52858-59-0Relevant academic research and scientific papers
ABC Triblock Terpolymers with Orthogonally Deprotectable Blocks: Synthesis, Characterization, and Deprotection
Elladiou, Marios,Patrickios, Costas S.
, p. 7503 - 7512 (2015)
The development and availability of new protecting groups are vital for all branches of synthetic chemistry. Equally vital is the facile and selective removal of these groups, leaving intact other protecting groups which are to be cleaved later. Herein we demonstrate this concept of orthogonal deprotection by combining three different forms of protected methacrylic acid (MAA) in the same terpolymers. One of these protected monomers was 2-(pyridin-2-yl)ethyl methacrylate (PyEMA), recently developed by us, whose units can be readily converted to MAA units either under alkaline hydrolysis conditions or thermally. The second monomer was tetrahydro-2H-pyran-2-yl methacrylate (THPMA) which can be cleaved either via acidic hydrolysis or by thermolysis. The third form of protected MAA was benzyl methacrylate (BzMA) which can be subjected to hydrogenolysis. Two ABC triblock terpolymers based on all three of these monomers were successfully synthesized-one by reversible addition-fragmentation chain transfer (RAFT) polymerization and the other by group transfer polymerization (GTP)-thus proving the feasibility of these demanding three-stage syntheses via both polymerization methods. The molecular weight characteristics and compositions of the terpolymers were determined by gel permeation chromatography and proton nuclear magnetic resonance spectroscopy (1H NMR), respectively. Subsequently, the ABC triblock terpolymers were sequentially subjected to conditions of alkaline hydrolysis, acidic hydrolysis, and hydrogenolysis, leading to the selective cleavage of the PyEMA, the THPMA and the BzMA units, respectively, without affecting the remaining types of protecting groups, according to analysis using 1H NMR spectroscopy. Similarly selective was the acidic hydrolysis followed by alkaline hydrolysis. Thermal treatment at 130 °C of the terpolymers led to the conversion of both the PyEMA and the THPMA units to MAA units, without affecting the BzMA units, yielding amphiphilic diblock copolymers whose self-assembly properties in water were investigated.
Synthesis and characterization of double-hydrophilic model networks based on cross-linked star polymers of poly(ethylene glycol) methacrylate and methacrylic acid
Georgiades, Savvas N.,Vamvakaki, Maria,Patrickios, Costas S.
, p. 4903 - 4911 (2002)
A series of model networks based on cross-linked star polymers of poly(ethylene glycol) methacrylate (PEGMA) and tetrahydropyranyl methacrylate (THPMA), a protected form of methacrylic acid (MAA), were synthesized by group transfer polymerization (GTP), covering various compositions (homopolymers and copolymers), arm architectures (homopolymer, block and statistical copolymers), and star architectures (heteroarm and star block). The synthesis took place in tetrahydrofuran (THF) using tetrabutylammonium bibenzoate (TBABB) as the catalyst and 1-methoxy-1-(trimethytsiloxy)-2-methyl-propene (MTS) es the initiator, and comprised a four- or six-step procedure: first, the formation of linear polymer chains upon the GTP of the monomer(s); next, the interconnection of the linear segments to star polymers ("arm-first" stars) by the in situ polymerization of the ethylene glycol dimethacrylate (EGDMA) cross-linker, followed by the addition of monomer(s) for a second time to grow new chains from the cores of the stars outward ("in-out" stars); finally, the cross-linking of the "in-out" stars to a network with the addition of more EGDMA. The molecular weights (MWs) and molecular weight distributions (MWDs) of all the linear and the star precursors to the networks were determined using gel permeation chromatography (GPC). The networks which contained THPMA were hydrolyzed under acidic conditions to convert the THPMA units to MAA units and thus to obtain polyelectrolytic, double-hydrophilic model networks. The aqueous degrees of swelling of all the networks were measured as a function of pH. At low pH, where MAA is protonated, low degrees of swelling were obtained, which increased with the network content in PEGMA. An increase of the degrees of swelling was observed at high pH. These high pH degrees of swelling were found to be dependent on both the composition and the structure of the network.
