Ethene and Propene Copolymers Containing Silsesquioxane Side Groups(含POSS的乙烯丙烯共聚物)
Ethene and Propene Copolymers Containing Silsesquioxane Side
Groups
Akira Tsuchida,?Carsten Bolln,?Friedrich G.Sernetz,?
Holger Frey,*,?and Rolf Mu1lhaupt?
Institut fu¨r Makromolekulare Chemie und Freiburger Materialforschungszentrum(FMF)
der Albert-Ludwigs-Universita¨t Freiburg,Stefan-Meier-Strasse21/31,D-79104Freiburg,
Germany,and Department of Applied Chemistry,Faculty of Engineering,Gifu University,
Yanagido,Gifu501-11,Japan
Received June11,1996;Revised Manuscript Received February28,1997X
ABSTRACT:The novel monovinyl-functional silsesquioxane cage1-(9-decenyl)-3,5,7,9,11,13,15-heptaethylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane has been prepared and copolymerized with ethene
and propene.The monovinyl-functional spherosiloxane was obtained from the octahydridosilsesquioxane
(HSiO3/2)8via hydrosilation with dibrominated decadiene,followed by reaction of the nonreacted SiH
groups with ethene,debromination,and chromatographic separation.Homopolymerization and copo-lymerization with ethene and propene was performed using different methylalumoxane-activated metallocene catalysts.Depending on catalyst structure comonomer incorporation between17and25wt
%was achieved.High molar mass copolymers were obtained containing pendant octasiloxane cubes. Characterization by13C,1H,and29Si NMR spectroscopy confirmed that the catalyst did not modify the
Si-O-Si framework.Incorporation up to25wt%(1.2mol%)of the spherosiloxane-based monomer accounted for a decrease of the melting temperature by18K with respect to polyethene.As demonstrated
by means of thermal gravimetric analysis,thermostability under air was improved in the polyethene copolymer in comparison to polyethene.
Introduction
Spherosiloxanes,inorganic cage molecules consisting of a silicon-oxygen-based framework,continue to fas-cinate both inorganic chemists and materials scientists. These compounds belong to the class of silsesquioxanes, which are generally characterized by the composition (RSiO3/2)n,in which R is an organic group or hydrogen. Silsesquioxanes are interesting building units for or-ganic-inorganic hybrid materials,in which the incor-porated inorganic segment is expected to contribute to unusual properties,such as thermal stability and abra-sion resistance.Silsesquioxanes have also been con-sidered as molecular silicate units and possess analogies with structures found in zeolites.1,2
The cube-shaped molecule1,3,5,7,9,11,13,15-octa-hydridopentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane(1), referred to as H8T8,is well characterized and available in reasonable yields via the synthetic route described by Agaskar et al.3Various substitution methods4-8for H8T8have been developed.Hydrosilation of H8T8can be conveniently employed to prepare substituted deriva-tives with different degrees of functionalization.Highly cross-linked thermosets9,10as well as linear polymers with main chain silsesquioxane units11-13or silsesqui-oxane side groups11,14,15have been synthesized.Brown and Vogt discovered incompletely condensed silanols and demonstrated that the trisilanols can be corner-capped with silanes.18This elegant route to mono-and difunctional T8units was further developed by Feher et al.16,17and also described by Lichtenhan et al.11,14,15,19-20In these works,after controlled hydrolysis of cyclopentyl-,cyclohexyl-,or cycloheptyltrichloro-silane,a T8precursor compound with exactly one missing corner with the composition(cy)7Si7O9(OH)3 was obtained.Subsequently,this trisilanol was mono-or difunctionalized by“corner-capping”with a trichlo-rosilane bearing the desired functional moiety.How-ever,in this case the silsesquioxane unit is substituted by large organic groups.
Our interest is centered on metallocene-catalyzed polymerization of1-alkenes as well as copolymerization of1-alkenes with ethene and propene.Consisting of only one type of catalytically active center,metallocene catalysts,in contrast to conventional Ziegler-Natta catalysts,are able to produce copolymers with narrow molar mass distribution and uniform comonomer distribution.21-23A well-known type of copolymer is linear low-density polyethene(LLDPE).24In order to modify the properties of LLDPE,it is of interest to copolymerize1-alkenes with functional groups.25Dif-ferent approaches have been used recently to employ functionalized monomers in the copolymerization of R-olefins.26-30There are no reports concerning LLDPE or other olefin copolymers with pendant silsesquioxane cubes.
