bg hhpolyme ch2 phan ung tong hop goc

Chng 2: PHN NG TNG HP POLYME1. Phn ng trng hp gc (radical polymerization)1.1. S phn ng1.2. Cc giai on phn ng1.2.1. Giai on khi mo1.2.2. Giai on pht trin mch1.2.3. Giai on t mch1.3. Phn ng chuyn mch1.4. Phn ng hm trng hp1.5. ng hc phn ng trng hp gc1.6. Cc yu t nh hng n phn ng trng hp gc2. Cc phng php tin hnh trng hp gc 3.1. Trng hp khi 3.2. Trng hp dung dch 3.3. Trng hp huyn ph 3.4. Trng hp nh tng3. Phn ng trng hp ion (ionic polymerization)2.1. Trng hp cation2.2. Trng hp anion

Polymer Center- HUTS *n M( - M - )n

Polymer Center- HUTS

Polymer Center- HUTS *Phn loi Da vo thnh phn v cu trc ca polyme to thnh, Carothers chia phn ng trng hp thnh 2 loi: phn ng trng hp chui v phn ng trng ngng.

Phn ng trng hp (addition polymerization) l phn ng to thnh polyme c mt xch c bn vi cng thc phn t tng t vi monome tham gia to thnh polyme.

Phn ng trng ngng (condensation polymerization) l phn ng to thnh polyme vi mt xch c bn c t nguyn t hn monome to thnh, v thng to ra sn phm ph c khi lng phn t thp nh: H2O, HCl

Tuy nhin phng php chia ny cng gp phi mt s hn ch nh: mt s phn ng trng ngng li c vi c im ca phn ng trng hp chui v ngc li.


Polymer Center- HUTS *Da trn c ch ca qu trnh trng hp, chia lm 2 loi ln sau:

Phn ng trng hp tng bc (step polymerization): mch polyme pht trin tng bc bi phn ng c th xy ra bt k gia 2 phn t.

Phn ng trng hp chui (chain growth polymerization): mch polyme pht trin ch bng phn ng gia monome v nhm cui hot ng (trung tm hot ng) ca on mch ang pht trin. Phn ng ny lun cn phn ng khi mo (initial reaction) gia monome v cht khi mo bt u pht trin mch


Polymer Center- HUTS * Phn ng trng hp (addition polymerization)Mn + M Mn+1 Phn ng trng hp gc Phn ng trng hp ion (cation, anion, carbonyl) coordination polymerization Phn ng trng hp dng xc tc Ziegler Natta (Ziegler Natta Polymeriztion) Trng hp m vng (Ring opening metathesis polymerization) Phn ng trng ngng (condensation polymerization)Mx + My Mx+y + H2O, HCl, .2 phng php chnh chuyn cc hp cht ban u (monome) thnh polyme


TS.Tran Hai Ninh - Polymer Center- HUTS *1. Phn ng trng hp gc (radical polymerization)monomeR : H, Halogen, - CH3, -C2H5 .

TS.Tran Hai Ninh - Polymer Center- HUTS

*TS.Tran Hai Ninh - Polymer Center- HUTS


1.1. S phn ng

Khi mo (initiation)I R*R* + M R M*

Pht trin mch (propagation)R M* + M R MM* R MM* + n M R Mn+1 - M*

t mch (termination)

Vinyl monomeI : cht khi moR* : gc t doKt hp (coupling)Phn ly (Dispropotionation)*TS.Tran Hai Ninh - Polymer Center- HUTS


TS.Tran Hai Ninh - Polymer Center- HUTS *1.2. Cc giai on phn ng1.2.1. Giai on khi moI R*

R* + M R M*(to thnh cc gc t do)(to thnh trung tm hot ng) Cc phng php khi mo Phn hy nhit cht khi mo Khi mo bng phn ng oxi ha-kh Khi mo bng sng in t (nh sng, tia UV, gama) Khi mo bng nhit


TS.Tran Hai Ninh - Polymer Center- HUTS *a. Phn hy nhit cht khi mo Thng p dng cho cht khi mo c cha nhm peroxy (- O O - ) v nhm azo ( - N=N-), khong nhit phn ly 50 1000C, nng lng phn ly khong 25-40kcal/mol


TS.Tran Hai Ninh - Polymer Center- HUTS *


TS.Tran Hai Ninh - Polymer Center- HUTS *Phn hy nhit cht khi mo


TS.Tran Hai Ninh - Polymer Center- HUTS *Mt s gc t do b phn hy tip


TS.Tran Hai Ninh - Polymer Center- HUTS *b. Khi mo bng phn ng oxi ho-kh Phn ng trng hp nhit thp (do nng lng hot ho to ra cc gc t do rt thp 42kJ/mol). S dng rng ri trong qu trnh trng hp huyn ph v nh tng trong mi trng nc. H khi mo oxi ho-kh: Fe2+/H2O2H2O2 + Fe2+ HO - + Fe3+


TS.Tran Hai Ninh - Polymer Center- HUTS *- H khi mo oxi ho-kh gia Fe2+ v hydroperoxit hoc peroxit


TS.Tran Hai Ninh - Polymer Center- HUTS *1.2.1. Giai on khi mo (tip theo)I R*

R* + M R M*(to thnh cc gc t do)(to thnh trung tm hot ng)To thnh trung tm hot ng(I) chim u th!(II)


TS.Tran Hai Ninh - Polymer Center- HUTS *Phn ng ph lm gim hm lng gc t dobenzoyl peroxit


TS.Tran Hai Ninh - Polymer Center- HUTS *1.2.2. Giai on pht trin mchu ni uiu ni u


Polymer Center- HUTS * Various arrangements are possibleIn most polymer the head to tail configuration predominates ?


