Co-reporter:Peng Yang, Marpe Bam, Parasmani Pageni, Tianyu Zhu, Yung Pin Chen, Mitzi Nagarkatti, Alan W. Decho, and Chuanbing Tang
ACS Infectious Diseases November 10, 2017 Volume 3(Issue 11) pp:845-845
Publication Date(Web):October 4, 2017
DOI:10.1021/acsinfecdis.7b00132
Bacterial infections, particularly by Gram-negative pathogens, have become a serious threat to global healthcare due to the diminishing effectiveness of existing antibiotics. We report a nontraditional therapy to combine three components in one macromolecular system, in which boronic acid adheres to peptidoglycan or lipopolysaccharide via boron-polyol based boronolectin chemistry, cationic metal polymer frameworks interact with negatively charged cell membranes, and β-lactam antibiotics are reinstated with enhanced vitality to attack bacteria via evading the detrimental enzyme-catalyzed hydrolysis. These macromolecular systems exhibited high efficacy in combating pathogenic bacteria, especially Gram-negative strains, due to synergistic effects of multicomponents on interactions with bacterial cells. In vitro and in vivo cytotoxicity and hemolysis evaluation indicated that these multifunctional copolymers did not induce cell death by apoptosis, as well as did not alter the phenotypes of immune cells and did not show observable toxic effect on red blood cells.Keywords: antibiotics; antimicrobial; boronic acid; boronolectin; cationic macromolecules; cobaltocenium;
Co-reporter:Zhongkai Wang, Liang Yuan, and Chuanbing Tang
Accounts of Chemical Research July 18, 2017 Volume 50(Issue 7) pp:1762-1762
Publication Date(Web):June 21, 2017
DOI:10.1021/acs.accounts.7b00209
ConspectusSustainable elastomers have undergone explosive growth in recent years, partly due to the resurgence of biobased materials prepared from renewable natural resources. However, mounting challenges still prevail: How can the chemical compositions and macromolecular architectures of sustainable polymers be controlled and broadened? How can their processability and recyclability be enabled? How can they compete with petroleum-based counterparts in both cost and performance? Molecular-biomass-derived polymers, such as polymyrcene, polymenthide, and poly(ε-decalactone), have been employed for constructing thermoplastic elastomers (TPEs). Plant oils are widely used for fabricating thermoset elastomers. We use abundant biomass, such as plant oils, cellulose, rosin acids, and lignin, to develop elastomers covering a wide range of structure–property relationships in the hope of delivering better performance.In this Account, recent progress in preparing monomers and TPEs from biomass is first reviewed. ABA triblock copolymer TPEs were obtained with a soft middle block containing a soybean-oil-based monomer and hard outer blocks containing styrene. In addition, a combination of biobased monomers from rosin acids and soybean oil was formulated to prepare triblock copolymer TPEs.Together with the above-mentioned approaches based on block copolymers, multigraft copolymers with a soft backbone and rigid side chains are recognized as the first-generation and second-generation TPEs, respectively. It has been recently demonstrated that multigraft copolymers with a rigid backbone and elastic side chains can also be used as a novel architecture of TPEs. Natural polymers, such as cellulose and lignin, are utilized as a stiff, macromolecular backbone. Cellulose/lignin graft copolymers with side chains containing a copolymer of methyl methacrylate and butyl acrylate exhibited excellent elastic properties. Cellulose graft copolymers with biomass-derived polymers as side chains were further explored to enhance the overall sustainability.Isoprene polymers were grafted from a cellulosic backbone to afford Cell-g-polyisoprene copolymers. Via cross-linking of these graft copolymers, human-skin-mimic elastomers and high resilient elastomers with a well-defined network structure were achieved. The mechanical properties of these resilient elastomers could be finely controlled by tuning the cellulose content. As isoprene can be produced by engineering of microorganisms, these elastomers could be a renewable alternative to petroleum products.In summary, triblock copolymer and graft copolymer TPEs with biomass components, skin-mimic elastomers, high resilient biobased elastomers, and engineering of macromolecular architectures for elastomers are discussed. These approaches and design provide us knowledge on the potential to make sustainable elastomers for various applications to compete with petroleum-based counterparts.
Co-reporter:Wenyue Ding, Shu Wang, Kejian Yao, Mitra S. Ganewatta, Chuanbing Tang, and Megan L. Robertson
ACS Sustainable Chemistry & Engineering December 4, 2017 Volume 5(Issue 12) pp:11470-11470
Publication Date(Web):November 7, 2017
DOI:10.1021/acssuschemeng.7b02676
A rosin-derived polymethacrylate, poly(dehydroabietic ethyl methacrylate) (PDAEMA), was evaluated as a sustainable end block in triblock copolymer-based thermoplastic elastomers. Triblock copolymers containing glassy PDAEMA end blocks and a rubbery poly(n-butyl acrylate) (PnBA) midblock were synthesized through atom transfer radical polymerization. The volume fraction of PDAEMA in the triblock copolymer was varied at constant midblock molecular weight. At lower PDAEMA content, the triblock copolymers exhibited microphase separated morphologies lacking long-range order, which transitioned to a well-defined cylindrical morphology as the PDAEMA content was increased. Observed thermal properties were consistent with the presence of distinct PDAEMA and PnBA domains. The order–disorder transition temperature increased with increasing PDAEMA content in the block copolymer, and the Flory–Huggins interaction parameter of PDAEMA/PnBA was strongly temperature-dependent yet small in value. The triblock copolymers exhibited elastomeric behavior at room temperature and accessible order–disorder transitions, appropriate for thermoplastic elastomer applications.Keywords: Entanglement; Microphase separation; Polymethacrylate; Renewable resource polymers; Rosin; Sustainability; Thermoplastic elastomers;
Co-reporter:Parasmani Pageni;Mohammad Pabel Kabir
Journal of Inorganic and Organometallic Polymers and Materials 2017 Volume 27( Issue 4) pp:1100-1109
Publication Date(Web):29 April 2017
DOI:10.1007/s10904-017-0561-5
Cationic cobaltocenium-containing polyelectrolytes have a unique ability to form ionic complex with various anionic species. We carried out two sets of model study to compare the relative binding strength of a cobaltocenium-containing polyelectrolyte. First, the nature and relative strength of intermolecular interaction between cobaltocenium-containing polyelectrolytes and different anionic probes were investigated by spectroscopic methods. A dye-displacement method was used to monitor absorbance and fluorescence emissions. Second, the binding strength of this cobaltocenium-containing polyelectrolyte was compared with a classical quaternary ammonium polymer. Formation of polyelectrolyte complex between the cobaltocenium-containing polyelectrolyte and a common anionic polyelectrolyte at various concentrations was examined by optical absorption and light scattering.
Co-reporter:Liang Yuan;Zhongkai Wang;Mitra S. Ganewatta;Md Anisur Rahman;Meghan E. Lamm
Soft Matter (2005-Present) 2017 vol. 13(Issue 6) pp:1306-1313
Publication Date(Web):2017/02/08
DOI:10.1039/C6SM02003H
Sustainable bioelastomers with high elastic recovery, high resilience and mendability are conceptualized with low chain-entanglement polymers that are predominantly originated from renewable biomass. Polymers with plant oil-derived fatty groups at the side chain were installed with furan, which allowed Diels–Alder addition to introduce dynamic covalent crosslinking. These elastomers are mendable via retro Diels–Alder. Reprocessing of these polymers led to the formation of elastomers with preservation of excellent resilience and elastic recovery.
