothiophene‐S,S‐dioxide (DOSO) unit improved the solubility of the polymers and broadened the optical band gap from 2.95 to 3.20 eV as the content of DOSO unit increases. The electroluminescence (EL) spectra of polymers show CIE coordinates around (0.16, 0.07) independent of the ratio of DOSO units in the polymers, owing to the ICT and steric hindrance dual‐function. A high efficiency of 3.1 cd · A−1 (EQE = 3.9%) was obtained with the configuration of ITO/PEDOT:PSS/polymer/Ba/Al. The results indicate that PF‐3,7DOSOs could be a promising candidate for saturated blue‐emitting polymers with spectral stability and high efficiency.
Novel water‐developable negative resists were designed to induce both crosslinking and polarity change upon exposure and bake. The matrix polymers were synthesized by copolymerization of glyceryl methacrylate and methacrolein. The acid‐catalyzed acetalization of the polymer induced crosslinking, polarity change, and an increase in dry‐etch resistance. The resist formulated with this polymer and cast in a water/ethanol mixture showed 0.7 μm line and space patterns using a mercury–xenon lamp in a contact printing mode and pure water as a developer.
The acid‐catalyzed acetalization of poly(GMA‐co‐MA) to form the water‐insoluble acetal. 相似文献
Summary: Novel biodegradable copolymers derived from succinate, butan‐1,4‐diol, and butan‐1,4‐diamine were synthesized by two‐step polycondensation reactions. The obtained copolymers had a periodical‐sequence structure consisting of ester and amide units, and the melting temperatures of the periodic copolymers increased with an increase in amide content. The crystalline structure of the periodic copolymers differs from that of butylene succinate homopolymer (PBS), and these results suggest that the periodically introduced amide units are included in the crystalline phase forming a novel crystalline structure.
Periodic copolyester‐amides derived from succinate, butane‐1,4‐diol, and butan‐1,4‐diamine 相似文献
α‐Methoxy‐ω‐alkyne poly(ethylene glycol) (PEG) was tagged with pendent N‐hydroxy‐succinimidyl activated esters by photografting of a molecular clip. This easily synthesized heterofunctional PEG was found to be a versatile building block for (i) conjugation with an amino derivative and (ii) grafting to azido functional aliphatic polyesters backbone by Huisgen's 1,3‐dipolar cycloaddition. This original combination of “clip” and “click” reactions provides a versatile and straightforward pathway for the synthesis of functional amphiphilic and degradable copolymers valuable for biomedical applications such as in drug‐delivery.
Summary: A novel fluorometric saccharide detection strategy has been established by utilizing saccharide‐induced conformational changes in copolymers containing boronic acid and fluorescent units. The polymer chain changes its conformation due to an alteration of the charge state induced by binding with saccharides. The conformational changes are conveniently detected by monitoring excimer to monomer intensity ratio in the fluorescence spectra. Thus, the present strategy would be a promising way for the creation of highly selective and sensitive saccharide‐sensing systems.
Saccharide‐induced conformational change in copolymers containing boronic acid units. 相似文献
A novel amphiphilic diblock copolymer composed of a hydrophilic poly(ethylene oxide) and a hydrophobic polymethacrylate with photochromic azopyridine moieties in the side groups was synthesized by atom transfer radical polymerization. The copolymeric vesicles showed photoinduced circular process including fusion, damage and defect formation, disruption, disintegration and rearrangement in H2O/THF during the irradiation of UV light. The process of photoresponsive cycle can be inhibited at any moment by visible light.
