Blends of deuterated polystyrene

Bruder and Brenn (1992) studied the spinodal decomposition in thin films of a blend of deuterated polystyrene (dPS) and poly(styrene-co-4-bromostyrene) (PBrxS) by TOF-ERDA. They examined the effect of different substrates on the decomposition process. In one series of experiments, a solution of the polymers in toluene was spread on a silicon wafer to form a film of thickness 550 nm which was then heated in vacuum at 180°C for various times. 

Binary Blend of Deuterated Polystyrene and Poly(vinyl methyl ether).119... 

A particularly striking observation was reported by Bruder and Brenn [72] for films of asymmetric blends of deuterated polystyrene (dPS) and poly(sty-rene-4-co-bromostyrene), PBrxS, with Ndps=5714, NPBxS =1660, using films of... 

Figure 4.21. Mutual diffusion coefficients as functions of the concentration for blends of deuterated polystyrene N = 9.8 X 10 ) and normal polystyrene N = 8.7 X 10 ). The diffusion temperatures were 166 °C (o), 174 °C (A), 190 °C (O) and 205 °C ( ). The solid lines are the predictions of equation (4.4.11). The decrease in diffusion coefficient for volume fractions aroimd a half is a direct result of the unfavourable thermodynamies of mixing - thermodynamic slowing down . After Green and Doyle (1987).

To test this prediction of the crossover from mean-field to Ising-t5q)e behavior, very precise small-angle neutron scattering measurements were completed on blends of deuterated polystyrene (d-PS) and poly(vinyl methyl ether) (PVME) at the critical concentration for a series of temperatures as the one-phase mixture approaches the temperature of phase separation (ie, the critical point Tc in Fig. 7) (61). The data were analyzed by fitting the measured I (q) to the random phase approximation to estimate l(g=0) for each temperature, where the temperature is controlled to 0.01 K... 

We have used forward recoil spectrometry to measure the mutual diffusion and tracer diffusion coefficients, D and D, in the miscible polymer blend of deuterated polystyrene (d-PS) poly(xylenyl ether) (PXE). Using the fast theory of mutual diffusion, D is related to the D, degree of polymerization N, and volume fraction of the individual blend components by,... 

Zink et al. used a blend of polystyrene (hPS) and its deuterated counterpart (dPS), both of molecular weight 1.95 x 106 (abbreviated 1.95 M). The average volume fraction (4>dPS) of deuterated polystyrene was 30%. The polymers were dissolved in toluene and spin cast on thin silicon wafers (about 10 x 10 mm), the resulting film thickness being about 300 nm. The samples were annealed at 245°C for 8 days, and the measurement of the resulting depth profiles was conducted by NRA using a monoenergetic 700 keV 3He beam. The nuclear reaction employed can be written ... 

Consider a binary polymer blend [43] of deuterated polystyrene, PSD, (Mw = 1.95 x 10s g/mole, Mw/Mn = 1.02) and poly(vinyl methyl ether), PVME, (Mw = 1.59 x 10s g/mole, Mw/M = 1.3) with a composition of 48.4% PSD (volume fraction). SANS data were taken at various temperatures ranging from ambient to 160°C. De Gennes s RPA formula ... 

Figure 2.10 / versus volume fraction of deuterated polystyrene in an isotopic blend of deuterated... 

The neutron scattering technique also makes it possible to study the inter-molecular function Hn(q) in the entire observation window (15.1.23). Here, experiments are carried out on blends of deuterated and non-deuterated chains, following the method described in Chapter 7, Section 3.1.2. This has been done by Nierlich and Cotton,4 on polystyrene samples of molecular mass Mw = 114000, in carbon disulphide (a good solvent). The resulting functions H>l(q) and Hz(q) are then combined to test the hypothesis derived from the... 

Fig. 15.4. Representation of experimental results of neutron scattering by blends of atactic polystyrenes, deuterated and non-deuterated. (From Tangari et al.9.)...

Affrossman, S., Henn, G., O Neill, S.A., Pethrick, R.A., Stamm, M. Surface topography and composition of deuterated polystyrene-poly(bromostyrene) blends. Macromolecules 29(14), 5010-5016 (1996)... 

Affrossman, S., Hartshome, J.M., Pethrick, R.A., Richards, R.W. Surface segregation in blends of hydrogenous polystyrene and perfluorohexane end-capped deuterated polystyrene, studied by SSIMS and XPS. Macromolecules 27, 1588-1591 (1994)... 