Co-reporter:Zhongkai Wang, Yaqiong Zhang, Liang Yuan, Jeffery Hayat, Nathan M. Trenor, Meghan E. Lamm, Laetitia Vlaminck, Stijn Billiet, Filip E. Du Prez, Zhigang Wang, and Chuanbing Tang
ACS Macro Letters 2016 Volume 5(Issue 5) pp:602
Publication Date(Web):April 27, 2016
DOI:10.1021/acsmacrolett.6b00243
We report biomass-derived, shape-memory materials prepared via simple reactions, including “grafting from” ATRP and TAD click chemistry. Although the biomass, including plant oils and cellulose nanocrystals, has heterogeneous chemical structures in nature, these materials exhibit excellent multiple shape-memory properties toward temperature, water, and organic solvents, which are comparable to petroleum counterparts. The work presented herein provides burgeoning opportunities to design the next-generation, low-cost, biomass-prevalent, green materials for niche applications.
Co-reporter:Zhongkai Wang, Liang Yuan, Feng Jiang, Yaqiong Zhang, Zhigang Wang, and Chuanbing Tang
ACS Macro Letters 2016 Volume 5(Issue 2) pp:220
Publication Date(Web):January 21, 2016
DOI:10.1021/acsmacrolett.5b00843
Natural resilin possesses outstanding mechanical properties, such as high strain, low stiffness, and high resilience, which are difficult to be reproduced in synthetic materials. We designed high resilient elastomers (HREs) with a network structure to mimic natural resilin on the basis of two natural abundant polymers, stiff cellulose and flexible polyisoprene. With plasticization via mineral oil and mechanical cyclic tensile deformation processing, HREs show ultrahigh resilience, high strain, and reasonable tensile strength that closely mimic natural resilin. Moreover, the mechanical properties of HREs can be finely tuned by adjusting the cellulose content, providing the opportunity to synthesize high resilient elastomers that mimic different elastic proteins, such as elastin.
Co-reporter:Liang Yuan, Zhongkai Wang, Nathan M. Trenor and Chuanbing Tang
Polymer Chemistry 2016 vol. 7(Issue 16) pp:2790-2798
Publication Date(Web):03 Mar 2016
DOI:10.1039/C6PY00048G
Amidation of plant oils with amino alcohols was methodologically examined. Twenty one amino alcohols, varying in alcohol substitutions, linkers and amino substitutions, were respectively reacted with high oleic soybean oil. The structural factors of amino alcohols controlled their reactivity in amidation. While most of them resulted in quantitative conversion of triglycerides, steric hindrance on secondary amines resulted in much lower yields. Subsequent synthesis and radical polymerization of (meth)acrylates led to polymers with a distinct dependence essentially originating from the amino alcohols. Depending on the backbone and amide structures in the side chain, these polymers exhibited wide glass transition temperatures with a difference of more than 100 °C, ranging from viscoelastic materials to thermoplastics. A proof-of-concept hydrogenation of unsaturated double bonds was carried out, providing an approach to precisely controlling the thermal and mechanical properties of plant oil-derived polymers.
Co-reporter:Xiaodong Yin, Yali Qiao, Matthew R. Gadinski, Qing Wang and Chuanbing Tang
Polymer Chemistry 2016 vol. 7(Issue 17) pp:2929-2933
Publication Date(Web):26 Feb 2016
DOI:10.1039/C6PY00233A
The design of novel dielectric polymers currently employs approaches on capitalizing main-chain and side-chain architectures respectively. This paper reports a concerted macromolecular architecture synergistically tuning both the polymeric backbone and side chain. Our approach relies on an oligomer thiophene side chain and a norbornene backbone. This architecture results in highly flexible and transparent dielectric polymers, superior to methacrylate polymer counterparts. A facile hydrogenation of the polynorbornene backbone results in more than two fold increase in the electric field breakdown strength with the conservation of low dielectric loss.
Co-reporter:Peng Yang, Parasmani Pageni, Mohammad Pabel Kabir, Tianyu Zhu, and Chuanbing Tang
ACS Macro Letters 2016 Volume 5(Issue 11) pp:1293
Publication Date(Web):November 4, 2016
DOI:10.1021/acsmacrolett.6b00743
We report the synthesis of cationic cobaltocenium and neutral ferrocene containing homopolymers mediated by photoinduced reversible addition–fragmentation chain transfer (RAFT) polymerization with a photocatalyst fac-[Ir(ppy)3]. The homopolymers were further used as macromolecular chain transfer agents to synthesize diblock copolymers via chain extension. Controlled/“living” feature of photoinduced RAFT polymerization was confirmed by kinetic studies even without prior deoxygenation. A light switch between ON and OFF provided a spatiotemporal control of polymerization.
Co-reporter:Mitra S. Ganewatta, Wenyue Ding, Md Anisur Rahman, Liang Yuan, Zhongkai Wang, Nasrollah Hamidi, Megan L. Robertson, and Chuanbing Tang
Macromolecules 2016 Volume 49(Issue 19) pp:7155-7164
Publication Date(Web):September 30, 2016
DOI:10.1021/acs.macromol.6b01496
Utilization of biomass for commodity polymers has gained tremendous interest. We report a method to prepare high molecular weight renewable homopolymers and block copolymers derived from natural rosin. Monomers with high renewable content (70 wt %) were prepared via a simple esterification reaction between dehydroabietic alcohol and 5-exo-norbornenecarboxylic acid. Living and controlled polymerization of these monomers were achieved by ring-opening metathesis polymerization to obtain polymers with molecular weight up to ∼500 kg/mol. These homopolymers exhibit structure-dependent glass transition temperatures, excellent thermal stabilities, and thermoplastic properties. Chain entanglement molecular weight was determined via rheological assessments for such polymers with bulky side moieties. Using the living ROMP, dehydroabietic-based homopolymer was chain-extended with a soybean oil-derived norbornene monomer to yield triblock copolymers, which showed behaviors of thermoplastic elastomers.
Co-reporter:Yanming Han, Liang Yuan, Gaiyun Li, Luohua Huang, Tefu Qin, Fuxiang Chu, Chuanbing Tang
Polymer 2016 Volume 83() pp:92-100
Publication Date(Web):28 January 2016
DOI:10.1016/j.polymer.2015.12.010
•Copper-free azide-alkyne click chemistry for sustainable polymers.•Lignin utilization in combination with biodegradable polyesters.• The copper-free click chemistry could be extended to other biomass.The heterogeneous and multifunctional characteristics of lignin is a paradox for its potential in polymer applications, despite its renewable and aromatic nature. We demonstrate a simple approach to the preparation of renewable lignin-grafted polymers via robust copper-free thermal click chemistry. High lignin content polymers were prepared between polymer pairs containing azide and alkyne groups with tunable compositions including PEG, PCL and PLA.
Co-reporter:Jifu Wang, Liang Yuan, Zhongkai Wang, Md Anisur Rahman, Yucheng Huang, Tianyu Zhu, Ruibo Wang, Jianjun Cheng, Chunpeng Wang, Fuxiang Chu, and Chuanbing Tang
Macromolecules 2016 Volume 49(Issue 20) pp:7709-7717
Publication Date(Web):October 11, 2016
DOI:10.1021/acs.macromol.6b01997
Well-defined polymers derived from biomass feedstock (e.g., soybean oil, rosin acid, and furfural) were successfully prepared by metal-free atom transfer radical polymerization (ATRP). In the presence of photoredox catalysts and UV irradiation, three biomass-based methacrylate monomers were efficiently polymerized with good control over molecular weight and dispersity. NMR and MALDI-TOF MS confirmed high fidelity of chain end groups originated from initiators. Furthermore, block copolymers from these monomers were also achieved through chain extension by metal-free ATRP.
