Superhydrophobic surfaces were obtained by coating with microspheres formed by the self-assembly of poly[2-(perfluorooctyl)ethyl
acrylate-ran-2-(dimethylamino)ethyl acrylate] (P[POA-r-DAA]) in the presence of dicarboxylic acids in supercritical carbon dioxide. The P[POA-r-DAA] random copolymer aggregated into micellar microspheres through the hydrogen bond cross-linking of the amino groups via
the carboxylic acids. The size of the microspheres and the amount of the acids needed to produce them were dependent on the
kinds of acids. Glutaric acid (Glu) and perfluorosuccinic acid (Psuc) provided microspheres at a 0.5 molar ratio of the acid/DAA.
Psuc produced smaller microspheres than Glu. Maleic acid (Ma), succinic acid (Suc), and azelaic acid (Az) required a higher
molar ratio to produce the microspheres. These acids provided spherical particles at the ratio of 1.0. The microspheres produced
by Suc and Az contained particles with a several hundred nanometer size. The surface coated with the microspheres showed high
water contact angles of 164°–172°.
The morphology control was attained in supercritical carbon dioxide (scCO2) for poly[2-(perfluorooctyl)ethyl acrylate (POA)-co-tert-butyl acrylate (TBA)] random copolymers with POA/TBA molar ratios of 9:1, 8:2, 7:3, 6:4, 5:5, and 4:6. The copolymers showed
a different solubility and morphology in scCO2 depending on the POA/TBA ratio. There was a tendency that the copolymers with a lower TBA content, such as 9:1, 8:2, and
7:3, showed a higher solubility in scCO2 and formed a fiber-like structure in the heterogeneous state below their cloud point. On the other hand, the copolymers with
the higher TBA contents of 6:4, 5:5, and 4:6 provided micrometer-sized spherical particles. Furthermore, the morphology was
controlled by the CO2 pressure because the fiber-like morphology for the copolymer with the 6:4 ratio changed to spherical by decreasing the CO2 pressure. 相似文献
Poly[2-(perfluorooctyl)ethyl acrylate-co-poly(ethylene glycol) methacrylate], P(POA-co-PEGm) was prepared as a new surfactant for scCO2. The random copolymer was obtained by the radical polymerization of 2-(perfluorooctyl)ethyl acrylate (POA) and poly(ethylene
glycol) methacrylate (PEGm) in DMF. The molar ratio of the POA and PEGm units in the copolymer was POA/PEGm = 0.972/0.028
by 1H NMR. The molecular weight and molecular weight distribution were estimated by size exclusion chromatography to be Mn = 133,000
and Mw/Mn = 8.25, respectively. It was suggested that the copolymer formed micellar aggregates with the cores of the PEGm
chains in scCO2, based on the analyses of the copolymer in hexafluorobenzene by 1H NMR and dynamic light scattering. The copolymer was soluble in scCO2 and had a cloud point at a much higher pressure than the critical pressure. It was found that the copolymer solubilized CO2-insoluble proteins such as bovine serum albumin and subtilisin Carlsberg in scCO2. The solubility of the copolymer was not influenced by the presence of the proteins; however, the solubility decreased in
the presence of a small amount of water along with the protein. The activity of the subtilisin slightly decreased when only
placed in scCO2, whereas a marked decrease in the activity was observed for the subtilisin in the presence of the copolymer in scCO2. The subtilisin activity decreased as the CO2 pressure increased. 相似文献
Spherical particles were prepared from poly[2-(perfluorooctyl)ethyl acrylateco-acrylic acid] random copolymers (P(POA-co-AA)) by self-assembly in supercritical carbon dioxide (scCO2). The P(POA-co-AA) copolymers with 9:1, 8:2, 7:3, and 6:4 molar ratios of the POA/AA unit completely dissolved in scCO2, however, the solubility was dependent on the POA/AA ratio. The copolymer with the higher AA content had a lower solubility. The scanning electron microscopy (SEM) observations revealed that the spherical particles were obtained in a heterogeneous state at pressures lower than the cloud point pressure. Dynamic light scattering and 1H NMR studies demonstrated that the copolymers formed random copolymer micelles consisting of the shells of the CO2-philic POA units and the cores of the CO2-phobic AA units and main chains. It was found that the formation of spherical particles could be optimized by the manipulation of the CO2 pressure and temperature for the different compositions of the copolymers. 相似文献
