Organometallic polymers. IV. Organometallic modifications of halogen-containing polymers

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<ul><li><p>Organometallic Polymers. IV. Organometallic Modifications of Halogen-Containing Polymers* </p><p>ALON GAL,+ MICHAEL CAIS, and DAVID H. KOHN, Department of Chemistry, Technion-Israel Institute of Technology, Haifa, Israel </p><p>Synopsis </p><p>The synthesis of ferrocene-containing polymers by chemical modification of chlorinated poly- ethylenes, polyvinyl chloride (PVC), and other halogenated polymers, under Friedel-Crafts condi- tions, is described. The effect of reaction conditions on the structure and composition of the products obtained with various substrates was investigated. Soluble polymers of up to 62% ferrocene content were obtained. In most cases, substitution was accompanied by dehydrohalogenation. The fer- rocene-to-vinylene ratio was higher in the reaction products of chlorinated polyethylenes than in those of PVC. </p><p>INTRODUCTION </p><p>Poly(viny1 chloride) (PVC) has been reported to undergo Friedel-Crafts substitution reactions with monomeric (e.g., t ~ l u e n e ~ . ~ ) and polymeric (poly- styrene4) aromatic organic compounds. Similar reactions with a number of organometallic compounds have been described,5p6 substitution in the case of ferrocene being less than 0.5%. Another case of Friedel-Crafts modification is that of chloromethylated polystyrene, whose hydroquinone derivative has been used as electron e~changer .~ </p><p>In this paper, we present the ferrocene modification of chlorinated poly- ethylenes, PVC, and other halogenated polymers in solution obtained under Friedel-Crafts conditions. Surface reactions of metallocenes with solid polymers, such as chlorinated polyethylene sheets, will be described in a subsequent arti- cle. </p><p>EXPERIMENTAL </p><p>Materials </p><p>Chlorinated polyethylenes were prepared by chlorination of polyethylene in sym-tetrachloroethane solution according to the method of Canterino8 by using a General Electric H-4-AB ultraviolet lamp. The reaction temperature was 115OC for Hostalen G, 108OC for Ipethene 300, and 87C for Ipethene 900. The polymeric starting materials used were received as gifts from the manufacturers listed in Table I. The nonpolymeric materials used were already described.l </p><p>* For part 111, see Gal et al.' t Present address: Hydrophilics Ltd., P.O.B. 6221, Haifa, Israel. </p><p>Journal nf Polymer science: Polymer Chemistry Edition Vol. 16,71-76 (1978) 0 1978 John Wiley &amp; Sons, Inc. 0360-6376/78/0016-0071$01.00 </p></li><li><p>72 GAL, CAIS, AND KOHN </p><p>0 25 50 75 100 125 </p><p>Reaction time (rrcondr) </p><p>Fig. 1. Effect of reaction time on (A) composition and ( B ) gelation of chlorinated Ipethene 900 ( r = 32 mol % Cl). Solvent, 1,2-dichloroethane; polymer concentration, 1 g/dl solution; ferrocene, 20 mol/equiv C1; AlC13 (uncomplexed), 2 mol/equiv C1; temperature, 5OOC. </p><p>Modification Processes </p><p>The reactions of chlorinated polymers with ferrocene were carried out in a manner similar to that described in our paper on modification of diene po1ymers.l In some of the experiments, the polymer solution was added to a solution of ferrocene and catalyst, whereas in