355120-40-0Relevant articles and documents
Synthesis of magnetic polystyrene nanoparticles using amphiphilic ionic liquid stabilized RAFT mediated miniemulsion polymerization
Chakraborty, Sourav,Jaehnichen, Klaus,Komber, Hartmut,Basfar, Ahmed A.,Voit, Brigitte
, p. 4186 - 4198 (2014)
Imidazole based amphiphilic ionic liquids (ILs) were used as surfactants in miniemulsion polymerization (MEP) of styrene using a free radical process as well as reversible addition-fragmentation chain transfer (RAFT). Monodisperse polystyrene (PS) nanoparticles were obtained, demonstrating the efficiency of the amphiphilic IL as surfactant in MEP. IL stabilized miniemulsion was furthermore used to prepare polystyrene based magnetic nanoparticles (MNP). A large increase of the possible MNP content associated with very good colloidal stability was achieved using IL stabilized RAFT mediated MEP where a carboxyl functionalized chain transfer agent (CTA) was applied, allowing interaction with the MNP surface. The molecular weight and dispersity index of polystyrene, the content of MNP, and the morphologies of the hybrid nanoparticles were controlled by proper optimization of the concentration of initiator and CTA. The materials have been analyzed by NMR, GPC, DLS, SEM, TEM, and TGA. Finally, the magnetic properties of the materials were determined by vibrating sample magnetometer (VSM) analysis.
Engineering a sharp physiological transition state for poly(n- isopropylacrylamide) through structural control
Chang, Kai,Dicke, Zachary T.,Taite, Lakeshia J.
, p. 976 - 985 (2012)
Poly(N-isopropylacrylamide) (pNIPAAm), a well-studied, biologically inert polymer that undergoes a sharp aqueous thermal transition at 32 °C, has been a subject of widespread interest for possible biological applications. A major hindrance to its successful application is due to the difficulty of maintaining a sharp transition when the polymer is modified for a physiological transition temperature, especially in isotonic solutions. Current copolymer blends raise the transition temperature but also make the transition significantly broader. We have combined the use of reversible addition-fragmentation chain transfer (RAFT) polymerization with tacticity control to synthesize well-defined pNIPAAm that demonstrates sharp transitions under physiological conditions. By selecting a RAFT agent with appropriate end groups, controlling molecular weight, and increasing the racemo diad content, we were able to increase the thermal transition temperature of pure pNIPAAm to a sharp transition at 37.6 °C under isotonic conditions.
Poly(N-isopropylacrylamide) hydrogels fabricated via click chemistry: Well-defined α,ω-bis propargyl linear poly(N-isopropylacrylamide)s as crosslinkers
Wang, Jianquan,Kang, Zeyu,Qi, Bin,Zhou, Qiushi,Xiao, Shengyuan,Shao, Ziqiang
, p. 51510 - 51518 (2014)
A series of poly(N-isopropylacrylamide) (PNIPA) hydrogels were fabricated through click chemistry by using a well-defined azido-PNIPA carrying pendant azido groups, and linear α,ω-bis propargyl PNIPAs with different chain lengths. Here linear α,ω-bis propargyl PNIPAs were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization by using a bis propargyl terminal chain transfer agent, whose chain lengths were modulated by changing polymerization conditions. The obtained hydrogels showed increasing ESR values in the swollen state and increasing volume phase transition temperatures (VPTTs) with increasing molecular weights of bis propargyl PNIPAs, ascribed to the lengthening distance between crosslinks and improving hydrophilicity. The incorporation of amine together with crosslinking modified the hydrophilicity of a click hydrogel, resulting in the elevated VPTT and additional pH sensitivity. The present study provided a facile method to regulate swelling properties and/or to impart special functions for PNIPA hydrogels, by adjusting the chain length of crosslinkers or by introducing other functional groups. This journal is
A strategy for effective radioprotection by chitosan-based long-circulating nanocarriers
Zhou, Yuan,Hua, Song,Yu, Jiahua,Dong, Ping,Liu, Fenju,Hua, Daoben
supporting information, p. 2931 - 2934 (2015/04/22)
We demonstrate a strategy for effective radioprotection by chitosan-based long-circulating nanocarriers with radio-protective agents. The stable encapsulation does not restrain its radioprotective capability, and exhibits prolonged retention time in blood with a half-life of ～10 h, thereby showing more beneficial effects than the pure agent in therapeutic efficacy for irradiated mice.
