Glycodendrimersomes with programmable surface display of glycan, together with artificially engineered galectins, were used to understand the physiological significance of human lectins with homodimeric and tandem-repeat-type displays. The mode of topological surface presentation and the density of glycan affected vesicle aggregation mediated by multivalent carbohydrate–protein interactions. The cross-linking capacity of homodimeric lectins was enhanced by covalent connection of the two carbohydrate-binding sites. These findings highlight the value of glycodendrimersomes as versatile cell membrane mimetics, and assays provide diagnostic tools for protein functionality. This work also provides guidelines for the design of cell separators, bioactive matrices, bioeffectors, and other biomedical applications.

Glycodendrimersomes with programmable surface display of glycan, together with artificially engineered galectins, were used to understand the physiological significance of human lectins with homodimeric and tandem-repeat-type displays. The mode of topological surface presentation and the density of glycan affected vesicle aggregation mediated by multivalent carbohydrate–protein interactions. The cross-linking capacity of homodimeric lectins was enhanced by covalent connection of the two carbohydrate-binding sites. These findings highlight the value of glycodendrimersomes as versatile cell membrane mimetics, and assays provide diagnostic tools for protein functionality. This work also provides guidelines for the design of cell separators, bioactive matrices, bioeffectors, and other biomedical applications.

Single electron transfer-living radical polymerization (SET–LRP) of two amphiphilic acrylates, 2-methoxyethyl acrylate up to [M]₀/[I]₀ = 1,000 and di(ethylene glycol) 2-ethylhexyl ether acrylate up to [M]₀/[I]₀ = 200, is accomplished with good control of molecular weight and molecular weight distribution in 2,2,2-trifluoroethanol at 25 °C using hydrazine activated Cu(0) wire as catalyst, methyl 2-bromopropionate as initiator, and Me₆-TREN as ligand. The chain end functionality of the resulting polymers has been analyzed by MALDI-TOF spectrometry to demonstrate the synthesis of perfect or near-perfect chain-end functional amphiphilic homopolymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 294–303

An accelerated modular synthesis produced 18 amphiphilic Janus glycodendrimers with three different topologies formed from either two or one carbohydrate head groups or a mixed constellation with a noncarbohydrate hydrophilic arm. By simple injection of their THF solutions into water or buffer, all of the Janus compounds self-assembled into uniform, stable, and soft unilamellar vesicles, denoted glycodendrimersomes. The mixed constellation topology glycodendrimersomes were demonstrated to be most efficient in binding plant, bacterial, and human lectins. This evidence with biomedically relevant receptors offers a promising perspective for the application of such glycodendrimersomes in targeted drug delivery, vaccines, and other areas of nanomedicine.

An accelerated modular synthesis produced 18 amphiphilic Janus glycodendrimers with three different topologies formed from either two or one carbohydrate head groups or a mixed constellation with a noncarbohydrate hydrophilic arm. By simple injection of their THF solutions into water or buffer, all of the Janus compounds self-assembled into uniform, stable, and soft unilamellar vesicles, denoted glycodendrimersomes. The mixed constellation topology glycodendrimersomes were demonstrated to be most efficient in binding plant, bacterial, and human lectins. This evidence with biomedically relevant receptors offers a promising perspective for the application of such glycodendrimersomes in targeted drug delivery, vaccines, and other areas of nanomedicine.

Self-assembling dendrons are biologically inspired complex systems that can form self-organized periodic arrays in the bulk state. Here we adopt the point of view of Constitutional Dynamic Chemistry (CDC) to discuss the design and properties of self-assembling dendrimers and dendronized structures. Among other objectives, CDC seeks to generate chemical diversity through constitutional dynamics, and to improve the design of dynamic materials using adaptive systems. Can we address these issues with dendrimer chemistry? We will show that generational and co-assembly approaches in the synthesis of self-assembling dendritic systems lead to a remarkable collection of periodic lattices and quasi-periodic arrays. Moreover, in some cases the morphological properties of the resulting supramolecular structures can be tuned by external signals. These dendron-based adaptive systems find applications in various fields such as nano-machines and switches or porous protein mimics.

The efficient Cu(0) wire-catalyzed single-electron transfer-living radical polymerization (SET-LRP) of oligo(ethylene oxide) methyl ether methacrylate (OEOMA) in DMSO and binary mixtures of DMSO with H₂O is reported. Addition of 10–80% H₂O to DMSO resulted in an increase in the apparent rate constant of propagation ( ), corresponding to an increase in the polarity and extent of disproportionation. At higher H₂O content, decreases, and in H₂O is slightly lower than that in DMSO. This unexpected behavior was attributed to the physical inaccessibility of Cu(0) wire catalyst to the hydrophobic reactive centers of OEOMA and initiator which self-assemble in H₂O into micellar aggregates and vesicles. This hypothesis was confirmed by the faster polymerization in H₂O than in DMSO during catalysis with Cu(0) nanoparticles generated by disproportionation of CuBr. SET-LRP of OEOMA can be performed in protic and dipolar aprotic solvents in air by the addition of hydrazine hydrate. The polymerization exhibited no induction period and identical as in the degassed experiment, and led to polymers with narrow molecular weigh distribution. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3110–3122

The commercially available tris(2-aminoethyl)amine (TREN) was used as ligand to mediate the single-electron transfer-living radical polymerization (SET-LRP) of methyl acrylate in dimethyl sulfoxide initiated with the bifunctional initiator bis(2-bromopropionyl)ethane and catalyzed by both nonactivated and activated Cu(0) wire. A comparative study between TREN and tris(2-dimethylaminoethyl)amine (Me₆-TREN) ligand, that is more commonly used in SET-LRP, demonstrated that TREN provided a slower polymerization but the chain-ends functionality of the resulting bifunctional poly(methyl acrylate) was near quantitative and comparable to that obtained when Me₆-TREN was used as a ligand. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.

