Monodisperse PMMA

Monodisperse pol mier particles can be s mthesized. Monodisperse pol5nner particles provide an opaque ink with improved color brilliancy (5). 

Monodisperse particles based on fluorinated, crosslinked poly-(meth)acrylates are preferably used for the inkjet ink composition. Pol5miers of this t q)e may be produced by suspension pol mieriza-tion of the monomers. 

As fluorinated polymers, poly[(N-3-n-perfluorooctyl propionyl-ethylenimine)-f7-(N-propionylethylenimine)] can be used (6). Alternatively a water-soluble B block can be synthesized first, and a fluorinated nucleophilic compound then used to terminate the living ends to provide the fluorine containing A block (6). The preparation of the polymers has been described in detail (6). 

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The most studied catalyst family of this type are lithium alkyls. With relatively non-bulky substituents, for example nBuLi, the polymerization of MMA is complicated by side reactions.4 0 These may be suppressed if bulkier initiators such as 1,1-diphenylhexyllithium are used,431 especially at low temperature (typically —78 °C), allowing the synthesis of block copolymers.432,433 The addition of bulky lithium alkoxides to alkyllithium initiators also retards the rate of intramolecular cyclization, thus allowing the polymerization temperature to be raised.427 LiCl has been used to similar effect, allowing monodisperse PMMA (Mw/Mn = 1.2) to be prepared at —20 °C.434 Sterically hindered lithium aluminum alkyls have been used at ambient (or higher) temperature to polymerize MMA in a controlled way.435 This process has been termed screened anionic polymerization since the bulky alkyl substituents screen the propagating terminus from side reactions. 

The core first method has been applied to prepare four-arm star PMMA. In this case selective degradation of the core allowed unambiguous proof of the star structure. However, the MWD is a little too large to claim that only four-arm star polymers are present [81], Comb PMMAs with randomly placed branches have been prepared by anionic copolymerization of MMA and monodisperse PMMA macromonomers [82], A thorough dilute solution characterization revealed monodisperse samples with 2 to 13 branches. A certain polydispersity of the number of branches has to be expected. This was not detected because the branch length was very short relative to the length of the backbone [83]. Recently, PMMA stars (with 6 and 12 arms) have been prepared from dendritic... 

A series of monodisperse PMMA latexes was synthesized and characterized with respect to refractive index, percent solids, and solution density. The particle size of each latex was analyzed by several different instrumental methods. The methods used include DCP, SFFF, HDC, Quasielastic Light Scattering (QELS), TEM, and turbidity. 

A similar experiment is reported in (60) in-situ polymerization of PMMA in presence of MWCNT at analogous experimental conditions (in methanol, using PVP as stabilizer and AIBN as initiator) produced monodisperse PMMA/MWCNT microspheres only with the help of mechanical stirring. The spheres diameters decreased from about 11.6 pm to 6.0 pm as the content of MWCNT increased from 0 to 0.03 wt%. Additional analyses identified carbon nanotubes to be present both in the interior and on the surface of the particles. 

Koehler and Provder [317] sized monodisperse PMMA latexes with a range of instruments Disc centrifugal sedimentation (DCP), sedimentation field flow fractionation (SFFF), hydrodynamic chromatography (HDC), photon correlation spectroscopy (PCS), turbidimetry and transmission electron microscopy (TEM). TEM gave the smallest sizes, DCP and SFFF were in fair agreement in the center and PCS the highest sizes. 

Fig. 35 a. Median tensile strains for craze initiation s, (A) and craze fibril breakdown ( ) in the ultraclean samples versus molecular weight. Also shown are the values of (O) for the unfiltered samples (From Ref. courtesy Macromolecules (ACS)), b Craze fibril stability — 8 in nearly monodisperse PMMA as a function of molecular weight c Craze fibril stability in nearly monodiaperse PaMS as a function of molecular weight . The solid lines in b and c are predictions from the model of fibril breakdown (Eq. (41)) using values for of 88 s (PMMA) and 364 s (PaMS)... 

Fig. 40a. Craze fibril stability (e — e ) versus n, the mean number of effectively entangled strands per fibril for monodisperse PS (circles) PS molecular weight blends (squares) monodisperse PMMA (diamonds) and monodisperse PotMS (stars) The solid lines are the predictions of the model using the parameters given in the text, b Craze fibril stability (e — e ) vereus 1 / where is the mean force per effectively entangled strand in the fibrils. Same symbols and lines as in a...

Cairns et al. (220) studied monodispersed PMMA latex with a particle diameter of about 156 nm suspended in dodecane and stabilized by covalently attached poly(12-hydroxystearie acid) with a thickness of A = 9 nm. They found that the resistance to compression starts to increase drastically around = 0.55, and at 0 = 0.566 the compression resistance was very strong, indicating that the suspension would not yield to compression when the maximum packing limit is reached. 

The 1,1-dihydroperfluorooctylacrylate side chain is C02-philic and the acrylate backbone forms thfe anchor segment. A dispersion polymerization of MMA in supox ritical CO2 using PFOA was effective in producing monodisperse PMMA microspheres with diameters around 2 pm. 

After this first report of NIR electroluminescence using Er hydroxyquinolinate, H. Suzuki et al. investigated the luminescence characteristics of this complex under different sample forms which can further be used as NIR emissive materials. Three types of samples have been prepared vacuum-deposited thin-films, doped spin-coated IR polymer films and doped polymer microparticles (Suzuki et al., 2003). Typical NIR luminescence of the Er ion was observed at 1.55 pm for each sample form and with higher intensities when excitation was performed in the ligand absorption bands instead of directly in the Er excited levels. This clearly indicates that sensitization of Er -centered luminescence occurs through ligand-to-metal energy transfer. For the doped monodispersed PMMA microparticles the lower lumi-... 

