5873-93-8Relevant academic research and scientific papers
Controlled free radical polymerization in water-borne dispersion using reversible addition-fragmentation chain transfer
Vosloo,De Wet-Roos,Tonge,Sanderson
, p. 4894 - 4902 (2002)
A novel approach to conducting controlled free radical polymerization in water-borne organic dispersions using reversible addition-fragmentation chain transfer (RAFT) has been studied. The novel approach in this study focused on eliminating monomer and oligomer transport and comprised two fundamental steps: the synthesis of dithiobenzoate-end-capped styrene oligomers in bulk followed by emulsification of these oligomers to yield a polymerizable water-borne dispersion. Dithioesters that act as chain transfer agents in the RAFT process were synthesized in situ. The free radical polymerization of the dithiobenzoate-end-capped styrene oligomers in the water-borne organic dispersion proceeded in a controlled manner: molar mass increased in a linear fashion with increasing conversion, while polydispersities remained low. The familiar red layer formation associated with RAFT polymerization in conventional emulsions was not observed under these conditions. The effects of changing the costabilizer (hydrophobe) and the degree of polymerization of the emulsified oligomers were investigated. Better control was achieved with a less hydrophilic costabilizer and for the shorter of the oligomers tested.
Intramolecular folding of triblock copolymers via quadrupole interactions between poly(styrene) and poly(pentafluorostyrene) blocks
Lu, Jie,Ten Brummelhuis, Niels,Weck, Marcus
, p. 6225 - 6227 (2014)
β-Hairpin formation is one of the fundamental folding actions in biomacromolecules. We present a linear triblock copolymer synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, that is able to mimic on a very basic level hairpin formation by using π-π stacking interactions between phenyl and 2,3,4,5,6-pentafluorophenyl residues. This journal is the Partner Organisations 2014.
Ubiquitous Nature of Rate Retardation in Reversible Addition-Fragmentation Chain Transfer Polymerization
Bradford, Kate G. E.,Petit, Leilah M.,Whitfield, Richard,Anastasaki, Athina,Barner-Kowollik, Christopher,Konkolewicz, Dominik
, p. 17769 - 17777 (2021/11/10)
Reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most powerful reversible deactivation radical polymerization (RDRP) processes. Rate retardation is prevalent in RAFT and occurs when polymerization rates deviate from ideal conventional radical polymerization kinetics. Herein, we explore beyond what was initially thought to be the culprit of rate retardation: dithiobenzoate chain transfer agents (CTA) with more active monomers (MAMs). Remarkably, polymerizations showed that rate retardation occurs in systems encompassing the use of trithiocarbonates and xanthates CTAs with varying monomeric activities. Both the simple slow fragmentation and intermediate radical termination models show that retardation of all these systems can be described by using a single relationship for a variety of monomer reactivity and CTAs, suggesting rate retardation is a universal phenomenon of varying severity, independent of CTA composition and monomeric activity level.
Tert-amyl methyl ether preparation method and light gasoline modification method
-
Paragraph 0088, (2018/06/14)
The invention discloses a tert-amyl methyl ether preparation method and a light gasoline modification method. The tert-amyl methyl ether preparation method comprises that methanol and isopentene contact an etherification catalyst under an etherification reaction condition to obtain the reaction product containing tert-amyl methyl ether, wherein the etherification catalyst is a polymer supported ionic liquid catalyst, and has a structure represented by a formula (I) or a formula (II). With the method of the present inventin, the tert-amyl methyl ether preparation reaction can maintain the highreactivity.
Design, synthesis, and phase behaviors of a novel triphenylene-based side chain liquid crystalline diblock copolymer
Ban, Jianfeng,Pan, Lulu,Shi, Bo,Zhang, Hailiang
, p. 13581 - 13588 (2018/08/21)
A novel double Tp-based liquid crystalline (LC) diblock copolymer (PMTS-b-PMT6S) composed of poly[3,6,7,10,11-pentakis (hexyloxy)-2-oxytriphenylene] (PMTS) and poly{6-[3,6,7,10,11-pentakis(hexyloxy)-2-oxytriphenylene]} (PMT6S) was designed and successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. While PMTS is a rigid columnar-shaped (ΦN) polymer, PMT6S is a stable hexagonal columnar phase (ΦH) polymer. The phase behaviors of diblock copolymers were studied by DSC, POM and 1D WAXD. The results showed that the weight fraction of PMT6S (fPMT6S) has a significant effect on the LC phase behaviors and phase structures of diblock copolymers. Both glass transition temperature and phase transition temperature of the diblock copolymers from LC phase to isotropic phase reduced with the weight fraction of PMT6S in the feed. When the fPMT6S ≤ 58.1%, PMTS-b-PMT6S-1 to PMTS-b-PMT6S-3 show similar properties to PMTS, which formed a stable columnar nematic phase (ΦN), while when the fPMT6S ≥ 64.2%, PMTS-b-PMT6S-4 and PMTS-b-PMT6S-5 show similar properties to PMT6S, which presented a hexagonal symmetry columnar phase (ΦH). Comparison between the diblock copolymer and homopolymer (PMTS and PMT6S) indicates that the content of the spacer was crucial to determine the LC structures. Through the study one can better understand the interrelation of microstructures and Tp DLC orders, which constitutes the key basis for various applications.
Synthesis, characterization, and biological interaction of glyconanoparticles with controlled branching
Liau, Walter T.,Bonduelle, Colin,Brochet, Marion,Lecommandoux, Sbastien,Kasko, Andrea M.