The single electron transfer-living radical polymerization of methyl acrylate (MA) initiated by bis(2-bromopropionyl)ethane (BPE) in dimethyl sulfoxide was carried out to 100% monomer conversion and complete absence of bimolecular termination under the following reaction conditions: [MA]/[BPE]/[Me₆-TREN]/[CuBr₂] = 60/1/0.21/0.01 and [MA]/[BPE]/[TREN]/[CuBr₂] = 60/1/0.25/0.05. These polymerizations were mediated by 0.5 cm of hydrazine-activated Cu(0) wire of 20 gauge (0.812 cm in diameter), corresponding to a surface area of 0.14 cm² of Cu(0) per 3 mL reaction volume (2/1 v/v monomer/solvent). A higher extent of bimolecular termination (5–13%) was observed at complete conversion when longer lengths of Cu(0) wire were used. In the absence of CuBr₂ the activated Cu(0) wire/Me₆-TREN catalyst in dimethyl sulfoxide also allowed the synthesis of perfectly bifunctional and monofunctional PMAs at complete conversion. This was also demonstrated by the quantitative reinitiation experiments from the chain(s) end(s) of these macroinitiators. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Self-assembling and self-organizable dendrons, dendrimers, and dendronized polymers produce chiral supramolecular architectures that have been developed as biological mimics. Here we review our work on the self-assembly of homochiral, heterochiral, and racemic dendritic dipeptides, and address one of the most fundamental questions of biological systems: Why are biological systems homochiral and not heterochiral or racemic and, if they were heterochiral or racemic, how would they look and function by comparison with contemporary homochiral biological systems?

In the first part, this brief review discusses the discovery of the first example of supramolecular dendritic liquid quasicrystal, which represents also the first example of soft quasicrystal. In the second part, we show that soft quasicrystals generated from supramolecular spheres are scattered through libraries of self-assembling dendrons, dendrimers, and dendronized polymers. The supramolecular spheres forming soft quasicrystals are generated via at least two different mechanisms, and are chiral. Generation of quasicrystals from other organic building blocks is also discussed. Finally, potential applications in electronics, sensors, and as ionic liquid-based nanoreactors are also mentioned.

Computational studies on the heterolytic bond dissociation energies and electron affinities of methyl 2-bromopropionate (MBP) and ethyl 2-bromoisobutyrate (EBiB) in the dissociative electron transfer (DET) step of single electron transfer living radical polymerization (SET-LRP) of methyl acrylate (MA) combined with kinetic experiments were performed in an effort to design the most efficient initiation system. This study suggests that EBiB is more effective than MBP in the SET-LRP of acrylates catalyzed by Cu(0) wire, thus being a true electronic mimic of the dormant PMA species. EBiB allows for a more predictable dependence of the molecular weight evolution and distribution. This is exemplified by the absence of a deviation in the PMA molecular weight from theoretical values at low conversions, as a result of a faster SET activation with EBiB than with MBP. The enhanced control over molecular weight evolution was also observed in the SET-LRP of MA initiated with bifunctional initiators similar in structure to MBP and EBiB, suggesting a higher reactivity than MBP in the SET activation, which matches closely that of the polymer dormant chains. The use of bifunctional initiators in conjunction with activated Cu(0) wire in SET-LRP allows for dramatically accelerated polymerizations, although still providing for exceptional control of the molecular weight evolution and distribution. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Here we reported the acid dissolution of copper oxides as a methodology for the activation of Cu(0) wire used as catalyst in single-electron transfer living radical polymerization (SET-LRP). In this method, the oxide layer on the surface of commercial Cu(0) wire was removed by dissolution in a concentrated acid such as nitric acid, glacial acetic acid and hydrochloric acid. SET-LRP of methyl acrylate catalyzed with Cu(0) wire activated with acids showed comparable k value to that of the nonactivated Cu(0) wire-catalyzed counterpart. However, the polymerizations catalyzed with activated Cu(0) wire proceeded with no initial induction period, predictable molecular weight evolution with conversion, and narrow molecular weight distribution. Regardless of the activation method, the chain end functionality of α,ω-di(bromo) poly(methyl acrylate) (PMA) prepared from SET-LRP initiated with a bifunctional initiator is extremely high, maintaining a 100% chain end functionality at ∼90% monomer conversion. The degree of bimolecular termination increased as the polymerization exceeds 92% conversion. However, for binfunctional initiators this small amount of bimolecular termination at high conversion maintains a perfectly bifunctional polymer. Structural analysis by MALDI-TOF upon thioetherification of α,ω-di(bromo) PMA with thiophenol and 4-fluorothiophenol confirmed the high fidelity of bromide chain ends. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

