PVPh/PEO

Fig. 10.11. (a) Pulse sequence for the modified Goldman-Shen experiment with detection and (b) plots of H magnetization change versus square root of the spin-diffusion time for PVPh/PEO = 58/42 at 310 K. Straight lines are drawn through the initial linear portion of the data to determine the intercept time L. (Reprinted with permission from Ref. [34]. 1992 American Chemical Society, Washington, DC.)... 

Model C is mostly found for a blend of crystalline and amorphous polymers. In general, the miscibility for the crystalline/amorphous blends would be better in an amorphous component-rich system than that of a crystalline-rich system. For example, when the crystalline PEO composition is more than 60 wt% in PEO/amorphous PVPh, PEO in the blend showed two Tip relaxation times (Table 10.2) [34]. One of the two Tip agrees well with Tip... 

The difference of relaxation times in different domains makes it possible to observe the spectrum of one of the domains. Figure 10.23(a), shows the Ti-selected spectrum of PVPh/PEO = 40/60 [34]. Since the Ti of crystalline PEO ( 15 s) is much longer than that of the amorphous phase (—0.1 s), it is possible to observe the spectrum of crystalline PEO selectively (indicated by arrow in Fig. 10.23(a)). On the other hand, for the miscible PVPh-rich blend (PVPh/PEO = 58/42), the crystalline-PEO peak is not appreciable. This is in agreement with the above-mentioned results (Table 10.2). The signals of mobile domains/component polymers can be observed selectively by utilizing the weaker dipolar interaction between H. To name a few examples, the dipolar dephasing [128,131,152], the cross-polarization-depolarization [152] and the pulse saturation transfer [151] techniques have been applied. 

Copolymerization with other vinylic monomers (i.e., styrene, vinyl acetate) allows even further modification. The ease of structural modification to yield desired blend properties (miscibility) is well-documented in the experimental literature. The common acrylate polymer is PMMA and has been noted to be miscible with various other polymers noted in this chapter (PVF2, styrene copolymers, PVC, PVPh, PEO) and thus will not be discussed in this section. 

Chang et al. reported the miscibility of poly(vinylphenol) (PVPh) with poly(methyl methacrylate) (I MMA) Figure 1 shows the C CP/MAS spectra of pure PVPh, PMMA, PVPh-co-PMMA, PEG, and PVPh-co-PMMA/ poly(ethylene oxide) (PEO) blends of various compositions with peak assignments. VPh contents of PVPh-co-PMMA is 51 mol% and Mn of PEO is 20,000. The spin lattice relaxation time in the rotating frame (Tip ) was measured to examine the homogeneity of PVPh-co-PMMA/PEO blends on the molecular scale. 

Table 1. Tip (ms) values of pure PVPh and various PVPh-co-PMMA/PEO blend compositions...

Table 1 also shows that both pure PVP and PVPh-co-PMMA/PEO blends exhibit only single-exponential relaxation through out all of the blends at... 

A typical value of D is 10 m" s . For Ti of 5 ms, the dimensions of these PVPh-co-PMMA/PEO blends are below 2-3 nm in the amorphous phase. Interestingly, the has a minimum value for the PVPh-cu-PMMA = 40/60 blend showing that the overall chain mobility is maximal at this composition. This observation agrees with the earlier result concerning hydroxyl group association obtained by FTIR and solid-state NMR. In addition, all of the blends show a shorter Ti,/ than that of the pure PVPh-co-PMMA implying that the PVPh-co-PMMA mobility also increases with the increase of PEO content. 

Pfefferkom et al., 2011), poly (iso-butyl methaciylate) (PiBMA) (Katime and Cadenato, 1995), poly(tert-butyl methaciylate) (PtBMA) (Katime and Cadenato, 1995), and poly(4-vinylphenol-co-2-hydroxyethyl methaciylate) (PVPh-HEM) (Pereira and Rocco, 2005) are found to be miscible with PEO. Owing to the vast differences both in the surface stractuie and T s of PEO and PMMA (T s for PEO... 

Figure 6.9 Infrared spectra of various blends of PVPh and PEO. Reprinted from Polymer, 26, Moskala, E. J., Varnell, D. F. and Coleman, M. M., Concerning the miscibiiity of poly(vinyl phenol) blends - FTIR study , 228-234, Copyright (1985), with permission from Elsevier.

Figure 20.2 Variation of P2/A with composition for various PVPh-based blends. , PEO X=1.5 O, PEOX = 3.0 , PVMEX=1.5 , PVME >l = 3.0 A, PET O, PMMA. Reprinted with permission from Ref [42] 2003, Elsevier.

PVPh content was 60 mass%, orientation was clearly detectable and varied linearly for both components of the blend. This was in contrast to the PVPh orientation in blends with polyethylene oxide (PEO) and with polyvinylmethylether (PVME), which was attributed tentatively to a change in the relaxation regime. 

Figure 20.18 FTIR spectra recorded at room temperature in the 2700-4000cm region for pure PVPh and various PVPh-co-PMMA/PEO blends, (a) pure PVPh (b) 100/0 (c) 90/10 ...

Figure 14 The schematic representation and TEM images of PEO-i>-PCL/PVPh blends showing different morphologies in (a) pristine block copolymer, (b) 20 wt%, and (e) 40wt% of PVPh concentration. Salim et al. [30]. Reproduced with permission of American Chemical Society.

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