PE-b-PMMA

By contrast, much of the work performed using ruthenium-based catalysts has employed well-defined complexes. These have mostly been studied in the ATRP of MMA, and include complexes (158)-(165).400-405 Recent studies with (158) have shown the importance of amine additives which afford faster, more controlled polymerization.406 A fast polymerization has also been reported with a dimethylaminoindenyl analog of (161).407 The Grubbs-type metathesis initiator (165) polymerizes MMA without the need for an organic initiator, and may therefore be used to prepare block copolymers of MMA and 1,5-cyclooctadiene.405 Hydrogenation of this product yields PE-b-PMMA. N-heterocyclic carbene analogs of (164) have also been used to catalyze the free radical polymerization of both MMA and styrene.408... 

As described in Section 9.1.2.2.3, several lanthanocene alkyls are known to be ethylene polymerization catalysts.221,226-229 Both (188) and (190) have been reported to catalyze the block copolymerization of ethylene with MMA (as well as with other polar monomers including MA, EA and lactones).229 The reaction is only successful if the olefin is polymerized first reversing the order of monomer addition, i.e., polymerizing MMA first, then adding ethylene only affords PMMA homopolymer. In order to keep the PE block soluble the Mn of the prepolymer is restricted to <12,000. Several other lanthanide complexes have also been reported to catalyze the preparation of PE-b-PMMA,474 76 as well as the copolymer of MMA with higher olefins such as 1-hexene.477... 

The resulting PE-fr-PMMA was purified by soxhlet extraction with THF and characterized by NMR, DSC, and TEM micrography (Table 1). The TEM of the obtained PE-fr-PMMA revealed unique morphological features which depended on the content of the PMMA segment. The block copolymer possessing 75 wt % PMMA contained 50-100 nm spherical polyethylene lamellae uniformly dispersed in the PMMA matrix (Fig. 12). Moreover, the PE-b-PMMA block copolymers effectively compatibilized homo-PE and homo-PMMA at a nanometer level (Fig. 13). 

Fig. 13 TEM images of a homo-PE/homo-PMMA/PE-f>-PMMA blended sample (homo-PE/homo-PMMA/PE-b-PMMA = 4/6/1 wt ratio) and b homo-PE/homo-PMMA blended sample (homo-PE/homo-PMMA = 4/6 wt ratio)...

Figure 7. TEM Micrographs of (a) PP/PMMA (Weight ratio 68/32) (b) PP/PMMA/PP-g-PMMA (Weight ratio 68/32/5) (c) PLA/EBR (Weight ratio 85/15) (d) PLA/EBR/PE-b-PMMA (Weight ratio 85/15/5)...

Fig. 3 Series of EFM images taken for PE (a), PVC (b), PMMA (c), and PA (d). The images show the initial states without deposited charges, the states immediately after deposition of charges by the silicon cantilever (t = 0) and after different time spans (t = /,). The positions of the deposited charges are indicated by a white circle. Negative charges appear pale, positive charges are dark. All measurements were carried out at a relative humidity of tp = 30%...

Figure 5.1. Molecular structures of the chemical repeat units for common polymers. Shown are (a) polyethylene (PE), (b) poly(vinyl chloride) (PVC), (c) polytetrafluoroethylene (PTFE), (d) polypropylene (PP), (e) polyisobutylene (PIB), (f) polybutadiene (PBD), (g) c/5-polyisoprene (natural rubber), (h) traw5-polychloroprene (Neoprene rubber), (i) polystyrene (PS), (j) poly(vinyl acetate) (PVAc), (k) poly(methyl methacrylate) (PMMA), ( ) polycaprolactam (polyamide - nylon 6), (m) nylon 6,6, (n) poly(ethylene teraphthalate), (o) poly(dimethyl siloxane) (PDMS).

Fig. 21.1 Valence XPS of four polymers (upper, experimental, lower simulated) (a) PE, (b) PS, (c) PMMA, and (d) PVC...

Fig. 25 (a) Fluorescence SNOM image of a PMMA gel labeled with Pe and Eo dyes (b) Fluorescence decay curves of Pe observed for (curves A and B) PMMA gel at points A and B indicated in panel a, (curve C) PMMA bulk sample without crosslinker, (curve D) spin-cast PMMA film containing Pe dyes. Reprinted with permission of [26], copyright (2003) The Chemical Society of Japan... 

