Open-aired synthesis of star-shaped poly[2-(methacryloyloxy)ethyl trimethylammonium chloride]

Abstract

A series of star-shaped poly[2-(methacryloyloxy)ethyl trimethylammonium chloride]s with different arm lengths were synthesized via open-aired enzymatically assisted ATRP using the 2-hydroxypropyl β-cyclodextrin derivative as an initiator. The resulting PMETAs with narrow molecular weight distribution (Đ = 1.06-1.12) created thin hydrophilic films with thickness < 40 nm exhibiting water contact angle (WCA) values < 50°. Higher interfacial tension values obtained for star-shaped polymers in comparison with the linear analog indicate that surface wettability can be modified by changing the polymer topology. AFM was used to analyze the relationship between macromolecule topology, surface roughness, and WCA.

Fig. 1. Reaction scheme for the synthesis of star polymers.

Fig. 2. SEC traces of eight-arm PMETA from RID detector.

Fig. 3. A comparative graph showing monomer conversion (left ordinate, semi-logarithmic) and molecular weight change from NMR data (right ordinate) over polymerization time C8.

Fig. 4. WCA as a function of DP per arm of obtained polymers at a concentration of 0.5 mg mL⁻¹ (A), a subset of the top graph showing only star-shaped polymers (B).

Fig. 5. Partial dissolution of PMETA at the point of contact between the coating and the water drop.