前言：硅膠是化工生產(chǎn)中的一大領(lǐng)域，在工業(yè)、手術(shù)、日化中均有運(yùn)用。本文以兩種硅油（端氫硅油&甲基氫硅油）為典例，研究了在硅氫合成有機(jī)硅彈性體時(shí)，硅油分子含氫量、分子結(jié)構(gòu)及乙烯基-硅氫鍵摩爾比對(duì)于反應(yīng)物交聯(lián)的影響，并探討了現(xiàn)象后因由。
1.1 淺談硅膠彈性體
交聯(lián)硅膠是一類低交聯(lián)密度的液體硅橡膠，耐高溫（200℃），耐低溫（-50℃~-80℃），絕緣，無(wú)副產(chǎn)物，收縮率小，無(wú)毒無(wú)味，無(wú)腐蝕，安全衛(wèi)生，機(jī)械密度低，低交聯(lián)密度又賦予其良好的吸震性，粘合性，密封性，防潮性及防污性。由于性狀柔軟，交聯(lián)硅膠受到輕微壓力即可引起形變，無(wú)色透明，流動(dòng)性好，宜填充精密結(jié)構(gòu)，故有其以下三種特殊用途。
1）LED電子封裝膠
2）醫(yī)療整容
3）化妝品成分
1.1 Background
Additional silicone gel is a kind of liquid silicone rubber with low crosslinking density. It possesses the properties of high (200℃) and low (-50℃~-80℃) temperature resistance, electrical insulation, low shrinkage and mechanical strength without by-products, poison, smell and corrosion while ensuring safety and health. Low crosslinking density gives good shock absorption, adhesiveness, airtightness, moisture and soil resistance. Because of the soft character, it can easily change its shape under small load and low pressure. Meanwhile, its colorless and transparent appearance and good liquidity, which make it easy to fill in into fine parts of precise structures, lead to its specific end use as listed below:
1) Electronic Packaging for Light Emitting Diodes
2) Medical and Cosmetic Surgery
3) Cosmetic Products
1.2 有機(jī)硅彈性體的結(jié)構(gòu)
三維網(wǎng)狀聚合物的形成被稱之為交聯(lián)。交聯(lián)鍵可被看作長(zhǎng)硅鏈分支。 交聯(lián)鍵數(shù)量龐大, 故形成能黏性的不溶性網(wǎng)狀結(jié)構(gòu)或凝膠。
鉑催化水解反應(yīng)能形成網(wǎng)狀結(jié)構(gòu)，故常被用于含≡Si-H的低分子量聚硅氧烷與含≡Si-Vi的高分子量聚硅氧烷之間的反應(yīng)。
1.2 The Chemical Structure of Silicone Elastomers
Cross-links are junctions of polymer strands in a three-dimensional network. They may be viewed as long-chain branches that are numerous enough to form insoluble network or gel.
Platinum catalyzed hydrosilylation reactions, which are used to form network structures, are typically involved in reactions between a low molecular weight polysiloxane containing ≡Si-H groups, and a high molecular weight polysiloxane containing ≡Si-vinyl groups, vice versa.
