Quantitative Contrasts in the Copolymerization of Acrylate- and Methacrylate-Based Comonomers

Alb, Alina M.; Enohnyaket, Pascal; Drenski, Michael F.; Shunmugam, Raja; Tew, Gregory N.; Reed, Wayne F.

doi:10.1021/ma0616864

Cited by 24 publications

(39 citation statements)

References 51 publications

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“…Meanwhile, Yang's group prepared PEG‐ g ‐CS using purchased PEG‐nitrophenol carbonate and succinimidyl ester of PEG propionic acid (mPEG‐SPA) respectively, and its gene delivery efficiency as a nonviral carrier was evaluated 20, 21. Since the active esters can react readily with a variety of nucleophiles such as primary and secondary amines and these reactions progress almost quantitatively in most cases, this technique is widely used for conjugation of proteins and functionalized solid surfaces 22–24. Another advantage of using an active ester is that one precursor can lead to many functional polymers varying in chemical functionality 25, 26…”

Section: Introductionmentioning

confidence: 99%

Stepped association of comb‐like and stimuli‐responsive graft chitosan copolymer synthesized using ATRP and active ester conjugation methods

Bao

Gan

et al. 2009

J. Polym. Sci. A Polym. Chem.

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Herein, we report the synthesis of a comb‐like pH‐sensitive graft copolymer, poly[(2‐dimethylamino)ethyl methacrylate]‐graft‐chitosan, using atom transfer radical polymerization (ATRP) and active ester conjugation methods. The utilization of ATRP guaranteed the narrow molecular weight distribution of the side chains, which further led to the low polydispersity of the copolymer aggregates. The active ester reaction took place in the mild and homogeneous solutions, and the graft ratio reached 58%. The pH‐responsive association behavior of the graft copolymer in aqueous solution was examined by potentiometric titration, laser light scattering, surface tensiometry, and transmission electron microscopy. Because of the difference in proton dissociation between the amine groups of chitosan and DMAEMA segments, the copolymer exhibited the different conformations with pH variation: random coils at pH ∼ 4, core‐shell structured micelles at pH 5–6, double‐layered hard spheres at pH ∼ 7, and larger aggregates at pH ∼ 8. The beneath mechanism cause the microstructure changes as a function of pH was discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6682–6692, 2009

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Section: Introductionmentioning

confidence: 99%

Stepped association of comb‐like and stimuli‐responsive graft chitosan copolymer synthesized using ATRP and active ester conjugation methods

Bao

Gan

et al. 2009

J. Polym. Sci. A Polym. Chem.

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“…Using automatic continuous online monitoring of polymerization reactions (ACOMP), Tew and co-workers determined NMS and MMA to have ratios of 0.52 and 1.35, respectively. 37 However, the reactivity ratio trend between NMS and methacrylamides is the opposite, with NMS and N-(2-hydroxypropyl)methacrylamide (HPMA) having ratios of 3.46 and 0.12, respectively. 29 When acrylamides are used, semibatch methods with a separate addition of NMS are done to ensure sufficient incorporation of the acrylamide.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Copolymerization and Synthesis of Multiply Binding Histamine Ligands for the Robust Functionalization of Quantum Dots

