73232-07-2Relevant articles and documents
Seeded emulsion polymerization of block copolymer core-shell nanoparticles with controlled particle size and molecular weight distribution using xanthate-based RAFT polymerization
Smulders, Wilfred,Monteiro, Michael J.
, p. 4474 - 4483 (2004)
The work described here has shown for the first time that well-defined core-shell nanostructures with controlled particle size and molecular weight distributions (in which the molecular weight distributions of both blocks are independently controlled using the same RAFT controlling agent) can be prepared in an aqueous environment. These types of nanoparticles can lead the way to more novel and interesting structures in applications for drug delivery, biosensors, and other devices. A poly(methyl methacrylate) (PMMA) seed was used to control the particle size distribution, in which styrene (STY) in the presence of the RAFT agent was polymerized under batch conditions to give polymer particles with an number-average molecular weight (Mn) of 7000 and polydispersity (PDI) of 2. Butyl acrylate (BA) was then polymerized under semibatch conditions into these particles to give an overall Mn of 20 000 and PDI close to 1.3 for the block copolymer, in which greater than 90% block purity was observed. The calculated PDI of the second block (PBA) was close to 1.4, which is lower than the theoretically determined value under batch conditions (PDI = 1.6). The results show that by slow monomer addition feed into the reactor the PDI can be reduced and that by using the advantage of "random coupling" between the two blocks the PDI of the final block copolymer is lower than either of the individual blocks.
Functional biohybrid materials synthesized via surface-initiated MADIX/RAFT polymerization from renewable natural wood fiber: Grafting of polymer as non leaching preservative
Tastet, Damien,Save, Maud,Charrier, Fatima,Charrier, Bertrand,Ledeuil, Jean-Bernard,Dupin, Jean-Charles,Billon, Laurent
, p. 606 - 616 (2011)
Crude wood fibers represent a wide class of renewable resources. The surface modification of such materials via covalent grafting of polymer offers new surface properties with non-leaching coating. The grafting of the polymer chains was achieved by surface-initiated controlled radical polymerization through a grafted xanthate chain transfer agent. Macromolecular design via interchange of xanthate (MADIX) technique was chosen to graft poly(vinyl acetate), polystyrene, poly(n-butyl acrylate) and poly(4-vinylbenzyl chloride)-polystyrene amphiphilic cationic copolymers. Water contact angle measurements highlighted the hydrophobization of the wood fiber surface with a nanoscaled polymer monolayer indicating the appropriate coverage of the fiber. X-ray photoelectron spectroscopy showed the successful grafting of the polymer after drastic washing procedure. The quaternization of the grafted polystyrene-co-poly(4-vinyl benzyl chloride) copolymers with tertiary amine allows the introduction of biocide quaternary ammonium functions while preserving the hydrophobic character of the modified wood fiber when introducing a long alkyl chain in the statistical copolymer. Finally, the cationic copolymer was subjected to Coniophora Puteana to evaluate its propensity to limit the fungi expansion.
Reversible addition-fragmentation chain transfer polymerization of vinyl acetate under high pressure
Chen, Jing,Zhao, Xiaoning,Zhang, Lifen,Cheng, Zhenping,Zhu, Xiulin
, p. 1430 - 1436 (2015/05/05)
In this work, high molecular weight polyvinyl acetate (PVAc) (Mn,GPC = 123,000 g/mol, Mw/Mn = 1.28) was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) under high pressure (5 kbar), using benzoyl peroxide and N,N-dimethylaniline as initiator mediated by (S)-2-(ethyl propionate)-(O-ethyl xanthate) (X1) at 35 C. Polymerization kinetic study with RAFT agent showed pseudo-first order kinetics. Additionally, the polymerization rate of VAc under high pressure increased greatly than that under atmospheric pressure. The "living" feature of the resultant PVAc was confirmed by 1H NMR spectroscopy and chain extension experiments. Well-defined PVAc with high molecular weight and narrow molecular weight distribution can be obtained relatively fast by using RAFT polymerization at 5 kbar.
Polyvinyl alcohol as a biocompatible alternative for the passivation of gold nanorods
Kinnear, Calum,Burn, David,Clift, Martin J. D.,Kilbinger, Andreas F. M.,Rothen-Rutishauser, Barbara,Petri-Fink, Alke
supporting information, p. 12613 - 12617 (2015/04/13)
The functionalization of gold nanorods (GNRs) with polymers is essential for both their colloidal stability and biocompatibility. However, a bilayer of the toxic cationic surfactant cetyl trimethylammonium bromide (CTAB) adsorbed on the nanorods complicates this process. Herein, we report on a strategy for the biocompatible functionalization of GNRs with a hydrophobic polymeric precursor, polyvinyl acetate, which is then transformed into its hydrophilic analogue, polyvinyl alcohol. This polymer was chosen due to its well-established biocompatibility, tunable "stealth" properties, tunable hydrophobicity, and high degree of functionality. The biocompatibility of the functionalized GNRs was tested by exposing them to primary human blood monocyte derived macrophages; the advantages of tunable hydrophobicity were demonstrated with the long-term stable encapsulation of a model hydrophobic drug molecule.