2. 有機(jī)硅彈性體化學(xué)結(jié)構(gòu)與性能關(guān)系的實(shí)驗(yàn)驗(yàn)證
2.1 實(shí)驗(yàn)方法：
提前將 Gvi (甲基乙烯基硅橡膠)溶解于D5 (十二甲基環(huán)環(huán)硅氧烷) 中。分別加入不同摩爾比的 DH1000 和 MHS。觀察反應(yīng)過(guò)程和結(jié)果。
2.2 實(shí)驗(yàn)器材：
電子天平;玻璃棒;汞溫度計(jì);燒杯;恒溫水浴
2.3 反應(yīng)物：
DH1000-------------端氫硅油 (Mw=1000 1000, H%= 0.2%)
MHS----------------甲基氫硅油 (H%=1.6%, 梳狀結(jié)構(gòu))
Gvi------------------甲基乙烯基硅橡膠 (Mw= 570000, Vi%= 0.22%)
D5------------------十二甲基環(huán)戊硅氧烷
H2PtCl6/IPA(1%)---氯鉑酸的異丙醇溶液
2.4 溶液：
在實(shí)驗(yàn)過(guò)程中使用相同的乙烯基膠,即Gvi/D5 (20/80), Mw=570000, Vi%=22%
乙烯基膠制備：取20克 Gvi, 然后倒入80克 D5。攪拌不止至Gvi溶解，亦可室溫下靜置一宿。
2.5 操作示范--實(shí)驗(yàn)1
Gvi/D5 (20/80)------10g (0.000157mol -Vi)
DH1000-------------0.08g (0.00016mole -H)
Pt/IPA---------------0.014g (5ppm)
稱量10克 Gvi/D5 (20/80), 0.08g DH1000。滴入 H2PtCl6, 攪拌。將燒杯放置在70-90℃恒溫水浴池。20分鐘內(nèi)，溶液發(fā)生交聯(lián)。將溶液在恒溫水浴中保留2小時(shí), 形成透明、柔軟的凝膠。
2.6 實(shí)驗(yàn)結(jié)果與比較
實(shí)驗(yàn)對(duì)比 | |||||
反應(yīng)溫度 | 交聯(lián)時(shí)間 | 交聯(lián)程度 | 黏度 | 硬度 | |
端含氫硅油的活潑氫與乙烯基的摩爾比為1：1 |
80-90℃ | 20分鐘 | 固體(彈性體) | III | III |
端含氫硅油的活潑氫與乙烯基的摩爾比為2：1 | 黏度有增長(zhǎng)，但變化不明顯 | 液體 | / | / | |
高含氫硅油的活潑氫與乙烯基的摩爾比為1：1 | >60分鐘 | 固體(彈性體) | I | I | |
高含氫硅油的活潑氫與乙烯基的摩爾比為2：1 | 30分鐘 | 固體(彈性體) | V | V | |
黏度與硬度分為I、II、III、IV、V五級(jí)，其中“I”最強(qiáng)。 | |||||
2 Experiments to verify the relationship between chemical structure and properties of silicone elastomers
2.1 Experimental methods
Dissolve Gvi (methyl vinyl silicone rubber) in D5 (decamethylcyclopentasiloxane) in advance. Add DH1000 and MHS of different proportion of moles respectively. Observe reaction processes and results.
2.2 Laboratory apparatus
Electronic balance; Glass stick; Mercury thermometer; Beaker; Thermostatic water bath
2.3 Reagents
DH1000----------Hydrogen-terminated silicone oil (Mw=1000, H%=0.2%)
MHS------------ Methylhydrogen silicone oil (H%=1.6%， comb structure)
Gvi--------------Methyl vinyl silicone rubber (Mw=570000, Vinyl%=0.22%)
D5--------------Decamethylcyclopentasiloxane
H2PtCl6/IPA(1%) ---Chlorideplatinum acid dissolved in Isopropyl alcohol
2.4 Pre-solution
During the experiment, use the same vinyl gum, or Gvi/D5 (20/80), Mw=570,000, Vi%=0.22%.
Preparation： Take 20 grams of Gvi, then pour 80 grams of D5 into it. Stir until dissolved.
2.5 Operation Demo—Example 1
Gvi/D5 (20/80)-------10 grams (0.000157mole Vinyl)
DH1000--------------0.08 grams (0.00016mole -H)
Pt/IPA----------------0.014 gram (5ppm)
Weight 10 grams of Gvi/D5 (20/80), 0.08g DH1000. Add H2PtCl6 and stir in a beaker.The beaker was placed in a 80-90℃ thermostatic water bath. Gelation took place within 20 minutes. The gel was left in thermostatic water bath for 2 hours, resulting in a clear and soft gel.