The disproportionating solvent effect on the kinetics of single electron transfer living radical polymerization (SET-LRP) during catalysis with nonactivated Cu(0) wire coated with Cu₂O and activated Cu(0) wire free of Cu₂O was studied. In solvents such as dimethyl sulfoxide, MeOH and ethylene carbonate that in conjunction with Me₆-TREN promote extensitve disproportionation of Cu(I)X, faster polymerizations were achieved upon switching from nonactivated Cu(0) wire to activated Cu(0) wire. The results showed that the substantial rate enhancement was accompanied with excellent control of molecular weight evolution and distribution, and high fidelity of chain-end functionality. This can be attributed to a more effective equilibrium between activation and deactivation in the presence of Cu(0) free of Cu₂O. In nondisproportionating solvents, the kinetics of SET-LRP of methyl acrylate catalyzed by activated Cu(0) wire resembled that of the polymerizations catalyzed by nonactivated wire. This is the result of a competing effect between rapid activation and insufficient disproportionation. The absence of disproportionation effectively leads to the lack of first order kinetics, broad molecular weight distribution, significant loss of bromide chain-end functionality, and therefore, the absence of a living polymerization. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Single electron transfer-living radical polymerization (SET-LRP) of methyl acrylate (MA) in methanol, catalyzed with nonactivated and activated Cu(0) wires, was performed in the presence of nondeoxygenated reagents and was investigated under a simple blanket of nitrogen. The addition of a small amount of hydrazine hydrate mediates the deoxygenation of the reaction mixture by the consumption of oxygen through its use to oxidize Cu(0) to Cu₂O, followed by the reduction of Cu₂O with hydrazine back to the active Cu(0) catalyst. SET-LRP of MA in methanol in the presence of air requires a smaller dimension of Cu(0) wire, compared to the nonactivated Cu(0) wire counterpart. Activation of Cu(0) wire allowed the polymerization in air to proceed with no induction period, linear first-order kinetics, linear correlation between the molecular weight evolution with conversion, and narrow molecular weight distribution. The retention of chain-end functionality of α,ω-di(bromo) poly(methyl acrylate) (PMA) prepared by SET-LRP was demonstrated by a combination of experiments including ¹H NMR spectroscopy and matrix-assisted laser desorption ionization–time of flight mass spectrometry after thioetherification of α,ω-di(bromo) PMA with thiophenol. In SET-LRP of MA in the presence of limited air, bimolecular termination is observed only above 85% conversion. However, for bifunctional initiators, the small amount of bimolecular termination observed at high conversion maintains a perfectly bifunctional polymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Cu(0) was prepared via disproportionation of Cu(I)Br in the presence of Me₆-TREN in various solvents in a glove box. The resulting nanopowders were used as mimics of “nascent” Cu(0) catalyst in the single-electron transfer living radical polymerization (SET-LRP) of methyl acrylate (MA), providing faster polymerization than any commercial Cu(0) powder, Cu(0) wire, or Cu(I)Br and achieving 80% conversion in only 5 min reaction time. Despite the high rate, a living polymerization was observed with linear evolution of molecular weight, narrow polydispersity, no induction period, and high retention of chain-end functionality. In addition to providing an unprecedentedly fast, yet controlled LRP of MA, these studies suggest that the very small “nascent” Cu(0) species formed via disproportionation in SET-LRP are the most active catalysts. Thus, when bulk Cu(0) powder or wire may be the most abundant catalyst and dictates the overall kinetics, any Cu(0) produced via disproportionation will be rapidly consumed and contributes to the overall catalytic cycle. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 403–409, 2010

The single-electron transfer living radical polymerization (SET-LRP) of vinyl chloride (VC) initiated with CHBr₃ in dimethylsulfoxide (DMSO) at 25 °C was investigated using Cu(0) powder and Cu(0) wire as the catalyst. It was determined that living kinetics and high conversion are achieved only through the proper calibration of the ratio between Cu(0) and TREN and the concentration of VC in DMSO. For both Cu(0) powder and Cu(0) wire, optimum conversion was achieved with higher levels of TREN than reported in earlier preliminary reports and under more dilute conditions. Using these conditions, 85+% conversion of VC could be achieved with Cu(0) powder and wire to produce white poly(vinyl chloride) (PVC) with M_n = 20,000 and M_w/M_n = 1.4–1.6 in 360 min. The use of Cu(0) wire provides the most effective catalytic system for the LRP of PVC allowing for simple removal and recycling of the catalyst. In the Cu(0) wire-catalyzed SET-LRP of VC, the consumption of Cu(0) was monitored as a function of conversion. From these studies, it is evident that the catalyst can be recycled extensively before significant exchange of Cu(0) into Cu(II)X₂ and change in catalyst surface area is observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 164–172, 2010

Single Electron Transfer-Living Radical Polymerization (SET-LRP) represents a robust and versatile method for the rapid synthesis of macromolecules with well defined topology. In SET-LRP, certain combinations of solvents and ligands facilitate the disproportionation of in situ generated Cu(I) species into “nascent” Cu(0) and Cu(II) species. A combination of heterogeneous and “nascent” Cu(0) activation yields polymers with very high chain end functionality. Under suitable conditions the tolerance toward oxygen must be increased since Cu(0), the activator in SET-LRP, acts as an oxygen scavenger in all inert gas purification systems. Here we demonstrate that SET-LRP of methyl acrylate can be conducted in the presence of air. The addition of a small amount of reducing agent hydrazine hydrate to the reaction mixture reduces Cu₂O generated by the oxidation of Cu(0) with air, regenerating Cu(0) and allowing for the synthesis of polymers with predictable molecular weight and perfect retention of chain end functionality. The kinetics plots obtained under these conditions were identical to these generated by degassed samples. High conversions were achieved within a very short reaction time. In these SET-LRP experiments, the reagents were not deoxygenated or subjected to standard degassing procedures such as freeze-pump-thaw or nitrogen sparging. This simple SET-LRP procedure provides an efficient and economical approach to the synthesis of functional macromolecules. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1190–1196, 2010