The objective of this research was the preparation of monovinyl-functional spherosiloxanes as new class of comonomers useful in transition-metal catalyzed olefin copolymerizations.Attachment of T8substituted with alkyl groups as small as possible to a polymer chain appeared interesting to us.In this paper we describe the synthesis and copolymerization of1-(9-decenyl)-3,5,7,9,11,13,15-heptaethylpentacyclo[9.5.1.13,9.15,15.17,13]-octasiloxane(5,Scheme1)with ethene and propene, using methylalumoxane(MAO)activated metallocenes zirconocene dichloride(Cp2ZrCl2)(6a),dimethylsilyle-nebis(indenyl)zirconocene dichloride(Me2Si(C9H6)ZrCl2) (6b),and dimethylsilylene(tetramethylcyclopentadienyl)-(N-tert-butyl)titanium dichloride(Me2Si(Me4Cp)(N-t-Bu)TiCl2)(6c).These catalyst systems are well-known to produce homo-and copolymers of ethene or propene with higher R-olefins.31-34The copolymers were char-acterized with respect to comonomer incorporation of T8(1H,13C,29Si NMR spectroscopy,IR),molar mass (GPC)and thermal properties(DTA,DSC,TGA).
?Albert-Ludwigs-Universita¨t Freiburg.
?Gifu University.
X Abstract published in Advance ACS Abstracts,May1,1997.
2818Macromolecules1997,30,2818-2824
S0024-9297(96)00846-7CCC:$14.00?1997American Chemical Society
Experimental Section
Materials.Triethoxysilane (Wacker),trichlorosilane (Al-drich),anhydrous ferric chloride,sodium dodecyl sulfate,calcium carbonate,potassium chloride,decadiene,powdered zinc,and bromine (all reagents obtained from Fluka),acetone and hydrochloric acid (Riedel-De-Haen),and trichloromethane and dichloromethane (Roth)were obtained in p.a.quality and used without further purification.Toluene (Roth)was ex-tracted with concentrated sulfuric acid to remove thiophene and purified by distillation.Toluene employed for polymer-ization and hydrosilation reactions was purified by passing it through a column with acidic Al 2O 3,and it was distilled over LiAlH 4and refluxed over Na/K alloy,from which it was freshly distilled prior to use.Cyclohexane was dried over CaH 2.For synthesis of H 8T 8petroleum ether (technical grade),and for precipitation of the polymers methanol (technical grade)were used without purification.For column chromatography silica gel (Merck 60,230-400mesh)was employed.A solution of hexachloroplatinic acid (1wt %Pt in diglyme)was used for hydrosilation reactions.Methylalumoxane (MAO)was pro-vided by Witco GmbH as 10wt.-%solution in toluene.Cp 2-ZrCl 2was obtained from Aldrich.Propene (polymerization grade)was supplied by BASF AG,ethene was supplied by GHC Gerling,Holz &Co.Handels GmbH.
Methods.1H,13C,and 29Si NMR spectra were recorded on a Bruker ARX 300spectrometer operating at 300MHz for 1H,75.4MHz for 13C and 59.6MHz for 29Si,using TMS as internal standard in CDCl 3at ambient temperature.C 2D 2Cl 4was used as solvent at 100°C for the copolymer with ethene.IR spectra were measured with a Perkin-Elmer 1330IR spectrometer.GC spectra were recorded with a GC 6000Vega Series 2controlled by an ICU 600(Carlo Erba Instruments)using the following heating rates:start 60°C,20°C/min to 100°C (holding 1min),and 20°C/min to 300°C (holding 5min).Molar masses and molar mass distributions were determined by gel permeation chromatography (GPC).Homopolymer and pro-pene copolymer were analyzed by a combination of 105,103,and 100nm PL columns (Polymer Laboratories),using toluene as solvent at ambient temperature.Molar masses are refer-enced to narrow polystyrene standards.The ethene copolymer was analyzed with a combination of AT-800P,AT-80M/S 3x,and AT-807S 1x (Shodex GPC columns),using 1,2,4-trichlo-robenzene as solvent at 140°C.Molar masses are referenced to narrow and broad polypropene.Differential scanning calorimetry (DSC)was performed on a Perkin-Elmer DSC-4thermal analyzer at heating rates 9,16,and 25°C/min.Melting temperatures were obtained by extrapolation vs the square root of the heating rate to heating rate 0as a reliable standard method for comparison of melting points.Thermo-gravimetric (TGA)investigations and differential thermo analysis (DTA)data were recorded on a Netzsch simultaneous thermo analysis (STA)409controlled by a Netzsch TASC 412/2unit.Nitrogen-and air-atmosphere (flow:150cm 3/min)with a heating rate of 5K/min were employed.Synthesis of 1-(9-Decenyl)-3,5,7,9,11,13,15-heptaethyl-pentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane.The synthetic route to 5is shown in Scheme 1.Homo-and copolymerization with ethene and propene are shown in Scheme 2.Unless noted otherwise,all manipulations were carried out under dry argon atmosphere.