, p. 284 - 294 (2015/01/30)
Branched amphiphilic copolymers were synthesized through the reversible addition - fragmentation chain transfer (RAFT) chain extension of a poly(methyl acrylate) macro-chain transfer agent using a protected galactose monomer and a polymerizable chain transfer agent branching unit. After galactose deprotection, the copolymers were self-assembled via nanoprecipitation. The resultant nanoparticles were analyzed for their size, shape, and biological interaction with a galactose binding lectin. Using light scattering, the nanoparticles were determined to be solid spheres. Nanoparticles containing branched glycoblocks bound significantly more lectin than those containing comparable linear blocks. By adjusting the molecular weight and branching of the copolymer, the size of the self-assembled nanoparticle and the saccharide density on its surface can be varied. (Figure Presented).
Intracellular nitric oxide delivery from stable NO-polymeric nanoparticle carriers
Duong, Hien T. T.,Kamarudin, Zulkamal M.,Erlich, Rafael B.,Li, Yang,Jones, Mathew W.,Kavallaris, Maria,Boyer, Cyrille,Davis, Thomas P.
, p. 4190 - 4192 (2013/05/23)
The encapsulation of S-nitrosoglutathione into polymeric nanoparticles substantially improves NO stability in aqueous media without affecting the efficacy of intracellular delivery. The combination of nano-NO delivery and chemotherapy has been found to enhance antitumour activity of chemotherapeutics, as demonstrated using preliminary in vitro experiments with neuroblastoma cells.
First RAFT polymerization of captodative 2-acetamidoacrylic acid (AAA) monomer: An experimental and theoretical study
Dedeo?lu, Burcu,U?ur, Ilke,De?irmenci, Isa,Aviyente, Viktorya,Bar?in, Bilin?,?ayli, G?khan,Acar, Havva Yagci
, p. 5122 - 5132 (2013/09/02)
A capto-dative monomer, 2-acetamidoacrylic acid (AAA), was homopolymerized through RAFT polymerization method using 2-(2-cyanopropanyl dithiobenzoate) (CPDB) as a chain transfer agent and AIBN free radical initiator in DMF at 70 C. DFT calculations were performed in the selection of the CTA for this unique monomer as well as to elucidate the influence of cd-stabilized growing radical on the kinetic parameters in comparison to methacrylic acid (MAA) and N-(prop-1-en-2-yl)acetamide (NPAA), which represent the captive and dative groups of AAA, respectively. Keq for these three monomers is in the order of AAA β > k-add for NPAA and MAA, for AAA k-add is about four orders of magnitude larger than kβ. This is the major disadvantage in the RAFT process of AAA using CPDB. Yet, poly(AAA) could be achieved with PDI as low as 1.49. Molecular weight of the polymer can be tuned by the monomer/AIBN ratio. First block copolymers of AAA with MAA and MMA using poly(AAA) as a macro-CTA were also synthesized, indicating the presence of active chain ends.
Visible-light degradable polymer coated hollow mesoporous silica nanoparticles for controlled drug release and cell imaging
Yang, Shun,Li, Najun,Chen, Dongyun,Qi, Xiuxiu,Xu, Yujie,Xu, Ying,Xu, Qingfeng,Li, Hua,Lu, Jianmei
, p. 4628 - 4636 (2013/09/12)
A core-shell nanocomposite based on photo-degradable polymer coated hollow mesoporous silica nanoparticles (HMS) was successfully prepared for targeted drug delivery and visible-light triggered release, as well as fluorescence cell imaging. The HMS nanoparticles were first modified by the long-chain hydrocarbon octadecyltrimethoxysilane (C18) and fluorescent agent Rhodamine B isothiocyanate (RITC), and then encapsulated by a photodegradable amphiphilic copolymer via a self-assembly process. The obtained nanocarrier showed a high drug loading content due to the hollow core and mesopores of the HMS and could target folic acid receptor over-expressed tumor cells efficiently for conjugating folic acid (FA) in the amphiphilic polymer. The drug release could be triggered by the irradiation of green light (500-540 nm) due to the photodegradation of amphiphilic copolymer coated on the HMS. Furthermore, the targeted drug delivery and controlled release processes could be tracked by fluorescence imaging for the doping of RITC on the HMS. The In vitro results suggested that a smart visible light responsive drug delivery system was successfully prepared for the potential applications of cancer diagnosis and therapy.
A new selenium-based RAFT agent for surface-initiated RAFT polymerization of 4-vinylpyridine
Demirci, Serkan,Kinali-Demirci, Selin,Caykara, Tuncer
, p. 5345 - 5350 (2013/09/23)
A new selenium-based reversible addition-fragmentation chain transfer (RAFT) agent, 4-cyanopentanoic acid diselenobenzoate (RAFT-Se), was synthesized and utilized in the surface-initiated RAFT polymerization of 4-vinylpyridine (4VP) on silicon substrate. The results indicate that the RAFT-Se can control the surface-initiated RAFT polymerization, as evidenced by the number-average molecular weight that increase linearly with monomer conversion, molecular weights that agreed well with the predicted values, and the relatively low polydispersity indexes. The surface-initiated RAFT polymerization with the RAFT-Se was the same polymerization mechanism as its analog, 4-cyanopentanoic acid dithiobenzoate (RAFT-S). The grafting density of the poly(4-vinylpyridine) brushes prepared in the presence of RAFT-Se (σRAFT-Se) and RAFT-S (σRAFT-S) was estimated to be about 0.51 and 0.66 chains/nm2, respectively. In addition, the end of polymer chains on silicon substrate contains selenium element which may be useful in biosensor applications.