Bisphenol A (BPA) is a common compound used in the synthesis of many plastics and epoxy resins. However, recent studies have determined BP A is an emerging contaminant, which can disrupt the endocrine system and potentially cause cancer [115]. By molecular imprinting, Gao s group created numerous nanocavities in polymethyl methacrylate (PMMA) spheres, which can specifically target BPA (Fig. 37). The monodisperse PMMA spheres can be made into a CCA-based optical sensor. When the sensor is exposed to BPA solution, binding... 

Figo 3o Particle Size Histogram of a Typical Monodisperse PMMA LateXo... 

Monodispersed PMMA spheres (diameter 291 8 nm) were synthesized by literature techniques [63,75,76]. 1.60 g of potassium persulfate as a polymerization initiator and 720 ml of water were stirred at 300 rpm, heated at 353 K, and... 

A. Calibration. No monodisperse calibration standards were available for PMMA. Figures 2 and 3 show calibrations accomplished by two methods ... 

One possibility is that although averages for polystyrene standards require correction, those for PMMA would not According to symmetrical axial dispersion theory (5) the correction depends upon both the slope of the calibration curve (different for each polymer type) and the variance of the chromatogram of a truly monodisperse sample. Furthermore, the calibration curve to be utilized can be obtained from a broad standard as well as from monodisperse samples. The broad standard method may itself incorporate some axial dispersion correction depending upon how the standard was characterized. 

The rate of polymerization may be dramatically accelerated upon addition of a bulky Lewis acid. For example, addition of (184) to a sample of living PMMA generated by irradiation of (181)/MMA causes an increase in polymerization rate by a factor of >45,000.444 The dualcomponent systems (181)/(184), and (181)/(185), have been used to prepare monodisperse, ultra-high-molecular-weight samples of PMMA (Mn > 106, Mw/Mn= 1.2).445... 

Materials. The nearly monodisperse atactic PMMA, which was used for the electron beam lithography and fluorescence spectroscopy studies, was obtained from Pressure Chemical. It has a weight average molecular weight (Mw) of 188,100 and Mw/Mn< 1.08. Pyrenedodecanoic acid (PDA) used in the fluorescence studies was obtained from Molecular Probes and used as supplied. Spectroscopic grade benzene purchased from J.T. Baker was used as the spreading solvent in the PMMA and PMMA/PDA solutions. 

Kreuter and Speiser [77] developed a dispersion polymerization producing adjuvant nanospheres of polymethylmethacrylate) (PMMA). The monomer is dissolved in phosphate buffered saline and initiated by gamma radiation in the presence and absence of influenza virions. These systems showed enhanced adjuvant effect over aluminum hydroxide and prolonged antibody response. PMMA particles could be distinguished by TEM studies and the particle size was reported elsewhere to be 130 nm by photon correlation spectroscopy [75], The particle size could be reduced, producing monodisperse particles by inclusion of protective colloids, such as proteins or casein [40], Poly(methylmethacrylate) nanoparticles are also prepared... 

Owing to the simphcity and versatility of surface-initiated ATRP, the above-mentioned AuNP work may be extended to other particles for their two- or three-dimensionally ordered assemblies with a wide controllabiUty of lattice parameters. In fact, a dispersion of monodisperse SiPs coated with high-density PMMA brushes showed an iridescent color, in organic solvents (e.g., toluene), suggesting the formation of a colloidal crystal [108]. To clarify this phenomenon, the direct observation of the concentrated dispersion of a rhodamine-labeled SiP coated with a high-density polymer brush was carried out by confocal laser scanning microscopy. As shown in Fig. 23, the experiment revealed that the hybrid particles formed a wide range of three-dimensional array with a periodic structure. This will open up a new route to the fabrication of colloidal crystals. 

Near monodisperse Au NPs in the size range of 1—4nm can be obtained using dodecylthioether end-functionalized PMMA as stabilizer. Particle size is controlled by varying the concentration of the stabilizing polymer, which can be readily displaced by thiol ligands to yield MPCs of the usual type [97]. 

Dispersion copolymerization of PEO-MA macromonomers (Cj-fEO -MA, C1-(EO)48-C6-MA, C1-(EO)48-C10-MA) with MMA was successful in producing very stable PMMA dispersions of micron size [81]. In this case, however, Cr (EO)48-MA was more effective in giving monodisperse particles than C1-(EO)48-C10-MA (the reverse is true with styrene, see above). The particles obtained were found to have uneven surfaces with a number of craters. These results suggest that some compatibility between PMMA and PEO chains and also between PMMA and the medium (methanol/water) may play a role in controlling the particle formation. 

In order to make a better evaluation of the relative and absolute performance of various instruments, it was necessary to obtain well characterized, monodisperse latexes having a density greater than that of polystyrene. Polymethylmethacrylate PMMA) latex with a polymer density of approximately 1.21 gm/cm was selected for this purpose. 

Simultaneously, the molecular weight of the particles is reduced from M 10 g mol to M 10 g mol [9]. Fig. 2a and 2b illustrate the monodispersity of precrosslinked poly(organo-siloxane) particles and of PMMA grafted core/shell particles, respectively. 

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