TS.Tran Hai Ninh - Polymer Center- HUTS *1.2.3. Giai on t mch Kt hpPhn ly C 2 phn ng t mch u xy ra, mc khc nhau tu thuc vo monome v iu kin trng hp. V d: mch polystyren kt thc ch yu bng phn ng kt hp, trong khi mch poly(metyl metacrylat) kt thc ch yu bng phn ly c bit nhit trn 600C.


TS.Tran Hai Ninh - Polymer Center- HUTS *1.3. Phn ng chuyn mch Phn ng chuyn mch ln dung miCc gc mi to ra tip tc khi mo phn ng trng hp monome


TS.Tran Hai Ninh - Polymer Center- HUTS *1.3. Phn ng chuyn mch Phn ng chuyn mch ln monome(i vi styren khng c phn ng ny ?)


TS.Tran Hai Ninh - Polymer Center- HUTS * Phn ng chuyn mch ln cht khi moPhn ng chuyn mch xy ra vi hydroperoxyt butyl bc 3 xy ra vi cao hn ! Trong khi phn ng chuyn mch khng xy ra vi azo-bis-izo butylroniltril1.3. Phn ng chuyn mch


TS.Tran Hai Ninh - Polymer Center- HUTS *1.3. Phn ng chuyn mch Phn ng chuyn mch ln polyme to cc nhnh trn mch polymePhn ng chuyn mch ln polyme thng xy ra trong cc qu trnh trng hp cc dien


TS.Tran Hai Ninh - Polymer Center- HUTS *1.4. Phn ng hm trng hpVn tc ca phn ng trng hp gim t ngt hoc ngng hnhydroquinon


TS.Tran Hai Ninh - Polymer Center- HUTS *Cc gc to thnh ch c kh nng kt hp vi nhau hoc kt hp vi gc ang pht trin.


1.5. ng hc phn ng trng hp gcGi thit ng hc phn ng trng hp l tngCh c giai on khi mo, pht trin v t mch c xem xtTt c cc phn ng u khng thun nghchNng hiu qu ca cht khi mo l n nhNng ca gc i phn t l n nhNguyn l tng tc ho hc cn bng p dng cho phn ng pht trin mch v ngt mchPhn ng ngt mch ch tn ti khi hai gc i phn t ng thi mt hot tnh.Nng monome = hng s

1. Phn ng khi moTrong : n s gc t do to thnh khi ph v 1 phn t cht khi mo (n=1 hoc 2); M c th l phn t monome hoc n v monome trn mch polymeVn tc phn ng (2) ln hn vn tc phn ng (1) rt nhiu, do vn tc khi mo c quyt nh bi vn tc phn hy cht khi u. (2)(1)

b) Quang phn hy cht khi u (quang khi mo)[2.3]Io cng nh sng ti; kh nng hp th ca cht khi mo [1/mol]; trng lng ta) Nhit phn hy cht khi u[2.2]kd l hng s phn hu cht khi mo (kd = 10-4 - 10-6 s-1) f l h s c trng cho phn gc R tham gia phn ng trng hp (thng f =0,3 -0,8 do phn ng chuyn mch)

2. Phn ng pht trin mchNu gi thit hng s tc , kp, ca phn ng pht trin mch khng ph thuc vo chiu di mch ang pht trin, khi phn ng pht trin mch c th biu din bng mt phn ng tng qut n gin: (phn R c b qua d nhn )Lng monome tiu hao trong phn ng khi mo c c th b qua nu nh so snh vi lng monome tiu hao trong phn ng pht trin mchhocTc phn ng pht trin mch (tc tiu hao ca monome)

nuKhi [2.4]

3. Phn ng ngt mch(trong kkh v kpl l hng s ca phn ng kt hp v phn ly)Khi vn tc gc t do (trung tm hot ng bin mt) l: Trong : h s 2 v tng nng trung tm hot ng [M] xut hin l do 2 mch ang pht trin vi chiu di bt k tham gia mt phn ng ngt mch; kt = kkh + kpl[2.5]

Trng thi dng (trng thi Bodenstein) c nh ngha: tng nng tt c gc t do trng thi dng[2.6][2.7]

a) Tc phn ng trng hp: [2.8]hoca) Phn hu nhit khi mo[2.9][2.10]b) Quang khi mo[2.11]

b) Chiu di ng hc trung bnh - trng hp[2.12]( trng thi dng)[2.13]

y: q = kpl/kt ( 0 q 1 )Khi q = 0 phn ng ngt mch ch xy ra theo kiu kt hpKhi q = 1 phn ng ngt mch ch xy ra theo kiu phn ly trng thi dng: thay [2.14]