Preparation of 1,3,5,7,9,11,13,15-Octahydridopentacyclo-[9.5.1.13,9.15,15.17,13]octasiloxane (1).A 80g (0.49mol)sample of anhydrous FeCl 3,40mL of HCl conc (37wt %in water),3g (10mmol)of sodium dodecyl sulfate,and 1500mL of petroleum ether were stirred vigorously for 30min using a magnetic stirrer.Under vigorous stirring,a solution of 80mL (107.3g,0.79mol)of HSiCl 3in 800mL of petroleum ether was added dropwise to the flask in the course of 10h.After additional stirring for 30min,the petroleum ether layer was separated,dried,and neutralized with Na 2CO 3and CaCl 2.Subsequent to filtration,the petroleum ether was reduced to a residual volume of 200mL.After 30min the precipitated crystals were collected and thoroughly washed with petroleum ether (2.5mL ×4):yield 7.81g (18.6%).1H NMR (CDCl 3):δ4.23ppm (s,Si -H).29Si NMR (CDCl 3):δ-84.70ppm.MS(EI):m/z 424(100%)[M +].
Preparation of 9,10-Dibromo-1-decene (2).Under am-bient conditions 27.9g (175mmol)of bromine in 10mL of CHCl 3was added to a solution of 24.2g (175mmol)of decadiene in 25mL of CHCl 3.After evaporation of the solvent,the residue was distilled twice under reduced pressure:bp 90°C 0.1mbar ;yield 16.1g (31%).1H NMR (CDCl 3):δ1.21-2.23(m,-CH 2-,12H),3.54-3.91(m,CH 2Br,2H),4.06-4.24(m,CHBr,1H),4.84-5.07(m,C d CH 2,2H),5.70-5.91(m,C d CH s C,1H).
Preparation of 1-(9,10-Dibromodecanyl)-3,5,7,9,11,13,-15-heptahydridopentacyclo[9.5.1.13,9.15,15.17,13]octasilox-ane (3).A 10.4g (24.5mmol)sample of 1and 7.62g (25.6mmol)of 2were dissolved in 400mL of dry cyclohexane.Then 50μL of platinum catalyst solution were added and the solution was refluxed for 72h.Every 24h,50μL of Pt catalyst was added to continue the reaction.The reaction was termi-nated after disappearance of the signals for the terminal vinyl protons in 1H NMR spectrum.After the reaction was cooled to room temperature,4.1g (9.7mmol)of unreacted H 8T 8was collected by filtration of the cyclohexane solution.Subsequent to evaporation of the solvent,from the residual viscous oil another portion of 1.2g (2.8mmol)unreacted H 8T 8could be isolated.The crude product was used without further puri-fication.1H NMR (CDCl 3):δ0.70(q,Si -CH 2,2H),1.21-2.23(m,CH 2),3.62and 3.84(m,CH 2Br,2H),4.17(m,CHBr,1H),4.2-4.3ppm (m,SiH,7H).IR (KBr):2930,2880(νH -C -H ),2270(νSi -H ),1433,1375,1255(νSi -C ),1120(νSi -O ),965,875,840,785,715,645,570,460,390cm -1(νSi -O ).