other cases, solid catalyst was added to a so- </p><p>TABLE I Polymeric Starting Materials </p><p>Characteristic Name Source dataa </p><p>Chlorinated polymers: - Poly(viny1 chloride) Electrochemical Industries, Haifa DP = 1030 Chlorinated PVC Center for Industrial Research, 64 wt % C1 </p><p>Hydrin-100 Haifa </p><p>Goodrich Chemical Co. - DP = 5000 </p><p>(polyepichlorohydrin) Polyethylenes: </p><p>Hostalen G (linear polyethylene) Farbwerke Hoechst AG. d &gt; 0.950 Ipethene-300 (branched Petrochemical Industries Ltd., d = 0.919 </p><p>polyethylene) Haifa MFI = 2 Ipethene-900 (branched Petrochemical Industries Ltd., d = 0.915 </p><p>polyethylene) Haifa MFI = 50 </p><p>am = viscosity-average degree of polymerization; d = density; MFI = melt-flow index. </p></li><li><p>TA</p><p>BL</p><p>E I</p><p>1 R</p><p>eact</p><p>ions</p><p> of H</p><p>alog</p><p>en-C</p><p>onta</p><p>inin</p><p>g Po</p><p>lym</p><p>ers </p><p>with</p><p> Fer</p><p>roce</p><p>ne </p><p>Star</p><p>ting </p><p>mat</p><p>eria</p><p>ls </p><p>Solu</p><p>ble </p><p>prod</p><p>ucts</p><p> Po</p><p>lym</p><p>er </p><p>Vin</p><p>ylen</p><p>e C1</p><p> Fe</p><p>rroc</p><p>ene,</p><p> A</p><p>lC13</p><p>, Fe</p><p>rroc</p><p>ene </p><p>Chl</p><p>orin</p><p>e un</p><p>its </p><p>per1</p><p>00 </p><p>Con</p><p>cn, </p><p>mol</p><p>l m</p><p>ol/ </p><p>per1</p><p>00 </p><p>per </p><p>100 </p><p>per </p><p>100 </p><p>Rhe</p><p>o- </p><p>mer</p><p> gl</p><p>dl </p><p>equi</p><p>v eq</p><p>uiv </p><p>Tem</p><p>p, </p><p>Tim</p><p>e, </p><p>Yie</p><p>ld, </p><p>mer</p><p> m</p><p>er </p><p>mer</p><p> lo</p><p>gica</p><p>l 0 </p><p>!a P </p><p>Run</p><p> Ty</p><p>pe </p><p>units</p><p> so</p><p>lutio</p><p>na </p><p>c1 C</p><p>lb </p><p>OC </p><p>min</p><p> %</p><p> %</p><p> un</p><p>its </p><p>units</p><p> un</p><p>its </p><p>stat</p><p>eC </p><p>0 </p><p>13-1</p><p> C</p><p>l-LD</p><p>PEd </p><p>21 </p><p>1 25</p><p> 2 </p><p>50 </p><p>1.5 </p><p>95 </p><p>34 </p><p>8.6 </p><p>8.1 </p><p>4.3 </p><p>R </p><p>z 13</p><p>-4 </p><p>CIL</p><p>DPE</p><p>d 21</p><p> 1</p><p> 25</p><p> 2 </p><p>50 </p><p>100 </p><p>40 </p><p>29 </p><p>6.3 </p><p>5.2 </p><p>9.5 </p><p>R </p><p>R </p><p>13-9</p><p> C</p><p>l-LD</p><p>PEd </p><p>21 </p><p>108 </p><p>10 </p><p>0 20</p><p>5 60</p><p>0 10</p><p>0 15</p><p> 2.7</p><p> 9.</p><p>5 8.</p><p>8 12</p><p>-3 </p><p>C1-</p><p>HD</p><p>PE </p><p>31 </p><p>1 </p><p>8.7 </p><p>3.9 </p><p>50 </p><p>100 </p><p>43 </p><p>21.5</p><p> 5 </p><p>18.6</p><p> 7.</p><p>4 R</p><p> 12</p><p>-6 </p><p>Cl-</p><p>HD</p><p>PE </p><p>31 </p><p>1 </p><p>18.6</p><p> 3.</p><p>9 50</p><p> 10</p><p>0 44</p><p> 47</p><p>.1 </p><p>13.5</p><p> 14</p><p>-2 </p><p>PVC</p><p> 10</p><p>0 1</p><p> 4.</p><p>5 1' </p><p>22 </p><p>10 </p><p>100 </p><p>6.0 </p><p>1.7 </p><p>91 </p><p>7.3 </p><p>G </p><p>r 8 3 </p><p>3.7 </p><p>13.8</p><p> L </p><p>c 14</p><p>-4 </p><p>PVC</p><p> 10</p><p>0 1</p><p> 4.</p><p>5 2' </p><p>22 </p><p>10 </p><p>100 </p><p>24.9</p><p> 5.</p><p>5 72</p><p>.5 </p><p>22 </p><p>G </p><p>ij </p><p>14-5</p><p> PV</p><p>C </p><p>100 </p><p>1 </p><p>4.5 </p><p>2' 22</p><p> 10</p><p>0 10</p><p>0 35</p><p>.8 </p><p>14 </p><p>49 </p><p>37 </p><p>G </p><p>cd </p><p>14-9</p><p> PV</p><p>C </p><p>100 </p><p>1 </p><p>4.5 </p><p>2 22</p><p> 10</p><p> 64</p><p> 61</p><p>.8 </p><p>24 </p><p>4 72</p><p> G</p><p> 14</p><p>-6 </p><p>PVC</p><p> 10</p><p>0 0.