Gelation by Linking of Growing Spherulites in Poly(4-methyl-1-pentene) Cyclohexane Solution

Abstract

ABSTRACT:One of the two types of gelation in a cyclohexane solution of poly(4-methyl-lpentene) is caused by linking of growing spherulites which are nucleated from the one-phase solution. The mechanism is related to that of the spherulitic crystallization by using the Avrami equation. The rate of the crystallization can be estimated by a simple method which takes advantage of the variety of crystal morphology.KEY WORDS Thermo-reversible Gelation I Spherulite 1 Crystalline Particle I Morphology I Crystallization I Avrami Equation I Poly(4-methyl-1-pentene) I Recently, thermo-reversible gelation of polymers from solution was investigated in relation to liquid-liquid phase separation. Chosen for this were poorly crystallizable and amorphous polymers such as polyacrylonitrile,l poly(vinyl alcohol),l-3 atactic polystyrene,4 isotactic polystyrene, 5 agar, 6 and gelatin.1.2 Unfortunately, solutions of highly crystalline polymers such as polyolefines have not been studied from this viewpoint, owing to the very fast rate of crystallization and their complicated structures. We could, however, explain the relation between liquid-liquid phase separation and crystallization in a highly crystalline polymer of poly(4-methyl-l-pentene) (P4MlP)jcyclohexane gel, using peculiar morphology and variety of polymorphism of this polymer. 7 In the gel of P4MlP, two types of gelation mechanisms were found: one gelation is caused by the liquid-liquid phase separation which precedes the crystallization, and another gelation is caused by linking of the growing spherulites or crystalline particles from the one-phase solution. The mechanism of the nucleation and growth observed for the latter crystalline species was considered to be almost identical with that for general solutioncrystallization. There is a critical polymer concentration that distinguishes the gelation from the general solution-crystallization. If the concentration is higher than the critical value, the three-dimensional linking of the crystalline species stops the flow of its system. This is the gelation from one-phase solution of highly crystalline polymers.In this paper, the gelation mechanism by the spherulitic crystallization from the one-phase solution, which was visually observed in the previous work, 7 was more precisely analyzed by using the Avrami equation. 8 31

Rheological and Biological Impact of Printable PCL‐Fibers as Reinforcing Fillers in Cell‐Laden Spider‐Silk Bio‐Inks

“…PCL‐seeded eADF4(C16) solutions reached half maximum after 22.5 h, whereas for pure, non‐seeded eADF4(C16), half maximum occurred after 38.5 h, indicating a significantly accelerated fibrillization process (Figure 2B). In accordance with other literature, [ 25 ] the Avrami model turned out to be a sufficiently accurate fit for these self‐assembly kinetics:…”

Thermoreversible Gelation of Poly(ether ether ketone)

“…To date, crystallizable polymers reported to be capable of forming thermoreversible gels via crystallization from solution include syndiotactic polystyrene (sPS), 3−8 isotactic poly(propylene) (iPP), 9,10 polyethylene (PE), 11−13 poly(phenylene oxide) (PPO), 14,15 poly(vinylidene fluoride) (PVDF), 16,17 stereoregular poly(methyl methacrylate) (PMMA), 18,19 poly(vinyl chloride) (PVC), 2 and poly(4methyl-1-pentene) (P4M1P). 20 For the vast majority of other crystallizable polymers, the more common solution behavior upon cooling to a suitable crystallization temperature is simple precipitation (as opposed to gelation). However, based on the findings of this studythe discovery of a thermoreversible gel of poly(ether ether ketone) in DCAwe submit that an expansion in the number of gel-forming semicrystalline polymers may be realized by exploring solvent-borne phase behavior with a broader range of polymer−solvent pairs.…”

“…While a large number of polymers are known to develop semicrystalline morphologies, it is interesting to note that relatively few crystallizable polymers have been found to form thermoreversible gels. To date, crystallizable polymers reported to be capable of forming thermoreversible gels via crystallization from solution include syndiotactic polystyrene (sPS), − isotactic poly­(propylene) (iPP), , polyethylene (PE), − poly­(phenylene oxide) (PPO), , poly­(vinylidene fluoride) (PVDF), , stereoregular poly­(methyl methacrylate) (PMMA), , poly­(vinyl chloride) (PVC), and poly­(4-methyl-1-pentene) (P4M1P) . For the vast majority of other crystallizable polymers, the more common solution behavior upon cooling to a suitable crystallization temperature is simple precipitation (as opposed to gelation).…”

Thermoreversible Gelation in Poly(diphenylsiloxane)/Diphenyl Ether Systems Exhibiting Mesophase Behavior

“…The morphology depends on solution concentration, temperature, and the type of phase separation, i.e., whether the crystallization occurs directly from homogeneous solution or a liquid−liquid demixing precedes it . Meanwhile, there are several prominent examples of the formation of thermoreversible crystalline gels by stereoregular polymers, in particular in such binary systems as isotactic polystyrene−decalin, linear polyethylene−xylene, , poly(ethylene oxide)−xylene, and poly(4-methyl-1-pentene)−cyclohexane …”