Zou Aihua, Eastoe Julian, Mutch Kevin, Wyatt Paul, Scherf Günther, Glatter Otto, Grillo Isabelle
School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK.
J Colloid Interface Sci. 2008 Jun 15;322(2):611-6. doi: 10.1016/j.jcis.2008.03.016. Epub 2008 Mar 18.
Light sensitive lamellar (L(alpha)) phases have been generated in glycerol/water mixtures from blends of an inert ABA tri-block co-polymer (dimethylsiloxane-polyethylenoxide, (EO)(15)-(PDMS)(15)-(EO)(15)), and a photodestructible anionic surfactant C(6)PAS (sodium 4-hexylphenylazosulfonate). These L(alpha) systems have been formulated in a 6/4 glycerol/water (v/v) mixed solvent. Rheology, small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS) and dynamic light scattering (DLS) have been used to characterize the change in phase behavior and structure after the incorporated C(6)PAS is selectively degraded by UV light incident on the L(alpha) phases. The ABA co-polymer alone forms weakly structured lamellar mesophases, which are stabilized by thermal fluctuations and characterized by low shear moduli (L(alpha) phase-A). Addition of C(6)PAS (10 mM) introduces charge stabilization, generating more ordered and stiffer L(alpha) systems (L(alpha) phase-B). After UV irradiation (Hg lamp) of the L(alpha)-B phases, and subsequent degradation of the ionic C(6)PAS, the results of rheological and scattering studies are consistent with an irreversible change back to L(alpha) phase-A type systems. These formulations display a novel transition between electrostatically- and thermally-stabilized lamellae, which may be controlled by incident UV light.
通过惰性ABA三嵌段共聚物（二甲基硅氧烷 - 聚环氧乙烷，(EO)(15)-(PDMS)(15)-(EO)(15)）与光可降解阴离子表面活性剂C(6)PAS（4 - 己基苯基偶氮磺酸钠）的共混物，在甘油/水混合物中生成了光敏层状（L(α)）相。这些L(α)体系是在6/4甘油/水（体积比）的混合溶剂中配制的。利用流变学、小角X射线散射（SAXS）、小角中子散射（SANS）和动态光散射（DLS）来表征当入射到L(α)相上的紫外光选择性降解掺入的C(6)PAS后，相行为和结构的变化。单独的ABA共聚物形成结构较弱的层状中间相，其由热涨落稳定，且具有低剪切模量（L(α)相 - A）。加入C(6)PAS（10 mM）引入电荷稳定作用，生成更有序且更硬的L(α)体系（L(α)相 - B）。对L(α) - B相进行紫外照射（汞灯）并使离子型C(6)PAS随后降解后，流变学和散射研究结果与不可逆转变回L(α)相 - A型体系一致。这些配方展示了一种在静电稳定和热稳定薄片之间的新型转变，其可由入射紫外光控制。