Poly[2-(dimethylamino)ethyl acrylate] (PDAEA) and polymer complexes of 2-(dimethylamino)ethyl acrylate (DAEA) with nickel(II), copper(II), iron(III) and cobalt(II) chlorides were prepared and characterized by means of IR, electronic spectra and elemental analysis. The thermal stability of the homopolymer was compared with those of the polymer complexes, and the order of stability was given. The activation energies of the polymer complexes were calculated. 相似文献
Copolymers of 2‐(N,N‐dimethylamino)ethyl acrylate (DMAEA) and 2‐(tert‐Boc‐amino)ethyl acrylate (t BocAEA) are synthesized by reversible addition–fragmentation chain transfer polymerization in a controlled manner with defined molar masses and narrow molar masses distributions (Ð ≤ 1.17). Molar compositions of the P(DMAEA‐co‐t BocAEA) copolymers are assessed by means of 1H NMR. A complete screening in molar composition is studied from 0% of DMAEA to 100% of DMAEA. Reactivity ratios of both comonomers are determined by the extended Kelen–Tüdos method (r DMAEA = 0.81 and rtBocAEA = 0.99).
Here, we reported the synthesis of branched poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) via a combination of activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) and self-condensing vinyl polymerization (SCVP) techniques. The typical linear kinetics of the AGET ATRP of DMAEMA with the initiation of 2-(2-bromoisobutyryloxy) ethyl methacrylate (BIEM) was observed. The molecular weight (Mn) of the branched PDMAEMA increased with the monomer conversion. The GPC traces of these polymers were unimodal and the molecular weight distributions (Mw/Mn) were in the range of 1.30–2.10. The degree of branching (DB) determined by NMR spectra agreed with theoretical value. The branched amphiphilic copolymer functionalized with azobenzene was then prepared via AGET ATRP chain-extension of branched PDMAEMA with azobenzene monomer, 6-[4-(4-methoxyphenylazo)phenoxy]hexyl(meth)acrylate as the second monomer. The GPC traces of these branched copolymers showed the mono-peaks, which proved the successful preparation of copolymers. The properties of this branched copolymer in controlling drug release were also investigated. It was found that the drug release rate of chlorambucil can be controlled by various factors, such as polymer structure, light, temperature and pH values. 相似文献
Six amphiphilic star copolymers comprising hydrophilic units of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and hydrophobic units of methyl methacrylate (MMA) were prepared by the sequential group transfer polymerization (GTP) of the two comonomers and ethylene glycol dimethacrylate (EGDMA) cross-linker. Four star-block copolymers of different compositions, one miktoarm star, and one statistical copolymer star were synthesized. The molecular weights (MWs) and MW distributions of all the star copolymers and their linear homopolymer and copolymer precursors were characterized by gel permeation chromatography (GPC), while the compositions of the stars were determined by proton nuclear magnetic resonance (1H NMR) spectroscopy. Tetrahydrofuran (THF) solutions of all the star copolymers were characterized by static light scattering to determine the absolute weight-average MW () and the number of arms of the stars. The of the stars ranged between 359,000 and 565,000 g mol−1, while their number of arms ranged between 39 and 120. The star copolymers were soluble in acidic water at pH 4 giving transparent or slightly opaque solutions, with the exception of the very hydrophobic DMAEMA10-b-MMA30-star, which gave a very opaque solution. Only the random copolymer star was completely dispersed in neutral water, giving a very opaque solution. The effective pKs of the copolymer stars were determined by hydrogen ion titration and were found to be in the range 6.5-7.6. The pHs of precipitation of the star copolymer solutions/dispersions were found to be between 8.8-10.1, except for the most hydrophobic DMAEMA10-b-MMA30-star, which gave a very opaque solution over the whole pH range. 相似文献