Investigation of Free Radical Polymerization of Using Bifunctional Initiators

Transcription

1 Ivetigatio of Fee adical Polymeizatio of Uig Bifuctioal Iitiato Paula Machado 1, Cilee Faco 2, Liliae Loa 3, 1,2,3 Dep. de Poceo Químico - Fac. de Egehaia Química UNICAMP Cidade Uiveitáia Zefeio Vaz ; Ditito Baão Gealdo CEP: Campia SP Bail pmachado@feq.uicamp.b, liliae@feq.uicamp.b Peoxide moofuctioal iitiato ae exteively ued i idutie. Thi id of iitiato poduce two fee adical fo each decompoed molecule of iitiato. I ode to ehace poductivity, uually highe tempeatue o highe iitiato cocetatio ae ued. Howeve both alteative lead to lowe molecula weight. eeache i the developmet ad evaluatio of bifuctioal peoxide uig tyee ca be ee i ope liteatue. The effect of bifuctioal iitiato to diffeet moome beide tyee, epecially the oe that poduce log chai bache, i a impotat iue to be eeached. The objective of thi wo wa to ivetigate fee adical polymeizatio of moome that poduce liea ad bached polyme uig bifuctioal iitiato. Polyviyl acetate wa coideed a bached polyme. Simulatio eult wee compaed with expeimetal data i ode to validate the model popoed i thi wo. 1. Itoductio Nowaday, i the polyme iduty, the advatage of uig bifuctioal iitiato i to obtai at ame time high molecula weight ad high polymeizatio ate, which mae the utilizatio of bifuctioal iitiato a pomiig tategy of geat idutial iteet. I thi tudy expeimetal ad computatioal ivetigatio of fee adical polymeizatio of tyee (that poduce a liea polyme) ad viyl acetate (that poduce bached polyme) iitiated by dipeoxyete iitiato ha bee pefomed. Thee i a few wo epoted i liteatue uig bifuctioal iitiato to poduce liea polyme. All of them ue tyee a moome, which peet temiatio oly by combiatio ad doe ot have chai tafe eactio i it mechaim. A log a we ow, thee i o eeach epoted i liteatue uig bifuctioal iitiato to poduce bached polyme, a i the cae of polymeizatio of viyl acetate that peet tafe to moome ad tafe to polyme eactio, which ca affect the behavio of bifuctioal iitiato duig the polymeizatio. I thi wo polymeizatio of viyl acetate ad tyee i ampoule wee pefomed uig the bifuctioal iitiato 1,4-di (t-butyl-cabopeoxy) ciclohexae (Lupeox 531). The effect of thee paamete wee aalyzed: tempeatue, cocetatio ad fuctioality of the iitiato. The poduced polyme wa aalyzed i tem of coveio, ate of polymeizatio, molecula weight ad polydipeity. The mathematical model alo developed i thi wo (Machado 24; Machado ad Loa, 24; Machado ad Loa, 25) povide imulatio eult that agee with expeimetal data obtaied i thi wo.

2 2. Expeimetal Pat The mixtue of puified moome ad the iitiato i itoduced i ampoule, whee the bul polymeizatio will occu. The, the ampoule ae placed i a oil bath at a choe tempeatue. At choe iteval of time oe ampoule, at each iteval of time, i emoved fom the oil bath ad it i tafeed immediately to a bece with ice cube ad the to a bottle with liquid itoge to top the eactio. The cotet of the ampoule i emoved uig a olvet. The polyme i diolved uig ethaol ad the pecipitated uig methylee chloide. Afte the olvet evapoatio, the cotet of the ampoule i placed i a vacuum tove to full evapoatio of the olvet ad o-eacted moome. Coveio value ae obtaied by the gavimety method. The value of the aveage molecula weight wee obtaied though GPC (Gel Pemeatio Chomatogaphy) aalyi. 3. eactio Mechaim The eactio mechaim fo the fee adical polymeizatio of tyee ad viyl acetate uig bifuctioal iitiato ae ummaized below. 3.1 Bifuctioal Iitiato Iitiatio 2 d 1 i + i I (1) i 1 + M (2) 1 2 i M 1 + (3) P d + 2 i (4) 2 2 i P d + (5) M ia 3 21 (6) Popagatio p + M + 1 (7) Temiatio p + M + 1 (8) Combiatio

3 tc + P (9) + + P (1) tc + tc + P (11) + Depopotioatio + m td P + P (12) m td m P + Pm + (13) + m td P + P (14) m td m P + Pm + (15) Chai Tafe to Small Molecule ft + T P + T (16) ft + T P + T (17) T = iitiato, olvet, CTA, ihibito o impuity Chai Tafe to Polyme Log Chai Bach fp + P P + (18) fp + P P + (19) P + + (2) P + + (21) iteal adical, LCB tifuctioal