The single-electron transfer living radical polymerization (SET-LRP) of water-soluble monomers, N,N-dimethylacrylamide (DMA) and N-isopropylacrylamide (NIPAM), initiated with 2-methylchloropropionate (MCP) in dipolar aprotic and protic solvents is reported. The radical polymerization of acrylamides is characterized by higher rate constants of propagation and bimolecular termination than acrylates. Therefore, the addition of CuCl₂ is required to mediate deactivation in the early stages of the reaction. Through the use of Cu(0)-wire/Me₆-TREN catalysis, conditions were optimized to minimize the amount of externally added CuCl₂ required to maintain a linear evolution of molecular weight and narrow molecular weight distribution. By using less CuCl₂ additive, the amount of soluble copper species that must ultimately be removed from the reaction mixture is reduced. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1752–1763, 2010

Single electron transfer-living radical polymerization (SET-LRP) provides an excellent tool for the straightforward synthesis of well-defined macromolecules. Heterogeneous Cu(0)- catalysis is employed to synthesize a novel photoresist material with high control over the molecular architecture. Poly(γ-butyrolactone methacrylate)-co-(methyladamantly methacrylate) was synthesized. Kinetic experiments were conducted demonstrating that both monomers, γ-butyrolactone methacrylate (GBLMA) and methyl adamantly methacrylate (MAMA), are successfully homopolymerized. In both cases polymerization kinetic is of first order and the molecular weights increase linearly with conversion. The choice of a proper solvent was decisive for the SET-LRP process and organic solvent mixtures were found to be most suitable. Also, the kinetic of the copolymerization of GBLMA and MAMA was investigated. Following first order kinetics in overall monomer consumption and exhibiting a linear relationship between molecular weights and conversion a “living” process was established. This allowed for the straightforward synthesis of well-defined photoresist polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2251–2255, 2010

Single electron transfer-living radical polymerization (SET-LRP) represents a robust and versatile method for the rapid synthesis of macromolecules with defined architecture. The synthesis of poly(methyl methacrylate) via SET-LRP in dimethyl sulfoxide (DMSO) by using CCl₄ as initiator is demonstrated in this work. Resorting to a rather simple Cu(0)/Me₆-TREN catalyst a method was established that allowed for the straightforward design of well-defined poly(methyl methacrylate). The reactions were performed at various temperatures (25, 50, 60, and 80 °C) and complete monomer conversion could be achieved. The polymerizations obeyed first order kinetic, the molecular weights increased linearly with conversion and the polymers exhibited narrow molecular weight distributions all indicating the livingness of the process. By providing a small amount of hydrazine to the reaction mixture the polymerization could be conducted in presence of air omitting the need for any elaborated deoxygenation procedures. This methodology offers an elegant way to synthesize functionalized poly(methyl methacrylate) with perfect control over the polymerization process as well as molecular architecture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2243–2250, 2010

Single electron transfer-living radical polymerization (SET-LRP) represents a robust and versatile method for the rapid synthesis of macromolecules with defined architecture. The present article describes the polymerization of methyl methacrylate by SET-LRP in protic solvent mixtures. Herein, the polymerization process was catalyzed by a straightforward Cu(0)wire/Me₆-TREN catalyst while initiation was obtained by toluenesulfonyl chloride. All experiments were conducted at 50 °C and the living polymerization was demonstrated by kinetic evaluation of the SET-LRP. The process follows first order kinetic until all monomer is consumed which was typically achieved within 4 h. The molecular weight increased linearly with conversion and the molecular weight distributions were very narrow with M_w/M_n ∼ 1.1. Detailed investigations of the polymer samples by MALDI-TOF confirmed that no termination took place and that the chain end functionality is retained throughout the polymerization process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2236–2242, 2010

Traditionally the fluorous phase is generated with perfluorinated alkyl groups that are usually perfluorooctyl or longer and are bioaccummulative and biopersistent and therefore, are considered environmentally unfriendly. Here we report a new concept for the construction of the fluorous phase. This concept is based on the amplification of the fluorous effect with the help of dendritic architectures containing very short semifluorinated groups on their periphery. This new concept was demonstrated by the convergent synthesis of the first and second generation AB₃ and AB₂ benzyl ether dendrons functionalized on their periphery via catalytic nucleophilic addition of their phenolates to perfluoropropyl vinyl ether. The resulting dendrons are liquids. Their fluorous phase affinity was analyzed and demonstrated that the dendritic architecture amplifies the fluorous phase at a specific generation by the number of functional groups on the dendron periphery, and at different generations by increasing their generation number. Therefore, this concept is very efficient for the design and synthesis of new fluorous materials. In addition, by contrast with dendrons containing perfluoroalkyl groups on their periphery, the current dendrons mediate the disassembly of their parent building blocks but do not mediate the self-assembly in a supramolecular architecture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2498–2508, 2010

Cu(0)-wire/Me₆-TREN is a well established catalyst for living radical polymerization via SET–LRP. Here, it is demonstrated that this polymerization is not just living, but it is in fact the first example of immortal living radical polymerization. The immortality of SET–LRP mediated with Cu(0) wire was demonstrated by attempting, in an unsuccessful way, to irreversible interrupt multiple times the polymerization via exposure to O₂ from air. SET–LRP indeed stopped each time when the reaction mixture was exposed to air. However, the SET–LRP reaction, was restarted each time after resealing the reaction vessel and reestablishing the catalytic cycle with the same Cu(0) wire, to produce the same conversion as in the conventional uninterrupted SET–LRP process. Despite the interruption by O₂, the reactivated SET–LRP had a good control of molecular weight, molecular weight evolution, and molecular weight distribution, with perfect retention of chain-end fidelity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2716–2721, 2010

