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How latex film formation and adhesion at the nanoscale correlate to performance of pressure sensitive adhesives with cellulose nanocrystals
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences ( IF 5 ) Pub Date : 2021-08-02 , DOI: 10.1098/rsta.2020.0330
Elina Niinivaara 1, 2, 3 , Alexandra Ouzas 4 , Carole Fraschini 5 , Richard M Berry 6 , Marc A Dubé 4 , Emily D Cranston 1, 2, 7
Affiliation  

Emulsion polymerized latex-based pressure-sensitive adhesives (PSAs) are more environmentally benign because they are synthesized in water but often underperform compared to their solution polymerized counterparts. Studies have shown a simultaneous improvement in the tack, and peel and shear strength of various acrylic PSAs upon the addition of cellulose nanocrystals (CNCs). This work uses atomic force microscopy (AFM) to examine the role of CNCs in (i) the coalescence of hydrophobic 2-ethyl hexyl acrylate/n-butyl acrylate/methyl methacrylate (EHA/BA/MMA) latex films and (ii) as adhesion modifiers over multiple length scales. Thin films with varying solids content and CNC loading were prepared by spin coating. AFM revealed that CNCs lowered the solids content threshold for latex particle coalescence during film formation. This improved the cohesive strength of the films, which was directly reflected in the increased shear strength of the EHA/BA/MMA PSAs with increasing CNC loading. Colloidal probe AFM indicated that the nano-adhesion of thicker continuous latex films increased with CNC loading when measured over small contact areas where the effect of surface roughness was negligible. Conversely, the beneficial effects of the CNCs on macroscopic PSA tack and peel strength were outweighed by the effects of increased surface roughness with increasing CNC loading over larger surface areas. This highlights that CNCs can improve both cohesive and adhesive PSA properties; however, the effects are most pronounced when the CNCs interact favourably with the latex polymer and are uniformly dispersed throughout the adhesive film.

This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)’.



中文翻译:

纳米级乳胶膜的形成和粘附如何与具有纤维素纳米晶体的压敏粘合剂的性能相关联

乳液聚合胶乳压敏粘合剂 (PSA) 更环保,因为它们是在水中合成的,但与溶液聚合的对应物相比,其性能通常较差。研究表明,添加纤维素纳米晶体 (CNC) 后,各种丙烯酸类 PSA 的粘性、剥离和剪切强度都会同时提高。这项工作使用原子力显微镜 (AFM) 来检查 CNCs 在 (i) 疏水性 2-乙基己基丙烯酸酯/ n的聚结中的作用-丙烯酸丁酯/甲基丙烯酸甲酯 (EHA/BA/MMA) 乳胶膜和 (ii) 作为多种长度尺度上的粘附改性剂。通过旋涂制备具有不同固含量和 CNC 负载的薄膜。AFM 显示,CNC 降低了成膜过程中乳胶颗粒聚结的固体含量阈值。这提高了薄膜的内聚强度,这直接反映在 EHA/BA/MMA PSA 随着 CNC 负载增加而增加的剪切强度上。胶体探针 AFM 表明,当在表面粗糙度的影响可以忽略不计的小接触区域上进行测量时,较厚的连续乳胶膜的纳米附着力随着 CNC 负载的增加而增加。反过来,CNCs 对宏观 PSA 粘性和剥离强度的有益影响被增加的表面粗糙度和更大的表面区域的 CNC 负载增加的影响所抵消。这突出表明 CNC 可以提高内聚性和粘合性 PSA 性能;然而,当 CNC 与乳胶聚合物良好相互作用并均匀分散在整个粘合剂膜中时,效果最为明显。

本文是主题问题“用于新兴技术的生物衍生和仿生可持续先进材料(第 1 部分)”的一部分。

更新日期:2021-08-03
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