UCST-type behavior of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) in aliphatic alcohols: solvent, co-solvent, molecular weight, and end group dependences

Abstract

Poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) is shown to possess insoluble– soluble transitions (UCST-type phase behavior) in a large variety of aliphatic alcohols. Samples of different molecular weights ranging from 5 kg mol1 to 23 kg mol1 prepared by the RAFT process and featuring different end groups at each end were analyzed by cloud point measurements. Transitions occurred sharply and were fully reversible. The UCST was found to increase with an increasing molecular weight. Hydrophobic (alkyl chain) end groups were found to lower the critical temperature in isopropanol, while rigid aromatic end groups raised the transition temperature. In ternary mixtures of isopropanol/chloroform/POEGMA, the UCST decreased with an increasing chloroform concentration, with 10 vol% of chloroform accounting for a 30 C drop. In mixtures of isopropanol/ hexane/POEGMA, the cloud point increased significantly only with hexane concentrations above 30 vol%, at which level a 2 C transition temperature increase was found. Addition of water to isopropanol solutions had a strong effect, with 1 vol% of water causing a decrease of the transition temperature of 12.5 C. With an increasing chain length of the solvent, the cloud point increased, while a branching of the hydrocarbon chains lowered the cloud point. Samples of 23 kg mol1 POEGMA were for instance found to have cloud points of 22.0 C in ethanol, 35.7 C in isopentanol, and 75.4 C in dodecanol

Multi‐stimuli‐responsive Polymers Based on Calix[4]arenes and Dibenzo‐18‐crown‐6‐ethers

“…Thermal relaxation back to the trans form results in the polymers regaining their cloud point from prior to irradiation within 24h. Similarly to reports by Roth et al 33 , our tegylated poly(azocalix [4]arene)s and poly(azodibenzo-18-crown-6-ether)s showed strong dependence of the cloud point on water content within the alcohol sample. In the first case, minimal addition (0.5% v/v) of water to a polymer fraction AZTEGOMe20 in ethanol (2.5 g/L) resulted in a shift of the demixing temperature by 10°C.…”

“…In the past, systems based on poly(methyl methacrylate), PMMA 31 , poly(2-oxazolines) 32 and copolymers of hydroxyethyl methacrylate and acetoacetoxyethyl methacrylate in ethanol/water mixtures have also demonstrated the UCST-behaviour. Recently, poly(oligoethyleneglycol) methacrylate, POEGMA has been shown to undergo the UCST-type transitions in alcohols, which are strongly dependent on the degree of polymerization, concentration, alcohol and end groups 33 .…”

“…Recently, poly[oligo(ethylene glycol methyl ether) methacrylate], POEGMA has been shown to undergo LCST-type transitions in water 125 and UCST-type behaviour in alcohols 33 . Building on these studies, we wanted to prepare poly(azocalixa [4]arene)s derivatized with tetraethylene glycol monomethyl ether in the lower rim and investigate their thermo-responsiveness in the above mentioned solvents.…”

Thermo‐Induced Double Phase Transition Behavior of Physically Cross‐Linked Hydrogels Based on Oligo(ethylene glycol) methacrylates

“…[ 34 ] Roth et al showed that POEGMA based copolymers also exhibit a UCST behavior in alcohol/ water mixtures. [ 35,36 ] Hu and Paris et al prepared organic cross-linker cross-linked P(MEO 2 MA -co-OEGMA) hydrogels, which featured a controllable LCST depending on the monomer molar ratio. [ 37,38 ] Different from the previous linear polymers or thermosenstitive hydrogels, both of which exhibit only one UCST or LCST and have been reported extensively, we recently developed a series of clay/P(MEO 2 MA -co-OEGMA) nanocomposite (NC) hydrogels featuring double volume phase transition temperatures (UCST and LCST).…”

Swelling behavior of thermosensitive nanocomposite hydrogels composed of oligo(ethylene glycol) methacrylates and clay

“…Recently, oligo(ethylene glycol) methacrylate (OEGMA) based polymers have gained increasing attention because of their biocompatibility and adjustable VPTT [24][25][26]. Lutz et al first reported the thermosensitive copolymers by copolymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO 2 MA) and OEGMA units, showing obvious advantages such as non-toxicity, narrow hysteresis, and precisely tunable VPTT between 20 and 80°C, which could be adjusted by the length of the side chains and the copolymer composition [27][28][29].…”