Single-electron transfer living radical polymerization (SET-LRP) has emerged as a reliable, robust, and straight forward tool for the construction of well-defined polymers. This manuscript reports on the influence of acidity on the SET-LRP process. The SET-LRP of methyl methacrylate initiated with tosyl chloride and catalyzed by Cu(0)/Me₆-TREN at 50 °C in protic solvent mixtures containing acetic acid is described. The polymerization kinetics was recorded in the presence of various amounts of acetic acid. Hereby it was found that the SET-LRP process tolerates considerable acidity. The SET-LRP of MMA comprising 1, 2.5, 10, and 25% acetic acid were well controlled. The reactions followed first-order kinetic in monomer consumption and the molecular weights increased linearly with conversion while retaining narrow molecular weight distribution. In all cases, complete monomer conversion was achieved. Acetic acid could be also used as a solvent for the SET-LRP of MMA. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Single-electron transfer living radical polymerization (SET-LRP) has developed as a reliable, robust and straight forward method for the construction well-defined polymers. To span an even larger variety of functional monomers, we investigated the copolymerization of methyl methacrylate with methacrylic acid by SET-LRP. Copolymerizations were catalyzed by Cu(0)/Me₆-TREN and performed in MeOH/H₂O mixtures at 50 °C. The SET-LRP copolymerizations of varying methacrylic acid content were evaluated by kinetic experiments. At low (2.5%) and moderate (10%) MAA loadings, the copolymerizations obeyed perfect first order kinetics (k_p^app = 0.008 min⁻¹ and k_p^app = 0.006 min⁻¹) and exhibited a linear increase in molecular weights with conversion providing narrow molecular weight distributions. The SET-LRP of MMA/25%-MAA was found to be significantly slower (k_p^app = 0.0035 min⁻¹). However, a reasonable first-order kinetics in monomer consumption was maintained, and the control of the polymerization process was preserved since the molecular weight increased linearly with conversion and could therefore be adjusted. This work demonstrates that the copolymerization of methacrylic acid by SET-LRP is feasible and the design of well-defined macromolecules comprising acidic functionality can be achieved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

A simple method for the activation of the Cu(0) wire used as catalyst in single-electron transfer living radical polymerization (SET-LRP) is reported. The surface of Cu(0) stored in air is coated with a layer of Cu₂O. It is well established that Cu₂O is a less reactive catalyst for SET-LRP than Cu(0). We report here the activation of the Cu(0) wire under nitrogen by the reduction of Cu₂O from its surface to Cu(0) by treatment with hydrazine hydrate. The kinetics of SET-LRP of methyl acrylate (MA) catalyzed with activated Cu(0) wire in dimethyl sulfoxide (DMSO) at 25 °C demonstrated a dramatic acceleration of the polymerization and the absence of the induction period observed during SET-LRP catalyzed with nonactivated Cu(0) in several laboratories. Exposure of the activated Cu(0) wire to air results in a lower apparent rate constant of propagation because of gradual oxidation of Cu(0) to Cu₂O. This dramatic acceleration of SET-LRP is similar to that observed with commercial Cu(0) nanopowder except that the polymerization provides excellent molecular weight evolution, very narrow molecular weight distribution and high polymer chain-end functionality. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

The amine groups from the periphery of poly(propylenimine) dendrimers [DAB-(NH₂)_n] (n = 4 and 8) were reacted with the carboxylic groups of five different first and second generation self-assembling dendrons. The amidation was mediated by the peptide bond forming reagent 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT)/N-methylmorpholine (NMM). All the resulting dendronized dendrimers self-assemble into helical pyramidal columns that self-organize into columnar hexagonal and columnar rectangular 2D lattices and in supramolecular spheres that self-organize into 3D Pm3n and P4₂/mnm tetragonal lattices. The structural and retrostructural analysis of the supramolecular dendrimers by X-ray diffraction experiments demonstrated that supramolecular dendritic spheres are assembled from various spherical fragments, including conical and half-sphere in which the DAB dendrimer is confined to their apex. Dendritic-crown is the most frequently encountered conformation of the dendronized dendrimers that is responsible for the assembly of helical pyramidal columns.

Na₂S₂O₄-catalyzed single-electron transfer – degenerative chain transfer-mediated living radical polymerization (SET-DTLRP) of VC initiated with the bifunctional initiators 1,2-bis(iodopropionyloxy)ethane, dimethyl 2,5-diiodohexanedioate, and bis(2-methoxyethyl)-2,5-diiodohexanedioate as well as the tetrafunctional initiator pentaerythritol tetrakis(2-iodopropionate) is reported. This SET-DTLRP was performed in water at ambient temperature in the presence of polyvinyl alcohol and hydroxypropyl methylcellulose surfactants and provides methods for the synthesis of α,ω-di(iodo)PVC with two identical active chain ends and of four-arm star PVC with four identical active chain ends. These difunctional and tetrafunctional derivatives of PVC are also macroinitiators for the synthesis of ABA triblock copolymers and four-arm star block copolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 635–652, 2009

Pentaerythritol tetrakis(2-iodopropionate) was used as a tetrafunctional initiator for the Na₂S₂O₄ catalyzed SET-DTLRP of n-butyl acrylate in water at room temperature. The resulting tetrafunctional poly(n-butyl acrylate) macroinitiator with M_n = 14,864 or M_n = 3627 per arm was used to initiate the SET-DTLRP of vinyl chloride and provide the first examples of four-arm star-block copolymers [PVC-b-PBA-CH(CH₃)COOCH₂]₄C. The M_n of the PVC segment from each arm of the four-arm star-block copolymer varied between 353 and 33,622. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 628–634, 2009

