温度和ph值响应性聚合物.pdf

Colloid Polym Sci DOI 10.1007/s00396-011-2562-1 ORIGINAL CONTRIBUTION Temperature and pH dual-responsive behavior of polyhedral oligomeric silsesquioxane-based star-block copolymer with poly(acrylic acid-block-N-isopropylacrylamide) as arms Yu Bai Jia Wei Liping Yang Chaobin He Xuehong Lu Received: 14 April 2011 /Revised: 27 September 2011 /Accepted: 23 November 2011 # Springer-Verlag 2011 Abstract Poly(acrylic acid-block-N-isopropylacrylamide) Introduction (PAAc-b-PNIPAm)-tethered octafunctional polyhedral olig- omeric silsesquioxane (POSS) were synthesized via POSS- Thermo-responsive polymers are of great scientific and initialized atom transfer radical polymerization. When very technical interests in recent years owing to their rising short PAAc blocks are placed between the POSS core and potentials in various fields such as controlled drug delivery, PNIPAm short chains, the critical temperature (Tc) of POSS- gene delivery, and membrane separation [ 1–4]. Poly(N- PAAc-b-PNIPAm determined by cloud point measurements isopropylacrylamide) (PNIPAm) is the most widely studied varies in a wide temperature range with pH, and its Tc is thermo-responsive polymer which is soluble in aqueous even lower than that of POSS-PNIPAm with similar chain media at room temperature, whereas the solution shows a length at pH0 5.0, indicating a synergic effect between dramatic increase in turbidity at around 34 °C termed as the high local chain density and intramolecular interaction cloud point or critical temperature (T ) [5, 6]. At the T , c c between PAAc and PNIPAm. When