PVP-b-PMAA对CaCO3结晶形态的影响

Influence of PVP-b-PMAA Block Copolymer on the Morphology of CaCO_3 Crystals

采用可逆加成-断裂链转移(RAFT)自由基聚合合成了双亲水嵌段共聚物聚乙烯吡咯烷酮-b-聚甲基丙烯酸(PVP-b-PMAA)。经1H NMR确认其结构,由GPC测得其分子量为28 800,分子量分布指数为1.42。采用FT-IR、XRD、SEM等测试技术研究了PVP及PVP-b-PMAA对CaCO3结晶的影响。结果表明,二者调控下得到的CaCO3晶体均为方解石结构,但是晶体形态相差较大:不同质量浓度的PVP均聚物水溶液中形成的CaCO3晶体均为片层结构;随着PVP-b-PMAA质量浓度的增加,菱形及层状晶体数量减少,聚集晶体数量增多,当其质量浓度增加到1 g/L时,聚集晶体中间出现孔洞。

A novel double-hydrophilic block copolymer（DHBC） poly （vinyl pyrrolidone）-block-poly （methacrylic acid） （PVP-b-PMAA） , was synthesized via reversible addition fragmentation chain transfer （RAFT） polymerization. The structure of the resulting copolymer was characterized by m H NMR, and the molecular weight of the copolymer was 28 800 determined by gel permeation chromatography（GPC） , and the molecular weight distribution index was 1.42. The morphology of calcium carbonate（ CaCO3 ） in the presence of PVP-b- PMAA block copolymer was studied. It was found that with the increase of the mass concentration of the block copolymer, the morphology of the CaCO3 particles changed from layered to aggregate. When the mass concentration of the block copolymer was 1 g/L, some cavities were observed in the aggregated crystals.