Self-adapting peripherally heterofunctionalized hyperbranched polymers: Formation of janus and tripodal structures

Ashok Zachariah Samuel, S. Ramakrishnan

研究成果: Article

14 引用 (Scopus)

抜粋

A peripherally clickable hyperbranched polyester carrying numerous propargyl terminal groups was prepared by a simple melt transesterification polycondensation of a suitably designed AB2 monomer; this clickable hyperscaffold was then transformed into a variety of different derivatives by using the Cu-catalyzed azide-yne click reaction. Functionalization of the periphery with equimolar quantities of mutually immiscible segments, such as hydrocarbon, fluorocarbon, and PEG, yielded frustrated molecular systems that readapt and form structures wherein the immiscible segments appear to self-segregate to generate either Janus structures (when two immiscible segments are present) or tripodal structures (when three immiscible segments are present). Evidence for such self-segregation was obtained from a variety of studies, such as differential scanning calorimetry, Langmuir isotherms, AFM imaging, and small-angle X-ray scattering measurements. Crystallization of one or more of the peripheral segments reinforced this self-segregation; the weight-fraction-normalized enthalpies of melting associated with the different domains revealed a competition between the segments to optimize their crystalline organization. When one or more of the segments are amorphous, the remaining segments crystallize more effectively and consequently exhibit a higher melting enthalpy. AFM images of monolayers, transferred from the Langmuir trough, revealed that the thickness matches the expected values; furthermore, contact angle measurements clearly demonstrated that the monolayer films are fairly hydrophobic, and in the case of the tripodal hybramers, the presence of domains of hydrocarbon and fluorocarbon appears to impart nanoscale chemical heterogeneity that is reflected in the strong hysteresis in the advancing and receding contact angles.

元の言語English
ページ(範囲)1245-1257
ページ数13
ジャーナルLangmuir
29
発行部数4
DOI
出版物ステータスPublished - 2013 1 29
外部発表Yes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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