</p><p>5 10</p><p> 2 </p><p>22 </p><p>2 10</p><p>0 26</p><p>.4 </p><p>9 64</p><p> 27</p><p> G</p><p> 14</p><p>-7 </p><p>PVC</p><p> 10</p><p>0 0.</p><p>5 10</p><p> 2 </p><p>22 </p><p>10 </p><p>77 </p><p>55.1</p><p> 21</p><p> 16</p><p> 63</p><p> G</p><p> 14</p><p>-8 </p><p>PVC</p><p> 10</p><p>0 0.</p><p>5 10</p><p> 2 </p><p>22 </p><p>30 </p><p>40 </p><p>38.1</p><p> 9 </p><p>10 </p><p>81 </p><p>G </p><p>14-1</p><p>1 PV</p><p>C </p><p>100 </p><p>3.75</p><p>8 10</p><p> 0 </p><p>205 </p><p>130 </p><p>100 </p><p>21.4</p><p> 6 </p><p>64 </p><p>30 </p><p>G </p><p>16-3</p><p> H</p><p>ydrin</p><p>-100</p><p> 10</p><p>0 1</p><p> 14</p><p> 3 </p><p>50 </p><p>100 </p><p>100 </p><p>7.1 </p><p>R </p><p>15-6</p><p> C</p><p>l-H</p><p>DPE</p><p> 16</p><p>0 1</p><p> 3.</p><p>3 1.</p><p>5' 22</p><p> 10</p><p> 10</p><p>0 5.</p><p>6 G</p><p>a So</p><p>lven</p><p>t: 1,</p><p>2-di</p><p>chlo</p><p>roet</p><p>hane</p><p> (unl</p><p>ess o</p><p>ther</p><p>wis</p><p>e sp</p><p>ecifi</p><p>ed). </p><p>2 5 m 15</p><p>-5 </p><p>Cl-P</p><p>VC</p><p> 13</p><p>2 1</p><p> 3.</p><p>8 1.</p><p>8' 22</p><p> 10</p><p> 62</p><p> 7.</p><p>2 G</p><p> 2 </p><p>Intr</p><p>oduc</p><p>ed to</p><p> the </p><p>mix</p><p>ture</p><p> aft</p><p>er th</p><p>e po</p><p>lym</p><p>er (u</p><p>nles</p><p>s oth</p><p>erw</p><p>ise </p><p>spec</p><p>ified</p><p>). R</p><p> = ru</p><p>bber</p><p>y; L</p><p> = le</p><p>athe</p><p>ry; G</p><p> = g</p><p>lass</p><p>y. </p><p>Subs</p><p>trat</p><p>e: </p><p>Ipet</p><p>hene</p><p> 300</p><p>. So</p><p>lven</p><p>t: te</p><p>trah</p><p>ydro</p><p>naph</p><p>thal</p><p>ene.</p><p> ' Pr</p><p>evio</p><p>usly</p><p> com</p><p>plex</p><p>ed w</p><p>ith fe</p><p>rroc</p><p>ene.</p></li><li><p>74 GAL, CAIS, AND KOHN </p><p>20( 0 4ooo 3500 3ooo 2500 2Ooo 1600 1400 1200 wxx) 800 (an9 </p><p>Fig. 2. Infrared spectrum (KBr pellet) of ferrocene-substituted PVC (run 14-7 in Table 11). </p><p>lution containing the polymer and ferrocene. In addition, a number of uncat- alyzed reactions were performed in molten ferrocene, to which tetrahydrona- phthalene (20%) was added to avoid sublimation. </p><p>Characterization </p><p>Polymer compositions were determined by elemental analysis. The methods of determination and measurement of iron content, infrared spectra, molecular weight, and glass transition temperature have been described in a previous paper of this series.l </p><p>RESULTS AND DISCUSSION </p><p>Our experiments with various halogen-containing polymers, such as chlori- nated polyethylenes and poly(viny1 chloride) showed that the ferrocene substi- tution is accompanied by side reactions, mainly dehydrohalogenation. The process, involving substitution and dehydrochlorination, can be depicted sche- matically as in eq. (1). </p><p>-(CH2-CH2)~(CH2-CHk + Ferrcene 4 c1 </p><p>AICI, I -(CH2-CH2),r;-(CH,-CH)~(CH,-CH)~(CH=CH)~ + ZHCl (1) </p><p>I I </p><p>The subscript r denotes the degree of chlorination of the hydrocarbon chain, i.e., the number of C1 atoms per 100 ethylene units, 1 is the fraction of C1 atoms that had left the polymer during the process, and s represents the extent offer- rocene substitution (mole % ferrocene). The numerical values