Preparation of 1-(9,10-Dibromodecanyl)-3,5,7,9,11,13,-15-heptaethylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane (4).The viscous reaction product from the previous step containing 3was transferred to a 250mL two-necked flask
Scheme 1.Synthesis of Monomer
5
Macromolecules,Vol.30,No.10,1997
Ethene and Propene Copolymers 2819
and dried in vacuo.Then 100mL of dry toluene and 50μL of Pt catalyst solution were added.The solution was refluxed under stirring and saturated with a continuous flow of ethene.Another 50μL of Pt catalyst solution was added after 24h to continue the reaction.The disappearance of the Si -H bond (ν)2250cm -1)was confirmed by IR spectroscopy.After removal of the solvent,the remaining product solidified during cooling.The crude product still contained isomerized 2which was removed by washing with hot methanol (20mL ×5)and decantation after cooling.Finally the solid product was dried in vacuo.No further purification was carried out.1H NMR (CDCl 3)beside other peaks:δ0.60(q,Si -CH 2,16H),0.98(t,CH 3,21H),1.20-2.24(m,CH 2),3.62and 3.84(m,CH 2Br,2H),4.17ppm (m,CHBr,1H).IR (KBr):2960,2920,2880,2860,(νH -C -H ),1460(νCH 3),1430,1255and 1230(νSi -C ),,1120(νSi -O ),1010,965,880,800,760,695,645(νC -Br ),550,465,390cm -1(νSi -O ).
Preparation of 1-(9-Decenyl)-3,5,7,9,11,13,15-hepta-ethylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane (5).The complete portion of 4from the previous step was transferred into a 100mL two-necked flask and 3.0g (45.9mmol)of powdered zinc and 40mL of acetic acid were added.The reaction mixture was refluxed for 4h.Acetic acid was removed under reduced pressure and the residue was washed with acetone and successively with dichloromethane.A yield of 6.8g of crude product obtained after drying was purified by column chromatography,using petroleum ether:toluene (20:1)as eluant.By collection of all fractions with a R f value of 0.45(silicagel-TLC;monitoring with iodine chamber),5was obtained as a white solid:mp 67.5°C;yield 3.9g (43%based on H 8T 8).1H NMR (CDCl 3):δ0.59(q,Si -CH 2,16H),0.98(t,CH 3,21H),1.21-1.47(m,CH 2,12H),1.95-2.09(q,d CH s C H 2,2H), 4.88-5.02(m,C d CH 2,2H), 5.70-5.88ppm (m,C d C H s C,1H).13C NMR (CDCl 3):δ4.08(Si -C H 2-CH 3),6.51(Si -CH 2-C H 3),11.89(Si -C H 2-),22.78(CH 2),29.0(CH 2),29.18(CH 2),29.24(CH 2),29.39(CH 2),32.58(CH 2),33.86(CH 2),114.10(C H 2d CH -),139.20ppm (d CH -).29Si NMR (CDCl 3):δ-65.68(Si -Et,3Si),-65.79(Si -Et,4Si),-66.29ppm (Si -Dec,1Si).IR (KBr):3070(νC d C s H ),2960,2920,2880,2850,2740(νH -C -H ),1640(νC d C ),1460(νCH 3),1410,1250,1230,(νSi -C ),1120(νSi -O ),1015,960,800,755,695,535,465,390cm -1(νSi -O ).Anal.Calcd for C 24H 54Si 8O 12:C,37.99;H,7.18.Found:C,40.02;H,7.62.
Polymerization.Experimental details for all polymeriza-tions are summarized in Table 1.Homo-and copolymeriza-tions were carried out in a 100mL Schlenk flask,which was filled with 5,toluene,and part of the methylalumoxane (MAO).Subsequently,argon was removed by evacuation and the reaction mixture saturated with either ethene or propene,respectively,which was then kept under a constant flow.The catalyst (6a ,6b ,or 6c )was dissolved in 10wt %MAO toluene solution and then injected into the reactor for an in situ start of the copolymerization.The following polymerization condi-tions were used:[catalyst])100μmol/L,Al:Zr or Ti )1000,
Scheme 2.Oligomerization of 5and Copolymerization of 5with Ethene and
Propene
Table 1.Copolymerization of Decenyl-Functionalized Silsesquioxane (5)with Ethene and Propene Using
Methylalumoxane-Activated Metallocene Catalysts a comonomer in the copolymer
run a 5concn (mol/L)ethene pressure (bar)
propene pressure (bar)t (h)yield (g)catalyst activity b mol %wt %
T g (°C)T m (°C)
?H (J/g)
M w M w /M n 10.021120.219100100150020.0530.8
129.7637 1.117.0-40
3300 1.530.0160.80.25 1.167500.717.2125.0n.d.203000 6.440.0060.80.080.8178000.919.6123.5101318000 3.35
0.016
0.8
2
1.1
834
1.2
24.5
115.0
77
234000
1.9
a
Catalysts:runs 1-3,zirconocene dichloride (Cp 2ZrCl 2)/MAO;run 4,dimethylsilylenebis(indenyl)zirconocene dichloride (Me 2Si(C 9H 6)ZrCl 2)/MAO;run 5,dimethylsilylene(tetramethylcyclopentadienyl)(N -tert -butyl)titanium dichloride (Me 2Si(Me 4Cp)(N-t -Bu)TiCl 2)/MAO.Polym-erization conditions:[cat])100μmol/L,Al:Zr or Ti )1000,total volume )50mL,ambient temperature.b Activity in [kg polymer/mol Ti ?h ?mol/L].
