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Cooperative Folding of Linear Poly(dimethyl siloxane)s via Supramolecular Interactions
Macromolecular Rapid Communications ( IF 4.2 ) Pub Date : 2017-11-06 , DOI: 10.1002/marc.201700566
Marcin L. Ślęczkowski 1 , E. W. Meijer 1 , Anja R. A. Palmans 1
Affiliation  

The synthesis and characterization of graft copolymers are reported based on linear poly(dimethyl siloxane) (PDMS) and chiral, pendant benzene‐1,3,5‐tricarboxamides (BTAs). The copolymers differ in degree of polymerization (DP) and BTA graft density. Characterization of the bulk materials at room temperature reveals that the BTAs aggregate in a helical fashion via threefold hydrogen‐bond formation within the PDMS matrix. A significant degree of hydrogen bonding persists up to 180 °C, regardless of DP and BTA content. Analysis of the solution behavior by 1H NMR spectroscopy indicates that BTA aggregation occurs in CDCl3, a solvent normally suppressing aggregation. Circular dichroism (CD) spectroscopy in 1,2‐dichloroethane shows strong CD effects and reveals that increasing the DP and decreasing the BTA graft density results in an increase in the cooperativity of the BTA aggregation. Dynamic light scattering indicates the formation of particles with sizes of 400 nm. This is the first time that polymers with pendant BTAs show a sharp transition between a nonaggregated and aggregated state, a behavior similar to the one observed for “free” BTAs. The cooperative aggregation is attributed to the strong phase‐segregation between the PDMS backbone and the BTAs, in combination with a high propensity of these polymers to form multichain aggregates.

中文翻译:

通过超分子相互作用的线性聚(二甲基硅氧烷)的合作折叠。

据报道,接枝共聚物的合成和表征是基于线性聚二甲基硅氧烷(PDMS)和手性悬垂苯-1,3,5-三甲苯酰胺(BTA)。共聚物的聚合度(DP)和BTA接枝密度不同。室温下对散装材料的表征表明,BTA通过PDMS基质中的三重氢键形成以螺旋形式聚集。无论DP和BTA的含量如何,氢键都可在高达180°C的温度下持续存在。通过1 H NMR光谱分析溶液行为表明BTA聚集发生在CDCl 3中,通常可抑制聚集的溶剂。1,2-二氯乙烷中的圆二色性(CD)光谱显示出很强的CD效应,并且表明增加DP和降低BTA接枝密度会导致BTA聚集体的协同作用增加。动态光散射表明形成了尺寸为400 nm的颗粒。这是带有侧链BTA的聚合物首次显示出非聚集态和聚集态之间的急剧转变,这种行为类似于“游离” BTA所观察到的行为。合作聚集归因于PDMS主链和BTA之间的强相分离,以及这些聚合物形成多链聚集体的高倾向性。
更新日期:2017-11-06
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