An ATRP-based approach towards water-borne anisotropic polymer–Gibbsite nanocomposites

Abstract

This paper describes the synthesis of anisotropic polymer–Gibbsite nanocomposites with “muffin-like” morphology via a starved-feed ATRP emulsion polymerisation.

Design and Preparation of Highly Filled Water‐Borne Polymer–Gibbsite Nanocomposites

“…Since it is clearly seen from Figure d,e that platelets are not stacked, these particles are most likely due to coalesced particles already containing a single platelet. Finally, sample G‐8, with φ f = 35 wt%, was the only sample in which two types of morphology were observed (Figure e), i.e., the desired particles with the Gibbsite fully encapsulated and the so‐called “muffin‐like” morphology, which we previously observed in ATRP‐mediated nanocomposite formation . Particle counting (>100 particles) showed that about 70% of the particles had the former morphology and about 30% the latter.…”

“…Butyl acrylate – tert ‐butyl acrylate copolymerization with a monomer composition of 1:2 was carried out under ATRP conditions as previously described . The reaction was performed using [M]:[2‐bromo‐2‐methyl propionic acid phenyl ester]:[ N , N , N′ , N″ , N″ ‐pentamethyldiethylenetriamine]:[CuBr] = 200:1:1:1 in 10 vol% dimethylformamide at 70 °C.…”

“…1 H NMR (400 MHz, CDCl 3 , δ): 7.41, 7.25, 7.13 (aromatic H), 4.02 (OCH 2 ), 2.22 (CH 2 CH 2 ), 1.821.52 (CH 2 CH 2 C(C=O), 1.45 (OC(CH 3 ) 3 ), 0.96 (CH 3 ). The cooligomer composition was determined using 1 H NMR from the integrated intensity ratios of the area for the aromatic protons (δ = 7.13–7.41) of the end group to the area for the methyl group (δ = 0.96) of butyl acrylate or to the area for tert ‐butyl group (δ = 1.45) of tert‐ butyl acrylate, respectively . Selective hydrolysis of tert ‐butyl acrylate units using TFA was conducted as described previously .…”

“…The cooligomer composition was determined using 1 H NMR from the integrated intensity ratios of the area for the aromatic protons (δ = 7.13–7.41) of the end group to the area for the methyl group (δ = 0.96) of butyl acrylate or to the area for tert ‐butyl group (δ = 1.45) of tert‐ butyl acrylate, respectively . Selective hydrolysis of tert ‐butyl acrylate units using TFA was conducted as described previously . From the integrations of the proton signals between 0.8 and 2.8 ppm, it was calculated that 97% of the t BA was converted into acrylic acid (AA).…”

“…The discovery of a reversible addition‐fragmentation chain transfer (RAFT)‐mediated encapsulation method for filler materials, however, caused a significant shift in encapsulation strategy and many examples now exist in which this method was applied successfully . We recently extended this method to an atom transfer radical polymerization (ATRP)‐based method, which only in the presence of a cross‐linker led to encapsulated particles; without cross‐linker so‐called “muffin‐structures” were obtained . Realizing that the charged, reactive, oligomers used in both the RAFT and ATRP approaches in first instance act as stabilizers for the initial clay dispersion and subsequently for the polymer particles, we then used the charged oligomers as unreactive surfactants in a conventional starved‐feed emulsion polymerization .…”