Diblock copolymers,micelles, and shell‐crosslinked nanoparticles containing poly(4‐fluorostyrene): Tools for detailed analyses of nanostructured materials

Amphiphilic core–shell nanostructures containing ¹⁹F stable isotopic labels located regioselectively within the core domain were prepared by a combination of atom transfer radical polymerization (ATRP), supramolecular assembly, and condensation‐based crosslinking. Homopolymers and diblock copolymers containing 4‐fluorostyrene and methyl acrylate were prepared by ATRP, hydrolyzed, assembled into micelles, and converted into shell‐crosslinked nanoparticles (SCKs) by covalent stabilization of the acrylic acid residues in the shell. The ATRP‐based polymerizations, producing the homopolymers and diblock copolymers, were initiated by (1‐bromoethyl)benzene in the presence of CuBr metal and employed N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the coordinating ligand for controlled polymerizations at 75–90 °C for 1–3 h. Number‐average molecular weights ranged from 2000 to 60,000 Da, and molecular weight distributions, generally less than 1.1 and 1.2, were achieved for the homopolymers and diblock copolymers, respectively. Methyl acrylate conversions as high as 70% were possible, without observable chain–chain coupling reactions or molecular weight distribution broadening, when bromoalkyl‐terminated poly(4‐fluorostyrene) was used as the macroinitiator. Poly(4‐fluorostyrene), incorporated as the second segment in the diblock copolymer synthesis, was initiated from a bromoalkyl‐terminated poly(methyl acrylate) macroinitiator. After hydrolysis of the poly(methyl acrylate) block segments, micelles were formed from the resulting amphiphilic block copolymers in aqueous solutions and were then stabilized by covalent intramicellar crosslinking throughout the poly(acrylic acid) shells to yield SCKs. The SCK nanostructures on solid substrates were visualized by atomic force microscopy and transmission electron microscopy. Dynamic light scattering was used to probe the effects of crosslinking on the resulting hydrodynamic diameters of nanoparticles in aqueous and buffered solutions. The presence of fluorine atoms in the diblock copolymers and resulting SCK nanostructures allowed for characterization by ¹⁹F NMR in addition to ¹H NMR, ¹³C NMR, and IR spectroscopy. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4152–4166, 2001     

Octahydrogenated retinoic acid‐conjugated glycol chitosan nanoparticles as a novel carrier of azadirachtin: Synthesis,characterization, and in vitro evaluation

Environment‐friendly and controlled release formulation is highly promising for reducing environmental pollution and achieving the most effective utilization of pesticides. As a novel “green” nanocarrier of pesticides, amphiphilic self‐assembled nanoparticles were prepared by chemical conjugation of octahydrogenated retinoic acid (OR) to the backbone of glycol chitosan (GC). In aqueous media, the synthesized OR‐GC conjugates formed nanosized particles with a diameter of 257 nm. Hydrophobic azadirachtin (AZA) was efficiently loaded into the OR‐GC nanoparticles at a feed weight ratio of up to 1:4 using a simple dialysis method, the maximum drug‐loading efficiency of which was 74%. AZA‐OR‐GC (25 wt %) nanoparticles also showed sustained release of the incorporated AZA (65% of the loaded dose was released in 7 days at 27 °C in phosphate‐buffered saline; pH 7.2). Cytotoxicity tests and cell cycle arrest assays confirmed that OR‐GC exhibits good biocompatibility; AZA‐OR‐GC (25 wt %) nanoparticles also showed favorable inhibition of cell proliferation in Sl‐1 cells compared with free AZA in organic solvents. Overall, controlled release AZA‐OR‐GC may be a promising environment‐friendly formulation for integrated pest management. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3932–3940     

PNIPAM‐b‐(PEA‐g‐PDMAEA) double‐hydrophilic graft copolymer: Synthesis and its application for preparation of gold nanoparticles in aqueous media