Co-reporter:Lin Lu, Liang Yuan, Jing Yan, Chuanbing Tang, and Qian Wang
Biomacromolecules 2016 Volume 17(Issue 7) pp:
Publication Date(Web):June 1, 2016
DOI:10.1021/acs.biomac.6b00032
We previously reported the coassembly of various proteins with poly(4-vinylpyridine) (P4VP) to form core–shell nanoparticles (CSNPs). However, P4VP suffers from its cytotoxicity and in vivo toxicity, which prohibit it from many potential biomedical applications. Here, pyridine-grafted diblock copolymer poly(caprolactone-graft-pyridine)-block-poly(caprolactone) [P(CL-g-Py)-b-PCL] was prepared through a combination of ring-opening polymerization and Cu(I) catalyzed azide–alkyne cycloaddition reaction. CSNPs could be readily constructed by the self-assembly of transferrin (Tf) and P(CL-g-Py)-b-PCL, which showed a narrower range of particle sizes, improved stability, and higher loading capacity for anticancer drug doxorubicin (DOX), compared with similar particles prepared from the coassembly of Tf and P4VP. Additionally, the drug-loaded Tf/P(CL-g-Py)-b-PCL CSNPs could effectively target MCF7 cancer cells via the binding of Tf to transferrin receptors (TfR).
Co-reporter:Zhongkai Wang, Liang Yuan, Nathan M. Trenor, Laetitia Vlaminck, Stijn Billiet, Amrita Sarkar, Filip E. Du Prez, Morgan Stefik and Chuanbing Tang
Green Chemistry 2015 vol. 17(Issue 7) pp:3806-3818
Publication Date(Web):11 May 2015
DOI:10.1039/C5GC00822K
We report the preparation of plant oil based triblock copolymers based on soybean oil monomers. The monomers were polymerized via atom transfer radical polymerization with subsequent chain extension, resulting in poly(styrene-b-soybean oil acrylate-b-styrene) (PS-b-PSBA-b-PS) and poly(styrene-b-soybean oil methacrylate-b-styrene) (PS-b-PSBMA-b-PS) triblock copolymers. These polymers, ranging from thermoplastics to thermoplastic elastomers (TPEs), were obtained by tuning molecular structures. We employed a “click coupling” strategy using triazolinedione (TAD) chemistry to create chemical junctions between the soft middle blocks of the triblock copolymers, which behave similar to physical chain entanglements. This method helps to overcome the drawbacks of plant oil based polymers, allowing for increase of tensile strength without sacrificing elongation. Cyclic tensile tests show that the “click coupled” triblock copolymers exhibit excellent elastic recovery characteristics.
Co-reporter:Juan Yu;Jifu Wang;Chunpeng Wang;Yupeng Liu;Yuzhi Xu;Fuxiang Chu
Macromolecular Rapid Communications 2015 Volume 36( Issue 4) pp:398-404
Publication Date(Web):
DOI:10.1002/marc.201400663
Co-reporter:Jeffery Hayat, Indranil Mitra, Yali Qiao, Gila E. Stein, Chuanbing Tang
European Polymer Journal 2015 Volume 71() pp:476-489
Publication Date(Web):October 2015
DOI:10.1016/j.eurpolymj.2015.08.019
•Decreasing solvent annealing time by one order of magnitude via reduction of chamber size.•Achieving ordering of block copolymers in thin films using a few industry-friendly solvents.•Carrying out simple numerical simulation to understand the annealing process.This paper addresses two challenges in humidity-controlled solvent annealing of poly(ethylene oxide)-b-polystyrene thin films: (1) reduction in annealing time by nearly an order of magnitude for toluene under high humidity, which is achieved by decreasing the annealing chamber volume; (2) utilization of two industry-benign solvents, methyl ethyl ketone (MEK) and propylene glycol monomethyl ether acetate (PGMEA), to achieve ordered surface patterns under high humidity. When toluene is employed for annealing, the rate of block copolymer ordering is controlled by the time required to saturate the vapor phase, which depends on the chamber size in this study. The kinetics with MEK and PGMEA are more complex: While saturation time plays a role, these solvents reduce the incompatibility between PS and PEO, so longer annealing times are required to achieve good lateral order. We also present evidence that lateral ordering is faster than lattice swelling in the small chamber, so large grains are achieved without inflating the domain size and periodicity.
Co-reporter:Liang Yuan, Nasrollah Hamidi, Shaleesh Smith, Felicia Clemons, Amid Hamidi, Chuanbing Tang
European Polymer Journal 2015 Volume 62() pp:43-50
Publication Date(Web):January 2015
DOI:10.1016/j.eurpolymj.2014.10.023
•The first study on the molecular conformation of rosin-derived polymers.•Side-chain bulky rosin-containing PCL has a flexible coil conformation.•This study may help understand many physical properties of rosin polymers.Renewable resin acid-substituted polycaprolactone is prepared for characterization of physical properties of polymers. Six samples of dehydroabietic acid-substituted polycaprolactone (PCL-g-DAPE) with various molecular weight were synthesized by a combination of ring-opening polymerization and click chemistry. These polymers were characterized by on-line two angle light scattering and differential pressure viscosity. The values of dn/dc, average molecular weight, intrinsic viscosity, hydrodynamic radius, and radius of gyration were determined. Mark-Houwink double logarithmic relations of intrinsic viscosity and weight average molecular weight as well as Stockmayer–Fixman plots were established to scale the dimensions and conformation of PCL-g-DAPE chains related to their molar mass. The results indicated that PCL-g-DAPE is a flexible-coil polymer, similar to poly(methyl acrylate). Such properties were somewhat unexpected, considering the bulky group in the polymer side chains.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Yali Qiao;Xiaodong Yin
Science China Chemistry 2015 Volume 58( Issue 11) pp:1641-1650
Publication Date(Web):2015 November
DOI:10.1007/s11426-015-5434-6
In contrast to conventional main-chain conjugated polymers, incorporation of electronically active conjugated oligomers into non-conjugated polymer backbones as pendant groups represents a promising alternative strategy to developing novel electroactive polymer materials that are desirable for potential applications in organic electronics. This review focuses on polymers with thiophene in the side chain and summarizes the most important synthetic approaches to these polymers, including direct controlled polymerization techniques (e.g., ATRP, ROMP, and RAFT) as well as post-polymerization modifications. Additionally, various properties and applications of these polymers are discussed.
Co-reporter:Yali Qiao, Md. Sayful Islam, Xiaodong Yin, Kuo Han, Yi Yan, Jiuyang Zhang, Qing Wang, Harry J. Ploehn, Chuanbing Tang
Polymer 2015 Volume 72() pp:428-435
Publication Date(Web):18 August 2015
DOI:10.1016/j.polymer.2015.02.011
•Oligothiophene-containing polymer brushes were prepared and evaluated as nanodielectrics.•Transparent free-standing films could be readily fabricated for capacitor applications.•Polymer brushes exhibited consistent permittivity and low dielectric loss over a wide range of frequencies.We report the synthesis of oligothiophene-containing polymer brushes and their application as nanodielectric materials in capacitors. Specifically, terthiophene-containing methacrylate polymer brushes were synthesized via a “graft from” technique by a combination of ring-opening metathesis polymerization (ROMP) and reversible addition fragmentation chain transfer (RAFT) polymerization. Both X-ray scattering and thermal studies indicated that polymer brushes led to the formation of small nanoscale crystalline domains (∼2 nm) dispersed in an amorphous matrix. Notably, the film forming capability and processability are greatly improved in comparison with corresponding homopolymers. Transparent free-standing films could be readily fabricated based on these polymer brushes and used for dielectric property studies. The adoption of polymer brush architecture into the oligothiophene-containing polymers has been proved to be an effective strategy to improve the mechanical robustness of films.
