Temperature-Responsive Polymers

Chapter 4 Poly(N‐vinylcaprolactam): From Polymer Synthesis to Smart Self‐assemblies

Fei Liu Veronika Kozlovskaya and Eugenia Kharlampieva

Chemistry Department, University of Alabama at Birmingham, Birmingham, AL, 35294, USA

4.1 Introduction

Poly(N‐vinylcaprolactam) (PVCL) is a nonionic, water‐soluble polymer that exhibits a lower critical solution temperature (LCST) in aqueous solutions. In contrast to another ubiquitous temperature‐responsive polymer, poly(N‐isopropylacrylamide) (PNIPAM), PVCL possesses a classical Flory–Huggins thermoresponsive phase diagram with a continuous coil‐to‐globule phase transition from 36 to 50 °C, depending on molar mass and concentration [1, 2]. This feature allows for convenient control of PVCL temperature sensitivity by varying its molecular weight. PVCL is well documented for its ability to form complexes with electron‐donating molecules and its better stability against hydrolysis and, thus, excellent biocompatibility. Unlike PNIPAM, the amide group in the lactam ring of PVCL is directly connected to the chain backbone that increases the molecular stability, prohibiting the generation of small cytotoxic–toxic primary amines upon molecule hydrolysis [3].

A diverse pool of PVCL‐based polymeric structures has been already developed with their properties extensively investigated for applications in biosensing, controlled drug delivery, and stimuli‐dependent targeting. A variety of PVCL‐based temperature‐responsive materials include microgels, ...