A series of well‐defined double‐hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) (PNIPAM‐b‐PEA) backbone and poly(2‐(dimethylamino)ethyl acrylate) (PDMAEA) side chains, were synthesized by the combination of single‐electron‐transfer living radical polymerization (SET‐LRP) and atom‐transfer radical polymerization (ATRP). PNIPAM‐b‐PEA backbone was first prepared by sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with 2‐chloropropionyl chloride. The final graft copolymers with narrow molecular weight distributions were synthesized by ATRP of 2‐(dimethylamino)ethyl acrylate initiated by the macroinitiator at 40 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system via the grafting‐from strategy. These copolymers were employed to prepare stable colloidal gold nanoparticles with controlled size in aqueous solution without any external reducing agent. The morphology and size of the nanoparticles were affected by the length of PDMAEA side chains, pH value, and the feed ratio of the graft copolymer to HAuCl₄. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1811–1824, 2009     

A convergence of photo‐bergman cyclization and intramolecular chain collapse towards polymeric nanoparticles

Employing enediynes as crosslinking precursors, a novel yet efficient strategy, namely photo‐triggered Bergman cyclization, was integrated with intramolecular chain collapse to yield polymeric nanoparticles with the size regime below 20 nm. Enediyne motif was designed delicately to possess a high photo‐reactivity, with the double bond locked in a methyl benzoate ring while triple bonds substituted with phenyls. Single electron transfer‐living radical polymerization was conducted to provide linear acrylate copolymers with controlled molecular weights and narrow polydispersities. Poly(butylarylate‐co‐ 5 ) went through UV‐irradiation with a concurrent Bergman cyclization, resulting in well‐defined ultrafine polymeric nanoparticles. Results from NMR, Raman scattering, photoluminescence and UV‐vis spectra corroborated the presence of conjugative structures in the polymeric nanoparticles, indicating the occurrence of photo‐induced Bergman cyclization. A series of other acrylate‐based nanoparticles were investigated to confirm the applicability of such a unique strategy in thermal sensitive but UV‐stable polymeric structures, making photo‐Bergman cyclization a promising tool towards polymeric nanoparticles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of triblock copolymers based on two isomer acrylate monomers by atom transfer radical polymerization

The syntheses of triblock copolymers by the atom transfer radical polymerization of tert‐butyl and iso‐butyl acrylates as inner blocks with cyclohexyl methacrylate as outer blocks are reported. The living behavior and blocking efficiency of these polymerizations were investigated in each case. The use of difunctional macroinitiators led to ABA triblock copolymers with narrow polydispersities and controlled number‐average molecular weights. These copolymers were prepared from bromo‐terminated macroinitiators of poly(tert‐butyl acrylate) and poly(iso‐butyl acrylate), with copper chloride/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalytic system, at 40 °C in 50% (v/v) toluene solutions. The block copolymers were characterized with size exclusion chromatography and ¹H NMR spectroscopy. Differential scanning calorimetry measurements were performed to reveal the phase segregation. The glass transition of the inner block was not clearly detected, with the exception of the copolymer synthesized with the longest poly(iso‐butyl acrylate) macroinitiator length. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4828–4837, 2005     

Synthesis and characterization of water‐soluble gold nanoparticles stabilized by comb‐shaped copolymers

The water‐soluble gold nanoparticles stabilized by well‐defined comb‐shaped copolymers have been synthesized successfully. The hybrid nanoparticles consist of gold core and poly[poly(ethylene oxide) methyl ether acrylate]‐block‐poly(N‐isopropylacrylamide) [P(A‐MPEO)‐block‐PNIPAM] shell. The water‐soluble comb‐shaped copolymers, P(A‐MPEO)‐block‐PNIPAM with PNIPAM as a handle, were successfully synthesized via a macromonomer technique using reversible addition fragmentation chain transfer (RAFT) polymerization method. The terminal dithioester group of the comb‐shaped copolymer was reduced to a thiol end group forming SH‐terminated copolymers, P(A‐MPEO)‐block‐PNIPAM‐SH. Successively they were used to stabilize gold nanoparticles by the “grafting‐to” approach. The hybrid nanoparticles were characterized by TEM, UV–vis, and HRTEM. Because of the thermosensitive property of PNIPAM in aqueous solution, the comblike copolymer‐tethered gold nanoparticles show a sharp and reversible phase transition at 30 °C in aqueous solution, which was determined by microdifferential scanning calorimetry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 341–352, 2008     

