Efficient Two-Step Synthesis of 11,11′-Dithiobis[1-(2-bromo-2-methylpropionyloxy)undecane], a Conventional Initiator for Grafting Polymer Brushes from Gold Surfaces via ATRP

AbstractWe investigated the interplay between different mechanisms of the lateral and vertical segregation in the synthesized via “grafting from” approach symmetric A/B (where A and B are poly(styrene-co-2,3,4,5,6-pentafluorostyrene) and poly(methylmethacrylate), respectively) polymer brushes upon exposure to different solvents. We used X-ray photoemission electron spectroscopy and microscopy (X-PEEM), AFM, water contact angle measurements, and oxygen plasma etching to study morphology of the brushes. The ripple morphology after toluene (nonselective solvent) revealed elongated lamellar-like domains of A and B polymers alternating across the surface. The dimple-A morphology consisting of round clusters of the polymer A was observed after acetone (selective solvent for B). The top layer was enriched with the polymer B showing that the brush underwent both the lateral and vertical phase segregation. A qualitative agreement with predictions of SCF theory was found.

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Multi-Stimuli-Responsive Mesoporous Membranes and Effect of Molecular Architecture on Thermo- and pH-Responsive Behavior of the grafted Block Copolymer brushes

10.26434/chemrxiv.7037699 ◽

2019 ◽

Author(s):

Yanchun Tang ◽

Kohzo Ito ◽

Hideaki Yokoyama

Keyword(s):

Polymer Brushes ◽

Diblock Copolymers ◽

Neutron Reflectivity ◽

Molecular Architecture ◽

Stimuli Responsive ◽

Responsive Polymer ◽

The Matrix ◽

Stable Part ◽

Copolymer Brushes ◽

Mesoporous Membranes

In this study, we prepared ultrafiltration membranes with a decoupled responses of filtration property to temperature and pH. The membrane preparation method was developed based on our previous work. We utilized methanol-supercritical carbon dioxide (methanol-scCO2) selective swelling method to introduce nanopores to block copolymers containing poly(diethylene glycol) methyl ether methacrylate (PMEO2MA), poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and polystyrene (PS) blocks. Formation of the mesoporous barrier layer with PS being the mechanically stable part of the matrix was driven by selective swelling of the PMEO2MA-b-PDMAEMA domains. Due to the selective swelling of PMEO2MA or PDMAEMA domains to introduce pores, the interior of the pores are covered with PMEO2MA or PDMAEMA blocks after pore formation. The PMEO2MA-b-PDMAEMA polymer brushes are naturally attached on the pore walls and worked as functional gates. PMEO2MA is a non-toxic, neutral thermo-responsive polymer with LCST at 26 ᴼC. PDMAEMA is a typical weak polyelectrolyte with pKa value at 7.0-7.5 and also a thermo-responsive polymer revealed a LCST of 20-80 °C in aqueous solution. Therefore, these membranes were expected to have multi dimensions as function of the combination of temperature and pH. Moreover, to understand the detail of the temperature and pH depended conformation transitions of PMEO2MA-b-PDMAEMA brushes, those diblock copolymers were end-tethered on flat substrates and analyzed via neutron reflectivity (NR).

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Numerical Simulations of Light Scattering from Rough One-Dimensional Gold Surfaces

10.21236/ada249794 ◽

1992 ◽

Author(s):

Eric I. Thorsos

Keyword(s):

Light Scattering ◽

Numerical Simulations ◽

Gold Surfaces ◽

One Dimensional

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