Nanoparticle-encapsulated P2X7 receptor antagonist in a pH-sensitive polymer as a potential local drug delivery system to acidic inflammatory environments
Lee, Sun-Mi,Cho, Joong-Heui,Lee, So-Deok,Kim, Yong-Chul
, p. 4197 - 4202 (2015/11/03)
We have developed nanoparticles of anti-inflammatory P2X7 receptor antagonist encapsulated in a pH-sensitive polymer, poly(tetrahydropyran-2-yl methacrylate) (poly(THPMA)), as a potential local drug delivery system to target to acidic inflammatory environments, in which P2X7 receptors are implicated in the pathology of inflammation via the activation of immune cells. The nanoparticles were prepared using single emulsion methods, also their size and shape were confirmed by microscopy and spectroscopy, etc. The profiles of the pH-dependent degradation, release of antagonist and biological activities were investigated. The nanoparticles that encapsulated the 3,5-dichloropyridine derivative (2) with poly(THPMA), were observed to be more slowly cleaved than the blank nanoparticles. Moreover, the free P2X7 receptor antagonists potently inhibited the receptor activation, whereas the nanoparticles of the 3,5-dichloropyridine derivative (2) encapsulated poly(THPMA) exhibited much lower P2X7 antagonistic activity through sustained encapsulation. Thus, the nanoparticles of the 3,5-dichloropyridine derivative (2) encapsulated poly(THPMA) may be utilized to develop a pH-sensitive local drug delivery system for controlled release of anti-inflammatory therapeutics in acidic physiological environments.
POSITIVE PHOTOSENSITIVE RESIN COMPOSITION, METHOD FOR FORMING CURED FILM, CURED FILM, ORGANIC EL DISPLAY DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE
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Paragraph 0400-0401; 0416, (2014/02/15)
A compound represented by the following formula (I): wherein in formula (I), R1 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkoxycarbonyl group, an acyl group, a carbamoyl group, a sulfamoyl group, a sulfo
End-linked poly[2-(dimethylamino)ethyl methacrylate]-poly(methacrylic acid) polyampholyte conetworks: Synthesis by sequential RAFT polymerization and swelling and SANS characterization
Pafiti, Kyriaki S.,Philippou, Zelina,Loizou, Elena,Porcar, Lionel,Patrickios, Costas S.
body text, p. 5352 - 5362 (2012/04/17)
Four well-defined end-linked triblock polyampholyte conetworks composed of positively ionizable 2-(dimethylamino)ethyl methacrylate (DMAEMA) repeating units and negatively ionizable methacrylic acid (MAA) repeating units were synthesized using one-pot, sequential reversible addition-fragmentation chain transfer (RAFT) polymerization, by employing 1,4-bis[2-(thiobenzoylthio)prop-2- yl]benzene (1,4-BTBTPB) as the chain transfer agent, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. From the four end-linked conetworks, three were based on ABA triblock polyampholytes with polyDMAEMA midblocks with a constant degree of polymerization (DP) and polyMAA end-blocks of different DPs. The fourth end-linked polyampholytic conetwork was based on an equimolar BAB triblock polyampholyte with a polyMAA midblock. Furthermore, two polyampholyte networks were also prepared: one based on an end-linked equimolar statistical polyampholyte, and one with a randomly cross-linked, rather than an end-linked, architecture. Finally, the two homopolymer networks based on the DMAEMA and the MAA monomers were also synthesized. The MAA units were introduced in the (co)networks via the polymerization of 2-tetrahydropyranyl methacrylate (THPMA) followed by its acid hydrolysis after (co)network formation. The linear precursors to the (co)networks were found to have molecular weights and compositions close to the expected values, whereas the extractables from the (co)networks were determined to be lower than 30%. In water, the degrees of swelling (DS) of all the polyampholyte (co)networks presented a characteristic minimum at intermediate pH values, around the (co)network isoelectric point (pI), while they increased at acidic and basic pHs. The pI values of the ampholytic (co)networks were estimated as the midpoints of the regions of reduced swelling and ranged between 5.3 and 6.8, decreasing with the increase of the MAA content in the (co)networks. Finally, small-angle neutron scattering (SANS) studies of the polyampholyte (co)networks swollen in D2O provided SANS profiles without any peaks but broad shoulders whose location was consistent with the spacing of the cross-linking cores.
Multiphoton writing of three-dimensional fluidic channels within a porous matrix
Lee, Jyh-Tsung,George, Matthew C.,Moore, Jeffrey S.,Braun, Paul V.
supporting information; experimental part, p. 11294 - 11295 (2011/03/19)
(Figure Presented) We demonstrate a facile method for fabricating novel 3D microfluidic channels by using two-photon-activated chemistry to locally switch the interior surface of a porous host from a hydrophobic state to a hydrophilic state. The 3D structures can be infilled selectively with water and/or hydrophobic oil with a minimum feature size of only a few micrometers. We envision that this approach may enable the fabrication of complex microfluidic structures that cannot be easily formed via current technologies.
Synthesis and aqueous solution properties of novel zwitterionic block copolymers
Lowe,Billingham,Armes
, p. 1035 - 1036 (2007/10/03)
A series of near-monodisperse poly[2-(dimethylamino)ethyl methacrylate-block-2-tetrahydropyranyl methacrylate] precursors is synthesised using group-transfer polymerisation chemistry; the 2-tetrahydropyranyl methacrylate protecting group is quantitatively removed under mild conditions and the resulting zwitterionic block copolymers undergo reversible temperature-induced micellisation in aqueous media.
