Investigation of the LCST-Thermoresponsive Behavior of Novel Oligo(Ethylene Glycol)-Modified Pentafluorostyrene Homopolymers

Applied Sciences

Matteo Calosi¹  Luca Bernazzani¹  Elisa Guazzelli¹  MariaRosaria Tiné¹  Elisa Martinelli¹  Chiara Pelosi¹  Celia Duce¹ 

[1] Dipartimento di Chimica e Chimica Industriale, Università di Pisa, 56124 Pisa, Italy;

关键词: amphiphilic polymer;    thermoresponsive polymer;    LCST;    DSC;    DLS;    turbidimetry;   

DOI  :  10.3390/app11062711

来源: DOAJ

【 摘 要 】

Amphiphilic tetrafluorostyrene monomers (EFS8) carrying in the para position an oligoethylene glycol chain containing 8 oxyethylenic units on average were synthesized and used for preparation via activator regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) of the corresponding amphiphilic homopolymers (pEFS8-x) with different degrees of polymerization (x = 26 and 46). Combining light transmittance and nano-differential scanning calorimetry (n-DSC) measurements revealed that pEFS8-x homopolymers displayed a lower critical solution temperature (LCST) thermoresponsive behavior in water solutions. Moreover, n-DSC measurements revealed the presence in heating scans of a broad endothermic peak ascribable to the dehydration process of the polymer single chains (unimers) and their collapse into aggregates. Consistently, dynamic light scattering (DLS) measurements showed below the LCST the presence of small nanostructures with a hydrodynamic diameter size D_h of 6–7 nm, which collapsed into concentration-dependent larger multichain aggregates (D_h = 300–3000 nm) above LCST. Interestingly, n-DSC data showed that the unimer-aggregate transition was reversible up to a specific temperature (T_rev) of each homopolymer, which in any case was higher than T_max. When heating above T_rev the transition was no longer reversible, causing the shift of T_onset and T_max at lower values, thus suggesting an increase in hydrophobicity of the polymer systems associated with a temperature-dependent dehydration process.

【 授权许可】

Unknown