Abstract
The aggregation behavior of three tadpole-shaped Polyhedral oligomeric silsesquioxane (POSS) based block copolymers using different blocks poly(methyl methacrylate) (PMMA) and poly(trifluoroethyl methacrylate) (PTFEMA) with different block sequence and ratio (POSS-PTFEMA161-b-PMMA236, POSS-PMMA277-b-PTFEMA130, and POSS-PMMA466-b-PTFEMA172) was investigated on the air-water interface. The interfacial rheology of three block copolymers was studied by surface pressure isotherm, compression modulus measurements, and compression and expansion hysteresis analysis on the Langmuir trough. The block sequence and ratio play a great role in self-assembly behavior at the interface. Based on surface pressure isotherm analysis, a thin film with low elasticity was achieved for the POSS-PTFEMA161-b-PMMA236. Moreover, for the block copolymer with same segment sequence (POSS-PMMA2-b-PTFEMA), the thin film compression capability is increased with increasing the PMMA ratio. The morphology of the deposited LB thin film was illustrated by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). We observed that a thin film was composed by crater-shaped quasi-2D micelles for POSS-PTFEMA-b-PMMA, while it was proved that only flaky texture was observed for both POSS-PMMA277-b-PTFEMA130 and POSS-PMMA466-b-PTFEMA172. The thickness and area of flaky aggregates were greatly related to PMMA ratio. The different interface self-assembly structure evolution was proposed based on the interfacial rheology and thin film morphology studies.
Highlights
Polyhedral oligomeric silsesquioxane (POSS), with the welldefined cage-like silica cubic nanoscale, has received considerable attention
The results showed that these alternating copolymer brushes could form spherical aggregates in water
The tadpole-shaped POSS-based copolymers used in this study were synthesized via atom transfer radical polymerization (ATRP) in our laboratory which is detailedly expressed in SI
Summary
Polyhedral oligomeric silsesquioxane (POSS), with the welldefined cage-like silica cubic nanoscale, has received considerable attention. POSS may be referred to as a silica nanoparticle consisting of a silica cage core, as well as other organic functional groups attached to the corners of the cage, which consist of hybrid organic-inorganic composition [1,2,3]. The design ability and compatibility of POSS are improved by the higher reactivity of organic functional or reactive groups. Since reported by Seo and coworkers [7], interfacial selfassembly of POSS-based small molecules or polymers has attracted great interest during the past few decades. A variety of POSS-based small molecules or polymers were synthesized and the different self-assembly behavior was achieved as well [8,9,10,11,12]. Jiang et al [14] prepared a POSS-based amphiphilic supramolecule from the host-guest inclusion complexation between a mono adamantane-functionalized
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