Co-reporter:Mitra S. Ganewatta, Chuanbing Tang
Polymer 2015 Volume 63() pp:A1-A29
Publication Date(Web):20 April 2015
DOI:10.1016/j.polymer.2015.03.007
•Summarized recent development on macromolecular architectures towards efficient antimicrobial agents against various microorganisms.•Capitalized macromolecular assembly and nanoparticles as new vehicles to fight against resistant bacteria.•Conceptualized future design principles and new directions in the field of antimicrobial polymers.Drug resistance of pathogenic bacteria is a major global problem leading humanity towards a pre-antibiotic era. Decline in the discovery of novel antibiotics and the lack of a resilient platform to develop novel antimicrobial agents worsens the situation. Amphiphilic antimicrobial polymers, which have roots coming from antimicrobial peptides, show promise as potent antimicrobials having low susceptibility for developing resistance, unlike small molecular antibiotics. This feature article highlights recent advances in the fabrication of membrane-active antimicrobial polymers. The design of various types of macromolecular architectures with control of structural parameters such as hydrophobicity/hydrophilicity balance, molecular weight, and ionic groups will be emphasized in order to achieve strong antimicrobial activities while minimizing toxicity to mammalian cells. Advanced polymeric assemblies with well-defined nanostructures including core/shell shaped nano-objects and polymeric vesicles are also discussed. Lastly, current challenges and future directions in the field of antimicrobial polymers for ensuing practical biomedical applications are presented.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Liang Yuan, Zhongkai Wang, Nathan M. Trenor, and Chuanbing Tang
Macromolecules 2015 Volume 48(Issue 5) pp:1320-1328
Publication Date(Web):February 25, 2015
DOI:10.1021/acs.macromol.5b00091
Sustainable fuels, chemicals, and materials from renewable resources have recently gained tremendous momentum in a global scale, although there are numerous nontrivial hurdles for making them more competitive with petroleum counterparts. We demonstrate a robust strategy for the transformation of plant oils into polymerizable monomers and thermoplastic polymer materials. Specifically, triglycerides were converted into N-hydroxyalkyl fatty amides with the aid of amino alcohols via a mild base-catalyzed amidation process with nearly quantitative yields without the use of column chromatography and organic solvents. These fatty amides were further converted into a variety of methacrylate monomers, cyclic norbornene monomers and imino ether monomers. Representative polymers from selected monomers exhibit drastic different physical properties with subtle structural variations, highlighting the potential of this particular amidation reaction in the field of biomass transformation.
Co-reporter:Yi Yan, T. Maxwell Deaton, Jiuyang Zhang, Hongkun He, Jeffery Hayat, Parasmani Pageni, Krzysztof Matyjaszewski, and Chuanbing Tang
Macromolecules 2015 Volume 48(Issue 6) pp:1644-1650
Publication Date(Web):March 11, 2015
DOI:10.1021/acs.macromol.5b00471
We report the first chemoselective, high yield synthesis of monosubstituted rhodocenium through a “η5 → η4 → η5” strategy detailing sequential nucleophilic addition and endohydride abstraction. Monosubstituted rhodocenium derivatives are then used as versatile synthons for the preparation of the first-ever vinyl monomers that allow controlled polymerizations including ROMP and RAFT, leading to rhodocenium-containing metallopolymers. Exploratory ion-exchange and self-assembly of this new class of polyelectrolytes cultivates the potential of side-chain rhodocenium-containing polymers.
Co-reporter:Yali Qiao, Xiaodong Yin, Lei Wang, Md. Sayful Islam, Brian C. Benicewicz, Harry J. Ploehn, and Chuanbing Tang
Macromolecules 2015 Volume 48(Issue 24) pp:8998-9006
Publication Date(Web):December 8, 2015
DOI:10.1021/acs.macromol.5b02018
This paper presents a novel strategy to modify the surface chemistry of barium titanate (BaTiO3, BT) with a bimodal population of oligothiophene polymer brushes using step-by-step reversible addition–fragmentation chain transfer (RAFT) polymerization. Compared with a previous strategy based on monomodal surface-tethered brushes, these hybrid nanoparticles, BaTiO3 coated with bimodal oligothiophene polymer brushes, demonstrate extremely good dispersion behaviors as dielectric nanofillers in a matrix of oligothiophene polymers. These nanodielectric composites exhibit greatly improved dielectric performance and maintain linear displacement–polarization (D–E) profiles under high applied electric fields. This promising bimodal strategy could be generalized to a variety of nanoparticles for the development of novel dielectric nanocomposite systems.
Co-reporter:Mitra S. Ganewatta, Kristen P. Miller, S. Parker Singleton, Pegah Mehrpouya-Bahrami, Yung P. Chen, Yi Yan, Mitzi Nagarkatti, Prakash Nagarkatti, Alan W. Decho, and Chuanbing Tang
Biomacromolecules 2015 Volume 16(Issue 10) pp:
Publication Date(Web):August 31, 2015
DOI:10.1021/acs.biomac.5b01005
We report antibacterial, antibiofilm, and biocompatible properties of surface-immobilized, quaternary ammonium-containing, resin acid-derived compounds and polycations that are known to be efficient antimicrobial agents with minimum toxicities to mammalian cells. Surface immobilization was carried out by the employment of two robust, efficient chemical methods: Copper-catalyzed azide–alkyne 1,3-dipolar cycloaddition click reaction, and surface-initiated atom transfer radical polymerization. Antibacterial and antibiofilm activities against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were strong. Hemolysis assays and the growth of human dermal fibroblasts on the modified surfaces evidenced their biocompatibility. We demonstrate that the grafting of quaternary ammonium-decorated abietic acid compounds and polymers from surfaces enables the incorporation of renewable biomass in an effective manner to combat bacteria and biofilm formation in biomedical applications.
Co-reporter:Christopher G. Hardy, Jiuyang Zhang, Yi Yan, Lixia Ren, Chuanbing Tang
Progress in Polymer Science 2014 Volume 39(Issue 10) pp:1742-1796
Publication Date(Web):October 2014
DOI:10.1016/j.progpolymsci.2014.03.002
Work on side-chain transition metal-containing polymers prepared by controlled and living polymerizations is summarized, including living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). These polymers include metallocene-containing polymers, ferrocenylsilane polymers with additional metal at the side chain, metal carbonyl complex polymers, and ligated metal complex polymers.
Co-reporter:Jiuyang Zhang ; Yung Pin Chen ; Kristen P. Miller ; Mitra S. Ganewatta ; Marpe Bam ; Yi Yan ; Mitzi Nagarkatti ; Alan W. Decho
Journal of the American Chemical Society 2014 Volume 136(Issue 13) pp:4873-4876
Publication Date(Web):March 17, 2014
DOI:10.1021/ja5011338
Bacteria are now becoming more resistant to most conventional antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug-resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community settings by deactivating conventional β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, through various mechanisms, resulting in increased mortality rates and hospitalization costs. Here we introduce a class of charged metallopolymers that exhibit synergistic effects against MRSA by efficiently inhibiting activity of β-lactamase and effectively lysing bacterial cells. Various conventional β-lactam antibiotics, including penicillin-G, amoxicillin, ampicillin, and cefazolin, are protected from β-lactamase hydrolysis via the formation of unique ion-pairs between their carboxylate anions and cationic cobaltocenium moieties. These discoveries could provide a new pathway for designing macromolecular scaffolds to regenerate vitality of conventional antibiotics to kill multidrug-resistant bacteria and superbugs.
