Microwave-responsive Shape Memory Properties Of Based-poly(Vinyl Alcohol) Interpenetrating Network Composites

Shape memory materials are said to be developing and a new class of intelligent polymer materials since the 1980s because of rapidly being responsive to external environmental stimulis. They offer inherent advantages of being light weight and easily processable, in addition to a much bigger degree of deformation and remarkable memory effect, so are widely used in mechanical systems and medical equipments fields. Recent years researchers have explored a variety of triggers that stimulate shape memory material recover and have acquired good results. However, despite current drivers of SMPs have achieved diversify, the corresponding study have not extended to microwave that is considered to be efficient, fast and potential.Considering microwave-heating effect and shape memory mechanism, microwave-absorbing medium SiC inorganic nanoparticles and ionic liquid polymer respectively are introduced into the PVA matrix, constructed interpenetrating polymer network based on PVA system, prepared SiC/PVA/PAA inorganic-organic IPN composite materials and PIL/PVA organic-organic IPN composite materials with microwave-responsive.Microwave-responsive SiC/PVA/PAA SIPN-SMPs composites are formed from PVA molecular chains run through the PAA cross-linked network structure and functional inorganic SiC nanoparticles acted as absorbing MW medium, which has excellent shape memory property. The mechanism is via SiC dispersed in PVA matrix under alternating electric field to generate heat that are used to stimulate recovery.Similar to above SiC/PVA/PAA SIPN-SMPs composites, current most functional composites are via adding inorganic particles to achieve functionalization that may lead to some problems such as poor compatible between inorganic fillers and polymers, unstable to some extent. Therefore, the paper on the basis of the previous stage puts forward whether we can choose an organic filler even polymer as absorbing MW medium to shape memory effect of interpenetrating polymer network. Considering ionic liquids often used as reaction medium in MW-assisted synthesis and strong absorptive capacity under MW irradiation, then we wonder whether ionic liquids could be introduced into polymer structure to achieve microwave-responsive shape memory behavior of polymer composites. Therefore, the second stage research work of this paper is studying microwave-responsive shape memory poly(ionic liquid)/poly(vinyl alcohol) interpenetrating networks organic/organic composites. In this system, functioned styrene imidazoleionic liquid monomer is synthesized and then polymerized by situ polymerization in PVA solution, forming P[VBBI][BF4]/PVA-SIPN SMPs composites. PIL were introduced into PVA matrix as transfer heat medium to achieve shape memory effect, this is the novelty of this topic. Moreover, considering the shortages of current semi-interpenetrating (SIPNs) or interpenetrating networks (IPNs) polymer in shape memory field. So the paper focuses on the based PVA system IPN composites that could rapidly respond to MW to provide theoretical foundation for exploring the relationship between IPNs structure and properties of the composites and expansion in shape memory driving force aspect.The reason of the topic choosing microwave this efficient, time-saving, uniform-heating and clean energy as driving force is despite current domestic and foreign scholars began to use infrared, optical, electromagnetic fields and other types of special energy as an indirect triggers, there still exist some problems such as uneven-heating, low recovery, long responsive time ect,. MW-responsive shape memory interpenetrating network composites use the interaction of dipoles or ion groups whose dielectric loss factor are larger with alternating electric field, generating heat via friction, thereby provide the energy needed to recovery. This non-contact heating method is different from the traditional contact way, high efficiency-heating, without preheating, and suit for remote control. Therefore, we propose microwave as a new trigger, which has important scientific significance in shape memory material area.In short, based-PVA shape memory composites is a new type of polymer material. The paper combines microwave thermal effect and shape memory polymer through indirect-heating, with SiC and PIL as microwave-absorbing medium, to design SIPN composites with different structures. This not only makes full use of excellent performance of the selected material, but also further broadens the application of PVA. For some biomedical elements that need the help of an external heat sources to stimulate shape memory recovery, developing as high efficiency, time-saving, no two pollution, suit for remote control MW-responsive shape memory materials has very important scientific significance.