The development of a novel nucleophilic thio-bromo “Click” reaction, specifically base-mediated thioetherification of thioglycerol with α-bromoesters was reported in an earlier article. The combination of this thio-bromo click reaction with subsequent acylation with 2-bromopropionyl bromide provides an iterative two-step divergent growth approach to the synthesis of a new class of poly(thioglycerol-2- propionate) (PTP) dendrimers. In this article, the addition of a third step, the single-electron transfer living radical polymerization (SET-LRP) of methyl acrylate (MA), was shown to provides access to a three-step “branch” and “grow” divergent approach to dendritic macromolecules wherein poly(methyl acrylate) (PMA) connects the branching subunits. This facile methodology can provide a diversity of dendritic macromolecular topologies and will ultimately provide the means to the development of self-organizable dendritic macromolecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3940–3948, 2009

The development of a novel nucleophilic thio-bromo “Click” reaction, specifically base-mediated thioetherification of thioglycerol with α-bromoesters, is reported. Combination of this thio-bromo click reaction with subsequent acylation with 2-bromopropionyl bromide provides an iterative two-step divergent growth approach to the synthesis of a new class of poly(thioglycerol-2-propionate) (PTP) dendrimers. This approach is demonstrated in the rapid preparation of four generation (G1–G4) of PTP dendrimers with high-structural fidelity. The isolated G1–G4 bromide-terminated dendrimers can be used directly as dendritic macroinitiators for the synthesis of star-polymers via SET-LRP. Additionally, the intermediate hydroxy-terminated dendrimers are analogs of other water-soluble polyester and polyether dendrimers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3931–3939, 2009

The synthesis, structural, and retrostructural analysis of a library of self-assembling dendrons containing triethyl and tripropyl ammonium, pyridinium and 3-methylimidazolium chloride, tetrafluoroborate, and hexafluorophosphate at their apex are reported. These dendritic ionic liquids self-assemble into supramolecular columns or spheres which self-organize into 2D hexagonal or rectangular and 3D cubic or tetragonal liquid crystalline and crystalline lattices. Structural analysis by X-ray diffraction experiments demonstrated the self-assembly of supramolecular dendrimers containing columnar and spherical nanoscale ionic liquid reactors segregated in their core. Both in the supramolecular columns and spheres the noncovalent interactions mediated by the ionic liquid provide a supramolecular polymer and therefore, these assemblies represent a new class of dendronized supramolecular polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4165–4193, 2009

The development of Cu(0)/TREN/CuBr₂-catalyzed SET-LRP of VC initiated with CHBr₃ in DMSO at 25 °C is reported. The use of CuBr₂ additive allows for the first LRP of low molecular weight VC (target DP = 100), as well as lower Cu powder loading levels, improved I_eff and control in the synthesis of higher molecular VC, targeted degree of polymerization = 350, 700, 1,000, 1,400. ¹H NMR and HSQC confirm the bifunctionality of CHBr₃ as an initiator and suggest that deleterious side-reactions such as the formation of allylic chlorides occur primarily at the onset of the reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4130–4140, 2009

The effect of initial ligand concentration on the apparent rate constant of propagation of single-electron transfer living radical polymerization (SET-LRP) of MA in DMSO at 25 °C was examined using various lengths of Cu(0) wire as catalyst. It was determined that unlike other parameters such as initiator concentration, solvent concentration, and deactivator concentration, no simple external rate-order for the ligand concentration could be determined. Rather, the response of the rate of SET-LRP to initial ligand concentration is complex and is likely determined by a competition of ligand-dependent extent of disproportionation as well as the role of ligand concentration in the surface mediated activation process. Results suggest that a minimum concentration of ligand is needed to achieve both acceptable reaction rate and reaction control, and therefore, ligand concentration must be considered in designing experimental conditions for SET-LRP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5629–5638, 2009

Disproportionation of Cu(I)X is the major step in Single-Electron Transfer Living Radical Polymerization (SET-LRP). The disproportionation of Cu(I)X mediated by Me₆-TREN in various solvents was studied through UV–vis spectroscopy and Dynamic Light Scattering (DLS). UV–vis experiments reveal that disproportionation is dependent on both solvent composition and concentration of Me₆-TREN, consistent with a revised equilibrium expression and corroborated by mathematical models. Electrochemistry data do not accurately predict the extent of disproportionation in the presence of Me₆-TREN. Exemplified by DMSO, a favored solvent for SET-LRP, UV–vis spectroscopy shows that under certain conditions disproportionation is four-orders of magnitude greater than the value reported from electrochemistry experiments. Through UV–vis and DLS analysis, it was demonstrated that DMSO, DMF, DMAC, and NMP, stabilize colloidal Cu(0), while acetone, EtOH, EC, MeOH, PC, and H₂O facilitate agglomeration of Cu(0) particles. Additionally, for colloidal Cu(0) stabilizing solvents, the amount of ligand and solvent composition decide the particle size distribution. Therefore, the kinetics of SET-LRP are cooperatively and synergistically determined by the complex interplay of solvent polarity, the extent of disproportionation in the solvent/ligand mixture, and the ability of that mixture to stabilize colloidal Cu(0) or control particle size distribution. The implications of these results for SET-LRP are discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5606–5628, 2009

