Polymethacrylamide—An underrated and easily accessible upper critical solution temperature polymer: Green synthesis via photoiniferter reversible addition–fragmentation chain transfer polymerization and analysis of solution behavior in water/ethanol mixtures. Issue 21 (18th September 2020)

• Record Type: Journal Article
• Authors: Eckert, Tilman; Abetz, Volker
• Is Part Of: Journal of polymer science. Volume 58:Issue 21(2020)
• Page Start: 3050
• Page End: 3060
• Publication Date: 2020-09-18
• Subjects: dynamic light scattering -- reversible addition–fragmentation chain transfer -- thermoresponsive polymers -- upper critical solution temperature; Polymers -- Periodicals; Polymerization -- Periodicals; Polymerization; Polymers; Periodicals; 547.7
• DOI: 10.1002/pol.20200566
• Languages: English
• ISSNs: 2642-4150

Abstract

Abstract: Within the group of stimuli‐responsive, "smart" materials, upper critical solution temperature (UCST) polymers remain sparsely investigated. Thus, this work focusses on a vastly ignored UCST polymer: polymethacrylamide (PMAAm). A cost‐efficient photoiniferter reversible addition–fragmentation chain transfer (RAFT) polymerization yielding narrowly dispersed ( Đ < 1.1) PMAAm is presented. This PMAAm exhibits highly thermoreversible UCST‐type phase transitions (PT) in water/ethanol mixtures (ethanol content: 17–35 wt%) which are investigated via temperature dependent dynamic light scattering (DLS). Apart from the ethanol content, the PT temperature is affected by polymer mass fraction and chain length and varies between 10–80 °C depending on the three mentioned parameters. Lastly, PMAAm's propensity towards amide hydrolysis and concomitant PT‐suppression is investigated. Below temperatures of 40 °C, PMAAm solutions show no sign of amide hydrolysis for at least three days, however, if heated to 70 °C, the thermoresponsiveness gradually degrades within hours. Abstract : This work provides a pathway to a cost‐efficient and readily available stimuli‐responsive polymer via an eco‐friendly, aqueous, photoinduced, controlled radical polymerization. This polymer exhibits a fully thermoreversible phase separation in different water/ethanol mixtures upon cooling of the polymer solution. The temperature of this phase transition strongly depends on the polymer mass fraction and chain length. Being robust against amide hydrolysis at temperatures below 40 °C for at least three days, this polymer provides highly promising features for potential biomedical applications.