PE-g-PMMA

The metallocene catalyst with cationic nature and spatially opened active site provides favorable condition for the incorporation of p-alkylstyrene (p-ms) to polyolefins. The p-ms groups can be easily metallated to produce "stable" polymeric anions for graft-from polymerization. With the coexist of anion-polymerizable monomers, we have prepared many graft copolymers, such as PE-g-PS, PE-g-PMMA, PE-g-PAN, PP-g-PS, PP-g-PB, PP-g-PI and PP-g-PMMA. 

In addition, borane-containing POs can be prepared by copolymerization of olefin with borane monomers or by hydroboration of polyolefins including unsaturated groups, such as olefin-divinylbenzene copolymer and olefin-diene copolymers. Many kinds of graft copolymers, such as poly-elhylene-gra/f-poly( vinyl alcohol), PE-g-PMMA, polypropylcnc-gra/f-poly-(maleicanhydride-co-styrene), polypropylene-gra/f-poly(methacrylic acid), polypropylene-gra/f-poly(vinyl alcohol), polypropylene-gra/f-polycaprolac-tone (PP-g-PCL), polypropylcnc-gra/f-poly(methyl methacrylate) (PP-g-PMMA), poly( ethylene-co-propylene)-gra/f-poly(methyl methacrylate) (EPR-g-PMMA), and poly(ethylene-co-propylene)-gra/f-poly(maleic anhydride-costyrene), have been synthesized by such a method resulting in controllable composition and molecular microstructures [63-66]. 

PE graft copolymers were synthesized from PE-OH by Inoue et al. using ATRP techniques, adopting similar techniques as mentioned above [74]. PE-g-PMMA and Polyclhylcnc-gra/f-poly( -bulyl acrylate) (PE-g-PnBA) were prepared through the combination of metallocene-catalyzed ethylene/10-undecen-l-ol copolymerization and conversion of the copolymer into P E-g-Br, as a macroinitiator, for ATRP. Well-defined graft copolymers, PE-g-PMMA and PE-g-PnBA, were confirmed by analyses of the detached side chains. Resulting PE-g-PMMA worked well as a compatibilizer. 

The copolymer of ethylene withp-MS was available as a PE macroinitiator. PE-g-Br, which works as a PE macroinitiator for ATRP, was prepared from PE-g-MS by bromination with NBS [78], and PE-g-Br can be used to prepare PE-g-PMMA, PE-g-PS and PE-g-PnBA. 

PE-g-PS graft copolymer was produced by a coupling reaction, too. a-Carboxyl PS prepared by an ATRP technique was reacted with PE-g-glycidyl methacrylate (GMA) to produce PE-g-PS [121]. A PP-fc-PMMA block copolymer was synthesized using a magnesium bromide terminated PP as an initiator for the radical polymerization of MMA, which was prepared from the vinylidene terminated PP obtained with the Et(Ind)2ZrCl2/MAO catalyst system [122],... 

The nature and number of the terminal groups, the type of bonds, the presence of aromatic cycles and carbonate groups in the unsaturated ester molecule, as well as other structural features affect polymer flammability. The slope of the straight lines increases from methacrylate to acrylate polymers. Thus, for polymers of alkylene glycol dimethacrylates it is 2,82x 10 kJ/kg, for polymers with carbonate bonds 2.86 X 10 -2.9 X 10 kJ/kg for acrylic polymers it is somewhat higher, 3.27 x 10 kJ per kg. Linear polymers, e.g. PMMA, PE, etc. have a smaller slope corresponding to... 

Some synthetic examples of polyolefin hybrids are shown in Figure 2. RAFT polymerization of PE-/-CTA for MMA was initiated by AIBN in toluene at 60 °C. PE-/)-PMMA (PMMA contents 23 wt%) was successfully obtained . PE-/)-PMMA having the contents of PMMA (73 wt%) was yielded from PE-g-Br by ATRP for MMA with RuCl2(PPh3)3/Bu2NH as a catalyst. ATRP for acrylonitrile/styrene using PP-g-Br as a PO-MI was carried out to produce PP-g-AS (poly(acrylonitrile-co-styrene)). Then, EBR-g-PS was obtained from EBR-g-Br as a PO-Ml by ATRP for styrene. By selecting the kinds of PO-MIs and polar monomers for CRP, various kinds of PO hybrids have been obtained. 

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)...

We already performed the detailed analysis for valence XPS of more than 60 polymers by DFT calculations using the model molecules [14]. In this section, we aim to simulate valence XPS, IR, and solution NMR spectra of PE, PS, PMMA, and PVC polymers using the model oligomers by B3LYP/6-31+G(d, p) basis calculations and to secondly clarify the electronic states of valence XPS, IR spectra, and solution NMR chemical shifts for the polymers. 