End group polarity and block symmetry effects on cloud point and hydrodynamic diameter of thermoresponsive block copolymers
Xiang, Xu,Ding, Xiaochu,Chen, Ning,Zhang, Beilu,Heiden, Patricia A.
, p. 2838 - 2848 (2016/01/09)
Thermoresponsive block copolymers are of interest for delivery vehicles in the body. Often an interior domain is designed for the active agent and the exterior domain provides stability in the bloodstream, and may carry a targeting ligand. There is still much to learn about how block sequence and chain end identity affect micelle structure, size, and cloud points. Here, hydrophilic oligo(ethylene glycol) methyl ether acrylate and more hydrophobic di(ethylene glycol) methyl ether methacrylate monomers were polymerized to give amphiphilic block copolymers with amphiphilic chain ends. The block sequence and chain end identity were both controlled by appropriate choice of RAFT chain transfer agents to study the effect of 'matched' and 'mismatched' chain end polarity with amphiphilic block sequence. The affect of matching or mismatching chain end polarity and block sequence was studied on the hydrodynamic diameter, cloud point, and temperature range of the chain collapse on linear di- and triblock copolymers and star diblock polymers. The affects of matching or mismatching chain end polarity were significant with linear diblock copolymers but more complex with triblock and star copolymers. Explanations of these results may help guide others in designing thermoresponsive block copolymers.
Highly protein-resistant coatings and suspension cell culture thereon from amphiphilic block copolymers prepared by RAFT polymerization
Haraguchi, Kazutoshi,Kubota, Kazuomi,Takada, Tetsuo,Mahara, Saori
, p. 1992 - 2003 (2014/06/24)
Novel amphiphilic block copolymers composed of hydrophobic (poly(2-methoxyethyl acrylate): M) and hydrophilic (poly(N,N-dimethylacrylamide) : D) segments were synthesized by living radical polymerization: a reversible addition-fragmentation chain-transfer polymerization. Two types of amphiphilic block copolymers, triblock (MDM) and 4-arm block ((MD)4) copolymers with specific compositions (D/M = (750-1500)/250), were prepared by a versatile one-pot synthesis. These copolymers show good adhesion to various types of substrates (e.g., polystyrene, polycarbonate, polypropylene, Ti, and glass), and the surface coating showed high protein repellency and a low contact angle for water, regardless of the substrate. The two opposing characteristics of high protein repellency and good substrate adhesion were achieved by the combined effects of the molecular architecture of the block copolymers, the high molecular weight, and the characteristics of each segment, that is, low protein adsorption capability of both segments and low glass transition temperature of the hydrophobic segment. Further, a polystyrene dish coated with the MDM block copolymer could be sterilized by γ-ray irradiation and used as a good substrate for a suspension cell culture that exhibits low cell adhesion and good cell growth.
RAFT polymers for protein recognition
Tominey, Alan F.,Liese, Julia,Kraft, Arno,Wei, Sun,Kowski, Klaus,Schrader, Thomas
supporting information; experimental part, (2010/11/05)
A new family of linear polymers with pronounced affinity for arginine- and lysine-rich proteins has been created. To this end, N-isopropylacrylamide (NIPAM) was copolymerized in water with a binding monomer and a hydrophobic comonomer using a living radical polymerization (RAFT). The resulting copolymers were water-soluble and displayed narrow polydispersities. They formed tight complexes with basic proteins depending on the nature and amount of the binding monomer as well as on the choice of the added hydrophobic comonomer.
TOUGHENED VINYL ESTER RESINS
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Page/Page column 33-34, (2010/02/13)
A vinyl ester resin is derived from the reaction of an unsaturated acid with an epoxy terminated polymer made from a dithio or a trithio initiator, and optionally from an epoxy resin. The vinyl ester resin can be blended with a miscible toughener and a diluent to provide a time stable system and subsequently crosslink to provide a composition with improved toughening properties.
S-(alpha, alpha'-disubstituted-alpha"-acetic acid) substituted dithiocarbonate derivatives for controlled radical polymerizations, process and polymers made therefrom
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Page 21, (2008/06/13)
Dithiocarbonate derivatives are disclosed, along with a process for preparing the same. The dithiocarbonate compounds can be utilized as initators, chain transfer agents and/or terminators in controlled free radical polymerizations. The dithiocarbonates can be used to produce polymers having narrow molecular weight distribution. Advantageously, the compounds of the present invention can also introduce functional groups into the resulting polymers. The dithiocarbonate compounds have low odor and are substantially colorless.