Co-reporter:Juan Yu, Yupeng Liu, Xiaohuan Liu, Chunpeng Wang, Jifu Wang, Fuxiang Chu and Chuanbing Tang
Green Chemistry 2014 vol. 16(Issue 4) pp:1854-1864
Publication Date(Web):26 Sep 2013
DOI:10.1039/C3GC41550C
A class of sustainable and renewable cellulose–rosin copolymers were prepared by immobilizing rosin-derived polymer chains on the backbone of ethyl cellulose (EC) by “grafting from” atom transfer radical polymerization (ATRP). Four different rosin based polymers derived from dehydroabietic acid (DA), one of the major resin acids in natural rosin, were attached to 2-bromoisobutyryl-functionalized EC. Meanwhile, DA-grafted EC was prepared by the simple esterification reaction between DA and EC. Kinetic studies showed that the polymerization of all monomers was controlled. These grafted copolymers adopt a worm-like or rod-like structure in tetrahydrofuran, verified by light scattering experiments. These copolymers have a tunable glass transition temperature and higher thermal stability in contrast to EC. Surface morphology by AFM analysis indicated good film-forming property when rosin polymers were grafted from EC. Additionally, the introduction of DA and rosin polymers remarkably enhanced the hydrophobicity of EC. The static contact angles of all these modified copolymers are above 90°. XPS analysis revealed that the surface of these rosin-modified EC copolymers was dominated by a hydrocarbon-rich rosin moiety. The UV absorption of modified EC composites is indicative of their potential application in UV-absorbent coating materials.
Co-reporter:Mitra S. Ganewatta, Yung Pin Chen, Jifu Wang, Jihua Zhou, Jerry Ebalunode, Mitzi Nagarkatti, Alan W. Decho and Chuanbing Tang
Chemical Science 2014 vol. 5(Issue 5) pp:2011-2016
Publication Date(Web):07 Feb 2014
DOI:10.1039/C4SC00034J
Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community-settings, resulting in increased mortality rates and hospitalization costs. Emergence of resistance even to vancomycin, the standard reference for MRSA treatment, builds up pressure for the search of novel alternatives. We report potent natural resin acid-based cationic antimicrobial compounds and polymers that exhibit surprising antimicrobial activity against a range of MRSA strains, yet are largely non-toxic against mammalian cells. Molecular dynamics simulations and dye-leakage assays with anionic phospholipid membrane mimics of bacteria demonstrate a membrane-lysing effect induced by unique fused ring structures of resin acids that may constitute the principal mechanism of action for selective lysis of bacterial cells over mammalian cells. Our antimicrobial materials are derived from an unlikely yet abundant natural source, and offer a novel alternative to currently-used approaches.
Co-reporter:Jiuyang Zhang, Yi Yan, Jihua Chen, W. Michael Chance, Jeffery Hayat, Zheng Gai, and Chuanbing Tang
Chemistry of Materials 2014 Volume 26(Issue 10) pp:3185
Publication Date(Web):April 30, 2014
DOI:10.1021/cm5007058
We reported the utilization of a series of heterobimetallic diblock copolymers to prepare different iron–cobalt/carbon and iron–cobalt phosphide/carbon magnetic materials. Through the control of compositions of ferrocene- and cobaltocenium-containing blocks, a transition of final inorganic materials from metal phosphide to metal alloy was observed. These metal elements were embedded on amorphous carbon films or encapsulated in crystallized multiwalled carbon nanotubes. Detailed magnetic characterization showed that all these inorganic materials were ferromagnetic under room temperature with great difference in their magnetic susceptibilities. The saturated magnetization was related with the weight fraction of phosphorus and cobalt, indicating the ability to control the magnetization of these inorganic materials via polymer compositions.
Co-reporter:Yupeng Liu, Kejian Yao, Xiaoming Chen, Jifu Wang, Zhongkai Wang, Harry J. Ploehn, Chunpeng Wang, Fuxiang Chu and Chuanbing Tang
Polymer Chemistry 2014 vol. 5(Issue 9) pp:3170-3181
Publication Date(Web):20 Dec 2013
DOI:10.1039/C3PY01260C
Two series of graft copolymers, cellulose-g-poly(n-butyl acrylate-co-dehydroabietic ethyl methacrylate) (Cell-g-P(BA-co-DAEMA)) and cellulose-g-poly(lauryl methacrylate-co-dehydroabietic ethyl methacrylate) (Cell-g-P(LMA-co-DAEMA)), were prepared by “grafting from” atom transfer radical polymerization (ATRP). In these novel graft copolymers, cellulose, DAEMA (derived from rosin), and LMA (derived from fatty acids) are all sourced from renewable natural resources. The “grafting from” ATRP strategy allows the preparation of high molecular weight graft copolymers consisting of a cellulose main chain with acrylate copolymer side chains. By manipulating the monomer ratios in the P(BA-co-DAEMA) and P(LMA-co-DAEMA) side chains, graft copolymers with varying glass transition temperatures (−50–60 °C) were obtained. Tensile stress–strain and creep compliance testing were employed to characterize mechanical properties. These novel graft copolymers did not exhibit linear elastic properties above about 1% strain, but they did manifest remarkable elasticity at strains of 500% or more. These results suggest that these cellulose-based, acrylate side-chain polymers are potential candidates for service as thermoplastic elastomers materials in applications requiring high elasticity without rupture at high strains.
Co-reporter:Yi Yan;Jiuyang Zhang;Yali Qiao
Macromolecular Rapid Communications 2014 Volume 35( Issue 2) pp:254-259
Publication Date(Web):
DOI:10.1002/marc.201300558
Co-reporter:Yali Qiao, Rachel Ferebee, Bongjoon Lee, Indranil Mitra, Nathaniel A. Lynd, Jeffery Hayat, Gila E. Stein, Michael R. Bockstaller, and Chuanbing Tang
Macromolecules 2014 Volume 47(Issue 18) pp:6373-6381
Publication Date(Web):September 2, 2014
DOI:10.1021/ma501057m
The synthesis, characterization, and self-assembly of a series of linear poly(ethylene-b-styrene-b-isoprene) (PEO−PS−PI) triblock copolymers containing nearly equal volume fractions of PEO and PI (fPEO ≈ fPI) and various fractions of the middle PS block (70.8 vol % ≤ fPS ≤ 75.6 vol %) is reported. A range of azide-functionalized poly(ethylene oxide-b-styrene) diblock copolymers were prepared by atom transfer radical polymerization (ATRP) of styrene using the same batch of PEO-macroinitiator, followed by azide-functionalization. Monohydroxyl-terminated poly(cis-1,4-isoprene) was first alkyne-functionalized and then sequentially attached to azide-functionalized PEO−PS via copper(I)-catalyzed azide−alkyne cycloaddition reaction, producing PEO−PS−PI triblock copolymers with low dispersity. Bulk samples of each linear triblock copolymer reveal the formation of a binary microdomain structure in which a PS and PI domains mix to form a uniform matrix for spherical PEO microdomains, and the PEO microdomains are arranged in a BCC lattice. Additionally, the thin film ordering of these triblock copolymers was investigated using a high-humidity solvent annealing process, both with and without low concentrations of a lithium salt. The morphology was analyzed by atomic force microscopy and GISAXS, revealing layers of spherical PEO domains arranged with in-plane hexagonal symmetry. The inclusion of salt increased both the size and periodicity of PEO domains.
Co-reporter:Yali Qiao;Mohammed Sayful Islam;Kuo Han;Eric Leonhardt;Jiuyang Zhang;Qing Wang;Harry J. Ploehn
Advanced Functional Materials 2013 Volume 23( Issue 45) pp:5638-5646
Publication Date(Web):
DOI:10.1002/adfm.201300736
Abstract
The discovery of nanodipolar π-conjugated oligomer-containing polymers as high performance nanodielectric materials with high permittivity and low dielectric loss over a wide range of frequency (100 Hz–4 MHz) is reported. Terthiophene-containing methacrylate polymers are synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Both X-ray and thermal studies indicate the formation of small crystalline domains of terthiophene side chains dispersed in amorphous matrix. The highly polarizable and fast-responsive nanodipoles from the nanoscale crystalline domains (<2 nm) are believed to dictate the performance. These polymers uniquely satisfy nanodipole architectures conjectured two decades ago to guide the design of high performance nanodielectric materials. This unprecedented approach can be generalized to a variety of π-conjugated oligomer-containing polymers for the development of high energy density capacitor materials.
