Polymethylmethacrylate microspheres

Uniform polymeric microspheres of micron size have been prepared by dispersion polymerization. This process is usually utilized for the production of uniform polystyrene and polymethylmethacrylate microspheres in the size range of 0-1-10.0 /Am. 

Hyodo T, Inoue H, Motomura H, Matsuo K, Hashishin T, Tamaki J, Shimizu Y, Egashira M (2010) NO sensing properties of macroporous InjO -based powders fabricated by utilizing ultrasonic spray pyrolysis employing polymethylmethacrylate microspheres as a template. Sens Actuators B Chem 151 265-273... 

The development of this technique was based on early experiences with the use of injection techniques. As a result of a perceived putative efficacy, attention was directed to the identification of inert, biocompatible substances that might safely function as bulking agents at the LES. An early report in 2001 by Feretis described a technique of endoscopic submucosal injection of polymethylmethacrylate microspheres suspended in gelatin into the LES of ten patients. At 7 months follow-up, there was a significant fall in 24-hour acid exposure (24.5% to 7.2%) that was, in addition, supported by a comparable improvement in symptom scores. 

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

Shimizu and coworkers (Hieda et al. 2(X)8 Hayashi et al. 2009 Morio et al. 2009 Hyodo et al. 2010) have shown that, by using a modified sol-gel technique, pyrolysis or a physical vapor deposition process employing a polymethylmethacrylate (PMMA) microsphere film as a macropore template, macroporous (mp-) films of various materials promising for gas sensor application can be fabricated. They established that different kinds of gas sensors fabricated with the mp-semiconductor films (SnOj and In Oj to detect H, NO, and H S), photoluminescence-type (SnO mixed with Eu Oj to detect and NO ), and quartz crystal microbalance type (BaCOj to detect NO ) showed stronger gas responses as well as fast response and recovery speeds in comparison with those fabricated with a conventional film and powders without macropores (Hayashi et al. 2(X)9 Yuan et al. 2011 Hyodo and Shimizu 2011). 

Figure 2 Polymethylmethacrylate (PMMA) microspheres on a dipalmitoylphosphati-dylcholine (DPPC) monolayer supported by an aqueous subphase (density 1.26 g/mL) at (A) a surface tension of 40 mN/m, and (B) at 30 mN/m. Note the appearance of the labeled particle at decreasing film surface tensions. D (80 i,m) indicates the total diameter, d is the diameter of the segment exposed to air d is decreasing with the surface tension, indicating increasing particle immersion. (From Ref. 56.)...

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