Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (10): 1914-1923.doi: 10.3866/PKU.WHXB201508263

• SOFT MATTER • Previous Articles     Next Articles

Synthesis of P(MEO2MA-co-OEGMA) Random Copolymers and Thermally Induced Phase Transition Behaviors in Aqueous Solutions

Yi. GUO,Heng-Jiang. LIU,Jie-Qiong. CHEN,Ya-Zhuo. SHANG(),Hong-Lai. LIU   

  • Received:2015-05-18 Published:2015-10-10
  • Supported by:
    the National Natural Science Foundation of China(21173079, 91334203, 21476072)

Abstract:

Random copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA, Mn = 500 g·mol-1) were synthesized by atom transfer radical polymerization (ATRP). Thermally induced aggregation of the co-polymers P(MEO2MA-co-OEGMA) in aqueous solutions was investigated with dynamic light scattering (DLS), UV-Vis absorption, and transmission electron microscopy (TEM). In addition, the lower critical solution temperature (LCST) in aqueous solutions of P(MEO2MA-co-OEGMA), and its change with respect to the composition of the copolymer, were obtained. The results indicate that the copolymers have an appreciably reversible thermal responsivity that can be attributed to a delicate balance between hydrogen bonds between the copolymers and water molecules and hydrophobic interactions of polymer segments. If the balance is broken, the polymers attain a new thermodynamic equilibrium by spontaneously changing the extent of aggregation. The LCST correlates linearly with the mole fraction of OEGMA units in the copolymer, and can be adjusted by changing the mole ratio of the two monomers.

Key words: Random copolymer, Thermo-responsive, Lower critical solution temperature, Phase transition

MSC2000: 

  • O648