Co-reporter:Yali Qiao;Mohammed Sayful Islam;Kuo Han;Eric Leonhardt;Jiuyang Zhang;Qing Wang;Harry J. Ploehn
Advanced Functional Materials 2013 Volume 23( Issue 45) pp:
Publication Date(Web):
DOI:10.1002/adfm.201370230
Co-reporter:Christopher G. Hardy, Md. Sayful Islam, Dioni Gonzalez-Delozier, Joel E. Morgan, Brandon Cash, Brian C. Benicewicz, Harry J. Ploehn, and Chuanbing Tang
Chemistry of Materials 2013 Volume 25(Issue 5) pp:799
Publication Date(Web):February 17, 2013
DOI:10.1021/cm304057f
We report a simple and low-cost strategy to enhance the dielectric permittivity of polystyrene by up to an order of magnitude via incorporating an oligoaniline trimer moiety at the end of the polymer chains. The oligoaniline-capped polystyrene was prepared by a copper-catalyzed click reaction between azide-capped polystyrene and an alkyne-containing aniline trimer, which was doped by different acids. By controlling molecular weight of polystyrene, the end-capped polymers can be induced to form nanoscale oligoaniline-rich domains embedded in an insulating matrix. Under an external electric field, this led to an increase in dielectric polarizability while maintaining a low dielectric loss. At frequencies as high as 0.1 MHz, the dielectric permittivity and dielectric loss (tan δ) were ∼22.8 and ∼0.02, respectively. This strategy may open a new avenue to increasing the dielectric permittivity of many other commodity polymers while maintaining relatively low dielectric loss.Keywords: dielectric polymers; energy storage; nanodomain; oligoaniline; polystyrene;
Co-reporter:Jing Wang, Kejian Yao, Chongzhi Wang, Chuanbing Tang and Xiqun Jiang
Journal of Materials Chemistry A 2013 vol. 1(Issue 17) pp:2324-2332
Publication Date(Web):05 Mar 2013
DOI:10.1039/C3TB20100G
Well-defined amphiphilic poly(ethylene glycol) and poly(dehydroabietic ethyl methacrylate) block copolymers (PEG-b-PDAEMA) were prepared by atom transfer radical polymerization. The methacrylate block contains a characteristic hydrophobic, biocompatible and economical dehydroabietic moiety. PEG-b-PDAEMA block copolymer micellar nanoparticles loaded with piperlongumine (PLGM) were successfully prepared by a nanoprecipitation method. In vitro and in vivo behaviors of these nanoparticles were thoroughly examined by a set of characterization techniques. Confocal laser scanning microscopy study revealed that these nanoparticles could be well taken up by cancer cells. In vivo near-infrared fluorescence imaging showed that the PLGM-loaded nanoparticles effectively targeted the tumor site by the enhanced permeability and retention (EPR) effect in H22 tumor-bearing mice. The in vivo antitumor examination found that PLGM-loaded nanoparticles exhibited superior efficacy in impeding the tumor growth compared to the commercially available Taxol® and free PLGM formulation. The changes in body weights and blood biochemical profiles were also compared to investigate the safety of PLGM and PEG-b-PDAEMA nanoparticle drug delivery system.
Co-reporter:Christopher G. Hardy, Lixia Ren, Shuguo Ma and Chuanbing Tang
Chemical Communications 2013 vol. 49(Issue 39) pp:4373-4375
Publication Date(Web):11 Oct 2012
DOI:10.1039/C2CC36756D
Well-defined ferrocene-containing triblock copolymers were synthesized by atom transfer radical polymerization and self-assembled into highly ordered hexagonal arrays of cylinders via solvent annealing. The thin films were further used as a template and converted into highly ordered iron oxide nanoparticles (α-Fe2O3) by UV/ozonolysis and thermal pyrolysis.
Co-reporter:Ying Chen, Perry A. Wilbon, Juhua Zhou, Mitzi Nagarkatti, Chunpeng Wang, Fuxiang Chu and Chuanbing Tang
Chemical Communications 2013 vol. 49(Issue 3) pp:297-299
Publication Date(Web):15 Nov 2012
DOI:10.1039/C2CC37386F
Multifunctional abietane-based polymer nanogels were fabricated for label-free cell imaging and drug delivery. The self-fluorescent abietane as the framework of carriers enables the imaging without the need for external fluorescent probes, while abietane-based nanogels exhibit low in vitro cytotoxicity.
Co-reporter:Kejian Yao, Chuanbing Tang, Jun Zhang and Clay Bunyard
Polymer Chemistry 2013 vol. 4(Issue 3) pp:528-535
Publication Date(Web):13 Sep 2012
DOI:10.1039/C2PY20626A
We report a class of degradable stimuli-responsive random copolymers that exhibit high sensitivity to ionic strength (salt concentration). Cationic random copolymers, poly(ε-caprolactone)-co-poly(ε-caprolactone-graft-quaternary ammonium) (PCL-co-P(CL-g-QA)), were synthesized by a combination of ring-opening polymerization and copper-catalyzed click chemistry. Random copolymers with various compositions of QA were prepared by adjusting the ratio of CL and substituted CL. Due to the presence of cationic QA groups at the polymer side chain, these random copolymers showed salt concentration (or ionic strength)-dependent solubility. In salt-free water or water with low ionic strength of salt (NaCl, CaCl2), random copolymers were soluble due to the overwhelming domination of electrostatic repulsive Coulomb interactions between cationic QA species over attractive hydrophobic interactions between CL segments. The solubility of copolymers decreased with the increase of ionic strength of salt solution due to the screening effect of free ions to reduce the repulsive Coulomb interactions between QA species and thus a significant change of macromolecular conformations. It was found that the salt responsiveness of synthesized random copolymers was maximized when the CL-g-QA fraction was ∼15 mol% in the copolymers. These random copolymers were readily degradable under dilute acidic conditions.
Co-reporter:Kejian Yao;Ying Chen;Jun Zhang;Clay Bunyard
Macromolecular Rapid Communications 2013 Volume 34( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/marc.201370024
Co-reporter:Kejian Yao;Ying Chen;Jun Zhang;Clay Bunyard
Macromolecular Rapid Communications 2013 Volume 34( Issue 8) pp:645-651
Publication Date(Web):
DOI:10.1002/marc.201300088
Co-reporter:Perry A. Wilbon;Fuxiang Chu
Macromolecular Rapid Communications 2013 Volume 34( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/marc.201370001
Co-reporter:Perry A. Wilbon;Fuxiang Chu
Macromolecular Rapid Communications 2013 Volume 34( Issue 1) pp:8-37
Publication Date(Web):
DOI:10.1002/marc.201200513
Abstract
The development of sustainable renewable polymers from natural resources has increasingly gained attention from scientists, engineers as well as the general public and government agencies. This review covers recent progress in the field of renewable bio-based monomers and polymers from natural resources: terpenes, terpenoids, and rosin, which are a class of hydrocarbon-rich biomass with abundance and low cost, holding much potential for utilization as organic feedstocks for green plastics and composites. This review details polymerization and copolymerization of terpenes such as pinene, limonene, and myrcene and their derivatives, terpenoids including carvone and menthol, and rosin-derived monomers. The future direction on the utilization of these natural resources is discussed.
