聚合物纳米复合材料
Hongbin Lu, Steven Nutt, Macromol. Chem. Phys. 2003, 204: 1832-1841
玻璃化转变的热力学- 玻璃化转变的热力学-动力学相关性
(C. A. Angell et al, Nature, 2001, 410, 663-667)
玻璃化转变的构象熵模拟
∆C p = CT2 / T
τ = τ 0 exp{
B } T [1 − (T2 / T f )]
Results
High surface area + Good interface adhesion Lower configurational entropy Slower segmental motion Good stability and mechanical properties
Brian C. Sales, Science, 2002, 295, 1248
有机热电材料
基本原理、 基本原理、性能参数
Seebeck 效应 效应:温差产生电流 Peltier 效应 效应: 电场导致冷却 热电性能表征 热电优值 ZT = S2σT/κ κ
S - Seebeck 系数;σ - 电导率;κ - 热导率。 σ κ
CTE Flexible chain
High
Topological Structure Adjustment
Semi-Stiff chain
No polymer network No particle network Polymer network + Interpenetrating polymer local particle network and particle networks
i =1
u (t ) = ∫ dt ' / τ (t ' )
0
τ (T , S c ) = A exp(
B ) TS c (T )
φ (u ) = exp(−u β )
H c (T ) = H =H
lim c
[T (t )] − ∑ [ H clim (Ti ) − H clim (Ti −1 )]φ[u (t ) − u (t i −1 )]
家用冰箱的能量转换效率(卡诺系数):30% 大型中央空调设备的卡诺系数: 现有热电材料(ZT ~ 1.0)的卡诺系数: 90% < 10%
有机热电材料
最好的热电材料- 最好的热电材料-PbSeTe/PbTe QDSL
ZT = 2.0 at 300 K,
κ = 3.3 W/m.K,
∆T = 42.7 K
Contribution to CTE and mechanical properties Stiff chain
Low
Low
High
(2) Low CTE Nanoparticles
Montmorillonite Attapulgite MWCNT Polyoxometalate
固体颗粒表面改性
蒙脱土/环氧纳米复合材料蒙脱土/环氧纳米复合材料-受限松弛 (1)
相同条件下的纯树脂和复合材料的 DSC 曲线:10 oC/min 曲线:
相同过冷度下的不同材料的焓松弛 比较: 退火372小时 比较:Tg-20 oC 退火 小时
蒙脱土/环氧纳米复合材料蒙脱土/环氧纳米复合材料-受限松弛 (2)
Anastasiadis, S.H., Phys. Rev. Lett. 2000, 84(5):915-918 (Greece);
Electrical conductivity
104 S/cm; higher than amorphous metal Calcium-Aluminum (103 S/cm)
Thermal conductivity
MWNT: > 3000 W/m-K; higher than graphite (2000 W/m-K)
2. Nanobuilding blocks: (Inorganic clusters with low CTE) • (SiW10O36(RPO)2)4-)
• Zr10O6(OH)4(OPr)18(AAA)6
Mesoporous particle
有机热电材料
应用前景、 应用前景、研究现状
• 加电制冷 加电制冷--绿色冰箱,红外传感器制冷,电脑芯片制冷等; • 温差发电 温差发电--太阳能热电转换电池,热机式原子能电池,人 造卫星电源等。
Nonlinearity:
β
Non-equilibrium glass
Tf=Tg
x∆h * (1 − x) ∆h * τ = τ 0 exp[ + ] RT RT f
Nonexponentiality:
∆ h*
Equilibrium liquid Sc’, Tf ’ Temperature, T
φ (t ) = exp[−(t / τ ) β ]
多壁碳纳米管/ 多壁碳纳米管/环氧纳米复合材料
Only characteristic adsorptions of amine groups, no isocyanate groups 3.7 ± 0.9 % weight loss of organic molecules
多壁碳纳米管/ 多壁碳纳米管/环氧纳米复合材料
DSPN Components: Low CTE Inorganic Nanoparticles
1. Mesoporous nanoparticles: • ZrW2O8 (CTE =~ -8.5×10-6 K-1)
• HfW2O8 (CTE =~ -5.3×10-6 K-1)
Polymer molecules
多壁碳纳米管/ 多壁碳纳米管/环氧纳米复合材料
Discovered by Iijima in 1991 Outstanding properties: Tensile modulus
SWNT: ~ 1.25 TPa ; 56 times higher than steel wire 1.7 times higher than silicon carbide nanonods
Hongbin Lu, Steven Nutt, Macromolecules, 2003, 36(11):4010-4016
受限松弛的唯象解释 (1)
Segmental Relaxation
Heat capacity or enthalpy, Cp or Sc Non-Debye relaxation process
聚合物纳米复合材料
卢红斌 博士、副教授 博士、 复旦大学高分子科学系 跃进楼210室 跃进楼 室 电话: 电话:55664589(办) ( Email:hongbinl@ 2004年10月13日 年 月 日
研究思路
(1) Structural adjustment
Molecular Structure Adjustment
(TNM Model) )
x
受限松弛的唯象解释 (2)
Adam-Gibbs model:
* N A s c ∆µ τ = τ 0 exp( ) kTS c
Overview
Using cooperatively rearranging concept to elucidate the change in configurational entropy during segmental motions.
Sonication
多壁碳纳米管/ 多壁碳纳米管/环氧纳米复合材料
Simple Functionalization Method with Commercial Potential
Advantages: (1) rather mild reaction conditions (reflux at 80 oC) (2) shorter reaction time (~ 1 h) (3) higher functionalization efficiency (~ 4 wt %)
(Wei, Nano Letters, 2, Macromolecules, 2001, 34, 3041)
即将开展的工作
• 零膨胀有机高分子材料 • 有机热电材料 • 受限链段动力学 • 聚合物纳米复合材料流变学
零膨胀材料
New Concepts and New Materials
(1) Montmorillonite (MMT)
+ Na+ Na Na+ + Na+ Na Na+
Ion Exchange
(2) Attapulgite (ATT)
-OH -OH -OH
Activation, Covalently Bonding
(3) Multiwall Carbon Nanotubes (MWCNT) Oxidation, Functionalization (4) Polyoxometalate (POM) Coordination/Anion Exchange
多壁碳纳米管/ 多壁碳纳米管/环氧纳米复合材料
Dynamics simulation for SWNT-PS: CTE increases, whether in rubber state or in glass state Neutron reflectivity experiments: CTE decreases in the rubber state, due to the boundary confinement of polymer films
i =1 n Ti
n
lim c
lim [T (t )] − ∑ ( ∫ ∆C p (T )dT ) × exp( −( ∫ i =1 Ti −1