Figure 13.9 Comparison of the fire properties of polymeric systems of ZnAl and MgAl. The % reduction in PHRR is plotted versus the LDH loading (wt%) (A) PE systems (B) PMMA systems. Reproduced with permission from Ref. [47].

Fig. 16 GPC curves of two PE-h-PMMA diblock copolymers with (a) Mn = 98,000 g/mol and M,v/M = 2.3and( 6)M = 62,000 g/mol and M,v/M = 2.4. (c) GPC curve Iot the starting PE-/-B polymer (M = 43,000 g/mol and M /M = 2.2). Inset. Plot of polymer molecular weight versus monomer conversion. The line indicates theoretical values estimated from [g of monomcu con-sumed]/[mole of initiator].

Fig. 17 NMR spectra of three PE-i)-PMMA diblock copolymers containing (a) 22 mol%, (b) 40 mol%, and (c) 85 mol% of MMA units (solvent, C2D2CI4 temperature, 110°C)...

Considering ten different polymeric sohds (PS, PE, PET, PMMA, PVC, etc.) he found that the /-parameter is proportional to a polar surface tension component of the liquid but he states that it is possibly a complex function of the polar contributions to the surface tension from both liquids and sohds. There is also some scatter in these plots and he does not propose the simple square root expression adopted by Owens and Wendt (Equation 3.22b). Similar results were presented with the same method by others as well (Schultz et al, 1977a,b) who used it to determine the surface energy components of high... 

Fig. 1. Relative molecular weight (A,B,C), relative intrinsic viscosity (D) of the residue versus conversion in pyrolysis of poly(methyl methacrylate) (PMMA) (3) and polyethylene (PE) (2). PMMA initial molecular wei t A, 44,000 B, 94,000 and C, 725,000. PE initial intrinsic viscosity D, (> ]o = 20 dL/g.

In the absence of the reactions considered in Sections 15.2.2 and 15.2.3, homolysis of the polymer chain may occur as in Scheme 1. Subsequent behaviour then depends on the nature of the chain substituents X and Y. There are three situations (a) X = Y = H, no monomer produced, extensive transfer by H abstraction le,g. polyethylene (PE)] (b) X = H, amount of monomer depends on nature of Y, extensive transfer by H abstraction le.g, polypropylene (PP), polystyrene (PS), poly(methyl acrylate) (PMA)] (c) X, Y H, large amount of monomer (up to 100%) transfer present or absent depending on nature of X, Y, e,g. poly(methyl methacrylate) (PMMA), poly(a-methyl styrene) (PAMS). Monomer results by depropagation from the polymer radical chain end produced on homolysis (Scheme 2). 

Figure 6 (A) Non-isothermal chemiluminescence runs for oxidation of polystyrene (PS), polyethylene terephthalate) (PETP) and polyfmethyl methacrylate) (PMMA), in oxygen, heating rate 2.5°C/min. (B) Non-isothermal chemiluminescence runs for oxidation of polypropylene (PP), polyamide 6 (PA 6), poly(vinyl pyrrolidone) (PVP), polyethylene (PE) and polyamide 66 (PA 66), in oxygen, heating rate 2.5°C/min.

Group 4 metallocene catalysts are also applicable to the above sequential block co-polymerization method to furnish polyolefin and polar polymer block co-polymers. Frauenrath et al. and Chen and Jin " reported the synthesis of PE-/ -PMMA and PP-3-PMMA, respectively, using metallocene catalysts (e.g., raz--(C2H4)(Ind)2ZrMe2/ B(C5F5)3, iPP-/ -iPMMA PP segment 4/ = 8900, PDI= 1.90 block co-polymer 4/n = 10900, PDI = 1.66, MMA content = 17.1 mol%). 

PCP = polychloroprene, PDMS = polydimethylsiloxane, PE = polyethylene, B-PE = branched polyethylene, L-PE = linear polyethylene, PEO = poly(ethylene oxide), PE VAc = poly(ethylene-co-vinyl acetate), PIB = polyisobutylene, PMMA = poly(methyl methacrylate), PnBMA = poly(n-butyl methacrylate), PiBMA = poly(isobutyl methacrylate), PtBMA = poly(t-butyl methacrylate), PP = polypropylene, PS = polystyrene, PTMO = poly(tetramethylene oxide) or polytetrahydrofuran, PVAc = poly(vinyl acetate). 

Heini PE, Walchli B, Berlematm U (2000) Percutaneous transpedicular vertebroplasty with PMMA operative technique and early results. Eur Spine J 9(5) 445—450... 

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