et al. 2014

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The polymeric functionalization of quantum dots via ligand exchange is a robust method for the preparation of stable fluorescent particles with high quantum yields. For most biological applications of quantum dots, water solubility is a key requirement; to achieve biocompatibility, polymeric ligand systems that can provide water solubility as well as effective anchoring groups are advantageous. In this work, histamine functional polymers bearing poly(ethylene glycol) (PEG) side chains were prepared using RAFT polymerization. A versatile postmodification strategy using activated ester units of Nmethacryloxysuccinimide (NMS) and poly(ethylene glycol) methacrylate in the polymer chain afforded copolymers ranging from 6K to 50K with low polydispersities, along with tailored composition of each monomer along the copolymer chain. By controlling the monomer ratio, PEGMA molecular weight, time, and temperature, the composition could be tuned to study its effect on quantum dot functionalization. Representative oleate-capped CdSe/Cd x Zn 1−x S QDs purified by a recently established gel permeation chromatography (GPC) method were used to test the effectiveness of the histamine-bearing polymers for preparation of water-soluble QDs. Successful ligand exchange of the QDs was characterized by good dispersions in water, lack of aggregation between QDs, and good quantum yields in water. Overall, the synthetic method demonstrates a facile and robust postmodification strategy for the formation of multiply binding, histamine-bearing copolymers, which can be applied to nanomaterials for fundamental investigations and bioimaging/biodistribution studies. ■ INTRODUCTIONIn the past decade, considerable progress has been seen in applications of semiconductor nanocrystals (quantum dots, QDs) in areas such as light-emitting diodes, 1 solar cells, 2 and bioimaging applications. 3,4 Based on the size and choice of material, the emission and absorption wavelengths of quantum dots can be tuned, allowing for narrow emission bands and high quantum yields. 5,6 The right choice of surface functional groups prevents aggregation of the quantum dots, allows for good dispersions in its environment, passivates the quantum dot surface, and maintains high fluorescence quantum yield. 7 This in turn allows for its successful implementation in various high performance applications.Hence, the need for soft functional materials that allow for quantum dots to be well dispersed in a variety of environments and facilitate stability over extended periods of time is essential. In the case of well-represented II−VI, III−V, and IV−VI compound semiconductors, colloidal quantum dots are synthesized with hydrophobic ligands such as oleic acid and trioctylphosphine; these ligands are necessary to manage precursor reactivity and colloidal stability during high-temperature growth but lead to QDs with low solubility in polar solvents. 7 Encapsulation with surfactants, silica shells, or amphiphilic copolymers can yield stable and water-soluble QDs but adds considerably to hy...

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“…Using small pore columns, the SEC approach will probably be useful in copolymerization, and possibly terpolymerization, for monitoring the conversion of comonomers33 when other spectroscopically interfering agents are used in the reaction, such as RAFT agents, copper ions, etc.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous continuous, nonchromatographic monitoring and discrete chromatographic monitoring of polymerization reactions

Alb

Drenski

Reed

2009

J of Applied Polymer Sci

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Automatic continuous nonchromatographic monitoring and discrete chromatographic monitoring were coupled together for the first time and used to monitor free radical and controlled-radical polymerization reactions. This was achieved by adding a multidetector Size Exclusion Chromatography (SEC) system (alternatively termed Gel Permeation Chromatography, GPC) to the ACOMP platform (Automatic Continuous Online Monitoring of Polymerization reactions). The fact that the reactor solution is already preconditioned in the ACOMP front-end to the concentration levels used in SEC makes direct coupling possible. Kinetics from two different types of reactions, Reversible Addition Fragmentation Transfer (RAFT) and free radical polymerization of butyl acrylate were studied, including the production of a bimodal population. Complementary and contrasting features from the continuous and SEC approaches are highlighted. The main advantage of the SEC detection is to follow the evolution of full molecular weight distributions (MWD), especially in 'living' type reactions, where polydispersity decreases with monomer conversion, whereas the continuous detection provides a much more detailed characterization of the reaction. Interestingly, in the case where a bimodal molecular weight distribution was produced, the continuous method automatically detected the onset of the second mode in a model independent fashion, whereas SEC could only discern the bimodality by applying preconceived models. The SEC approach will have valuable niche applications, however, such as when reactions are relatively slow, monitoring narrow polydispersity is of primary importance, and also in copolymerization and terpolymerization reactions where complex mixtures of reagents (e.g., RAFT agents, copper ions, etc.) make unfractionated spectroscopic resolution of comonomers difficult.

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Quantitative Contrasts in the Copolymerization of Acrylate- and Methacrylate-Based Comonomers

Cited by 24 publications

References 51 publications

Stepped association of comb‐like and stimuli‐responsive graft chitosan copolymer synthesized using ATRP and active ester conjugation methods

Stepped association of comb‐like and stimuli‐responsive graft chitosan copolymer synthesized using ATRP and active ester conjugation methods

Copolymerization and Synthesis of Multiply Binding Histamine Ligands for the Robust Functionalization of Quantum Dots

Simultaneous continuous, nonchromatographic monitoring and discrete chromatographic monitoring of polymerization reactions

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