MMA-PMMA

Fig. 19. Theoretical prediction (—) of the variation of the exit concentration of a volatile component with extraction pressure. The prediction is based on Eq. (38) with [ kia)iy pVL = 0.115. The circles are selected experimental (MMA/PMMA) data points taken from Fig. 17.

Collins [62] has shown that Cp2ZrMe BPh4 will also initiate polymerization of MMA. PMMA with Mn in the 100,000 can be made (Scheme 26). Cost may be holding back development of these types of initiators. 

The gelation plane of the polyurethane is illustrated in Figure 6.4, see G -MMA-PMMA. For completeness, the gelation plane Gj of the PMMA from Figure 6.3 is also shown. The gelation plane G occurred after about 67% conver-... 

Figure 6.4. The metastable phase diagram, same compositions as Figure 6.3, illustrating the PU gelation plane, G2-MMA-PMMA.

As shown in Fig. 6.3, Mishra et al. (1995) presented a tetrahedron as the spatial form of their metastable phase diagram, the comers of which represented MMA, PMMA, urethane prepolymer U , and PU. The PMMA contained 0.5 % tetraethylene glycol dimethacrylate, causing it to gel after about 8 % conversion see the Gi- U -PU plane. The phase separation curve for the ternary system MMA-PMMA- U (front triangle) on polymerization of only the MMA is indicated by the points C-D-A-E. Similarly, the phase separation curve for the MMA-PMMA-PU system (see rear triangle. Fig. 6.3) is represented by the points J-B-K-L. Thus, the entire tetrahedron volume is divided into two regions one phase separated and the other single phased, separated by the curvilinear constmction C-D-A-E-L-B-J. This surface exhibits a characteristic sail-like shape. 

The gelation plane of the polyurethane is illustrated in Fig. 6.4 see G2-MMA-PMMA. For completeness, the gelation plane Gj of the PMMA from Fig. 6.3 is also shown. The gelation plane G2 occurred after about 67 % conversion of the PU. The intersection of the two planes, G1-G2, illustrates the line of simultaneous gelation of the two polymers. Reactions passing to one side or the other of this line will have one polymer or the other gelling first. It must be noted that the line G1-G2 also intersects the line A-B of Fig. 6.3, not shown. The intersection of these two curves expresses the presence of a triple critical point, where both polymers simultaneously gel and phase separate. While this triple critical point represents the ideal SIN synthesis condition, it would not, in general, produce the best physical or mechanical properties. 

It is possible to think about the phase separation in this system from the above discussion by looking at Fig. 8.34, which is the schematic diagram showing a triangle phase diagram of the MMA/PMMA/PS system at 80 °C. Since the PS weight fraction was fixed at 20 wt%, the initial binary solution of MMA/PS is... 

Multiscale surface structures have been directly obtained by simple spin-coating from diblock copolymer/homopolymer blends. For instance. Park et al. [89] prepared films from PS-b-P2VP/PMMA blends. These films were prepared from a selective solvent either for PS or PMMA. The pure block copolymers (BCP) form nanometer-sized micelles as a consequence of the microphase separation due to the incompatibility between the constituent blocks (Fig. 6.13(a)). However, blending the BCP with a homopolymer induces macrophase separation between the BCP micelles and the PMMA and the formation of isolated PMMA micrometer-size domains (Fig. 6.13(b)-(e)). Other groups including Jeong et al. [50] or Ibarboure et al. [42] also used homopolymer/BCP blends to fabricate multiscale ordered surfaces. Jeong and coworkers used P(S-b-MMA)/PMMA blends with variable composition. 

Consider the case of poly(methyl methacrylate) and polyurethane simultaneous polymerizations see Figures 13.21 and 13.22 (44). The four corners of the tetrahedrons indicate methyl methacrylate monomer, poly(methyl methacrylate), the urethane prepolymer, U, and the fully polymerized polyurethane. If one were polymerizing pure methyl methacrylate, for example, the MMA-PMMA edge would be followed. 

In the specific system examined, the poly(methyl methacrylate) contained 0.5% tetraethylene glycol dimethacrylate as a cross-linker, causing gelation after about 8% conversion, as indicated by the Gi-U-PU plane. The phase separation curve for the ternary system MMA-PMMA- U is indicated by the line C-D-A-E. The inset in Figure 13.20 shows the actual experimentally determined curve, with data points just behind the MMA-PMMA- U face of the tetrahedron. Similarly the phase separation curve for the... 

MMA-PMMA-PU system, rear triangle (Figure 13.21) is illustrated by the points 7-5-A -L.Thus the entire tetrahedron volume is divided into phase separated and single phased regions, separated by C-D-A-E-L-K-B-J. 

Application of these relationships require the knowledge of the glass temperature of the polymer, Tgp and the diluent, Tgd the expansion coefficient of the polymer Op and of the diluent, ad- The value of On is very close to 4.8 X 10-4 per oc for most polymers and 10-3 per OC for most diluents. We studied, for example, the polymerization of MMA PMMA. Here Tgp = 1100C,Tgd = -102.80C. 

From conversion-time measurements for MMA bulk polymerization initiated by AIBN at T = 700C we could determine the volume fraction of the polymer Vp. One can thus compute the change in Vf and q of MMA/PMMA mixtures as a function of conversion, using Equations (8) and (9) respectively. 

Thermodynamic data for MMA, PMMA, and the solution are given in Table 8.2 (Biesenberger et al 1990). 

A mixture of MMA, PMMA resin containing polymerisation initiator (dibenzoylperoxide, 1 wt%), and PC in a suitable ratio 1.50 ml MMA, 1.00 ml PC, 0.70 g PMMA is placed in a flask and kept for 5 days at room temperature in a desiccatorThe polymerisation process is then finished by warming at 90 °C. The method of preparation guarantees good mechanical properties and electrochemical stability for weeks. The gel is an elastic and odourless material required foils can be easily cut out. The 0.2-1 M solutions of anhydrous lithium or sodium perchlorate were used as the supporting electrolytes. 

To determine the influence of polymer solubility on the stability of microemulsions for polar pol3miers, Gan and Chew [38] carried out studies on a w/o microemulsion system containing water, methyl methacrylate (MMA), PMMA, SDS, and acrylic acid (AA) and found that a microemulsion consisting of 29.7 % AA, 19.8 % MMA, 17.5 % H2O, and 3.3 % SDS is compatible with 29.7 % PMMA My, = 81,800). They were also able to produce transparent solid polymers by fuUy polymerizing a microemulsion containing 54 % MMA, 34 % AA, 10 % H2O, and 2 % SDS [38]. 

For the monomer, was about 120 times larger for MMA (PMMA-I) than St (PSt I) with the same catalyst tolyl-Gel3, indicating that the catalytic activity strongly depends on monomer. The order of the catalytic activity among the catalysts may also be different between St and MMA. 

Figure 7.14 Plot of kact r. [TMEDAJo for the MMA/PMMA-I/TMEDA systems in bulk (90°C) [MMA]o = 8M [PMMA-I]o = 0.5mM [TMEDA]o = 2-5mM. Reproduced from ref. 16 by permission of American Chemical Society.

---