Synthesis and radical polymerization properties of thermal radical initiators based on o‐imino‐isourea: The effect of the alkyl side chain on the radical initiation temperature

Four types of thermal radical initiators (TRIs) that are based on o‐imino‐isourea with cyclohexyl and isopropyl groups were successfully synthesized, namely, C‐HexDCC, DiiprDCC, C‐HexDIC, and DiiprDIC. The free radical polymerization and thermal properties of those synthesized TRIs were determined via differential scanning calorimetry (DSC) (using n‐butyl acrylate) and thermogravimetric analysis (TGA), respectively. The TRI derivatives showed peak temperatures (T_max) from 89 to 97 °C in n‐butyl acrylate, and DiiprDIC, with isopropyl groups on both sides of the N O group, showed the lowest peak temperatures. The rates of N O bond homolysis (k_d) of all the TRIs were calculated from their half‐lives determined using real‐time nuclear magnetic resonance (NMR) spectroscopy, and their theoretical bond dissociation energies (BDEs) were calculated using density functional theory (DFT) calculations. The free radical polymerization of n‐butyl acrylate using each TRI was efficiently determined from T_peak of the DSC curves; conversions depending on polymerization temperature (80, 90, and 100 °C) were monitored to observe kinetic information of TRIs during polymerization. Furthermore, to investigate the use of TRIs in curing, we applied them to an automotive clear coating system and monitored the real‐time evolution of the elastic modulus (G′) during thermal curing using a rheometer for representative DiiprDIC. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1749–1756     

Superior Photostability and Photocatalytic Activity of ZnO Nanoparticles Coated with Ultrathin TiO2 Layers through Atomic‐Layer Deposition

Atomic‐layer deposition (ALD) is a thin‐film growth technology that allows for conformal growth of thin films with atomic‐level control over their thickness. Although ALD is successful in the semiconductor manufacturing industry, its feasibility for nanoparticle coating has been less explored. Herein, the ALD coating of TiO₂ layers on ZnO nanoparticles by employing a specialized rotary reactor is demonstrated. The photocatalytic activity and photostability of ZnO nanoparticles coated with TiO₂ layers by ALD and chemical methods were examined by the photodegradation of Rhodamine B dye under UV irradiation. Even though the photocatalytic activity of the presynthesized ZnO nanoparticles is higher than that of commercial P25 TiO₂ nanoparticles, their activity tends to decline due to severe photocorrosion. The chemically synthesized TiO₂ coating layer on ZnO resulted in severely declined photoactivity despite the improved photostability. However, ultrathin and conformal ALD TiO₂ coatings (≈0.75–1.5 nm) on ZnO improved its photostability without degradation of photocatalytic activity. Surprisingly, the photostability is comparable to that of pure TiO₂, and the photocatalytic activity to that of pure ZnO.     

Thermal radical initiator derivatives based on O‐imino‐isourea: Synthesis,polymerization, and characterization

The new thermal radical initiators (TRIs) with linear and cyclic type groups based on derivatives of O‐imino‐isourea have been designed and synthesized. The radical polymerization property of the synthesized TRI derivatives as a radical initiator in n‐butyl acrylate was monitored by differential scanning calorimetry analysis. TRI derivatives with linear type groups, such as 3‐PenDCC, 3‐HexDCC, and 4‐HepDCC, showed peak temperatures (T_peak) of 80–84 °C, whereas those with cyclic type groups, such as C‐PenDCC, C‐HexDCC, and C‐HepDCC, exhibited a wide T_peak distribution in the 74–87 °C range. The polymerization efficiency using new TRIs in n‐butyl acrylate was elaborately identified from the molecular weights and conversion obtained using gel permeation chromatography analysis and NMR spectroscopy. To consider their possible application to automotive clearcoats, the real‐time evolution of the rheological properties of clearcoat resins during the crosslinking process with newly synthesized TRI derivatives was measured, confirming the different crosslinking kinetics of TRI derivatives in real thermal curing process. The results were found to be well correlated with data from the radical polymerization experiments of TRIs. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3593–3600.     

