Phase Behavior of Poly(2-vinylpyridine)-block-Poly(4-vinylpyridine) Copolymers Containing Gold Nanoparticles,Macromolecules

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Phase Behavior of Poly(2-vinylpyridine)-block-Poly(4-vinylpyridine) Copolymers Containing Gold Nanoparticles
Macromolecules ( IF 5.1 ) Pub Date : 2017-12-01 00:00:00 , DOI: 10.1021/acs.macromol.7b01590
Jaeyong Lee ₁ , Jongheon Kwak ₁ , Chungryong Choi ₁ , Sung Hyun Han ₁ , Jin Kon Kim ₁

Affiliation

We studied the phase behavior of the poly(2-vinylpyridine)-block-poly(4-vinylpyridine) copolymer (P24VP) containing gold nanoparticles, by rheometry, small-angle X-ray scattering, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). Although both blocks of P24VP exhibited attractive interaction to gold precursors, unusual phase behavior was observed depending on the amount of gold nanoparticles. As the amount of gold nanoparticles increased, the order-to-disorder transition temperature (T_ODT) of P24VP with gold nanoparticles decreased first, then increased, and finally decreased again. To explain this phenomenon, we prepared two block copolymers: polystyrene-block-poly(2-vinylpyridine) copolymer (PS2VP) and polystyrene-block-poly(4-vinylpyridine) copolymer (PS4VP) containing gold nanoparticles. With increasing the amount of gold particles, the T_ODT of PS2VP increased continuously, whereas that of PS4VP gradually decreased. For PS4VP containing gold nanoparticles, because P4VP chains can interact with the gold nanoparticle surface, density fluctuations exist near the gold nanoparticle surfaces, which causes the T_ODT to decrease. On the other hand, although the pyridine ring in P2VP could be associated with the gold surface, P2VP chains become stretched due to steric hindrance arising from the ortho position of nitrogen in P2VP. The chain stretching increases the T_ODT. Thus, the decrease of T_ODT for P24VP originates from P4VP microdomains containing gold nanoparticles, while the increase of T_ODT is attributed to the P2VP microdomains containing gold nanoparticles. With increasing the amounts of gold nanoparticles, the contribution of P4VP microdomains containing gold nanoparticles on the T_ODT becomes dominant, causing the T_ODT to redecrease. To verify the gold nanoparticle position in both P2VP and P4VP microdomains, we performed TEM and scanning transmission electron microscopy (STEM) experiments. At lower amounts of gold nanoparticles, they are mainly located inside P4VP microdomains. With increasing the amount of the gold nanoparticles, they are distributed in both P2VP and P4VP microdomains, though the amount of gold nanoparticles in P4VP microdomains is larger than that in P2VP microdomains.

中文翻译：

含金纳米粒子的聚（2-乙烯基吡啶）-嵌段-聚（4-乙烯基吡啶）共聚物的相行为

我们研究了聚（2-乙烯基吡啶）的相行为-块含有金纳米颗粒-聚（4-乙烯基吡啶）共聚物（P24VP），通过流变测定法，小角度X射线散射，透射电子显微镜（TEM）和差扫描量热法（DSC）。尽管P24VP的两个嵌段均显示出与金前体的吸引力相互作用，但根据金纳米颗粒的量，观察到了异常的相行为。随着金纳米颗粒数量的增加，具有金纳米颗粒的P24VP的有序到无序转变温度（T _ODT）先降低，然后升高，最后再降低。为了解释这种现象，我们制备了两种嵌段共聚物：聚苯乙烯嵌段-聚（2-乙烯基吡啶）共聚物（PS2VP）和包含金纳米颗粒的聚苯乙烯-嵌段-聚（4-乙烯基吡啶）共聚物（PS4VP）。随着金颗粒数量的增加，PS2VP的T _ODT持续增加，而PS4VP的T _ODT逐渐降低。对于包含PS4VP的金纳米颗粒，由于P4VP链可与金纳米颗粒表面相互作用，因此在金纳米颗粒表面附近存在密度波动，这导致T _ODT降低。另一方面，尽管P2VP中的吡啶环可能与金表面缔合，但由于P2VP中氮的邻位引起的位阻，P2VP链被拉伸了。链条拉伸增加了T _ODT。因此，P24VP的T _ODT的减少源自含有金纳米颗粒的P4VP微域，而T _ODT的增加归因于含有金纳米颗粒的P2VP微域。随着金纳米颗粒数量的增加，含金纳米颗粒的P4VP微域在T _ODT上的贡献占主导地位，从而导致T _ODT减少。为了验证金纳米颗粒在P2VP和P4VP微域中的位置，我们进行了TEM和扫描透射电子显微镜（STEM）实验。在较少量的金纳米颗粒下，它们主要位于P4VP微域内部。随着金纳米颗粒的数量增加，它们在P2VP和P4VP微域中均分布，尽管P4VP微域中的金纳米颗粒的数量大于P2VP微域中的金纳米颗粒的数量。

更新日期：2017-12-01

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