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Self-organizing cyclolinear organosilicon polymers in bulk and on the surface of water.

Makarova NN, Astapova TV, Buzin AI, Polishchuk AP, Chizhova NV, Petrova IM - Int J Mol Sci (2013)

Bottom Line: It was shown that on introduction of CH2 groups into the methylcyclohexasiloxane unit, the polymer retains the ability to self-organize with formation of a mesomorphic state in a wide temperature range, while on introduction of (CH2)2 fragments in a cyclotetrasiloxane unit or in a bridge connecting two methylcyclotetra(hexa)siloxane units it does not.It was revealed that all polymers form monomolecular films at the air/water interface, excluding those having longer hydrophobic fragment than hydrophilic ones.The ability to form multilayers depends on the surroundings of Si atom in the bridge between the cycles.

View Article: PubMed Central - PubMed

Affiliation: Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilova str., Moscow 119991, Russian Federation. buzin@cc.nifhi.ac.ru.

ABSTRACT
Cyclolinear organocarbosiloxane polymers with varying content and location of (CH2)n groups in the monomer unit were synthesized by reactions of heterofunctional polycondensation and polyaddition of difunctional organocyclosiloxanes and organocyclocarbosiloxanes. Their bulk properties were studied by differential scanning calorimetry and X-ray structural analysis. It was shown that on introduction of CH2 groups into the methylcyclohexasiloxane unit, the polymer retains the ability to self-organize with formation of a mesomorphic state in a wide temperature range, while on introduction of (CH2)2 fragments in a cyclotetrasiloxane unit or in a bridge connecting two methylcyclotetra(hexa)siloxane units it does not. Comparison of the X-ray data of dihydroxy derivatives of decamethylcyclohexasiloxane and decamethyl-5-carbocyclohexasiloxane with packing of cyclolinear organosilicon polymers in bulk shows that the polymer inherits the layered type of crystalline structure typical for monomers. Langmuir films of cyclolinear polymethylcarbosiloxanes with different design of monomer units were studied as well. It was revealed that all polymers form monomolecular films at the air/water interface, excluding those having longer hydrophobic fragment than hydrophilic ones. The ability to form multilayers depends on the surroundings of Si atom in the bridge between the cycles.

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The height of the first step of the surface pressure π1 plotted vs. ratio of the number of hydrophilic to the number of hydrophobic groups in the monomer unit of methyl substituted CL PMCS. For comparison, the π1 values for CL PMS I-Me, II-Me, poly[oxy(2,4,4,6,8,8,10,10-octamethylcyclopentasiloxane-2,6-diyl)] (XII-Me), and poly[oxy(2,4,4,6,6,8,10,10,12,12,14,14-dodecamethylcycloheptasiloxane-2,8-diyl)] (XIII-Me) are shown.
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f11-ijms-14-18215: The height of the first step of the surface pressure π1 plotted vs. ratio of the number of hydrophilic to the number of hydrophobic groups in the monomer unit of methyl substituted CL PMCS. For comparison, the π1 values for CL PMS I-Me, II-Me, poly[oxy(2,4,4,6,8,8,10,10-octamethylcyclopentasiloxane-2,6-diyl)] (XII-Me), and poly[oxy(2,4,4,6,6,8,10,10,12,12,14,14-dodecamethylcycloheptasiloxane-2,8-diyl)] (XIII-Me) are shown.

Mentions: Figure 11 presents the dependence of the collapse surface pressure of a Langmuir monolayer on the ratio of the number of hydrophilic (oxygen atoms) to the number of hydrophobic (methyl and methylene groups) moieties in the monomer unit of CL PMCS IV–VI and IX–XI. For comparison, we also present the values of the collapse surface pressure of the monolayer π for CL PMS I-Me, II-Me, and two other CL PMS with asymmetric central fragment of the chain unit, namely, poly[oxy(2,4,4,6,8,8,10,10-octamethylcyclopentasiloxane-2,6-diyl)] (XII-Me) and poly[oxy(2,4,4,6,6,8,10,10,12,12,14,14-dodecamethylcycloheptasiloxane-2,8-diyl)] (XIII-Me) [7]. From the data for the series of CL PMS I-Me, II-Me, XII-Me, and XIII-Me it follows that variation of the number of siloxane bonds in the polymer backbone (from cyclotetra- to cycloheptasiloxane) does not cause significant variations of the collapse surface pressure of monolayer. At the same time, partial replacement of siloxane bonds in the monomer unit by carbosilane bonds leads to a decrease in the collapse surface pressure of monolayer in proportion to the ratio of the number of hydrophilic to the number of hydrophobic groups in the monomer unit of CL PMCS.


