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. Cc yu t nh hng n qu trnh trng hp gc2. Phn ng trng hp ion (ionic polymerization)2.1. Trng hp cation2.2. Trng hp anion3. 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 tng

2.2. Phn ng trng hp ion (ionic polymerization)Trng hp anionTrng hp cationKhi no phn ng trng hp ion xy ra?(Trng hp c xc tc)

Trng hp anionAcrylonitril (AN) PANizobutylen Trng hp cation Styren monome ?

Khc bit gia trng hp gc v trng hp ion C ch trng hp ion khng c r rng nh trng hp gc v l phn ng phn ng d th (xc tc v c, monome hu c).Vn tc trng hp ion ln hn rt nhiu so vi trng hp gc, phn t polyme c KLPT cao c to ra rt nhanh phn ng xy ra trong iu kin khng ng nht. Mch ion pht trin lun km theo ion tri du; phn cc ca dung mi v kh nng solvat ha ion tri du c nh hng ln n qu trnh trng hp ion; Phn ng t mch khng th xy ra gia hai trung tm hot ng l ion.

2.3.1 Trng hp cationa. Xc tc Xc tc Fridel-Krafts (AlCl3, BF3, SnCl4, TiCl4, FeCl3): l nhng cht nhn in t. Axit proton: HClO4, H2SO4, H3 PO4 (t c s dng) Cht tr xc tc H2O, ru, axit, v mt s cht halogen hu c khcTc phn ng trng hp cation l rt cao nhit thp. V d: trng hp isobutylen - 100oC vi xc tc AlCl3, BF3 to thnh polyme c KLPT khong 106 ch trong vi giy!. Nhit tng lm gim tc phn ng v KLPT ca polyme, nhit phng KLPT c polyme nh hn khi tng hp bng P trng hp gc

b. C ch phn nga) Khi mob) Pht trin mchc) t mchd) Chuyn mch: chuyn mch ln dung mi, tp cht (H2O), polyme (to mch nhnh)(Ch yu theo kiu u ni ui)Do phn ng thng c tin hnh trong dung mi hydrocacbon (phn cc thp), nn tc pht trin mch, tt mch v chuyn mch ph thuc vo bn cht ca cp ion (lc tng tc tnh in gia cation v anion)

V d: trng hp isobutylen bng BF3 a) Khi mob) Pht trin mch

c) Tt mchChuyn mch ln monome

c. ng hc phn ngM = monomeRH = ng xc tcH+ AR- = phc ca xc tc v ng xc tc

Vn tc phn ng khi mo RiVn tc phn ng tt mchM+ = mch ang pht trin trng thi cn bng Ri = RtVn tc phn ng trng hp cation

trng hp trung bnh s Phn ng tt mch l ch yuPhn ng chuyn mch l ch yu trng hp ph thuc c vo nng monome v nng xc tc

a. Xc tcCc hp cht c kh nng nhng i e baz Lewis: KOH, NaOH, KNH22.3.2 Trng hp anion Cc hp cht c kim mang tnh baz rt mnh

b) Cc hp cht c kh nng lm chuyn dch 1e cho monome - thng l kim loi kim (Li, Na, K, ) hoc l gc ion c to thnh t naphtalen v kim loi kim. Loi ny c ng dng thc t nhiu nht.Tu thuc vo phn cc ca mi trng m trung tm hot ng ca phn ng trng hp anion l ion t do hay cp ion. Tu thuc vo bn cht ca xc tc m chng ta c cc phng trnh ng hc ca phn ng khc nhau.Ch :

V d: Trng hp acrylonitril di tc dng ca KNH2 trong mi trng NH3 lng.Pht trin mchKhi moChuyn mch

b. ng hc phn ngTrong mi trng amoniac lng c phn cc rt cao b qua [K+] trong pt ng hc

Vn tc phn ng khi mo RiVn tc phn ng tt mch trng thi cn bng Ri = Rt

Vn tc phn ng trng hp trng hp

Trong trng hp trng hp styren nng lng hot ho ca phn ng chuyn mch ln hn nng lng hot ho ca phn ng pht trin mch v nng NH3 rt cao, do phn ng chuyn mch ln NH3 nhanh hn phn ng pht trin mch thu c khi lng phn t polystyren thp cho d phn ng c tin hnh nhit thp. Trng hp anion di tc dng cu hp cht c kim (khng c phn ng t mch) Trng hp anion di tc dng ca kim loi kim khi mo bng chuyn e v khng c phn ng t mch

Nu phn ng xy ra trong iu kin khng c tp cht th c th nhn c polyme c khi lng phn t ln, ng u cao v c cu trc u n.Dng tng hp cc copolyme khi (t cc polyme sng !)Tng hp cc oligome khng cha v c cha nhm chc cui mchb. c im ca phn ng trng hp ion

Dung mi nh hng rt ln n vn tc ca phn ngYu cu i vi monome v dung mi phi ht sc tinh khit. Loi b tt c cc tp cht nh: vt nc, CO2, v chng lm mt hot tnh ca xc tc