Conjugated polymer nanoparticles with aggregation induced emission characteristics for intracellular Fe3+ sensing

In this article, a novel zwitterionic conjugated polyelectrolyte containing tetraphenylethene unit was synthesized via Pd‐catalyzed Sonogashira reaction. The resulting polymer (P2), which exhibited typical aggregation‐induced emission (AIE) properties, was weakly fluorescent in dilute DMSO solution and showed bright fluorescence emissions when aggregated in DMSO/water mixtures or fabricated into conjugated polymer nanoparticles (CPNs). The nanoparticles from P2 could be prepared by reprecipitation method with an average diameter around 23 nm. Notably, the cell‐staining efficiencies of lipid‐P2 nanoparticles could be enhanced with lipid encapsulation and these nanoparticles were endocytosed via caveolae‐mediated and clathrin‐mediated endocytosis pathways. Furthermore, the lipid‐P2 nanoparticles with low cytotoxicity, high photostability and efficient cell staining ability could be employed for in vitro detection of Fe³⁺ ions in A549 cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1686–1693     

Behaviors of self‐assembled diblock copolymer with pendant photosensitive azobenzene segments

A novel monomer, ethyl 4‐[4‐(11‐methacryloyloxyundecyloxy)phenyl azobenzoyl‐oxyl] benzoate, containing a photoisomerizable N?N group was synthesized. The monomer was further diblock copolymerized with methyl methacrylate. Amphiphilic diblock copolymer poly(methyl methacrylate‐block‐ethyl 4‐[4‐(11‐methacryloyloxyundecyloxy)phenyl azobenzoyl‐oxyl] benzoate ( PMMA ‐ b ‐ PAzoMA ) was synthesized using atom transfer radical polymerization. The reverse micelles with spherical construction were obtained with 2 wt % of the diblock copolymer in a THF/H₂O mixture of 1:2. Under alternating UV and visible light illumination, reversible changes in micellar structure between sphere and rod‐like particles took place as a result of the reversible E‐Z photoisomerization of azobenzene segments in PMMA ‐ b ‐ PAzoMA . Microphase separation of the amphiphilic diblock copolymer in thin films was achieved through thermal and solvent aligning methods. The microphases of the annealed thin films were investigated using atom force microscopy topology and scanning electron microscopy analyses. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1142–1148, 2010     

Synthesis of P(AA‐SA)/ZnO composite latex particles via inverse miniemulsion polymerization and its application in pH regulation and UV shielding

Poly(acrylic acid‐co‐sodium acrylate)/zinc oxide, P(AA‐SA)/ZnO, composite latex particles were synthesized by inverse miniemulsion polymerization. The ZnO nanoparticles were prepared by hydrothermal synthesis and undergone oleic acid (OA) surface treatment. The X‐ray diffraction pattern and FT‐IR spectra characterized the crystal structure and functional groups of OA‐ZnO nanoparticles. An appropriate formulation in preparing P(AA‐SA) latex particles, ensuring the dominant in situ particle nucleation and growth, was developed in our experiment first. Sodium hydroxide was chosen as a costabilizer, because of its ability to increase the deprotonation of acylic acid and enhance the hydrophilicity of monomer, acrylic acid besides providing osmotic pressure. The growth mechanism of P(AA‐SA)/ZnO composite particles was proposed. The OA‐ZnO nanoparticles were adsorbed on or around the surface of P(AA‐SA) latex particles by hydrophobic interaction, thus enhanced the interfacial tension over latex particles. The P(AA‐SA)/ZnO composite latex particles owned better thermal stability than pure latex particles. The pH regulation capacity was excellent for both ZnO and P(AA‐SA) particles. Combining P(AA‐SA) and ZnO nanoparticles into composite particles, the performance in pH regulation and UV shielding was discussed from our experimental results. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8081–8090, 2008     

Cobalt Single‐Atom Catalysts with High Stability for Selective Dehydrogenation of Formic Acid

Metal–organic framework (MOF)‐derived Co‐N‐C catalysts with isolated single cobalt atoms have been synthesized and compared with cobalt nanoparticles for formic acid dehydrogenation. The atomically dispersed Co‐N‐C catalyst achieves superior activity, better acid resistance, and improved long‐term stability compared with nanoparticles synthesized by a similar route. High‐angle annular dark‐field–scanning transmission electron microscopy, X‐ray photoelectron spectroscopy, electron paramagnetic resonance, and X‐ray absorption fine structure characterizations reveal the formation of Co^IIN_x centers as active sites. The optimal low‐cost catalyst is a promising candidate for liquid H₂ generation.     

