ORIGINAL PAPER Recyclable and transparent bacterial cellulose/hemiaminal dynamic covalent network polymer nanocomposite films Zhaoqian Li . Jia Qiu . Chonghua Pei Received: 9 November 2015 / Accepted: 6 May 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract Recyclable and transparent nanocompos- ite films based on bacterial cellulose (BC) and hemiaminal dynamic covalent network polymer (HDCN) have been synthesized by in situ polymer- ization of 4,4 0 -diaminodiphenyl ether (ODA) with paraformaldehyde. Transparency and structural and mechanical properties of such nanocomposite films are investigated. It was found that BC/HDCN nanocomposite films exhibits a high optical trans- parency (86 % at 550 nm). Scanning electron micro- scopy reveals excellent compatibility of the reinforcement of BC nanofibers and HDCN matrix, which leads to the improvement of 20 and 200 % in tensile strength and storage modulus, respectively, as compared to neat HDCN films. BC hydrogels are readily recoverable from nanocomposite films by the sulphuric acid treatment and ODA monomer is deposited and also recycled. Keywords Bacterial cellulose Á Hemiaminal dynamic covalent network polymer Á Nanocomposite Á Recyclable Introduction In recent years, bacterial cellulose (BC) has generated considerable interest to produce the nanocomposites due to its excellent mechanical properties. BC is a unique biopolymer gel produced by bacteria, which consist of water-swollen 3D cellulose nanofibers network in its native state (Ba ¨ckdahl et al. 2006; Yoon et al. 2006). Because of its ultrafine reticulated structure, BC possesses high water-holding capacity and mechanical strength (Feng et al. 2012; Nakayama et al. 2004). Therefore, BC has been seen as an ideal matrix or reinforcement for composites (Kramer et al. 2006). Several studies have reported the preparation of BC nanocomposite materials for various applications. BC combined with acrylic resins, phenolic resins, cellu- lose acetate butyrate, polyurethane and polyethylene fibers exhibits excellent properties even at the low BC content (Gindl and Keckes 2004; Nakagaito et al. 2005; Nogi et al. 2005; Nogi and Yano 2008; Pinto et al. 2013; Trovatti et al. 2010; Yeh et al. 2014). Apparently, people show more interest in BC com- posites associated with biodegradable polymer such as poly(L-lactic acid), chitosan, starch, polycaprolactone Z. Li (&) Á C. Pei (&) State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China e-mail: zqli995@gmail.com C. Pei e-mail: peichonghua@swust.edu.cn J. Qiu School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China 123 Cellulose DOI 10.1007/s10570-016-0956-4