Cabañas Albertina, Enciso Eduardo, Carbajo M Carmen, Torralvo M José, Pando Concepción, Renuncio Juan Antonio R
Departamento de Química-Física I, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Langmuir. 2006 Oct 10;22(21):8966-74. doi: 10.1021/la061539z.
The effect of supercritical CO(2) (scCO(2)) in 3D latex arrays formed by monodispersed particles of polystyrene (PS), PS cross-linked with divinylbenzene (PS-DVB), and PS block copolymers with 2-hydroxyethyl methacrylate (PS-HEMA), methacrylic acid (PS-MA), acrylic acid (PS-AA), itaconic acid (PS-IA), and a mixture of methacrylic and itaconic acid (PS-IA-MA) has been studied. Sorption of CO(2) into the polymer particles leads to a decrease in the glass transition temperature of the polymer and the swelling of the particles and induces their coalescence. 3D-latex arrays of the former compositions were treated in scCO(2) at temperatures and pressures ranging from 40 to 80 degrees C and from 85 to 197 bar, respectively. The effect of CO(2) on the polymeric template was assessed by scanning electron microscopy and N(2) adsorption analysis. Bare PS and PS-HEMA particles sintered readily in scCO(2) at 40 degrees C and 85 bar. On the other hand, particles containing carboxylic acid groups on their surface (PS-MA, PS-AA, PS-IA, and PS-IA-MA) were, at the same temperature and pressure, more resistant to the CO(2) treatment. For a given polymer composition, the sorption of CO(2) inside the polymer particles, the swelling, and the degree of coalescence depend on the pressure, temperature, and time of the CO(2) treatment. Analysis of the pore size distributions from the N(2) adsorption data has allowed us to quantify the degree of coalescence of the particles in the matrix. By careful control of the experimental variables, the coalescence of the 3D latex array could be finely tuned using CO(2).
研究了超临界CO₂（scCO₂）对由聚苯乙烯（PS）单分散颗粒、与二乙烯基苯交联的PS（PS-DVB）以及与甲基丙烯酸2-羟乙酯（PS-HEMA）、甲基丙烯酸（PS-MA）、丙烯酸（PS-AA）、衣康酸（PS-IA）和甲基丙烯酸与衣康酸混合物（PS-IA-MA）形成的三维乳胶阵列的影响。CO₂吸附到聚合物颗粒中会导致聚合物玻璃化转变温度降低、颗粒膨胀并引发它们的聚结。对前几种组合物的三维乳胶阵列分别在40至80℃的温度和85至197巴的压力下进行scCO₂处理。通过扫描电子显微镜和N₂吸附分析评估CO₂对聚合物模板的影响。裸露的PS和PS-HEMA颗粒在40℃和85巴的scCO₂中很容易烧结。另一方面，表面含有羧酸基团的颗粒（PS-MA、PS-AA、PS-IA和PS-IA-MA）在相同温度和压力下对CO₂处理更具抗性。对于给定的聚合物组合物，聚合物颗粒内部的CO₂吸附、膨胀和聚结程度取决于CO₂处理的压力、温度和时间。根据N₂吸附数据对孔径分布进行分析，使我们能够量化基质中颗粒的聚结程度。通过仔细控制实验变量，可以使用CO₂对三维乳胶阵列的聚结进行精细调节。