2.6 Comparison of experiment results
EXP. | Temperature | Crosslinking Duration | Product Phase | Viscosity | Hardness | |
1 | The molar ratio of hydrogen-terminated silicone oil and vinyl is 1:1. |
80-90℃
80-90℃ | 20 minutes | Solid (elastomer) | IV | IV |
2 | The molar ratio of hydrogen-terminated silicone oil and vinyl is2:1. | Crosslinking barely happens | liquid | I | I | |
3 | The molar ratio of methyl hydrogen silicone oil and vinyl is 1:1. | 60 minutes | Solid (elastomer) | III | III | |
4 | The molar ratio of methyl hydrogen silicone oil and vinyl is2:1. | 30 minutes | Solid (elastomer) | V | V | |
Viscosity and Hardness are divided into five degrees: I,II, III,IV,V, from strong to weak. | ||||||
3.1 結(jié)果與分析
1)交聯(lián)時(shí)，≡Si-H與≡Si-Vi物質(zhì)的量相同
現(xiàn)象：DH1000（端氫硅油）的反應(yīng)比MHS(甲基氫硅油)更快、更容易。
推論：DH1000（端氫硅油）活性較高。
猜想：乙烯基與MHS的交聯(lián)反應(yīng)受阻, 完全反應(yīng)困難而緩慢。
2)交聯(lián)時(shí)，≡Si-H 過(guò)量
現(xiàn)象：乙烯基與MHS（甲基氫硅油）反應(yīng)產(chǎn)物堅(jiān)硬，而與DH1000（端氫硅油）的產(chǎn)物是液體。
推論：乙烯基與MHS中的≡Si-H完全反應(yīng)，使該產(chǎn)品具有較高的交聯(lián)密度。
猜想：DH1000中硅氫反應(yīng)未充分進(jìn)行，僅有單端反應(yīng)。故該產(chǎn)品交聯(lián)程度非常低。
3.1 Results and Discussions
1) ≡Si-H groups and ≡Si-Vi groups are equimolar.
The reactions Hydrogen-terminated siliconeapplied are faster and easier than Methyl hydrogen silicone oil (H%=1.6% combstructure). Hydrogen-terminated is with higher activity.
Due to hindered reaction with MHS, the complete reaction is difficult and slowly.
2）Excess ≡Si-H groups
Reaction product with MHS is hard, vinyl reacted completely.Theproduct is provided with high crosslinking density.
Due to only partial hydrosilylation reaction with Vinyl-Si≡, only single end reacts. The product is rarely crosslinked.
4.1 總結(jié)
以DH1000(端氫硅油)為交聯(lián)劑, 僅有兩個(gè)官能團(tuán)。交聯(lián)產(chǎn)品可以是二維網(wǎng)狀結(jié)構(gòu)，亦可是三維立體網(wǎng)絡(luò)結(jié)構(gòu)。在使用MHS(甲基氫化硅油)作為交聯(lián)劑的同時(shí), 參與交聯(lián)的多個(gè)官能團(tuán), 形成了具有較高交聯(lián)密度的三維網(wǎng)絡(luò)結(jié)構(gòu)產(chǎn)物。
4.1 Conclusion
There are only two functional groups,when using Hydrogen-terminated silicone as crosslinking agent. The crosslinking products can form a two-dimensional network structure, or a three-dimensional network structure. When using methyl hydrogenated silicone oil as crosslinking agent, multiple functional groups are involved in the crosslinking stimutaniously, resulting in a three-dimensional network structure with higher crosslinking density.
參考文獻(xiàn)
1. 電子封裝中使用的有機(jī)硅彈性體
<www.wap.alighting.cn/webapp/view.aspx>
2. 辛松民， 有機(jī)硅合成工藝及產(chǎn)品應(yīng)用，化工出版社，2000
3. Kadlec, Donald Anthony, et al. US 6770708.2004
Works Cited
1. Silicone elastomers used in electronic packaging www.wap.alighting.cn/webapp/view.aspx?CategoryID=1&ContentID=158534 Accessed on 5 December, 2018.
2. Xin,Songmin, 辛松民.YoujiguiHechengGongyi Ji ChanpinYingyong有機(jī)硅合成工藝及產(chǎn)品應(yīng)用[Organic Silicon Synthesis Process andItsProductApplication].ChemicalIndustry Press, 2000.
3. Kadlec,Donald Anthony, et al. US 6770708.2004
來(lái)源：小v化學(xué)實(shí)驗(yàn)室
