两亲性嵌段共聚物PMnEOS-b-PAA的可控合成及与PS-b-PAA共组装体的形貌

在苯乙烯单体的对位引入具有亲水性链段的乙二醇单元, 利用可逆加成断裂链转移聚合方法(RAFT), 可控合成了几种新的两亲性嵌段共聚物聚(4-乙烯基苄基乙二醇单甲醚)-b-聚丙烯酸(PMnEOS-b-PAA, n=1~3), 对其温敏和pH敏性质进行了初步研究. 同时, 研究了PMnEOS-b-PAA分别在亲水性环境下(四氢呋喃/水)和亲脂性环境下(四氢呋喃/甲苯)自组装体的形貌. 将聚对二乙二醇单甲醚苯乙烯-b-聚丙烯酸与聚苯乙烯-b-聚丙烯酸按质量比1:1[m(PMDEOS-b-PAA)/m(PS-b-PAA)=1:1]共混进行共组装, 在四氢呋喃/甲苯体积比为2∶1的混合溶剂中, 发现了一类新型具有均匀分布内部孔道且表面光滑的球形组装体. 进一步研究了该组装体的可重复性和组装机理, 为其后期应用于工业上的负载催化、 小分子识别与释放提供了一种新的策略.

Controllable Synthesis of Amphiphilic Block Copolymer PMnEOS-b-PAA and co-Assembly Morphologies of PMDEOS-b-PAA/PS-b-PAA

The co-assembly of polymers has attracted increasing attention due to the ability of generating diverse assembly morphology. This paper describes the synthesis and self-assembly of several novel amphiphilic block copolymers（PMnEOS-b-PAA， n=1—3） as well as co-assembly of PMDEOS-b-PAA with typical polystyrene-b-polyacrylic acid（PS-b-PAA）. Namely， these block copolymers were fabricated by reversible addition fragmentation chain transfer（RAFT） polymerization of functionalized styrene bearing different glycol units on the para-position and acrylic acid， and characterized by ¹H nuclear magnetic resonance spectrum（¹H NMR）. The thermo-responsive and pH-responsive properties of these block copolymers were then investigated， and they showed good thermo- and pH- responsiveness. Furthermore， as a comparison， the self-assembly actions of these block copolymers were also examined in tetrahydrofuran（THF）/H₂O and THF/toluene（PhMe）， respectively. It was found that the different block copolymers with different glycol units displayed various morphologies， especially in two different solvent systems. More interestingly， the co-assembly action of PMDEOS-b-PAA/PS-b-PAA（mass ratio 1∶1） in a mixture of THF-PhMe（volume ratio 2∶1） was detaily studied and a new spherical nanoparticle with uniformly distributed internal channel and smooth surface was found. Also， thisco-assembly morphology could be well repeated. The corresponding self- and co-assembly mechanisms were also proposed. This novel co-assembly mode would have potential application for further supporting catalysts， small molecules recognition and release in industry.