Surface-Initiated Chain Growth Polyaramid Brushes

Abstract

Synthesis of well-defined, surface-initiated poly­(N-octyl-p-benzamide) brushes was demonstrated using a new “grafting from” chain growth technique. A solution-based chain growth polycondensation technique was adopted from literature and modified to form a polyaramid brush by taking advantage of the differences in substituent effects between the activated surface-grafted initiator (methyl 4-(methyl­(3-(trimethoxysilyl)­propyl)­carbamoyl)­benzoate) and the deactivated deprotonated monomer (methyl 4-(octylamino)­benzoate). The surface-immobilized polymer brushes on silicon wafers were characterized using ellipsometry, goniometry, grazing-angle attenuated total reflectance–Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. In addition, polyaramid brushes were grown from high surface area Stöber silica and studied using thermogravimetric analysis, and the degrafted polymers were characterized using gel permeation chromatography and nuclear magnetic resonance spectroscopy. This is believed to be the first report of polyaramid brushes prepared by the surface-initiated chain growth polymerization technique, and the overall method allows for the preparation of novel aromatic polymer brush structures that could not be previously synthesized.

Facile Synthesis of Optically Active and Magnetic Nanoparticles Carrying Helical Poly(phenyl isocyanide) Arms and Their Application in Enantioselective Crystallization

“…In order to verify the M n and M w /M n values of poly-l-1 100 arms on the nanoparticles, poly-l-1 100 arms were etched from the isolated hybrid Fe 3 O 4 nanoparticles using hydrofluoric acid followed the reported procedures. [32] The structures of poly-l-1 100 arms were confirmed by Fourier transform infrared spectroscopy (FT-IR) and size exclusion chromatography (SEC) ( Figure S1, Supporting Information). As expected, it exhibited a single model and symmetric elution peak on SEC trace.…”

“…Treated the Fe 3 O 4 ‐Pd(II) with the enantiopure phenyl isocyanide ( l ‐ 1 ) bearing l ‐alanine ester pendant with a hexyl chain in CHCl 3 at 55 °C ([ l ‐ 1 ] 0 = 0.2 m , [ l ‐ 1 ] 0 /[Pd] 0 = 100) led to the formation of an inorganic/organic hybrid nanoparticle Fe 3 O 4 ‐poly‐ l ‐ 1 100 containing magnetic Fe 3 O 4 core and optically active helical PPI arms. In order to verify the M n and M w /M n values of poly‐ l ‐ 1 100 arms on the nanoparticles, poly‐ l ‐ 1 100 arms were etched from the isolated hybrid Fe 3 O 4 nanoparticles using hydrofluoric acid followed the reported procedures . The structures of poly‐ l ‐ 1 100 arms were confirmed by Fourier transform infrared spectroscopy (FT‐IR) and size exclusion chromatography (SEC) (Figure S1, Supporting Information).…”

“…The “grafting from” method, on the hand, can usually achieves nanoparticles with high grafting densities. However, it commonly requires a controlled chain growth mechanism in order to produce uniform arms with controlled chain lengths . In this work, we report on facile synthesis of inorganic/organic hybrid Fe 3 O 4 nanoparticles carrying helical poly(phenyl isocyanide) (PPI) arms via both “grafting from” and “grafting onto” strategies.…”

“…[5,6] Growing efforts are currently focused on combining multifunctional properties into one single magnetic composite microsphere, such as electrical controlled chain growth mechanism in order to produce uniform arms with controlled chain lengths. [32] In this work, we report on facile synthesis of inorganic/organic hybrid Fe 3 O 4 nanoparticles carrying helical poly(phenyl isocyanide) (PPI) arms via both "grafting from" and "grafting onto" strategies. As expected, these nanoparticles exhibited both optical activity and magnetism, which can be recycle used in enantioselective crystallization with assistant of a magnetic field.…”

Hierarchical comb brush architectures via sequential light-mediated controlled radical polymerizations

“…As the polymer brush field has evolved from simple homopolymer systems to block copolymers, a wide range of applications have also developed. For example, stimuli‐responsive surfaces based on block copolymer brushes are now a major area of study . Architectures with additional complexity, such as comb or branched polymer brushes, offer greater design flexibility to engineer specific properties.…”