Photocuring kinetics of UV‐initiated free‐radical photopolymerizations with and without silica nanoparticles

We used photodifferential scanning calorimetry to investigate the photocuring kinetics of UV‐initiated free‐radical photopolymerizations of acrylate systems with and without silica nanoparticles. Two kinetics parameters—the rate constant (k) and the order of the initiation reaction (m)—were determined for hybrid organic–inorganic nanocomposite systems containing different amounts of added silica nanoparticles (0–20 wt %) and at different isothermal temperatures (30–100 °C) using an autocatalytic kinetics model. The kinetic analysis revealed that the silica nanoparticles apparently accelerate the cure reaction and cure rate of the UV‐curable acrylate system, most probably due to the synergistic effect of silica nanoparticles during the photopolymerization process. However, a slight decrease in polymerization reactivity that occurred when the silica content increased beyond 15 wt % was attributed to aggregation between silica nanoparticles. We also observed that the addition of silica nanoparticles lowered the activation energy for the UV‐curable acrylate system, and that the collision factor for the system with silica nanoparticles was higher than that obtained for the system without silica nanoparticles, indicating that the reactivity of the former was greater than that of the latter. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 658–670, 2005     

Synthesis of a new type of core–shell particle from hyperbranched polyglycerol

Based on hyperbranched polyglycerol (PG), a route to prepare particles with a novel topology was developed. The hydroxyls of PG were converted to trithiocarbonates, and the latter were used to mediate the surface graft polymerization of N,N‐dimethylaminoethyl acrylate. The poly(N,N‐dimethylaminoethyl acrylate) shell was crosslinked by 1,6‐dibromohexane and then parted from the core by the cleavage of trithiocarbonates with sodium borohydride. Novel particles with thiol groups located on the interface between the PG core and poly(N,N‐dimethylaminoethyl acrylate) shell were thus formed. The shell crosslinking could be performed at very high solid contents (2–4%). These polymer particles showed pH‐ and temperature‐dependent solubility. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5458–5464, 2005     

Structural,compositional and hardness properties of hydrogenated amorphous carbon nitride thin films synthesized by dense plasma focus device

The hydrogenated amorphous carbon nitride (a‐CN_x:H) thin films were synthesized on the SS‐304 substrates using a dense plasma focus device. The a‐CN_x:H thin films were synthesized using CH₄/N₂ admixture gas and 20 focus deposition shots on substrates placed at different distances from the anode top. X‐ray photoelectron spectroscopy and Raman analysis confirmed different C–N bonding in the a‐CN_x:H thin films. A decrease in the N/C ratio as well as the sp³/sp² ratio with an increase in the substrate distance has been observed. The higher amount of C–N formation for the film synthesized at 10 cm is observed which decreases with increasing distance. The X‐ray photoelectron spectroscopy and Raman analysis affirmed the C ≡ N presence in all the thin films synthesized at different distances. The morphology of the synthesized a‐CN_x:H thin films showed nanoparticles and nanoparticle clusters formation at the surface. The hardness results showed comparatively lower hardness of the a‐CN_x:H thin films due to the presence of C ≡ N. The C–N formation with lower amount of C ≡ N and a higher N/C ratio as well as a higher sp³/sp² ratio for the films synthesized at 10 cm show reasonably higher hardness. Copyright © 2016 John Wiley & Sons, Ltd.     