Self-organizing cyclolinear organosilicon polymers in bulk and on the surface of water.

Makarova NN, Astapova TV, Buzin AI, Polishchuk AP, Chizhova NV, Petrova IM - Int J Mol Sci (2013)

The height of the first step of the surface pressure π1 plotted vs. ratio of the number of hydrophilic to the number of hydrophobic groups in the monomer unit of methyl substituted CL PMCS. For comparison, the π1 values for CL PMS I-Me, II-Me, poly[oxy(2,4,4,6,8,8,10,10-octamethylcyclopentasiloxane-2,6-diyl)] (XII-Me), and poly[oxy(2,4,4,6,6,8,10,10,12,12,14,14-dodecamethylcycloheptasiloxane-2,8-diyl)] (XIII-Me) are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3794777&req=5

f11-ijms-14-18215: The height of the first step of the surface pressure π1 plotted vs. ratio of the number of hydrophilic to the number of hydrophobic groups in the monomer unit of methyl substituted CL PMCS. For comparison, the π1 values for CL PMS I-Me, II-Me, poly[oxy(2,4,4,6,8,8,10,10-octamethylcyclopentasiloxane-2,6-diyl)] (XII-Me), and poly[oxy(2,4,4,6,6,8,10,10,12,12,14,14-dodecamethylcycloheptasiloxane-2,8-diyl)] (XIII-Me) are shown.
Mentions: Figure 11 presents the dependence of the collapse surface pressure of a Langmuir monolayer on the ratio of the number of hydrophilic (oxygen atoms) to the number of hydrophobic (methyl and methylene groups) moieties in the monomer unit of CL PMCS IV–VI and IX–XI. For comparison, we also present the values of the collapse surface pressure of the monolayer π for CL PMS I-Me, II-Me, and two other CL PMS with asymmetric central fragment of the chain unit, namely, poly[oxy(2,4,4,6,8,8,10,10-octamethylcyclopentasiloxane-2,6-diyl)] (XII-Me) and poly[oxy(2,4,4,6,6,8,10,10,12,12,14,14-dodecamethylcycloheptasiloxane-2,8-diyl)] (XIII-Me) [7]. From the data for the series of CL PMS I-Me, II-Me, XII-Me, and XIII-Me it follows that variation of the number of siloxane bonds in the polymer backbone (from cyclotetra- to cycloheptasiloxane) does not cause significant variations of the collapse surface pressure of monolayer. At the same time, partial replacement of siloxane bonds in the monomer unit by carbosilane bonds leads to a decrease in the collapse surface pressure of monolayer in proportion to the ratio of the number of hydrophilic to the number of hydrophobic groups in the monomer unit of CL PMCS.

Bottom Line: It was shown that on introduction of CH2 groups into the methylcyclohexasiloxane unit, the polymer retains the ability to self-organize with formation of a mesomorphic state in a wide temperature range, while on introduction of (CH2)2 fragments in a cyclotetrasiloxane unit or in a bridge connecting two methylcyclotetra(hexa)siloxane units it does not.It was revealed that all polymers form monomolecular films at the air/water interface, excluding those having longer hydrophobic fragment than hydrophilic ones.The ability to form multilayers depends on the surroundings of Si atom in the bridge between the cycles.

View Article: PubMed Central - PubMed

Affiliation: Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilova str., Moscow 119991, Russian Federation. buzin@cc.nifhi.ac.ru.

ABSTRACT
Cyclolinear organocarbosiloxane polymers with varying content and location of (CH2)n groups in the monomer unit were synthesized by reactions of heterofunctional polycondensation and polyaddition of difunctional organocyclosiloxanes and organocyclocarbosiloxanes. Their bulk properties were studied by differential scanning calorimetry and X-ray structural analysis. It was shown that on introduction of CH2 groups into the methylcyclohexasiloxane unit, the polymer retains the ability to self-organize with formation of a mesomorphic state in a wide temperature range, while on introduction of (CH2)2 fragments in a cyclotetrasiloxane unit or in a bridge connecting two methylcyclotetra(hexa)siloxane units it does not. Comparison of the X-ray data of dihydroxy derivatives of decamethylcyclohexasiloxane and decamethyl-5-carbocyclohexasiloxane with packing of cyclolinear organosilicon polymers in bulk shows that the polymer inherits the layered type of crystalline structure typical for monomers. Langmuir films of cyclolinear polymethylcarbosiloxanes with different design of monomer units were studied as well. It was revealed that all polymers form monomolecular films at the air/water interface, excluding those having longer hydrophobic fragment than hydrophilic ones. The ability to form multilayers depends on the surroundings of Si atom in the bridge between the cycles.

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