Xiaoyu Cai’s research while affiliated with Dalian Polytechnic University and other places

In the current study, to obtain environmentally friendly printed cotton fabrics with a clear contour edge, ethylene glycol diglycidyl ether (EGDE) as a crosslinking agent and guar gum as a thickener were used with natural madder dye. The solid content of the thickener was assessed to determine the optimal viscosity of the printing paste. Scanning electron microscopy images and colour depth ( K/S ) values were used to analyse the surface morphology and printing properties. The pattern outline of the printed cotton fabric was assessed with an optical microscope. Also, the overall fastness properties of the printed fabrics were evaluated. The results showed that when the solid content of guar gum was 2.5%, the viscosity of the printing paste was close to 10 000 mPa.s, which was suitable for printing cotton fabrics. Scanning electron microscopy analysis showed that most of the printing paste was removed during the washing process, and did not affect the microstructure of the cotton fabric. Compared with direct printed cotton fabrics, the K/S values of mordant and crosslinked printed cotton fabrics increased by 3.12 and 4.01, respectively. In the optical microscopy photographs, the mordant and crosslinked printed cotton fabrics displayed a clear outline sharpness of the printed pattern, and excellent printed products were obtained. The colour fastness to washing, rubbing and light of the crosslinked printed cotton fabric were significantly improved, reaching levels of 4‐5.

In this study, functional coatings with N-halamine structure were formed on cotton fabrics by dopamine (DA) auto-deposition and DA/Polyethyleneimine (PEI) covalent co-deposition, respectively. SEM、UV-Vis and XPS had confirmed the deposition of DA and DA/ polydopamine (PDA) on the cotton fabrics. When the mass ratio of DA/PEI was 1:1.5, a uniform functional coating was formed. XRD had indicated that the coating and the oxidative sodium hypochlorite solution did not affect the crystal structure of cellulose. The DA/PEI co-deposited modified cotton fabric had excellent antibacterial property after chlorination, and the inactivation rate against E coli and S aureus could reach 100% with a contact time of 30 min. In vitro cell cytocompatibility studies demonstrated that the DA/PEI co-deposited modified cotton fabric has good biocompatibility. The functional coating on the cotton fabric remained stable after 50 washing cycles. The UPF values and the wrinkle recovery angle (WRA) tests showed that the DA/PEI co-deposited coating imparted great durable press and UV protective properties to the cotton fabric. The breaking strength loss rate of the modified cotton fabrics after chlorination was about 20%, which had little effect on the wearing property. Graphic abstract

In this study, functional coatings with N-halamine structure were formed on cotton fabrics by dopamine (DA) auto-deposition and DA/Polyethyleneimine (PEI) covalent co-deposition, respectively. SEM、UV-Vis and XPS had confirmed the deposition of DA and DA/ polydopamine (PDA) on the cotton fabrics. When the mass ratio of DA/PEI was 1:1.5, a uniform functional coating was formed. XRD had indicated that the coating and the oxidative sodium hypochlorite solution did not affect the crystal structure of cellulose. The DA/PEI co-deposited modified cotton fabric had excellent antibacterial property after chlorination, and the inactivation rate against E coli and S aureus could reach 100% with a contact time of 30 min. The functional coating on the cotton fabric remained stable after 50 washing cycles. The UPF values and the wrinkle recovery angle (WRA) tests showed that the DA/PEI co-deposited coating imparted great durable press and UV protective properties to the cotton fabric. The breaking strength loss rate of the modified cotton fabrics after chlorination was about 20%, which had little effect on the wearing property.

Cotton fabric dyed with natural madder dye exhibits poor dyeing properties. Although mordant improves the dyeing property of cotton fabric, it changes the madder dye colour tonality (the hue angle). In this study, ethylene glycol diglycidyl ether (EGDE) was used as a crosslinking agent to dye cotton fabrics with natural madder dye and improve the surface colour depth (K/S) and colour fastness. The molecular structure, crystal structure and surface morphology of crosslinked dyed cotton were analysed using Fourier Transform–infrared spectroscopy, X-ray diffractometry and scanning electron microscopy, respectively. The results showed that crosslinked dyed cotton fabric had two different ether bonds, and that crosslinked dyeing mainly occurred in the amorphous area. Compared with direct dyed cotton fabric, the hue angle (h°) of crosslinked dyed cotton fabric did not undergo an obvious change, K/S increased by 5, and the rubbing fastness, washing fastness and light fastness increased by 2-3 levels, indicating that the dyeing property of cotton fabric with natural madder dye could be improved by using EGDE as a crosslinking agent. Compared with raw cotton fabric, the bending length of crosslinked dyed cotton fabric was reduced by 2.28 cm, the wrinkle recovery angle increased by 80.7° and the ultraviolet protection factor value was more than 40, indicating that crosslinked dyed cotton fabric had great softness, wrinkle resistance and excellent ultraviolet resistance. In addition, the water contact angle of the cotton fabric only changed slightly after crosslinking dyeing, and the crosslinked dyed cotton fabric still had good hydrophilicity. Therefore, EGDE was a viable crosslinking agent for cotton fabric with madder dye.

Cotton fabrics were dyed with the madder and compounds of citric acid (CA) and dicarboxylic acids [tartaric acid (TTA), malic acid (MLA), succinic acid (SUA)] as cross-linking agents and sodium hypophosphite (SHP) as the catalyst. The molecular structures and crystal structures of the dyed cotton fabrics were analyzed using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD), respectively. The results showed that the polycarboxylic acids esterified with the hydroxyl groups in the dye and cellulose, respectively, and the reaction mainly occurred in the amorphous region of the cotton fabric. Compared with the direct dyed cotton fabric, the surface color depth (K/S) values of the CA, CA+TTA, CA+MLA, CA+SUA cross-linked dyed cotton fabrics increased by approximately 160%, 190%, 240%, 270%, respectively. The CA+SUA cross-linked dyed cotton fabric achieved the biggest K/S value due to the elimination of the negative effect by α-hydroxyl in TTA and MLA on esterification reaction, and the cross-linked dyed cotton fabrics had great levelness property. The washing and rubbing fastness of the cross-linked cotton fabrics were above four levels. The light resistance stability and the antibacterial property of the cross-linked dyed cotton fabrics was obviously improved. The sum of warp and weft wrinkle recovery angle (WRA) of the CA+SUA cross-linked dyed cotton fabric was 55° higher than that of raw cotton fabric, and its average UV transmittance for UVA was less than 5% and its UPF value was 50+, showing a great anti-wrinkle and anti-ultraviolet properties.