In this study, thermal sensitive microgels functionalized with carboxyl groups were synthesized directly from hydroxypropyl cellulose (HPC) and acrylic acid (AA) without using any organic solvent. Furthermore, covalently bonded hybrid microgels with novel thermosensitivity in terms of size and fluorescence were fabricated from these HPC-PAA microgels and cysteamine-capped CdTe quantum dots (QDs). The composition of the hybrid microgels were characterized by thermal thermogravimetric analysis (TGA) and coulometric titration. It was verified that the weight percent of CdTe QDs was ca. 40%, and the percent of poly(acrylic acid) varied between 9.0% and 13.6%. Through a systematic study, it was found that both the size and the fluorescent intensity of the microgels decreased as the temperature increased from below the lower critical solution temperature (LCST) to above the LCST of the HPC. Different from most reported cases, it was found that the thermal sensitive alteration of the current hybrid microgels' size and fluorescent intensity are reversible. The novel fluorescent properties are deduced to be related to the structural characteristics of the microgels, i.e., the QDs are covalently bonded to the microgels and the dispersion of QDs in the microgels is spatially homogeneous. As a consequence of this special structure, the refractive indexes of the microgels were changed and the surface defects of the QDs were reduced, and therefore affected the fluorescent properties of the resulting hybrid microgels.

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Summary: The self‐assembly of HPC and carboxyl‐ended surfactants such as Deac was studied in the present paper. Nanoparticles with multi‐morphologies were fabricated from HPC and Deac, and their diameter and morphology can be controlled by adjusting the molar ratio of glucose units and Deac and the environmental pH value. We also demonstrated the ubiquity of fabricating multi‐morphological nanoparticles from HPC and other carboxyl‐ended surfactants by substituting PDFOA for Deac, and it was confirmed by DLS characterization that nanoparticles with multi‐morphologies were formed at pH = 0.1. Thus the proposed approach shows a considerable potential to fabricate polysaccharide‐based multi‐morphological nanoparticles from water‐soluble polysaccharides and carboxyl‐ended surfactants.A schematic illustration of the self‐assembly of HPC and Deac to multi‐morphological nanoparticles.magnified imageA schematic illustration of the self‐assembly of HPC and Deac to multi‐morphological nanoparticles.

Cellulose-based nanoparticles having thermo-sensitivity and carboxyl functional groups were fabricated for the first time without using any surfactant and organic solvent. The nanoparticles exhibit rapid and reversible dispersion–aggregation changes in response to narrow range temperature alternation near our body temperature as demonstrated by dynamic light scattering, which may be utilized in biomedical fields.