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Effect of Side Chains on the Low-Dimensional Self-Assembly of Polyphenylene-Based “Rod–Coil” Graft Copolymers in Solution
Macromolecules ( IF 5.5 ) Pub Date : 2017-12-28 00:00:00 , DOI: 10.1021/acs.macromol.7b02002
Dongdong Wu 1 , Fugui Xu 1 , Yinjuan Huang 1 , Chuanshuang Chen 1 , Chunyang Yu 1 , Xinliang Feng 2 , Deyue Yan 1 , Yiyong Mai 1
Affiliation  

We synthesized a series of “rod–coil” graft copolymers containing a laterally expanded poly-p-phenylene (PPP) backbone grafted with nonionic poly(ethylene oxide) (PEO) or ionic poly(acrylic acid) (PAA) side chains (denoted as PPP-g-PEO or PPP-g-PAA). The effect of the side chains on the self-assembly of the graft copolymers in THF–water mixed solvents was investigated. The PPP-g-PEO copolymers exhibited temperature-dependent self-assembly behavior, which is affected by the grafting percentage (GP) and the degree of polymerization (DP) of PEO. At 25 °C, which is higher than the crystallization temperature (Tc) of the PEO chains, PPP-g-PEO self-assembled into ultralong helices with controlled pitches when P > lm/4b, where P represents GP, N denotes DP of PEO, lm expresses the length of a repeating unit in PPP, and b is Kuhn monomer length of a free jointed PEO chain; when P < lm/4b, only nonhelical nanowires were observed. At 10 °C, which is below Tc of PEO, PPP-g-PEO self-assembled into polygonal multilayer nanosheets when Plm/4b, while ultralong helices or nanowires were formed when P < lm/4b. The PPP-g-PAA copolymer showed pH-sensitive self-assembly behavior. An increase in the electrostatic repulsion among the PAA coils in response to the pH change of the aggregate solution from 3 to 7 resulted in the formation of multiple low-dimensional nanostructures, including multilayer nanosheets, nanostrips, and helical nanostrips.

中文翻译:

侧链对溶液中聚苯撑“杆-卷”接枝共聚物低维自组装的影响

我们合成了一系列“杆-线圈”接枝共聚物,这些共聚物包含侧向扩展的聚对亚苯基(PPP)主链,接枝了非离子聚环氧乙烷(PEO)或离子聚丙烯酸(PAA)侧链(表示为如PPP- g -PEO或PPP- g -PAA)。研究了侧链对THF-水混合溶剂中接枝共聚物自组装的影响。所述PPP--PEO共聚物展出依赖于温度的自组装行为,其由接枝百分比(GP)和聚合的PEO的(DP)程度的影响。在25°C时,高于PEO链的结晶温度(T c),PPP- gP > l m / 4 b时,-PEO自组装成节距可控的超长螺旋,其中P表示GP,N表示PEO的DP,l m表示PPP中重复单元的长度,b是Kuhn单体长度自由连接的PEO链;当P < l m / 4 b时,仅观察到非螺旋纳米线。在10℃,这低于Ť Ç PEO的,PPP--PEO自组装成多边形多层纳米片当P/ 4b,而当P < l m / 4 b时形成超长螺旋或纳米线。所述PPP--PAA共聚物表明pH敏感的自组装行为。响应于聚集溶液的pH从3到7的变化,PAA线圈之间的静电排斥力增加,导致形成了多个低维纳米结构,包括多层纳米片,纳米带和螺旋纳米带。
更新日期:2017-12-28
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