SET-LRP requires a combination of ligand and solvent that mediates the disproportionation of Cu(I)X into Cu(0) activator, and Cu(II) deactivator. The solvent also modulates the kinetics of the reaction. More polar solvents, including mixtures of water and organic solvents enhance the rate of polymerization in accord with the Dimroth-Reichardt parameter. Here, it is demonstrated that a similar effect is observed in binary mixtures of organic solvents, wherein the addition of a more polar solvent to a less polar solvent provides a linear increase in the apparent rate constant of propagation, k. However, this linear relationship does not hold for the entire range of volume fraction for binary mixtures when ethylene carbonate (EC) or MeOH are one of the two components. Results herein, suggest that the kinetics of SET-LRP in these solvent mixtures is cooperatively and synergistically determined by polarity, degree of disproportionation, and also by another parameter related to the ability of the solvent to stabilize colloidal Cu(0) and determine its particle size. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5591–5605, 2009

SET-LRP is mediated by a combination of solvent and ligand that promotes disproportionation of Cu(I)X into Cu(0) and Cu(II)X₂. Therefore, the diversity of solvents suitable for SET-LRP is limited. SET-LRP of MA in a library of solvents with different equilibrium constants for disproportionation of Cu(I)X such as DMSO, DMF, DMAC, EC, PC, EtOH, MeOH, methoxyethanol, NMP, acetone and in their binary mixtures with H₂O was examined. H₂O exhibits the highest equilibrium constant for disproportionation of Cu(I)X. The apparent rate constant of the polymerization exhibits a linear increase with the addition of H₂O. This is consistent with higher equilibrium constants for disproportionation generated by addition of H₂O to organic solvents. Furthermore, with the exception of alcohols and carbonates, the rate constant of polymerization in binary mixtures could be correlated with the Dimroth-Reichardt solvent polarity parameter. This is consistent with the single-electron transfer mechanism proposed for SET-LRP that involves a polar transition state. These experiments demonstrate that the use of binary mixtures of solvents with H₂O provides a new, simple and efficient method for the elaboration of a large diversity of reaction media that are suitable for SET-LRP even when one of the two solvents does not mediate disproportionation of Cu(I)X. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5577–5590, 2009

The synthesis, and structural and retrostructural analysis of a library of second-generation conical dendrons that self-assemble into spherical supramolecular dendrimers is reported. This library consists of amphiphilic dendrons with n-alkyl groups containing from 4 to 16 carbon atoms. The dendrons containing 6 to 16 carbon atoms in their n-alkyl groups self-assemble into spherical supramolecular dendrimers that self-organize in a Pmn cubic lattice. The structural and retrostructural analysis of the Pmn lattices generated from the supramolecular dendrimers demonstrated that the volume of the aromatic core of the spherical dendrimers is not dependent on the number of carbon atoms from their alkyl groups. This result facilitated the calculation of the average values of the absolute electron density of the aliphatic and aromatic domains of the spherical supramolecular dendrimers. The relative intensity of the higher order diffraction peaks of the Pmn lattice increases as the volume of the aliphatic part of the sphere mediated by the number of carbon atoms in the n-alkyl groups decreases. This study demonstrates the maximum increase of the relative intensity of the higher order diffraction peaks of the Pmn lattice generated from non-hollow supramolecular dendrimers.

Twin-dendritic organogelators have been prepared through selective functionalization of N-(3-aminopropyl)-1,3-propanediamine (APPDA) with self-assembling dendrons by using 1,1′-carbonyldiimidazole (CDI). Subsequent modification of the APPDA linker provided an additional degree of structural diversity by which to tailor the gelator self-assembly in bulk or in the gel state. These compounds are able to gel cyclohexane, toluene, n-butyl acetate, ethyl acetate, dichloromethane, and tetrahydrofuran. 3,4-Disubstituted apical branching units provided the most efficient organogelators and show a propensity to form thixotropic gels, wherein the gel recovers its elasticity after being subjected to shear. Structural and retrostructural analysis of the twin-dendritic organogelators reveals the bulk structural characteristics to be indicative of the subsequent gel properties. Diverse self-organized arrays were identified in bulk and all are able to form gels, thus indicating the role of quasiequivalence in mediating self-assembly in the gel state. Furthermore, we have found that porous columnar mesophases provide a strategy by which to prepare thixotropic gels. We demonstrate the importance of weak lateral hydrogen bonding within a column stratum versus hydrogen bonding along the length of the column for forming porous columnar mesophases and, by extension, thixotropic gels.

Alcohols are known to promote the disproportionation of Cu(I)X species into nascent Cu(0) and Cu(II)X. Therefore, alcohols are expected to be excellent solvents that facilitate the single-electron transfer mediated living radical polymerization (SET-LRP) mediated by nascent Cu(0) species. This publication demonstrates the ultrafast SET-LRP of methyl acrylate initiated with bis(2-bromopropionyloxy)ethane and catalyzed by Cu(0)/Me₆-TREN in methanol, ethanol, 1-propanol, and tert-butanol and in their mixture with water at 25 °C. The structural analysis of the resulting polymers by a combination of ¹H NMR and MALDI-TOF MS demonstrates the synthesis of perfectly bifunctional α,ω-dibromo poly(methyl acrylate)s by SET-LRP in alcohols. Moreover, this work provides an expansion of the list of solvents available for SET-LRP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2745–2754, 2008

The Cu(0)/Me₆-TREN-catalyzed single-electron transfer mediated living radical polymerization (SET-LRP) of methyl acrylate in the presence of the classic 4-methoxyphenol free radical inhibitor was investigated. Kinetic experiments, combined with ¹H NMR, and MALDI-TOF MS analysis of the resulting polyacrylates demonstrated that SET-LRP is a robust synthetic method that does not require the purification of the monomers to remove the radical inhibitor. It is anticipated that these results will contribute to the expansion of technological and fundamental applications of SET-LRP since it allows the synthesis of polymers with a structural perfection that previously was not accessible by any other method, starting from unpurified monomers, solvents, initiators, and ligands. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3174–3181, 2008

