Polymethylsiloxane polyhydrate

Polymethylsiloxane polyhydrate or polymethylsiloxane hydrogel is a polymeric organosilicon compound . It arises from incomplete polycondensation from methylsilanetriol . Compared to the higher or completely polycondensed forms polymethylsiloxane poly hydrate (PMS polyhydrate) significantly more hydrophilic and is characterized by a significant water content.

properties

During polycondensation, PMS polyhydrate is created in the form of nanoparticles . These form a net-like, porous gel structure. Since the polycondensation is incomplete, the reaction product contains free silanol groups, which make up its hydrophilic character. On the other hand, because of the methyl groups it contains , the polymer also has lipophilic properties. PMS polyhydrate appears as a homogeneous pasty white or almost white odorless mass. Due to the fine grain size of the primarily formed nanoparticles, PMS polyhydrate has a large specific surface area of ​​up to 300 m ² / g, so that it is similar to activated carbonor clay minerals , acts as an adsorbent . Compared to activated carbon, PMS polyhydrate has a lower sorption capacity compared to low to medium molecular weight substances with a molar mass of up to about 1500 Dalton , but a significantly higher sorption capacity compared to substances with a larger molar mass. In addition to adsorption on the surface of the nanoparticles, sorption also occurs through inclusion in the pores of the gel matrix.

use

Because of its intestinal compatibility, PMS polyhydrate (C _PMS ≈ 10% w / w), suspended in water, is used as an "enterosorbent". The viscous suspension is supposed to sorb toxic substances such as pathogenic bacteria and endotoxins in the digestive tract, more precisely in the intestine (Greek ἔντερον, enteron ) . Endotoxins are metabolic products of gram-negative bacteria and, from a chemical point of view, represent lipopolysaccharides (LPS). It is hoped that sorption will have a beneficial effect on the intestinal flora . PMS polyhydrate should also absorb breakdown products from blood components ( bilirubin ) that reach the intestine via the bile , as well as protein breakdown products . The term enterosorption was coined in 1982 for the method of "detoxification" by enteral sorption. The use of enterosorbents is widespread in Russia .

PMS polyhydrate is not absorbed in the gastrointestinal tract , but is completely excreted in the stool within about 12 hours.

synthesis

PMS polyhydrate was synthesized in the late 1970s to early 1980s at the Institute for Physical Chemistry in Kiev, named after L. V. Pisarshevsky . Since 1960 a group has been working there on the theoretical foundations and on the synthesis of organosilicon sorbents. PMS polyhydrate is produced by polycondensation from methyl silicic acid with elimination of water. Heating creates the highly cross-linked, hydrophobic PMS xerogel , which no longer contains any silanol groups, is largely anhydrous and has less good sorption properties .

Individual evidence

1. ↑ Gun'ko, Turov, Zarko, Goncharuk: Comparative characterization of polymethylsiloxane hydrogel and silylated fumed silica and silica gel . In: Journal of Colloid and Interface Science . 2007. doi : 10.1016 / j.jcis.2006.12.053 .
2. ↑ AV Grigoryev, VM Znamensky, LG Bondarenko, LG Kupchinskiy, IM Samodumova: SV Prozorovskiy (ed.): Adhesion of pathogenic microflora on siliconorganic sorbents ( rus ), Immunobiologicals of the new generation and methods of their control. Edition, NF Gamaleya Research Institute of Epidemiology and Microbiology (USSR Academy of medical sciences), Kiev State Institute of medical education improvement., Moscow 1988, pp. 114-120.
3. ↑ VG Nikolaev: enterosgels ( eng ) 2010, ISBN 978-966-425-009-9 , p. 39
4. ↑ Volodimir G. Nikolaev: S. Mikhalovsky, A. Khajibaev (eds.): Enterosgel: A Novel Organosilicon Enterosorbent with a Wide Range of Med. Application ( eng ), Biodefence (NATO Science for Peace and Security Series A Chemistry and Biology) , Adv. Matherial and Methods for Health Protection. Edition, Springer, Netherlands 2011, ISBN 978-94-007-0219-6 , pp. 199-221.  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
5. ↑ ^{a b} I.B. Slinyakova, TI Denisova: Kremniiorganicheskie adsorbenty: Poluchenie, svoistva, primenenie (Organosilicon-based adsorbents. Preparation, properties, application). . Naukova Dumka, Kiev 1988, ISBN 5-12-000224-2 .
6. ↑ VG Nikolaev, V. Strelko, JYU. Korovin: Sorption methods of detoxification and immunocorection in medicine ( russian ), Theoretical basis and practical use of method of enterosorption. 1982 edition, pp. 112-114.
7. ↑ VN Panfilova, TE Taranushenko: Application of Enterosorbents in Clinical Practice . In: Pediatricheskaya farmakologiya - Pediatric pharmacology. 2012; 9 (6): 34-39.
8. ↑ Natalia I. Yashina, Elena P. Plygan, Vladimir G. Semenov, Alexandr M. Martynenko, Oksana V. Glushchenko: Plinio, Yuriy L. Zub (eds.): Sol-Gel Technology of the Mesoporous Methylsilicic Acid Hydrogel: Medicine Aspects of Globular Porous Organosilicon Materials Application ( eng ), Sol-Gel Methods for Materials Processing Focusing on Materials for Pollution Control, Water Purification, and Soil Remediation. Edition, Springer, Netherlands 2007, ISBN 9781402085147 , pp. 481-488. Archived from the original on May 27, 2014 Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (Accessed May 27, 2014). 

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