4 P + + (22) P + + (23) coliig, tetafuctioal bach 4. Model The model wa built i Fota 9. The equatio of the model wee developed baed i the ietic mechaim popoed i ectio 3.1. Ma balace fo all pecie i the ampoule wee coideed (iitiato, moome, ihibito, all id of adical ad dead polyme). The Method of Momet wa ued to pedict the umbe aveage molecula weight ( M ), the weight aveage molecula weight ( M w ) ad the polydipeity idex (PDI). Due to the complexity of the model ad it tiffe, the Gea method wa ued to olve the equatio ytem. 5. eult ad Dicuio Figue 1 ad 2 peet the coveio cuve to tyee at 115ºC ad 125ºC, epectively. Compaig the eult obtaied fom the modelig pat with the expeimetal data, it i poible to veify the behavio of a bifuctioal iitiato with tyee. The model pedictio howed good ageemet with the expeimetal data. A good compaio betwee moo- ad bi-fuctioal iitiato ca be ee i Machado, 24 ; Machado ad Loa, 24; Machado ad Loa, 25 ad Faco, 26.,8 Styee - T= 115 C; [I]=,29 mol/l Styee - T= 125 C; [I]=,29 mol/l,8,6,6 Coveio,4 Coveio,4,2 Model - Bifuctioal Expeimetal - Bifuctioal,2 Model - Bifuctioal Expeimetal - Bifuctioal, Time(mi), Time (mi) Figue 1 Coveio x Time Figue 2 Coveio x Time Figue 3 peet the umbe aveage molecula weight ( M ) pofile to the ame coditio ued i figue 1. It wa achieved a ageemet betwee eult fom the model ad expeimetal data, but a optimizatio wo i beig doe to adjut all paamete, i ode to impove them. Alo the expeimetal pat ude thee coditio i beig epeated, i ode to geeate moe expeimetal data. Figue 4 peet the weight aveage molecula weight ( M w ) pofile to the ame coditio ued i figue 3. The expeimetal data howed good ageemet with the

5 model pedictio. A expected, the value of 2; Machado, 24 ad Faco, 26). M w ae geate tha M (Dhib et al.; 2 Styee - T= 115 C; [I]=,29 mol/l M M W Model - Bifuctioal Expeimetal - Bifuctioal 1 5 Expeimetal - Bifuctioal Model - Bifuctioal,,2,4,6,8 Coveio,,1,2,3,4,5,6,7 Coveio Figue 3 M x Coveio Figue 4 Mw x Coveio Figue 5 peet the coveio cuve to viyl acetate at 115ºC. Compaig the obtaied eult fom the modelig pat with the expeimetal data, it i poible to veify the behavio of the bifuctioal iitiato with the viyl acetate: the coveio i fate (i elatio to tyee). Thi wa expected ice the polymeizatio of viyl acetate geeate moe adical tha the polymeizatio of tyee. The model pedictio howed good ageemet with the expeimetal data. A good compaio betwee moo- ad bi-fuctioal iitiato with viyl acetate ca be ee i Machado, 24 ; Machado ad Loa, 24; Machado ad Loa, 25 ad Faco, 26. Viyl Acetate T= 115 C; [I]=,5mol/l 1,,8 Coveio,6,4,2 Expeimetal - Bifuctioal Iitiato Model - Bifuctioal Iitiato, Time (mi) Figue 5 Coveio x Time Figue 6 ad 7 peet the umbe aveage molecula weight ( M ) pofile ad the weight aveage molecula weight ( M w ) pofile to the ame coditio ued i figue 5. The expeimetal data howed good ageemet with the model pedictio. It i vey impotat to otice hee that the M w ad M obtaied with viyl acetate ae highe tha the oe obtaied with tyee depite uig jut le tha ¼ of the cocetatio of iitiato. Thi ca be explaied by the peece of bached chai fo polyviyl acetate. Alo the effect of a bifuctioal iitiato clealy iteified the iceaig i the molecula weight value a ca be ee i Machado, 24.

6 ,,2,4,6,8 Viyl Acetate - T = 115ºC, [I]=,5 mol/l 1 Viyl Acetate T = 115ºC, [I]=,5 mol/l 2 8 Expeimetal - Bifucioal Iitiato Model - Bifuctioal Iitiato 15 6 M M w Expeimetal - Bifuctioal Iitiato Model - Bifuctioal Iitiato 2 Coveio,,2,4,6,8 Coveio Figue 6 M x Coveio Figue 7 Mw x Coveio 6. Cocluio Thi wo how the advatage i uig bi-fuctioal iitiato i the fee adical polymeizatio of tyee (geeatig a liea polyme) ad viyl acetate (geeatig a bached polyme). It ca be cocluded baed o the coditio of thi tudy that thi type of iitiato allow to each high coveio ad high molecula weigh imultaeouly. 7. efeece Dhib,.; Gao, J.; Pelidi, A.; Polyme eactio Egieeig, 8(4), p , 2. Faco, C.M.; MSc Thei, Feq/Uicamp, 26 Machado, P.F.M.P.B.; MSc Thei, Feq/Uicamp, 24. Machado, P.F.M.P.B.; Loa, L.M.F.; Hitoical ecod Cobeq 24 (CD) Machado, P.F.M.P.B.; Loa, L.M.F.; E. Symp. o Comp. Aided Poc. Eg.-15, 25, 2 A,