Nanocomposites and nanomaterials 

POSS-containing  nanocomposites based on PU/PHPMA semi-IPNs: sorption properties and thermodynamic of interactions
Karabanova L.V.,  Honcharova L.A.
1 Institute of Macromolecular Chemistry of the NAS of Ukraine. Kharkivs’ke shose 48, Kyiv-02160, Ukraine;   E-mail: lyudmyla_karaban@ukr.net
The nanocomposites based on crosslinked polyurethane (PU), linear poly(hydroxylpropyl methacrylate) (PHPMA) contained 1,2-propandiolisobutyl-POSS (1-10 wt %) were created and isothermal sorption of methylene chloride vapour by samples was investigated, and thermodynamic parameters of interactions were calculated.  
		
Fig. 1 The isotherms of methylene chloride vapour sorption (a) and free energy of mixing Δgm  of samples with methylene chloride(b); x/m is the amount of methylene chloride relative to the dry sample; p/po is the relative pressure of methylene chloride; ω2 is weight fraction of solvent in the sample.	
The methylene chloride vapour sorption by the samples was studied using a vacuum installation and a McBain balance. With increasing amount of POSS in the samples the values of vapour sorption are less in compare with native matrix (Fig.1a), this means the formation of more dense structure of nanocomposites with high POSS content.
The thermodynamic parameters of PU and PHPMA interactions are calculated, the changes of the free energy of mixing Δgm of solvent with polymers are presented in Fig.1b. The calculated free energy  of PU and PHPMA mixing was positive. The introduction of 1-5 wt % of POSS lead to further phase separation in semi-IPNs. This is due to concentration of POSS particles in the PU’s nanodomain. The increasing of POSS content to 10 wt % lead to compatibilization in semi-IPNs. These is due to concentration of POSS nanoparticles not only in the PU’s nanodomain but also in the interphase region of semi-IPN.