2820Tsuchida et al.Macromolecules,Vol.30,No.10,1997
P (ethene))P (propene))0.8bar,T )25°C.The further procedure after termination of the polymerization is described in the following.
Homopolymer 7(Run 1).The toluene solution was poured into 500mL of acidic methanol to dissolve the catalyst system.The white precipitate formed was collected by filtra-tion.The filter cake was washed with hot methanol (40mL ×4)and dried under reduced pressure.After drying,the methanol-soluble part was 60mg,still containing some oligo-mer 7,while the methanol-insoluble part was 240mg,still containing a trace of monomer 5.Yield:240mg (30%).1H NMR (CDCl 3):δ0.57(q,Si -C H 2-CH 3,28H),0.97(t,CH 3,42H),1.18-1.46(m,CH 2,32H),1.97(q,d C(C H 2)2,4H),4.66ppm (s,d C H 2,2H).IR (KBr):3065(νC d C s H ),2955,2915,2850,2740(νH -C -H ),1640(νC d C ),1465(νCH 3),1410,1250,1230(νSi -C ),1120(νSi -O ),1015,960,800,760,698,535,465,390cm -1(νSi -O ).Anal.Calcd for C 24H 54Si 8O 12:C,37.99;H,7.18.Found:C,39.98;H,7.37.
Copolymers 8a -c (Runs 3-5).Immediately after the copolymerization was started in an analogous manner as in the case of 7,the reaction mixture became turbid and the viscosity increased.After 15min the toluene solution was poured into 250mL of diethyl ether containing 50mL of methanol and hydrochloric acid.After filtration,the white product was dried to constant weight in vacuo.Removal of remaining traces of monomer 5in the product was achieved by Soxhlet extraction with cyclohexane for 36h;yield 1.08g.1H NMR (C 2D 2Cl 4,373K):δ0.58(q,Si -C H 2-CH 3
,14H),0.95(t,Si -CH 2-C H 3,21H),1.25(s,PE-chain,507H,and CH 2-spacer of 5,16H).13C NMR (C 2D 2Cl 4,373K):δ4.10(Si -C H 2-CH 3), 6.16(Si -CH 2-C H 3),12.01(Si -C H 2-R,C 1of spacer),18.58(polymer chain endgroup),22.8(Si -CH 2-C H 2-R,C 2of spacer),27.0(R 2CH -CH 2C H 2-),29.65,30.17(PE-chain and C 4-C 7of spacer),31.88(polymer chain endgroup)32.50(C 3of spacer),34.29(R 2CH -C H 2),38,00(PE -R C H -PE),40.71ppm (polymer chain endgroup).IR (KBr):2960,2850(νH -C -H ),1468(νCH 3),1412,1370,1255,1230(νSi -C ),1115(νSi -O ),1015,760,718,700,540,470,390cm -1(νSi -O ).Anal.Calcd for PE:C,85.63;H,14.37.Found:C,78.09;H,13.49.Copolymer 9(Run 2).2-Propanol (10mL)was added to the toluene solution to terminate the reaction.After solvent removal,the viscous residue was dissolved in 200mL of petroleum ether and washed with dilute hydrochloric acidic (20mL ×3).After removal of petroleum ether under reduced pressure,10.2g of a viscous liquid was obtained.In order to separate remaining monomer 5from the copolymer,40mL of acetone was added to the product.The mixture was heated briefly.After cooling to room temperature,the acetone-soluble part was separated from the insoluble part by centrifugation.This procedure was repeated twice.After solvent removal and drying,the acetone-insoluble fraction (9a )yielded 4.27g of a turbid,viscous reaction product.The acetone-soluble part (9b )consisted of 5.40g of a clear viscous liquid.1H NMR of 9a (CDCl 3):δ0.59(q,Si -C H 2-,3.1H),0.81(m,CH(C H 3)in PP,54H),0.97(t,Si -CH 2-C H 3,3.1H),1.13(CH 2in PP,38H),1.24(CH 2in spacer,3.5H),1.58(m,CH,19H),1.67(s,d C s CH 3,3H),1.9-2.08(m,d C s CH 2-,2H),4.63(s)and 4.71(s)ppm (d CH 2,2H).13C NMR (CDCl 3):δ4.06(Si -C H 2CH 3),6.51(Si -CH 2-C H 3),11.9(Si -C H 2-R),14.4(CH 3of propyl end-group),18.9-21.4(CH 3in PP),22.23(d C(CH 3)s C H 2-),22.77(Si -CH 2-C H 2-R),26.9-27.8(CH in PP),27.86(CH at propyl end-group),29.3-29.9(C 3-C 7in spacer),35.29(PP -C H(CH 2R)-PP),40.47(PP-CH(C H 2R)-PP),43.7-57.4(CH 2in PP),111.28(d CH 2of PP end group),144.78ppm (d CH(CH 3)of PP end-group).29Si NMR (CDCl 3):δ-65.49(Si-Et,3Si),-65.60(Si -Et,4Si),66.07(Si -Dec,1Si).IR (neat):3060(νC d C s H ),2910,2875,2845,2725(νH -C -H ),1650(νC d C ),1460(νCH 3),1415,137812551230(νSi -C ),1115(νSi -O ),1015,972,988,810,760,700,540,470,390cm -1(νSi -O ).Anal.Calcd for PP:C,85.63;H,14.37.Found:C,77.86;H,11.75.
Results and Discussion
Monomer Synthesis.The synthesis of the mono-functionalized monomer 5was achieved via five steps as shown in Scheme 1.The cubic hydrido-
spherosiloxane 1,3,5,7,9,11,13,15-octahydridopentacyclo-[9.5.1.13,9.15,15.17,13]octasiloxane (1)(O h -H 8Si 8O 12or H 8T 8)was prepared according to the method of Agaskar and Desu by controlled hydrolysis of HSiCl 3.3,35We were able to obtain pure H 8T 8in good yields (18%)via a slightly modified procedure,using petroleum ether instead of the solvent mixture of toluene,methanol,and hexane isomers described by Agaskar.3It should be mentioned that partial solvent removal permitted us to isolate H 8T 8by fractionation crystallization and enabled us to separate it from a mixture containing H 8T 8and H 10T 10.
In order to protect one double bond,decadiene was partially brominated to yield 9,10-dibromo-1-decene (2).Subsequently,2was hydrosilated with H 8T 8to obtain 1-(9,10-dibromodecyl)-3,5,7,9,11,13,15-heptahydrido-pentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane (3)in a simi-lar manner as reported before.36The disappearance of the terminal vinyl protons of 2was confirmed by monitoring the reaction with 1H NMR spectroscopy.Unfortunately,during this reaction step,isomerization of approximately 50%of the terminal vinyl bonds (12.8mmol)of 2to internal double bonds was always ob-served as a side reaction of hydrosilation.The isomer-ized double bond could clearly be distinguished from the terminal vinyl group of 2in the 1H NMR spectrum (5.4ppm).On the other hand,51%of H 8T 8were recovered after the reaction,thus the actual molar ratio of H 8T 8:2was 1:1.02.It should be noted,that although isomer-ization of double bonds as a side reaction of hydrosila-tion is well-known,50%isomerization was unexpectedly high.H 8T 8seemed to promote the isomerization reac-tion.This result was observed by us in other H 8T 8-substitution reactions too.37
The product of the third step was successively used for the synthesis of 1-(9,10-dibromodecyl)-3,5,7,9,11,13,-15-heptaethylpentacyclo[9.5.1.13,9.15,15.17,13]octa-siloxane (4)without purification,because isomerized 2was no longer reactive to the Si -H bond.In the fourth step all remaining Si -H bonds of the hydridospherosi-loxane were concerted to Si -C 2H 5by hydrosilation with ethene in order to eliminate reactive SiH groups,which impede separation of the monofunctional T 8derivative by chromatography.Furthermore,nonalkylated T 8was expected to interact with the metallocene catalyst employed for the ensuing copolymerization.After completion of the ethylation,which was monitored by following the disappearance of the SiH vibration in IR,isomerized 2was separated and subsequently 4debro-minated with Zn/CH 3COOH to obtain monomer 5.After chromatography,5was obtained in 43%yield with respect to H 8T 8used.
