Chapter 12 Colloids and macromoleculesChapter 12 Colloids and macromolecules
12.1 Colloids
Dispersed systemDispersed phaseDispersed medium
Colloid dispersed system: 1-1000nm(10-9～ 10-6m)
Coarse dispersed system: >1m(10-6m)
Colloid or sol (lyophobic colloid)
Associated colloid (colloide electrolyte)
Macromolecular solution(lyophilic colloid)
Dispersed phase Dispersed medium Generally called e.g. Gas Liquid Foam
Liquid Liquid Emulsion Milk and crude oil with water Solid Liquid Colloids or
suspension Silver gel, printing ink and slurry, paints.
Gas Solid Solid foam Zeolite, foam. Liquid Solid pearl Solid Solid Plastic with color
Liquid Gas Aerosol fog Solid Gas Suspension Smoke and dust
Table 12-1Classfication of Dispersed System
preparation
Colloid system1nm ～ 1000nm
Solution<0.1nm
Agglomeration
Disperse
Coarse dispersed
system >1m
Replacingsolvent
reaction
Physicalagglomeration
rubbing ultrasonic
arc
12.2 Properties of Colloid
12.2.1 Tyndall Phenomena
02
20
22
20
22
240
2
cos122
9I
nn
nn
l
nvI
12.2.2 Movement Properties of Colloid
Fick’s first law of diffusion
Tx
nDA
t
N
d
d
(1) Diffusion
2/1
3
rL
tRTx
(2) Sedimentation
9
2
d
d 0B2 gr
t
x
120
BB
1
2 1ln hhRT
gM
n
n
Sedimentation equilibrium
)()/1(
)/ln(221
22
20
21B xx
nnRTM
12.2.3 The electrical double layer2
Stern potential ；
Moving potential
Thermodynamic potential e ；
++
++
++
++
+
--
--
-
-
-
++
++
+
+
++
-
-
--
-
-
+
-
-
-
Closed layer (stern layer)
Diffusion layer
e
Stern model
-
-
Solid surfaceStern section
Movable section
–
+
+
+
+
–
IHPOHP
固体表面水化阳离子
特性吸附阴离子
第一层水分子
第二层水分子
(b)博克里斯模型
–
滑动面
12.2.4 Structure of Colloids
AgNO3 +KI AgI
固相 紧密层 扩散层[ （ AgI ） m nAg+
（ n-x ） NO3]x+ xNO3-
溶液本体
胶核
胶粒 滑动面
胶团
NO3
-
NO
3 -N
O3
-
NO3-
NO3
-
NO
3-N
O 3-
NO 3-
NO
3 -
NO3-
NO3-
NO
3-
（ AgI ）m
Ag +A
g +
Ag + Ag +
Ag +
Ag +
Ag
+
Ag +
Ag +
Ag
+
Ag +
Ag +
12.2.5 Stabilization of Colloid
Kinetic stabilization
Coagulation stabilization
1. The effect of electrolyte on coagulation
Coagulation value
Schulze--Hardy rule
666 3
1:
2
1:
1
10.14:1.6:100
2. The effect of macromolecules on coagulation
bridging effect
dehydration effect
electric neutralization effect
12.2.6 DLVO theory
UR exp{∝ -x}
Umax
F
C
{x}
0
Born repulsion{U}
U
UA∝ nx
1
—Debye parameter
12.3 Macromolecules
Macromolecule MB>1 ～ 104kg.mol-1
Number-average molar mass <MN>
B
BBdef
N N
MNM
weight-average molar mass <Mm>
B
BBdef
m m
MmM
12.3. 1 Osmotic Pressure of Macromolecules Solution
3
B3B2B
B
1 BBM
RTΠ
B0
BB
lim
ΠRTM
12.3. 2 Membrane Equilibrium
Donnan equilibrium
Na+ (b)
Na + (b')
P x- (b')
Cl- (b)
Na+ (b)
Na + (b')
P 2- (b'/2)
Cl- (b)
P 2- Cl- Na +
Na + (b'+bx)
P 2- (b'/2)
Cl- (bx)
Na+ (b - bx)
Cl- (b- bx)
At equilibrium
(NaCl)(NaCl) RL
(NaCl)ln(NaCl)ln RL aRTaRT
R-
L- )](Cl)(Na[)](Cl)(Na[ aaaa
For dilute solution
2)()( xxx' bbbbb
bb
b
bb
b
b
b'
x
x
R
L
)NaCl(
)NaCl(
12.3. 3 Viscosity of Macromolecular Solution
Relative viscosity
A
def
r
Intrinsic viscosity
B
r
0
def 1lim
B
12.4 Coarse Dispersed System12.4.1 Emulsion
Emulsifier
Demulsification
12.4.2 Foam
12.4.3 Suspension
分散系统 性质
溶胶 大分子溶液
粒子大小 11000nm 11000nm 分散质存在的形
式 若干分子形成的胶粒 单个分子
能否透过 半透膜
不能 不能
扩散快慢 慢 慢 热力学稳定性 不稳定 稳定 均相系统
还是多相系统 多相 均相
丁达尔效应 强 微弱 粘度大小 小
（与介质粘度相似） 大
对电解质的 敏感性
敏感（少量电解质稳定，大量电解质聚沉）
不敏感（加入大量电解质才产生盐析现象）
聚沉物加入介质是否可逆复原
不可逆 可逆
表 10-2 胶体分散系统小结
