Modification of Cellulose by Using Atom Transfer Radical Polymerization and Ring-Opening Polymerization

Abstract

The cellulose chloroacetate (Cell-ClAc) with a degree of substitution (DS) value of about 2.1 was synthesized through acylation reaction of microcrystalline cellulose in a homogeneous solution of dimethylacetamide/lithium chloride (DMAc/ LiCl), and pyridine as the acid acceptor. Atom transfer radical polymerizations (ATRP) of 3-ethyl-3-methacryloyloxymethyloxetane (EMO) and methyl methacrylate (MMA) were carried out by using Cell-ClAc as the initiator. Furthermore, the second ATRP reactions of MMA and EMO by using the products of Cell-PEMO and Cell-PMMA as initiators were performed, respectively. It was based on the consideration of that the terminal halogens of Cell-PEMO or Cell-PMMA possess activity even after a long time period and could be used as initiator for another ATRP reaction. Different reactions including the activators generated by electron transfer (AGET) ATRP of EMO or MMA and the Ring-Opening Polymerization (ROP) of aliphatic cyclic ester (CE) ("-caprolactone (CL), or L-Lactide (LLA)) proceed in a same reaction system simultaneously by using the same initiator of Cell-ClAc or Cell-PEMO or Cell-PMMA were also carried out. For analyses of products, the measurements of FT-IR, DSC, TG-DTA, WAXD were performed, and a Polarizing Microscope (POM) was also used for crystal observation of the products. All the measurement results proved the proceeding of the reactions.KEY WORDS: Microcrystalline Cellulose / Modification / ATRP / the Second ATRP / AGET ATRP / ROP / Along with the increasingly rising awareness of environmental protection and of utilizing petroleum resources more rationally and economically, more and more researchers turn the study direction from petroleum to natural and renewable resources such as the developments of biodegradable plastics and green sustainable plastics. Among the natural renewable resources, cellulose is one of the most popular materials because cellulose is the most abundant natural polymer on earth and possesses many potential outstanding properties and attractive advantages for applications, such as, high modulus of crystalline cellulose combined with the low weight, 1 not expensive, good biodegradability and renewability. However, the unmodified cellulose is not used for applications because it couldn't be dissolved in most conventional solvents and has not a melting temperature (T m ). Therefore, the modification of cellulose is required for its applications.

The preparation of graft copolymers of cellulose and cellulose derivatives using ATRP under homogeneous reaction conditions

“…The highest DS reached was 1.8 which is lower than that achieved by the method of Chang et al 40 . This is explained by the decrease of the amount of reactant chloroacetyl chloride compared to AGU.…”

“…The first work related to cellulose modification using the ATRP process under homogeneous conditions was reported by" Chang et al 40 catalyst. The influence of the solvent on the process was investigated using solvents including DMSO, anisole and DMF.…”

“…Compared to the work of Chang et al 40 , a higher amount of catalyst was used to decrease the reaction time i.e. 7 h instead of approximately 20 h. In the ATRP process, the choice of the ligand is crucial as it determines both the rate of reaction and the extent of control of the polymerisation.…”

Cloroacetilação de Celulose Bacteriana

“…Essas propriedades aliadas a estrutura tridimensional nanométrica conferem uma amplo leque de áreas de aplicação que tem como principal o uso na área médica, além da indústria alimentícia e eletrônica. Na área médica destaca-se a aplicação como substituto temporário da pele no tratamento de queimados e feridas de difícil cicatrização 1 .…”

Effect of flexible spacer length on the mesophase structures of main-chain/side-chain liquid crystalline polymers based on ethyl cellulose

“…27,28 Cellulose, which is the main constituent of plant cell walls and is abundant in nature, is known for its excellent biocompatibility and thermal and mechanical properties. [29][30][31][32] Similar to polypeptides and DNA, cellulose can form cholesteric LC phases. 33 Werbowyj and Gray 34 first reported the cholesteric phase of aqueous hydroxypropyl cellulose in 1976.…”