of 1 and s have been computed from results of elemental analyses with the aid of eqs. (2) and (3). </p><p>(2) 185s </p><p>Ferrocene (%) = 100 28(1 - r ) + 62.5(r - 1 ) + 26(1 - S) + 212s </p><p>(3) 35.5(r - 1 ) </p><p>Chlorine (%) = 100 28(1 - r ) + 62.5(r - 1) + 26(1- s) + 212s </p></li><li><p>ORGANOMETALLIC POLYMERS. IV 75 </p><p>The results of a series of experiments performed with low-density polyethylene, chlorinated in solution, are recorded in Figure 1A. </p><p>A t very short reaction times, the extent of dehydrohalogenation was close to that of the substitution (s - l/&amp;, while in reactions that were allowed to proceed longer, about three chlorine atoms were expelled for each entering ferrocene molecule (s - I/&amp;. The partial gelation of the polymer is represented in Figure 1B. On the basis of results from earlier investigations?JO one can assume that crosslinking is closely related to dehydrochlorination. </p><p>It should be added that the infrared spectra of the sol and gel fractions were practically identical in all cases investigated. </p><p>Table I1 contains a number of representative experiments with various halo- gen-containing polymers. Long reaction times resulted usually in high gel content and increased vinylene-to-ferrocene ratio. The decrease of ferrocene content in several prolonged reactions, e.g., 100 min (run 13-4) versus 1.5 rnin (run 13-l), and 30 min (run 14-8) versus 2 min (run 14-6), points to chain frag- mentation,l' possibly involving elimination of stable a-ferrocenyl carbonium ions. The fragmentation of polymer molecules during the substitution process has been actually observed in the case of poly(viny1 chloride), whose molecular weight degraded within 10 min from Mu 64,000 to a,, 11,400 (run 14-4), and to an 2,500 in a further 90 rnin (run 14-5). </p><p>Since polyethylenes chlorinated to a C1 content of 20-3W0 were poorly soluble at lower temperatures, most experiments with these polymers were carried out at 5OOC. </p><p>It has been reported that some highly aromatic substances undergo substi- tution by haloalkanes, even in the absence of catalysts.12 Therefore, it was of interest to explore the feasibility of preparing ferrocene-substituted polymers by uncatalyzed reactions. The experiments were performed in molten ferrocene, to which 20% tetrahydronaphthalene was added to avoid sublimation. Entirely soluble products were obtained (runs 13-9 and 14-11), although the dehydro- chlorination-to-substitution ratio was rather high. </p><p>AlC13 dissolves readily in concentrated ferrocene solution by an exothermic reaction due to ferrocene's ability to form charge-transfer complexes with Lewis acids.13 AlC13, precomplexed to ferrocene, was found to be a milder catalyst than when added directly to a solution of the polymer and ferrocene. For instance, in run 14-9, carried out with crystalline AlClS, both substitution and crosslinking were substantially higher than in an analogous experiment in which the pre- complexed catalyst was employed (run 14-4). The extent of substitution is also closely affected by the concentration of ,catalyst (run 14-4 versus 14-2) and of ferrocene (run 12-6 versus 12-3). </p><p>Since dehydrohalogenation is believed to propagate by ally1 activation