The mutual diffusion couples consisted of two films of deuterated polystyrene (D-PS). -protonated PXE blends which have a small difference in the volume fraction of d-PS (--lOj), from 2 in the 350 nm-thick top film to < )-j in the 2 pm-thick bottom film. The initial step function of the d-PS concentration profile was broadened by mutual diffusion at T in vacuum (<10" torr). The volume fraction versus depth profile of d-PS was... 

Fig. 13. Single-chain PS(Q), interchain P,(Q) and total PT(0) structure factors for a blend mixture of deuterated and protonated polystyrene (PSD, PSH) in poly(vinyl methy ether) (PVME). The total PVME fraction was 51% and the PSD fractions were varied from 49% to 24%. The three curves correspond to sample pairs 1-2, 2-3 and 1-3 in each case...

Fig. 3 TEM images. Left 1 1 molar ratio blend of poly(4-trimethylsilylstyrene) and deuterated polystyrene end-decorated with complementary oligonucleotides. Reprinted with permission from [72]. 2006 American Chemical Society. Right blend of 60wt% mono-end-aminated polyisoprene with di-end-sulfonated polystyrene [73]...

Figure 4.5 Measurements of effective Flory-Huggins x parameter for deuterated polystyrene-poly(vinylmethylether) blends (Han et al, 1988) as a function of l/T. The temperature range is typically 100-150 °C, and the numbers near each set of data indicate the volume fraction of polystyrene. The observed linear dependence on 1/r provides the physical conclusion that first-order perturbation theory is a satisfactory treatment of attractive interactions here.

The temperature-independent term A is referred to as the entropic part of. while BjT is called the enthalpic part . The parameters A and B have been tabulated for many polymer blends and we list representative examples in Table 4.3. Isotopic blends typically have small positive x parameters (deuterated polystyrene blended with ordinary polystyrene f/PS/PS is an example) making them only phase separate at very high molar masses. PS/PMMA has four entries in Table 4.3, which reflect the differences encountered by labelling various species with deuterium. PS/... 

In the above, we have seen that a certain interpolymer interaction is required for different polymers to be miscible. Here, we will see that high resolution NMR enables us to locate interacting regions in component polymers. One of the most useful methods is the nuclear Overhauser effect (NOE) between H— H and H—NOE can be observed between spins whose distances are less than about 0.5 nm. The one- (ID) and two-dimensional (2D) NOE experiments have been used to reveal the spatial structure of biomolecules in solutions. Of course, these can be applied to locate interacting regions in a blend in solution and in solids [3]. For example, Crowther et al. [22] and Mirau et al. [23] applied NOE experiments to polystyrene/poly(vinyl methyl ether) (PS/PVME) in a toluene solution, and show that the interpolymer NOE signals between the aromatic protons of PS and the methoxy protons of PVME can be observed at polymer concentrations higher than 25 wt%. In the solid state, Heffner and Mirau [24] measured 2D H— H NOESY (NOESY nuclear Overhauser effect spectroscopy) spectra of 1,2-polybutadi-ene and polyisoprene (1,2-PB/PI) and observed NOE cross-peaks between these component polymers. White and Mirau observed interpolymer NOE interactions between the H spins of PVME and the spins of deuterated... 

Figure 6.2 Plot of /(0)-1 against 1 IT, where the extrapolated zero-angle intensity 7(0) was obtained by neutron scattering with blends of poly(vinyl methyl ether) and deuterated polystyrene. The molecular weight of poly(vinyl methyl ether) is 64.3 x 103, and the molecular weight and volume fraction of the deuterated polystyrene are, respectively, 783 x 103 and 0.13 for sample I, 379 x 103 and 0.13 for sample II, and 232 x 103 and 0.20 for sample III. (From Schwahn et al.6)...

Figure 9 Positive Time-of-Flight SIMS spectra of 50/50 (by weight) blends of high molecular weight polystyrene and fully deuterated polystyrene (Mw=l,950,000 for both polymers) before (a) and after (b) annealing for 24 hours at 200°C in an inert gas. The labeled ions 82,98 and 122 amu are the deuterated analogs formed by the deuterated pol5mer of the ions 77, 91 and 115 amu formed by polystyrene. The spectra demonstrate the increase of the surface concentration of the deuterated polystyrene upon annealing. Courtesy F.J. Boerio and P.P. Hong, University of Cincinnati.

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