Spin probe method

A review of the application of ESR to the study of free radical polymerisation is given by Yamada and co-workers [146]. A survey of the application ESR spectroscopy spin label/probe methods in heterogeneous polymer systems is provided by Veksli and co-workers [147]. Spin probe methods allow the study of the MD of the polymer, its free volume, phase separation and phase morphology. 

Kartel NT, Grischenko VI, Chernykh VP et al (2008) A study of cytotoxicity of carbon nanotubes by spin probe method. In Kartel MT (ed) Chemistry, Physics and Technology of Surface 14. Naukova dumka, Kiev, pp 557-564... 

A variety of spin probe methods have also been used to study the morphological features of the nano-channels present within MCM 41, as well as dynamical aspects connected to molecular diffusion in the inner pores,186-188 EPR has been used to investigate the adsorption and interactions of nitroxide-labelled de-ndrimers within porous silica.181 This method allows one to investigate the effective porosity of a solid surface (as a host) which is determined by the accessibility of the host surface to an adsorbed guest molecule. Information on the adsorption and interaction of dendrimers with the porous surface arises from computer-aided analysis of the EPR spectra based on of the well-established procedure proposed by Schneider and Freed.189... 

Yoshioka H, Haga H, Kubota M, Sakai Y. 2006. Interaction of ( + )-catechin with a lipid bilayer studied by the spin probe method. Biosci Biotechnol Biochem 70 395-400. 

Kuznetsov AN. The Spin Probe Method [in Russian]. 1976. Nauka, Moscow. 

Kuznetsov, L. N. "The Spin-Probe Method," Nauka, Moscow,... 

Glass-Rubber Transition Detected by the Spin Probe Method... 

The spin-probe method detects molecular motions of sohd polymers from ESR spectra of paramagnetic probes which are usually stable nitroxide radicals embedded in the polymer matrices. The spin-probe does not bond to the polymer chain and thus does not necessarily move with the polymer chain segment. Smaller probes only weakly interact with the chain and thus move independently with the chain... 

Figure 2. Membrane fluidity of human platelet as altered by adding a small amount of a-linolenic acid. The fluidity was determined by ESR spin probe method using 12-doxyl stearate.

The spin probe method was one of the first methods used to evaluate the free volume in polymers [1,7]. It is based on the principle that the rotational frequency of spin probes, usually stable nitroxyl radicals such as TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) is sensitive to the free volume. The relatively complex correlation between spectral data and FV makes this method more suitable for qualitative comparison of different polymers than for quantitative analysis of the FV [1,8]. 

Therefore, a purpose of the present work was to study the effect of DPhO and BM-DPhO in a wide range of concentration (10 -10 mol/1) on the endoplasmic reticulum membranes (microsomes) isolated from Balb-line mice. Electron paramagnetic resonance (EPR) technique and spin-probe method were used to study the dynamic structure of deep hydrophobic and surface lipid regions of microsomal membranes. We suggested the different effects of DPhO and IM-DPhO on the membrane lipids structure, because iod-methylate derivative is charged. 

Klepac extensively studied the effect of uniaxial deformation on the molecular chain segmental mobility of linear low density polyethylene (LLDPE) by ESR spin probe method. The simulated ESR spectra of undeformed and deformed (parallel and perpendicular) LLDPE samples at 0 °C are shown as dotted line in Figure 25.31. The results obtained by simulations indicate that the amount of slow components and corresponding Tr of LLDPE films deformed in both parallel and perpendicular directions are significantly larger than those of the undeformed LLDPE films. However, the amount of fast components decreased in the deformed sample. It was concluded from the results that uniaxial deformation reduces the molecular chain segmental mobility in the amorphous region and increased the amount of crystalline phase of the LLDPE films. 

Subczynski, W. K. and A.K. Kusumi. Detection of Oxygen Consumption During Very Early Stages of Lipid Peroxidation by ESR Nitroxide Spin Probe Method. 

F. Qiu, S. Chen, Z. Ping, Study of the miscibility and segmental motion of STMAA-PBMA polymer blends and semi-interpenetrating polymer networks by an spin probe method. Magnetic Resonance in Chemistry 43 (5) (2005) 411-416. 

FIG. 5 Disordering of intercellular lipid layers in stratum comeum Ordered structures of intercellular lipid bilayers in the stratum corneum are measured in terms of the order parameter (S) by the in vitro ESR spin-probe method. Intact stratum comeum showed a higher S value. With SLS treatment, structural deformation is evidenced by a smaller S value. (From Ref. 17.)... 

Application of Spin Label and Spin Probe Methods.184... 

Since the expression ESR application to the study of molecular motion easily reminds of the so-called spin label and spin probe methods, these topics are included in the present article the related problems will be considered in Sect. 9 and 10. However, any trapped free radical must be a label for the study of molecular motion when the temperature dependences of the spectral parameters are adequately measured. The discussion described in Sect. 6 is an example of the study using peroxy radicals as labels. The discussion in Sect. 4 is another example of ESR application to molecular motion study using the spectral intensity. Examples of molecular motion based on the changes of spectral parameters of trapped free radicals are presented in Sects. 5 and 8. All this should show how the trapped radicals can be used as direct labels in order to apply ESR without substantially modifying the investigated materials. 

A similar technique which stabilizes the unstable radicals by converting them to nitroxide radical adducts, called the spin trapping method is widely used. A few examples of the spin trapping method as they are applied to the study of molecular motion will be shown in the next section. The applications of the spin label and spin probe methods are described in various excellent textbooks review articles and proceedings of related symposia Therefore, in the present article, only a few examples will be considered. 

High-Field Spin Probe Method in the Study of Conductive Polymers 330... 

HIGH-FIELD SPIN PROBE METHOD IN THE STUDY OF CONDUCTIVE POLYMERS... 

AKH Akhmadeev, I.R., Gimerov, F.M., Sopin, V.F., and Marchenko, G.N., Study of phase equilibria in the cellulose nitrate-acetone system by the spin probe method (Russ.), Vysokomol. Soedin., Ser. S, 33, 543, 1991. 

ESR has been useful in studying the influence of dissolved gases on polymer mobility [801]. Stable nitroxyl radicals, such as 2,2,6,6-tetramethylpipe-ridin-l-oxyl (TEMPO) are widely employed as spectroscopic probes for observing binding sites and molecular motion of macromolecules [802]. ESR spectra of the TEMPO free radical in PC film at various temperature and in solution were reported [795]. The TEMPO spin probe method was also used to study diisooctylphthalate (DIOP) plasticiser diffusion in suspension polymerised PVC particles [803]. Similarly, the compatibility Umit of PVAc and di-nonylphthalate (DNP) was studied by means of 2,2-di-n-nonyl-5,5-dimethyl-3-oxazolidinyloxy spin probe ESR measurements and DSC [804] DNP is an effective plasticiser for PVAc for concentrations not exceeding 17 wt.%. According to ESR evidence BBP in PVC forms radicals more easily than DOP [805]. 

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