Co-reporter:Yi Yan, Jiuyang Zhang, Yali Qiao, Mitra Ganewatta, and Chuanbing Tang
Macromolecules 2013 Volume 46(Issue 22) pp:8816-8823
Publication Date(Web):November 12, 2013
DOI:10.1021/ma402039u
Ruthenocene-containing methacrylate homopolymer, poly(2-(methacrylolyoxy)ethyl ruthenocenecarboxylate) (PMAERu), was prepared by controlled polymerization methods such as reversible addition–fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). Kinetic studies showed that both the RAFT and ATRP process of monomer 2-(methacryloyloxy)ethyl ruthenocenecarboxylate (MAERu) followed a controlled/“living” polymerization behavior. The obtained polymer PMAERu was fully characterized by NMR, gel permeation chromatography, UV–vis spectroscopy, cyclic voltammetry, thermogravimetric analysis, and differential scanning calorimetry. By using the ruthenocene-containing homopolymer as a Macro-RAFT agent and 2-bromoisobutyryl end-capped poly(ethylene oxide) (PEO-Br) as a macroinitiator, different amphiphilic diblock copolymers were synthesized via successful chain extension. These amphiphilic diblock copolymers can self-assemble into micelles with different morphologies, including spherical and worm-like nanostructures.
Co-reporter:Jiuyang Zhang;Dr. Yi Yan;Michael W. Chance;Dr. Jihua Chen;Jeffery Hayat;Dr. Shuguo Ma;Dr. Chuanbing Tang
Angewandte Chemie International Edition 2013 Volume 52( Issue 50) pp:13387-13391
Publication Date(Web):
DOI:10.1002/anie.201306432
Co-reporter:Christopher G. Hardy
Journal of Polymer Science Part B: Polymer Physics 2013 Volume 51( Issue 1) pp:2-15
Publication Date(Web):
DOI:10.1002/polb.23174
Abstract
This review covers recent advances in developing square arrays in thin films using block copolymers. Theoretical and experimental results from self-assembly of block copolymers in bulk and thin films, directed self-assembly of block copolymers confined in small wells, on substrates with arrays of posts, and on chemically nanopatterned substrates, as well as applications as nanolithography are reviewed. Some future work and hypothesis are discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Co-reporter:Jiuyang Zhang, Perry J. Pellechia, Jeffery Hayat, Christopher G. Hardy, and Chuanbing Tang
Macromolecules 2013 Volume 46(Issue 4) pp:1618-1624
Publication Date(Web):February 5, 2013
DOI:10.1021/ma4000013
Metallocene-containing polyelectrolytes show many unique properties in a variety of electrochemical, optoelectronic, medicinal, and magnetic applications. The utilization of counterions plays crucial roles in many aspects of these polyelectrolytes. This paper reports the first quantitative analysis of counterion exchange in metallocene-containing polyelectrolytes. Particularly counterion exchange of cationic cobaltocenium-containing polyelectrolytes was analyzed by diffusion NMR, which determined molar fractions of dissociated and associated ions as well as ion-exchange constant. Qualitative impact of counterion exchange on macromolecular conformation was directly observed from cobaltocenium-containing molecular brushes. This study may provide valuable guidance on applications such as layer-by-layer assembly and ion-triggered drug delivery that are involved with ion exchange of polyelectrolytes.
Co-reporter:Feng Jiang, Zhongkai Wang, Yali Qiao, Zhigang Wang, and Chuanbing Tang
Macromolecules 2013 Volume 46(Issue 12) pp:4772-4780
Publication Date(Web):June 6, 2013
DOI:10.1021/ma4007472
Thermoplastic elastomers (TPEs) are ever sought using a simple robust synthetic approach. Widely successful first-generation TPEs rely on microphase-separated ABA triblock copolymers (Architecture I). Recent multigraft copolymers represent the second-generation TPEs in which multiple branched rigid segments are dispersed in a rubbery backbone matrix (Architecture II). This paper reports our discovery of the third-generation TPEs that are based on rigid backbone dispersed in a soft grafted matrix. This Architecture III allows the use of random copolymers as side chains to access a wide spectrum of TPEs that cannot be achieved by architecture designs of the first two generations. In this report, random copolymer-grafted cellulose, cellulose-graft-poly(n-butyl acrylate-co-methyl methacrylate) copolymers with only 0.9–3.4 wt % cellulose prepared by activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP), as novel thermoplastic elastomers are investigated.
Co-reporter:Kejian Yao and Chuanbing Tang
Macromolecules 2013 Volume 46(Issue 5) pp:1689-1712
Publication Date(Web):February 28, 2013
DOI:10.1021/ma3019574
Natural molecular biomass plays an important role in the field of renewable polymers, as they can be directly used or derivatized as monomers for controlled polymerization, in a way similar to many petroleum-derived monomers. We deliver this perspective primarily based on a monomer approach. Biomass-derived monomers are separated into four major categories according to their natural resource origins: (1) oxygen-rich monomers including carboxylic acids (lactic acid, succinic acid, itaconic acid, and levulinic acid) and furan; (2) hydrocarbon-rich monomers including vegetable oils, fatty acids, terpenes, terpenoids and resin acids; (3) hydrocarbon monomers (bio-olefins); and (4) non-hydrocarbon monomers (carbon dioxide). A variety of emerging synthetic tools (controlled polymerization and click chemistry) are particularly summarized. An overview on future opportunities and challenges, which are critical to promote biorefinery in the production of renewable chemicals and polymers, is given.
Co-reporter:Jiuyang Zhang;Dr. Yi Yan;Michael W. Chance;Dr. Jihua Chen;Jeffery Hayat;Dr. Shuguo Ma;Dr. Chuanbing Tang
Angewandte Chemie 2013 Volume 125( Issue 50) pp:13629-13633
Publication Date(Web):
DOI:10.1002/ange.201306432
Co-reporter:Lixia Ren;Jiuyang Zhang;Christopher G. Hardy;Shuguo Ma
Macromolecular Rapid Communications 2012 Volume 33( Issue 6-7) pp:510-516
Publication Date(Web):
DOI:10.1002/marc.201100732
Abstract
Side-chain cobaltocenium-containing block copolymers are prepared by ring-opening metathesis polymerization (ROMP). These block copolymers include one cobaltocenium-containing block, with the second block being either a nonmetal-containing segment or a cobaltocenium-containing segment with different counterions. These block copolymers are self-assembled into spherical core/shell micelles in solutions. A template strategy is used to prepare cobalt (II or III)-containing nanoparticles by treating the self-assembled micelles via UV/ozonolysis and pyrolysis. Characterization by X-ray photon spectroscopy and X-ray diffraction indicates that these nanoparticles consist of different oxidants of cobalt, depending on the chemical compositions of block copolymers.
Co-reporter:Christopher G. Hardy;Md. Sayful Islam;Dioni Gonzalez-Delozier;Harry J. Ploehn
Macromolecular Rapid Communications 2012 Volume 33( Issue 9) pp:791-797
Publication Date(Web):
DOI:10.1002/marc.201100849
Abstract
We report a new generation of nanodielectric energy storage materials based on supramolecular block copolymers. In our approach, highly polarizable, conducting nanodomains are embedded within an insulating matrix through block copolymer microphase separation. An applied electric field leads to electronic polarization of the conducting domains. The high interfacial area of microphase-separated domains amplifies the polarization, leading to high dielectric permittivity. Specifically, reversible addition fragmentation transfer (RAFT) polymerization was used to prepare block copolymers with poly(methyl acrylate) (PMA) as the insulating segment and a strongly acidic dopant moiety, poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA), as the basis for the conducting segment. The PAMPSA block was complexed with an oligoaniline trimer to form a dopant-conjugated moiety complex that is electronically conductive after oxidation. For the undoped neat block copolymers, the increase of the PMA block length leads to a transition in dielectric properties from ionic conductor to dielectric capacitor with polarization resulting from migration of protons within the isolated PAMPSA domains. The oligoaniline-doped copolymers show remarkably different dielectric properties. At frequencies above 200 kHz, they exhibit characteristics of dielectric capacitors with much higher permittivity and lower dielectric loss than the corresponding undoped copolymers.
