Abstract
For the preparation of thermoresponsive copolymers, for e.g., tissue engineering scaffolds or drug carriers, a precise control of the synthesis parameters to set the lower critical solution temperature (LCST) is required. However, the correlations between molecular parameters and LCST are partially unknown and, furthermore, LCST is defined as an exact temperature, which oversimplifies the real situation. Here, random N-isopropylacrylamide (NIPAM)/dopamine methacrylamide (DMA) copolymers were prepared under a systematical variation of molecular weight and comonomer amount and their LCST in water studied by calorimetry, turbidimetry, and rheology. Structural information was deduced from observed transitions clarifying the contributions of molecular weight, comonomer content, end-group effect or polymerization degree on LCST, which were then statistically modeled. This proved that the LCST can be predicted through molecular structure and conditions of the solutions. While the hydrophobic DMA lowers the LCST especially the onset, polymerization degree has an important but smaller influence over all the whole LCST range.
Highlights
The research on smart polymers is growing, owing to new advances of the scientific community as well as current and future applications
reversible addition-fragmentation chain transfer (RAFT) polymerization allowed for obtaining interesting copolymers to study the effect of the RAFT polymerization allowed for obtaining interesting copolymers to study the effect of the comonomer content and the molecular weight on lower critical solution temperature (LCST)
A good agreement was observed for the results comonomer content and the molecular weight on LCST
Summary
The research on smart polymers is growing, owing to new advances of the scientific community as well as current and future applications. The preparation of random copolymers is used as a valuable method for adding new functionalities or increasing the range of properties In this way, bioinspired materials grow a great interest owing to simulate the living tissues very useful for developing specific properties and getting non-invasive therapies. The introduction of reversible addition-fragmentation chain transfer (RAFT) polymerization allowed getting custom polymers due to a higher control on the final molecular features, namely polydispersity and molecular weight [19,20] This potential method is convenient for preparing copolymers, whose properties, such as the LCST, can be tailored to the specific necessities. The use of different characterization methods (calorimetry analysis, UV-visible spectroscopy, and rheology) allowed for detecting the sudden change from hydrophilic to hydrophobic behavior, i.e., the LCST
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