Monomer 5was characterized by 1H,13C,and 29Si NMR spectroscopy as well as IR-spectroscopy and elemental analysis.The signal pattern observed in the 29Si NMR spectrum (Figure 1,top)is in agreement with the general pattern for hetero-1:7-substituted spheric T 8derivatives (R 7R ′Si 8O 12),described by Marsmann 38recently.Three signals with signal ratio 1:3:4evidence monosubstitution.Silicon a (66.29ppm)bearing the decenyl group (1Si),the silicon atoms b (-65.68ppm)in the neighborhood of the former (3Si),and the silicon atoms which occupy the face-diagonal (c )and the body-diagonal (d )corners to silicon a .The signals for c and d can not be distinguished in the 29Si NMR spectrum;they appear as one signal (-65.79ppm).The 13C NMR spectrum (Figure 1,middle)shows large signals for the seven ethyl groups (4.08and 6.51ppm)as well as
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Ethene and Propene Copolymers 2821
signals for the terminal vinyl bond (114.1and 139.2ppm)and eight signals for the (CH 2)8spacer of the decenyl group (11.89-33.86ppm).The 1H NMR spec-trum (Figure 1,bottom)supplements characterization of 5.
Polymerizations.Polymerizations as shown in Scheme 2were carried out under dry argon atmosphere,using Schlenk flasks.Different MAO-activated metal-locene catalysts were used as explained in Table 1.Reaction times and other conditions employed are summarized in Table 1.The further procedure concern-ing workup of the resulting copolymers was different in each case.Homopolymerization as well as copolym-erization experiments with ethene and propene,respec-tively,have been performed.
Homopolymerization of 5yielded oligomers with an average degree of polymerization of 2-3,as clearly derived from the ratio of terminal vinyl protons and ethyl protons in the 1H NMR spectrum.Copolymeriza-tions of 5with ethene (Table 1,runs 3-5)and propene (Table 1,run 2)clearly led to incorporation of 5into the polyethene and polypropene chains,respectively,reaching up to 24.5wt %5incorporated into poly-(ethene-co -5).Calculation of the number of 5units per polymer chain (Table 2)revealed an average of four comonomeric units per copolymer chain in runs 4and 5.This confirms predominately incorporation of 5into the polymer chain with respect to possible chain termi-nation by 5.
The catalyst productivity was hardly affected.Evi-dently,the ethyl groups shield T 8sufficiently to prevent coordination reactions with catalyst and cocatalyst.In the case of poly(ethene-co -5)the 13C NMR spectrum (Figure 2)shows that isolated T 8-units were incorpo-rated,as expected for random copolymers containing 0.7-1.2mol %5.Due to the different conditions used for the NMR spectra of 5and the copolymer 8(C 2D 2Cl 4as solvent and higher temperature,100°C)the peaks are shifted slightly in comparison to the spectrum of 5.The signals at 12.01ppm (C 1in spacer),22.80ppm (C 2in spacer),and 32.47ppm (C 3in spacer)and for a part of the (CH 2)x spacer are unchanged after polymerization,similar to the peaks for the ethyl group at 4.10and 6.16ppm.The latter are substantially larger than the resonances of the decenyl carbons,as also observed in the spectrum of 5.A part of the (CH 2)x spacer of 5leads to signals in the same region of the spectrum as the polyethene chain at about 29.7ppm.The vinyl reso-nances of 5at 114.1and 139.2ppm as well as the signals due to the CH 2unit adjacent to the vinyl group at 33.86ppm disappeared.New peaks at 27.0(R 2CH -CH 2-C H 2),34.29(R 2CH 2-C H 2),and 38.0ppm (R 3C H)appear,due to the spacer attachment of 5to the PE chain.Additional peaks at 18.64,31.9,and 40.7ppm might be a result of chain termination after the inser-tion of comonomer 5.The content of 5incorporated
in
Figure 1.29Si NMR spectrum (top),13C NMR spectrum (middle),and 1H NMR spectrum (bottom)spectra of mono-mer 5
.
Figure 2.13C NMR spectrum of copolymer 8b ,poly(ethene-
co -5).