Co-reporter:Ying Chen, Perry A. Wilbon, Yung Pin Chen, Juhua Zhou, Mitzi Nagarkatti, Chunpeng Wang, Fuxiang Chu, Alan W. Decho and Chuanbing Tang
RSC Advances 2012 vol. 2(Issue 27) pp:10275-10282
Publication Date(Web):31 Aug 2012
DOI:10.1039/C2RA21675B
We prepared a class of novel cationic polymers as antimicrobial agents: quaternary ammonium-containing poly(N,N-dimethylaminoethyl methacrylate) with natural rosin as the pendant group (PDMAEMA-g-rosin). Different from most other amphipathic antimicrobial polymeric systems reported in the literature, our approach sandwiched the hydrophilic cationic group between the polymer backbone and bulky hydrophobic hydrophenanthrene side groups. A simple quaternization reaction was used to link the rosin ester chloride and PDMAEMA homopolymers. Both the Gram-positive bacterium Staphylococcus aureus (S. aureus) and Gram-negative bacterium Escherichia coli (E. coli) were tested against the PDMAEMA-g-rosin copolymers. PDMAEMA-g-rosin copolymers with the amphipathic structure exhibited effective antimicrobial activity against both E. coli and S. aureus. Both the degree of quaternization of rosin group and the molecular weight of PDMAEMA played roles in antimicrobial activities. Our results also indicated that conformation of hydrophobic group (particularly steric hindrance) played a role in dictating antibacterial efficacy. Scanning electron microscopy and confocal laser scanning microscopy were used to characterize morphological changes of bacteria after exposure with PDMAEMA-g-rosin copolymers. Possible mechanisms on a combination of ionic and hydrophobic interactions between bacterial cells and polymers are discussed.
Co-reporter:Christopher G. Hardy;Lixia Ren;Jiuyang Zhang
Israel Journal of Chemistry 2012 Volume 52( Issue 3-4) pp:230-245
Publication Date(Web):
DOI:10.1002/ijch.201100110
Abstract
This review summarizes recent work on side-chain metallocene-containing polymers prepared by controlled and living polymerizations, which include living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). The majority of efforts in the field are focused on side-chain ferrocene-containing polymers, while cobaltocenium-containing polymers have recently started to draw attention. Future direction on the development of other metallocene-containing polymers is discussed.
Co-reporter:Jiuyang Zhang, Lixia Ren, Christopher G. Hardy, and Chuanbing Tang
Macromolecules 2012 Volume 45(Issue 17) pp:6857-6863
Publication Date(Web):August 20, 2012
DOI:10.1021/ma3012784
Cobaltocenium-containing methacrylate homopolymer, poly(2-(methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate) (PMAECoPF6), was prepared by reversible addition–fragmentation chain transfer polymerization (RAFT). Using the homopolymer as a macroinitiator, three different diblock copolymers, including a novel heterobimetallic diblock copolymer with ferrocene units as the second block, were synthesized via chain extension. Kinetic studies showed that all chain extension followed a controlled/living process under relatively lower conversion. The heterobimetallic diblock copolymer self-assembled into spherical micelles in selective solvents. The formation of aggregates depended on the location of the ferrocene block in the micelles. While the ferrocene units were susceptible to oxidation toward decomposition, the cobaltocenium moiety exhibited extraordinary stability to maintain its structure integrity.
Co-reporter:Lixia Ren, Jiuyang Zhang, Christopher G. Hardy, Deon Doxie, Barbara Fleming, and Chuanbing Tang
Macromolecules 2012 Volume 45(Issue 5) pp:2267-2275
Publication Date(Web):February 16, 2012
DOI:10.1021/ma202725c
Cobaltocenium-labeled polymers were prepared by atom transfer radical polymerization (ATRP) using cobaltocenium-containing α-haloesters as initiators. The locations of the cobaltocenium moiety in the polymer chains (either at the end or in the middle) were dictated by the chemical structures of initiators. Kinetic studies showed that polymerizations of styrene, tert-butyl acrylate, and methyl methacrylate monomers followed a controlled/living manner, except that polymerization of methyl methacrylate with the aid of cobaltocenium monoinitiator displayed significant termination. All resultant polymers were redox-active and exhibited characteristic UV–vis absorption from the cobaltocenium moiety.
Co-reporter:Ying Chen, Perry A. Wilbon, Juhua Zhou, Mitzi Nagarkatti, Chunpeng Wang, Fuxiang Chu and Chuanbing Tang
Chemical Communications 2013 - vol. 49(Issue 3) pp:NaN299-299
Publication Date(Web):2012/11/15
DOI:10.1039/C2CC37386F
Multifunctional abietane-based polymer nanogels were fabricated for label-free cell imaging and drug delivery. The self-fluorescent abietane as the framework of carriers enables the imaging without the need for external fluorescent probes, while abietane-based nanogels exhibit low in vitro cytotoxicity.
Co-reporter:Christopher G. Hardy, Lixia Ren, Shuguo Ma and Chuanbing Tang
Chemical Communications 2013 - vol. 49(Issue 39) pp:NaN4375-4375
Publication Date(Web):2012/10/11
DOI:10.1039/C2CC36756D
Well-defined ferrocene-containing triblock copolymers were synthesized by atom transfer radical polymerization and self-assembled into highly ordered hexagonal arrays of cylinders via solvent annealing. The thin films were further used as a template and converted into highly ordered iron oxide nanoparticles (α-Fe2O3) by UV/ozonolysis and thermal pyrolysis.
Co-reporter:Jing Wang, Kejian Yao, Chongzhi Wang, Chuanbing Tang and Xiqun Jiang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 17) pp:NaN2332-2332
Publication Date(Web):2013/03/05
DOI:10.1039/C3TB20100G
Well-defined amphiphilic poly(ethylene glycol) and poly(dehydroabietic ethyl methacrylate) block copolymers (PEG-b-PDAEMA) were prepared by atom transfer radical polymerization. The methacrylate block contains a characteristic hydrophobic, biocompatible and economical dehydroabietic moiety. PEG-b-PDAEMA block copolymer micellar nanoparticles loaded with piperlongumine (PLGM) were successfully prepared by a nanoprecipitation method. In vitro and in vivo behaviors of these nanoparticles were thoroughly examined by a set of characterization techniques. Confocal laser scanning microscopy study revealed that these nanoparticles could be well taken up by cancer cells. In vivo near-infrared fluorescence imaging showed that the PLGM-loaded nanoparticles effectively targeted the tumor site by the enhanced permeability and retention (EPR) effect in H22 tumor-bearing mice. The in vivo antitumor examination found that PLGM-loaded nanoparticles exhibited superior efficacy in impeding the tumor growth compared to the commercially available Taxol® and free PLGM formulation. The changes in body weights and blood biochemical profiles were also compared to investigate the safety of PLGM and PEG-b-PDAEMA nanoparticle drug delivery system.
Co-reporter:Mitra S. Ganewatta, Yung Pin Chen, Jifu Wang, Jihua Zhou, Jerry Ebalunode, Mitzi Nagarkatti, Alan W. Decho and Chuanbing Tang
Chemical Science (2010-Present) 2014 - vol. 5(Issue 5) pp:NaN2016-2016
Publication Date(Web):2014/02/07
DOI:10.1039/C4SC00034J
Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community-settings, resulting in increased mortality rates and hospitalization costs. Emergence of resistance even to vancomycin, the standard reference for MRSA treatment, builds up pressure for the search of novel alternatives. We report potent natural resin acid-based cationic antimicrobial compounds and polymers that exhibit surprising antimicrobial activity against a range of MRSA strains, yet are largely non-toxic against mammalian cells. Molecular dynamics simulations and dye-leakage assays with anionic phospholipid membrane mimics of bacteria demonstrate a membrane-lysing effect induced by unique fused ring structures of resin acids that may constitute the principal mechanism of action for selective lysis of bacterial cells over mammalian cells. Our antimicrobial materials are derived from an unlikely yet abundant natural source, and offer a novel alternative to currently-used approaches.