We report a mechanistic study of the microsuspension polymerization of styrene stabilized by cellulose nanocrystals (CNCs) in its native form as well as graft-modified with copolymers of styrene and N-3-(dimethylamino)propyl methacrylamide (DMAPMAm) or N,N-(diethylamino)ethyl methacrylate (DEAEMA). Native CNCs and graft-modified CNCs were shown to form stable styrene emulsions with an average droplet diameter of 18-20 and 5-9 μm, respectively. Initiators of widely varying water solubilities [2,2'-azobisisobutyronitrile (AIBN), 2-2'-azobis(2,4-dimethylvaleronitrile) (Vazo-52), and lauroyl peroxide (LPO)] were employed for the polymerizations. The type of initiator and the type of CNC were shown to directly affect the microsuspension polymerization kinetics, particle size, and molecular weight distribution. Using AIBN and Vazo-52, submicron latex particles were observed in the final latex in addition to the desired 3-20 μm CNC-armored microsuspension particles. The resulting latex and microsuspension polystyrene particles were studied for their CNC coverage and surface charge. We found that the presence of CNCs in the aqueous phase did not lead to Pickering emulsion polymerization by heterogeneous nucleation.

中文翻译：

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使用纤维素纳米晶体作为Pickering乳化剂进行苯乙烯的微悬浮聚合：关于乳胶颗粒的演变。

我们报告了由纤维素纳米晶体（CNCs）以其天然形式以及苯乙烯与N-3-（二甲基氨基）丙基甲基丙烯酰胺（DMAPMAm）或N，N-甲基丙烯酸（二乙氨基）乙酯（DEAEMA）。天然CNC和接枝改性CNC显示形成稳定的苯乙烯乳液，平均液滴直径分别为18-20和5-9μm。在聚合反应中使用了各种水溶性的引发剂[2,2'-偶氮二异丁腈（AIBN），2-2'-偶氮二（2,4-二甲基戊腈）（Vazo-52）和月桂酰过氧化物（LPO）]。已证明引发剂的类型和CNC的类型直接影响微悬浮聚合动力学，粒径和分子量分布。使用AIBN和Vazo-52，除了所需的3-20μmCNC铠装微悬浮颗粒外，最终乳胶中还观察到了亚微米乳胶颗粒。研究了所得的胶乳和微悬浮聚苯乙烯颗粒的CNC覆盖率和表面电荷。我们发现水相中CNC的存在不会导致通过异相成核的Pickering乳液聚合。