Table 2.Calculation of the Number of 5Units per Polymer Chain for Poly(ethene-co -5)s from Runs 3-5
run M n 5content (mol %)no.of comonomer
5units per polymer chain
3320000.7 1.24960000.9 3.65
123000
1.2
4.3
2822Tsuchida et al.Macromolecules,Vol.30,No.10,1997
the copolymers was determined by 1H NMR spectros-copy and elemental analysis showing that up to 24.5mol %5were incorporated using 6c /MAO.This catalyst is known for its high degree of incorporation of R -olefins.34b
The 29Si NMR spectrum of the polypropene copolymer 9(Figure 3)evidences that no rearrangement reaction of T 8due to the Lewis acidic catalyst components took place.The catalyst employed led to atactic low molar mass oligopropene,which was obtained as a viscous liquid.The molar mass of 9(poly(propene-co -5))ac-cording to 1H NMR spectroscopy was determined to be M n )1000;GPC analysis shows a low molar mass of M w )2200with M w /M n )1.5.Similar molar masses are commonly observed for copolymerizations of propene with 1-octene in the presence of Cp 2ZrCl 2,giving soluble polymers of low molar mass.30
Thermal Properties of the Copolymers.Poly-(ethene-co -5)(8)resembles linear low density polyethene (LLDPE)in appearance,but its melting point (deter-mined by DSC and DTA)is 7K lower (125°C)than the melting point of pure PE (132°C).This is due to the structural irregularities,which are caused by the in-corporated spherosiloxane-bearing monomer.The varia-tion of the melting point may appear small;however,only 0.7mol %of 5was incorporated,leading to one pendant spherosiloxane every 140monomer units in the copolymer chain.Poly(propene-co -5)(9)is a viscous liquid,with a T g at -40°C.
Copolymer 8and 9have been investigated with respect to their thermostability,8under nitrogen-and air-atmosphere (Figure 4)and 9only under air atmo-sphere (Figure 5),using TGA.The thermostability was compared to that of pure PE and oligopropene,respec-tively.
Polyethene and poly(ethene-co -5)(8)show no differ-ence in thermostability under N 2(Figure 4,top),but under air the thermostability of 8is superior (Figure 4,bottom).The TGA curve under air is shifted to higher temperatures.The weight increase observed at 220°C under air is most probably due to elimination of ethyl groups and reaction of Si with oxygen.Similar effects were observed for T 8substituted with 8n -alkyl groups,such as n -octyl or n -decyl units,which were employed as model compounds.39Above 220°C,the T 8units are irreversibly linked,and the resulting material clearly shows an improved thermostability.Also copolymer 9shows a slight increase of weight and a higher thermo-stability in air (Figure 5).
Conclusion
1-(9-Decenyl)-3,5,7,9,11,13,15-heptaethylpentacyclo-[9.5.1.13,9.15,15.17,13]octasiloxane (5)has been prepared via a five-step synthesis.H 8T 8could be synthesized in a slightly simplified procedure according to the method of Agaskar.The yield of 5with respect to H 8T 8employed was 43%.Monomer 5was incorporated into copolymers with ethene (8a -c )and propene (9)via metallocene catalysis,yielding the first example of copolymers with polyolefin main chain and silsesqui-oxane cages as side groups.13C NMR spectroscopy of poly(ethene-co -5)shows covalent incorporation of 5into the copolymer with comonomer contents up to 24.5mol %.29Si NMR spectroscopy confirms that 5inserted without rearrangement of the cubic silsesquioxane part of 5in spite of the Lewis acidic catalyst
employed.
Figure 3.29Si NMR spectrum of copolymer 9,poly(propene-
co -5
).
Figure 4.TGA-trace of PE and copolymer 8a under N 2atmosphere (top)and under air atmosphere
(bottom).
Figure 5.TGA-trace of PP and copolymer 9under air atmosphere.
Macromolecules,Vol.30,No.10,1997Ethene and Propene Copolymers 2823
Thermal investigations of the copolymers showed that an increase of thermostability could be achieved.
The novel copolymers poly(ethene-co-5)and poly-(propene-co-5)are interesting materials with respect to the effect of T8as a structural irregularity on the crystallization and morphology of polypropene and https://www.sodocs.net/doc/d08409348.html,ing ansa-metallocene catalysts,it was possible to improve molar masses and comonomer incorporation with respect to the unbridged catalyst Cp2-ZrCl2/MAO.
Acknowledgment. F.G.S.is grateful for a fellow-ship by the Studienstiftung des deutschen Volkes and financial support by the BASF AG. A.T.as well as C.B. acknowledges support by the Graduiertenkolleg of the SFB60.We also want to thank Wacker Chemie for providing triethoxysilane.
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