of C1 atoms,'* it is not surprising to find that in ferrocene-substituted PVC, the vin- ylene-to-ferrocene ratio was higher than in the reaction products of chlorinated polyethylenes. Adjacent halogen atoms, like those existing in highly chlorinated polymers (runs 15-5 and 15-6) and primary halogen atoms, as in polyepichloro- hydrin (run 16-3), were found to be considerably less reactive than the isolated, secondary halogen atoms of moderately chlorinated polyethylenes and of poly- (vinyl chloride). </p><p>The ferrocene-substituted polymers were colored in various shades of yellow. The glass transition temperatures tended generally to increase with ferrocene </p></li><li><p>76 GAL, CAIS, AND KOHN </p><p>substitution. For instance, in the series obtained with chlorinated Ipethene 900 (Fig. lA), the penetrometric softening poipts were -25, -1, and +13OC for polymers containing 0,22, and 42.5 wt % ferrocene, respectively. The rheological states of other polymers 'are shown in the last column of Table 11. </p><p>Figure 2 shows the infrared spectrum of the soluble reaction product from run 14-7 (Table 11). This material contains only 16% of the substrate's original chlorine atoms, which accounts for the very low intensity of the characteristic PVC bands in the range of 970-1320 crn-I.l5 The absorptions of the various backbone methylene groups appear between 1420-1460 and at about 2900 cm-l.16 The alkene band between 1590-1640 cm-' is due to the extensive dehydrochlorination of the PVC substrate.15 Finally, the sharp peaks at 1000 and 1100 cm-l confirm the relatively high ferrocene content of the p01ymer.l~ </p><p>References </p><p>1. A. Gal, M. Cais, and D. H. Kohn, J. Polym. Sci. Polym. Chem. Ed., 15,461 (1977). 2. P. Teyssie and G. Smets, J. Polym. Sci., 20,351 (1956). 3. D. Hace and M. Bravar, in Poly(viny1 Chloride): Formation and Properties, (J. Polym. Sci. </p><p>4. P. H. Plesch, Chem. Ind. London, 1958,954. 5. K. -P. S. Kwei, J. Appl. Polym. Sci., 12,1543 (1968). 6. M. Kryszewski and M. Mucha, J. Polym. Sci. B, 5,1095 (1967). 7. K. A. Kun, J. Polym. Sci. A, 3,1833 (1965). 8. P. J. Canterino, in Encyclopedia of Polymer Science and Technology, Vol. 6, H. F. Mark, </p><p>9. J. C. Bevington and R. G. W. Noirish, J. Chem. Soc., 1948,771. 10. J. C. Bevington and R. G. W. Norrish, J. Chem. Soc., 1949,482. 11. A. Schriesheim, in Friedel-Crafts and Related Reactions, Vol. 2, G. A. Olah, Ed., Wiley-In- </p><p>12. G. A. Olah, in Friedel-Crafts and Related Reactions, Vol. 1, G. A. Olah, Ed., Wiley-Interscience, </p><p>13. A. Z. Rubezhav and S. P. Gubin, Adu. Organornet. Chem., 10,407 (1972). 14. B. Baum, SPE J., 17,71(1961). 15. E. Tsuchida, C. Shih, I. Shinohara, and S. Kambara, J. Polym. Sci. A, 2,3347 (1964). 16. H. J. Oswald and E. T. Kubu, Trans. SPE, 3,168 (1963). 17. M. Roseblum, Chemistry of the Iron Group Metallocenes, Wiley-Interscience, New York, </p><p>C, 33), B. SedWek, Ed., Wiley-Interscience, New York, 1971, p. 325. </p><p>N. G. Gaylord, and N. B. Bikales, Eds., Wiley-Interscience, New York, 1967, p. 434. </p><p>terscience, New York, 1964, p. 480. </p><p>New York, 1963, pp. 322 and 858. </p><p>1965, p. 38. </p><p>Received October 18,1976 </p></li></ul>

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