Resorcinarene‐based ATRP initiators for star polymers

Two novel multifunctional initiators for atom transfer radical polymerization (ATRP) were synthesized by derivatization of tetraethylresorcinarene. The derivatization induced a change in the conformation of the resorcinarene ring, which was confirmed by NMR spectroscopy. The initiators were used in ATRP of tert‐butyl acrylate and methyl methacrylate, producing star polymers with controlled molar masses and low polydispersities. Instead of the expected star polymers with eight arms, polymers with four arms were obtained. Conformational studies on the initiators by rotating‐frame nuclear Overhauser and exchange spectroscopy NMR and molecular modeling suggested that of eight initiator functional groups on tetraethylresorcinarene, four are too close to each other to be able to initiate the chain growth. Starlike poly(tert‐butyl acrylate) macroinitiators were used further in the block copolymerization of methyl methacrylate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4189–4201, 2004     

Synthesis,Photophysical Properties,and Antimicrobial Activity of Novel Styryl Colorants Derived from 7‐Methoxy‐1,4‐diphenethyl‐1,2,3,4‐tetrahydroquinoxaline‐6‐carbaldehyde

The novel 1,4‐diphenethyl‐1,2,3,4‐tetrahydro‐7‐methoxyquinoxalin‐6‐carbaldehyde was synthesized by reductive alkylation of 6‐methoxy quinoxaline with phenyl acetic acid and was further subjected to Knoevenagel condensation with various active methylene compounds to synthesize novel styryl colorants. Photophysical properties of styryl colorants were studied using UV–visible and fluorescence spectroscopy. These colorants displayed orange to violet hue and showed fluorescence emission maxima in the region of 560–640 nm, and displayed a large Stokes shift (85–104 nm). Compounds were subjected to thermogravimetric analysis which showed excellent stability up to 310°C. These styryl compounds were evaluated for their antimicrobial study as antifungal against Candida albicans C. albicans and Aspergillus niger and antibacterial against Escherichia coli and Staphylococcus aureus. The results revealed good antimicrobial activity against tested organisms. The synthesized chromophores were characterized using elemental analysis, FTIR, ¹³C‐NMR and ¹H‐NMR spectroscopy and mass spectrometry.     

Synthesis and characterization of sulfonated block copolymers by atom transfer radical polymerization

Well‐defined sulfonated polystyrene and block copolymers with n‐butyl acrylate (nBA) were synthesized by CuBr catalyzed living radical polymerization. Neopentyl p‐styrene sulfonate (NSS) was polymerized with ethyl‐2‐bromopropionate initiator and CuBr catalyst with N,N,N′,N′‐pentamethylethyleneamine to give poly(NSS) (PNSS) with a narrow molecular weight distribution (MWD < 1.12). PNSS was then acidified by thermolysis resulting in a polystyrene backbone with 100% sulfonic acid groups. Random copolymers of NSS and styrene with various composition ratios were also synthesized by copolymerization of NSS and styrene with different feed ratios (MWD < 1.11). Well defined block copolymers with nBA were synthesized by sequential polymerization of NSS from a poly(n‐butyl acrylate) (PnBA) precursor using CuBr catalyzed living radical polymerization (MWD < 1.29). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5991–5998, 2008     

Synthesis and characterization of functional gradient copolymers of allyl methacrylate and butyl acrylate

Functional spontaneous gradient copolymers of allyl methacrylate (A) and butyl acrylate (B) were synthesized via atom transfer radical polymerization. The copolymerization reactions were carried out in toluene solutions at 100 °C with methyl 2‐bromopropionate as the initiator and copper bromide with N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst system. Different aspects of the statistical reaction copolymerizations, such as the kinetic behavior, crosslinking density, and gel fraction, were studied. The gel data were compared with Flory's gelation theory, and the sol fractions of the synthesized copolymers were characterized by size exclusion chromatography and nuclear magnetic resonance spectroscopy. The copolymer composition, demonstrating the gradient character of the copolymers, and the microstructure were analyzed. The experimental data agreed well with data calculated with the Mayo–Lewis terminal model and Bernoullian statistics, with monomer reactivity ratios of 2.58 ± 0.37 and 0.51 ± 0.05 for A and B, respectively, an isotacticity parameter for A of 0.24, and a coisotacticity parameter of 0.33. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5304–5315, 2006