Synthesis And Properties Of Homopolymers And Copolymers With (Meth)Acrylates Containing Short Fluorocarbone Side Chain

In recent years, macromolecules synthetical technologies have progressed; process ways and means have innovated; and new materials have come forth continuously.-Selfcleansing materials with extremely low surface energies have received particular attention. Comb-shaped polymers with fluorocarbon segments in their side chains have extremely low surface energies. These polymers are indeed used as surface modification agents such as water-and-oil repellents and soil release on different substrates such as textiles, paper, leather, carpets, and nonwoven or building materials. Poly(fluoroalkyl acrylate)s with long perfluoroalkyl groups (≥8) are perfect polymer materials with extremely low surface energy. But their degradation leads to the release of biopersistent perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS). More research presently has focused on developing environmentally friendly and nontoxic alternative fluorinated materials to replace the traditional fluoroalkyl polymers associated with PFOA or PFOS.It was found that perfluorinated carboxylic and sulfonate containing chains of four or less perfluorinated carbon atoms do not bioaccumulate in the human body and are not biopersistent. But their water and oil repellencies are poor. Basing on the design of molecule construction, we synthesized the fluorinated (meth)acrylates with short perfluorobutyl and perfluorohexyl side chain. The structure and surface properties of poly(meth)acrylates with different main chain structures and spacer groups were studied in detail. Then, they were copolymerized with octadecyl acrylate respectively. The surface properties and coordinate interactional effects between fluorinated and nonfluorinated side chains were studied. At last, we prepared stable and environmentlly friendly copolymer emulsions with short fluorocarbon side chain. The water and oil repellencies on polyester-cotton blend fabrics were tested.1. Synthesis and reactivity ratios of acrylates with short perfluoroalkyl side chain(1) We designed the molecule construction of fluorinated (meth)acrylates C4A, C4MA, C6A, C6MA, C4SA, C4SMA, C6SA and C6SMA. The C4SA, C4SMA, C6SA and C6SMA were prepared.(2) The reactivity ratios of the four copolymerization systems were rC4SA= 0.26, rBMA=2.34; rCASMA=0.42, rBMA=1.04; rC6SA=0.86, rBMA=1.12; rC6SMA=0.45, rBMA =1.04. The results show that the reactivities of C4SA, C4SMA, C6SA and C6SMA are less active than BMA.(3) The Q and e values of fluorinated acrylates were QC4SA=0.43, eC4SA=0.98; QCASMA= 1.02, eCASMA= 1.19; QC6SA= 0.78, eC6SA= 0.48; QC6SMA= 1.00, eC6SMA= 1.15. They are analogous with the one of nonfluorinated acrylates.2. Structure and surface properties of polyacrylates with short fluorocarbon side chain:(1) The fluorinated homopolymers PC4A, PC4MA, PC4SA, PC4SMA, PC6A, PC6MA, PC6SA and PC6SMA were prepared by solution polymerization. They all exhibited very low surface free enengies.(2) With the same perfluoalkyl chain, PC6SA and PC6SMA with an N-methylsulfonamide spacer group were found to be organized in a liquid crystalline lamellar structure, whereas the other homopolymers were found to be amorphous. This was mainly attributed to the steric term and polarity of N-methylsulfonamide group that tended to facilitate the orientation of the perfluorinated segments in smectic phases.(3) The PC6SA, PC6SMA, PC4SA, PC4SMA, PC4MA and PC6MA had rich dynamic water repellency because of the low surface molecular mobility. This phenomenon relates to the crystallization of side chains or high glass transition temperature.(4) The smectic phase structure and high glass transition temperature tended to reduce the mobility of fluorinated side chains and surface reorientation, which can bring durable and stable low surface energy.3. Structure, surface properties, water/oil repellency of fluorinated copolymers with short fluorocarbon side chain(1) The batch emulsion polymerizations of FA and octadecyl acry late (SA) were carried out in this study respectively. The monomer molar ratio of FA/SA was 1 to 1. The static contact angle measurements indicated the surface free energies for copolymers were not different from the ones of fluorinated homopolymers obviously.(2) In the thermograms, each copolymer underwent one endothermic transition. The melting temperatures were lower than PSA homopolymer. The melting ranges become wider. Meanwhile, the enthalpies variation decreased. Accordingly, amorphous fluorinated monomers induced the increase in copolymers crystalline.(3) The copolymers are characteristic of a lamellar order. The interdigitating structure of PSA disappeared. With the same perfluoalkyl chain, the fluorinated and nonfluorinated pendant groups were found to be able to crystallize independently in P(C6SA/SA) and P(C6SMA/SA). For the other copolymers, the fluorinated side chains arranged between the crystallizeable side chains of SA.(4) The coordinate interactional effects appear between fluorinated and nonfluorinated side chains. Consequently, all copolymers exhibit excellent dynamic surface properties. The surface reorientation occurred infrequently.(5) Environmentally friendly copolymer emulsions of fluorinated acrylates (FA) and octadecyl acrylate (SA) were carried out in this study with cationic / nonionic composition emulsifier system with high conversion. The average size of latexes was 60-150nm. The polymorphism for copolymerization latexes were showed.(6) The water and oil repellency of polyester-cotton blend fabrics finished by fluorinated copolymer emulsions were tested. The water and oil repellency of P(C4SMA/SA/NMA), P(C6MA/SA/NMA), P(C6SA/SA/NMA) and P(C6SMA/SA /NMA) were 100 grade and more than 3 grade respectively. They demonstrate promising excellent hydrophobic and oleophobic properties while at the same time could avoid the environment problems caused by long perfluoroalkyl (Rf) groups.