We have analyzed valence XPS, IR spectra, and NMR shifts of four polymers (PE, PS, PMMA, PVC) by quantum chemical calculations (B3LYP/6-31+G(d,p) basis calculations in GAUSSIAN 09) using the model oligomers (H-(CH2-CH2)io-H, H- CH2-CH(C6H5) 3-H, H- CH2-C(CH3)C00CH3 3-H,... 

Liu and Sen ° have shown that syndiotactic polystyrene (sPS) can be partially brominated at the benzylic positions. Starting from these polymers, graft copolymers could be synthesized by ATRP using the partially brominated sPS as macroinitiator (Figure 10). They extended the strategy to PE-based graft copolymers such as poly(ethylene-co-styrene)- o/t-PMMA (P(E-co-S)-g-PMMA). This is an efficient compatibilizer for blends of poly(ethylene) and PMMA. ... 

Until 2003, Chen s [28], Qu s [29-31], and Hu s [32] groups independently reported nanocomposites with polymeric matrices for the first time the. In Hsueh and Chen s work, exfoUated polyimide/LDH was prepared by in situ polymerization of a mixture of aminobenzoate-modified Mg-Al LDH and polyamic acid (polyimide precursor) in N,N-dimethylactamide [28]. In other work, Chen and Qu successfully synthesized exfoliated polyethylene-g-maleic anhydride (PE-g-MA)/LDH nanocomposites by refluxing in a nonpolar xylene solution of PE-g-MA [29,30]. Then, Li et al. prepared polyfmethyl methacrylate) (PMMA)/MgAl LDH by exfoliation/adsorption with acetone as cosolvent [32]. Since then, polymer/LDH nanocomposites have attracted extensive interest. The wide variety of polymers used for nanocomposite preparation include polyethylene (PE) [29, 30, 33 9], polystyrene (PS) [48, 50-58], poly(propylene carbonate) [59], poly(3-hydroxybutyrate) [60-62], poly(vinyl chloride) [63], syndiotactic polystyrene [64], polyurethane [65], poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] [66], polypropylene (PP) [48, 67-70], nylon 6 [9,71,72], ethylene vinyl acetate copolymer (EVA) [73-77], poly(L-lactide) [78], poly(ethylene terephthalate) [79, 80], poly(caprolactone) [81], poly(p-dioxanone) [82], poly(vinyl alcohol) [83], PMMA [32,47, 48, 57, 84-93], poly(2-hydroxyethyl methacrylate) [94], poly(styrene-co-methyl methacrylate) [95], polyimide [28], and epoxy [96-98]. These nanocomposites often exhibit enhanced mechanical, thermal, optical, and electrical properties and flame retardancy. Among them, the thermal properties and flame retardancy are the most interesting and will be discussed in the following sections. 

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].

To evaluate the capabilities of the system, a polymer blend comprising PE and PMMA homopolymers and a PE/PMMA copolymer was prepared and analyzed. The molar masses of PE, PMMA and the copolymer were = 1,100 g/mol, = 263,000 g/mol and = 10,600 g/mol, respectively. The experiments were performed with TCB as the mobile phase. WET suppression was applied to the intrinsic solvent signals, i.e., the three aromatic proton signals were suppressed. 

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.

Some polymers like PE and NR get cross-linked on exposure to radiation while others like those based on vinylidene polymers, e.g., polymethylmethacrylate (PMMA), polyisobutylene, degrade. Certain other types of polymer stmctures (high aromatic content or thermoset) resist degradation by high-energy radiation. Coating polymers usually contain acrylic, methacryUc, or fumaric vinyl unsaturation along or attached to the backbone. 

Polymers are formed via two general mechanisms, namely chain or step polymerisation, originally called addition and condensation, respectively, although some polymerisations can yield polymers by both routes (see Chapter 2). For example, ring opening of cyclic compounds (e.g., cyclic lactides and lactams, cyclic siloxanes) yield polymers either with added catalyst (chain) or by hydrolysis followed by condensation (step). Many polymers are made via vinyl polymerisation, e.g., PE, PP, PVC, poly(methyl methacrylate) (PMMA). It could be argued that the ethylenic double bond is a strained cyclic system. 

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%). 

A special application of the high light transmittance of some polymers is the flexible light conductor, the so-called/ifcre optics. This is a bundle of PMMA fibres, in which each fibre is coated by a thin layer of another polymer, e.g. PE. Due to total reflection at the wall, light can be transported without noticeable loss of intensity along such a fibre, so that images can be transferred. 

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).

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