Single-electron transfer living radical polymerization (SET-LRP) proceeds by an outer-sphere single-electron transfer mechanism that induces a heterolytic bond cleavage of the initiating and propagating R-X (where X = Cl, Br, and I) species. Therefore, unlike the homolytic bond cleavage mechanism claimed for ATRP, SET-LRP is expected to show a small dependence of the nature of the halide group on the apparent rate constant of activation. This means the R-X with X = Cl, Br, and I must all be efficient initiators for SET-LRP and no chain transfer must be observed in the case of initiators with X = Br and I. Here, we report the SET-LRP of methyl acrylate initiated with the alkyl chlorides methyl-2-chloropropionate (MCP) and chloroform (CHCl₃) and catalyzed by Cu(0)/Me₆-TREN/CuCl₂ in DMSO at 25 °C. A combination of kinetic and structural analysis was used to elucidate the MCP and CHCl₃ initiating behavior under SET-LRP conditions, and to demonstrate the very small dependence of the SET-LRP apparent rate constant of propagation on X while providing polymers with well defined architecture. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4917–4926, 2008

The heterolytic dissociation process associated with the activation of Single Electron-Transfer Living Radical Polymerization is examined through the use of energy profile modeling. Monomer and initiator structure is correlated with the approximate activation barriers, energies of electrostatic ion-radical pair formation, and stability of ion-radical pair generated from the counteranion halide leaving group and the radical atom with partial positive charge density induced by its electron-withdrawing substituent. Energy profiles permit access not just to one, but to all local minima, in the dissociation pathway and the identification of a global minimum. The location and energy of this global minimum allows for the placement of various initiators and dormant propagating macroradicals on the spectrum between stepwise and concerted dissociative electron-transfer. The barrier for the activation step for alkyl-halides derived from acrylates, vinyl halides, and styrenes, as well as from initiators bearing electron-withdrawing groups is decreased in comparison to relatively more electron-rich alkyl halides. This rate enhancement is explained through the sticky dissociative model wherein electron-transfer is accelerated by the formation of strong ion-radical pairs between radicals with partial positive charge density and their counteranion leaving group. Greater electron-withdrawing capacity of the alkyl halide substituent increases the stability of the ion-radical pair, reduces its equilibrium bond length, and accelerates electron-transfer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5663–5697, 2008

Cu(I)Br/Me₆-TREN species are unstable and disproportionate into metallic Cu(0) and Cu(II)Br₂/Me₆-TREN in DMSO, whereas in toluene are stable and do not undergo disproportionation, at least at 25 °C. To estimate the role of the disproportionating solvent in single electron-transfer living radical polymerization (SET-LRP) a comparative analysis of Cu(0)/Me₆-TREN-catalyzed polymerization of MA initiated with methyl 2-bromopropionate at 25 °C was performed in DMSO and toluene. A combination of kinetic experiments and chain end analysis by 500-MHz ¹H NMR spectroscopy was used to demonstrate that disproportionation represents the crucial requirement for a successful SET-LRP of MA at 25 °C. In DMSO a perfect SET-LRP occurs and yields close to 100% conversion in 45 min. A first order polymerization in growing species up to 100% conversion and a PMA with perfectly functional chain ends are obtained. However, in toluene within 17 h only about 60% conversion is obtained, the polymerization does not show first order in growing species and therefore is not a living polymerization. Moreover, at 60% conversion the resulting PMA has only 80% active chain ends. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6880–6895, 2008

Hybrid dendrimers, obtained by complete monofunctionalization of the peripheral amines of a “zero-generation” polyethyleneimine dendrimer, provide structurally diverse lamellar, columnar, and cubic self-organized lattices that are less readily available from other modified dendritic structures. The reaction of tris(2-aminoethyl)amine (TREN) with 4-dodecyloxybenzimidazolide provides only the corresponding zero-generation TREN dendrimer. From the mixture of tri- and disubstituted TREN derivatives obtained from first-generation self-assembling dendritic imidazolides, the hybrid dendrimer and a twin dendron could be separated, purified, and characterized. The hybrid dendrimers display smectic, columnar hexagonal (Φ_h), and cubic (Pmn) lattices. The TREN twin dendrons, on which only two peripheral amines have been acylated, exhibit centered-rectangular columnar (Φ_r-c), Φ_h, and Pmn lattices. The existence of a thermoreversible Φ_h-to-Pmn phase transition in the first-generation hybrid dendrimers and twin dendrons is exploited to elucidate an epitaxial relationship between the two mesophases. We postulate a mechanism by which the transition proceeds. The thermoreversible Φ_h-to-Pmn phase change is accompanied by optical property changes that are suitable for rudimentary signaling or logic functions. This structural diversity reflects the quasiequivalence of flat-taper and conical self-assembling dendrons and the ability of flexible dendrimers to accommodate concomitant conformational and shape changes.

The single-electron transfer living radical polymerization (SET-LRP) of methyl acrylate initiated with bromoform (CHBr₃) and iodoform (CHI₃) and catalyzed by Cu(0)/Me₆-TREN in DMSO at 25 °C provides a reliable method to prepare poly (methyl acrylate) (PMA) with active chain ends and controlled structure that can undergo subsequent functionalization to provide strategies for the synthesis of different block copolymers and other complex architectures. A detailed kinetic and structural analysis was used to assess the scope and the limitations of CHBr₃ and CHI₃ as initiators under SET-LRP conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 278–288, 2008