Thay pt [2.2] vo pt [2.13] ta c:a) Phn hu nhit khi mob) Quang khi moThay pt [2.3] vo pt [2.13] ta c:[2.15][2.16]Nhn xt:

trng hp trung bnh s Xt trng hp khng c phn ng pht trin mch nhnh (side reaction): Trong : Mo = s phn t monome ban uMt = s phn t monome thi im tPt = s phn t polyme thi im t[2.17]Vi phn pt (2.16) theo thi gian:[2.18]

Ti thi im tc thi i, Xni l hng s: [2.18] Phn ng t mch theo c ch phn ly Phn ng t mch theo c ch kt hpTrng thi cn bng: Rt = Ri[2.19][2.20][2.21]

Phn ng t mch theo c ch phn ly Phn ng t mch theo c ch kt hp[2.12]Mt khc:Quan h gia trng hp trung bnh s v chiu di ng hc ca mch polyme:[2.22][2.23]

Xt trng hp phn ng chuyn mch(Phn ng chuyn mch l phn ng bc 2 v T l nng tc nhn gy ra phn ng chuyn mch)[2.24][2.25][2.26]Mt khc

Kt hp phng trnh (2.12) v (2.18):[2.27]: hng s chuyn mch[2.28] Khi hm lng tc nhn chuyn mch v tc phn ng chuyn mch tng ln, th chiu di ng hc mch polyme gim i tng ng. Nu s dng tc nhn chuyn mch c hot tnh rt cao (hp cht thiol) th ktr >> kp, thu c polyme c khi lng phn t rt thp, gi l telomer. Phn ng c gi l telomerization

TS.Tran Hai Ninh - Polymer Center- HUTS *1.6. Cc yu t nh hng n qu trnh trng hp gca) Nhit Phng trnh Arrhenius:[2.29][2.30][2.31]


i vi phn ng trng hp gc:Nng lng hot ha phn hy khong 30 kcal/molEp - Et /2 = 4 7 kcal/molDo : Khi T tng Rp tng trong khi khi lng phn t gim Trong trng hp quang v phng x trng hp,vn tc trng hp t ph thuc vo nhit hn m ph thuc chnh vo cng chiu sng

TS.Tran Hai Ninh - Polymer Center- HUTS *b) p sut p sut thp (vi chc n vi trm) t nh hng p sut cao (hng nghn atm) vn tc trng hp tng ln ng k, ng thi tng khi lng phn t polyme (ngc vi trng hp tng nhit )c) Oxy Oxy lm oxy ho monome to thnh peroxyt, tc phn ng tu thuc hot ng ca gc to thnh t peroxyt ny: nu gc sinh ra t hot tnh th O2 c tc dng hm qu trnh trng hp, cn nu gc trn hot ng th s lm tng vn tc trng hp gc Oxy lm chm quang trng hp ca vinylaxetat nhng lm tng vn tc trng hp styren


TS.Tran Hai Ninh - Polymer Center- HUTS *d) Nng cht khi u v nng monome:- Khi nng cht khi mo tng ln, vn tc trng hp tng nhng khi lng phn t trung bnh gim v trng hp trung bnh t l nghch vi nng cht khi mo Trong : K, K l hng s trng hp; [I] l nng cht khi mo; [M] l nng monome- Khi tng nng monome th vn tc trng hp v khi lng phn t polyme u tng, nhng ch tng c gii hn v nu hm lng monome cao qu s kh khng ch c phn ng.


TS.Tran Hai Ninh - Polymer Center- HUTS *e) nh hng ca cu trc monome: so snh monome styren v metyl metacrylat khi tham gia phn ng trng hp gc ?


Problem 2.1. Problems

Problem 2.2.

Problem 2.3.

Problem 2.4.

Problem 2.1. The decomposition of benzoyl peroxide is characterized by a half life of 7.3 h at 70oC and an activation energy of 29.7 kcal/mol. What concentration (mol/L) of this peroxide is needed to convert 50% of the original charge of a vinyl monomer to polymer in 6 hours at 60oC.(Data: f = 0.4; kp2/kt = 1.04x10-2 L/mol s at 60oC)Problem 2.2. For a new monomer 50% conversion is obtained in 500 min when polymerized in homogeneous solution with a thermal initiator. Predict the time for 50% conversion in another run at the same temperature but with four-fold initial initiator concentration.Problem 2.3. If a 5% solution of a monomer A containing 10-4 mol/L of peroxide P is polymerized at 70oC, 40% of the original monomer charge is converted to polymer in 1 h. How long will it take to polymerize 90% of the original monomer charge in a solution containing (initially) 10% A and 10-2 mol/L of peroxide P?(Advanced Polymer Chemistry, p.445)

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bg hhpolyme ch2 phan ung tong hop goc

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