Poly(vinylphosphonate)s with Widely Tunable LCST: A Promising Alternative to Conventional Thermoresponsive Polymers

Abstract

Novel statistic copolymers of dialkyl vinylphosphonates have been synthesized via rare earth metal-mediated group transfer polymerization using easily accessible tris-(cyclopentadienyl)ytterbium. The copolymerization parameters have been determined by activity measurements showing the formation of almost perfectly random copolymers (r 1 , r 2 ∼ 1). Thus, the polymerization rate of vinylphosphonate GTP is mainly limited by the steric demand of growing polymer chain end. The obtained copolymers of diethyl vinylphosphonate and dimethyl or di-n-propyl vinylphosphonate show thermoresponsive properties, i.e., exhibit a tunable lower critical solution temperature following a coil−globule transition mechanism, with cloud points between 5 and 92 °C. Hereby, the LCST can be precisely adjusted by varying the comonomer composition and correlates linearly with the content of hydrophilic/hydrophobic comonomer. These thermoresponsive poly(vinylphosphonate)s, exhibiting a sharp and reversible phase transition, and minor environmental effects such as concentration and additives on their cloud point, are promising candidates in biomedical applications.

Metal‐Catalyzed Group‐Transfer Polymerization: A Versatile Tool for Tailor‐Made Functional (Co)Polymers

“…Previous studies on DAVP‐polymers showed that statistical copolymers exhibit a tunable LCST between 5 and 92 °C. The cloud points correlate linear with the content of hydrophilic/hydrophobic comonomer . The same effect was shown in the block copolymers; the introduction of small amounts of dimethylvinylphosphonate (DMVP) or di‐ iso ‐propylvinylphosphonate (DPVP), statistically incorporated into the DEVP block, shifted the cloud points.…”

“…Random copolymers are prepared by pre‐addition mixing of monomers of the same kind (methyacrylates, acrylates, DAVP, etc.) and subsequent addition to the catalyst …”

Next Generation Multiresponsive Nanocarriers for Targeted Drug Delivery to Cancer Cells

“…However, REM‐GTP offers access to strictly linear polymer growth and very narrow molecular‐weight distributions ( Đ <1.1), and is applicable to a vast feedstock of monomers. In particular, dialkylvinyl phosphonates (DAVPs), which exhibit tunable thermoresponsive behavior, offer an alternative to the established polymers . Our group has made great progress in developing highly active catalysts for REM‐GTP and elucidating their mechanism of action .…”

Synthesis and tunable thermoresponsive solution morphologies of 2,2‐bis‐methylolpropionic acid dendron–azobenzene–poly(N‐isopropyl acrylamide) copolymers

“…For determination of LCST, a concentration of 0.2 wt% was used and measurements were performed at a fixed wavelength (600 nm), which is far from azobenzene absorption. LCST was defined as the temperature corresponding to 10% decrease in the optical transmittance based on literature reports . Precursor polymers N 3 ‐Azo‐PNIPAM 48 and N 3 ‐Azo‐PNIPAM 79 exhibited a sharp decrease in transmittance with an increase in temperature and the LCST was determined to be 28 and 32 °C, respectively.…”